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* [BUG] xl devd segmentation fault on xl block-detach
@ 2017-05-03  0:04 Reinis Martinsons
  2017-05-03 10:27 ` Wei Liu
  0 siblings, 1 reply; 8+ messages in thread
From: Reinis Martinsons @ 2017-05-03  0:04 UTC (permalink / raw)
  To: xen-devel

[-- Attachment #1: Type: text/plain, Size: 2462 bytes --]

Hi,

I would like to report a problem with storage driver domain. When 
detaching 2 virtual block devices from the same domain provided by the 
same driver domain, this generates a segmentation fault in the driver 
domain `xl devd` process. I observed the same problem both when manually 
detaching block devices from Dom0 and when shutting down guest domains 
with several block devices.

For ease of demonstration I am sharing my test results on a simple 
scenario where virtual block devices are provided from a storage driver 
domain (DomD) back to Dom0, but I observed identical results for other 
DomUs.

Both of my Dom0 and DomD are Arch Linux (kernel 4.10.11-1-ARCH). I built 
xen from Arch Linux User Repository (https://aur.archlinux.org/xen.git) 
latest commit 16894c15a19bfef23550ba09d58e097fe16c4792, which is using 
Xen 4.8.0 (commit b03cee73197f4a37bf2941b9367105187355e638). Please see 
the output of `xl info` attached in "xl info (Dom0).txt". When building 
xen for DomD, I enabled debugging symbols (`debug ?= y` in /Config.mk). 
I enabled xendriverdomain.service in DomD. DomD configuration file is 
attached in "DomD.cfg".

After 2 consecutive `xl block-attach` and `xl block-detach` commands in 
Dom0 I am observing the following output:

[root@arch-test-dom0 ~]# xl block-attach 0 
'format=raw,backendtype=phy,backend=arch-zfs-test,vdev=xvda,target=/dev/zvol/test_pool/test1'
[root@arch-test-dom0 ~]# xl block-attach 0 
'format=raw,backendtype=phy,backend=arch-zfs-test,vdev=xvdb,target=/dev/zvol/test_pool/test2'
[root@arch-test-dom0 ~]# xl block-detach 0 51712
[root@arch-test-dom0 ~]# xl block-detach 0 51728
libxl: error: libxl_device.c:1264:device_destroy_be_watch_cb: timed out 
while waiting for /local/domain/1/backend/vbd/0/51728 to be removed
libxl: error: libxl.c:2009:device_addrm_aocomplete: unable to remove vbd 
with id 51728
libxl_device_disk_remove failed.

The 2nd `xl block-detach` command is generating segmentation fault in 
DomD `xl devd` process (search_for_guest (libxenlight.so.4.8)) - please 
see full DomD log output attached in "journalctl (domD).txt".

I am also attaching "xenstored-access.log" and output of `xenstore-ls 
-fp` in "xenstore-ls.txt". In addition, I am attaching output of gdb 
`backtrace full` command on the generated coredump in DomD as 
"coredumpctl gdb (DomD).txt"

Please let me know if I should provide any other information for 
debugging this problem.

Kind regards

Reinis Martinsons

[-- Attachment #2: xl info (Dom0).txt --]
[-- Type: text/plain, Size: 1450 bytes --]

[root@arch-test-dom0 ~]# xl info
host                   : arch-test-dom0
release                : 4.10.11-1-ARCH
version                : #1 SMP PREEMPT Tue Apr 18 08:39:42 CEST 2017
machine                : x86_64
nr_cpus                : 16
max_cpu_id             : 15
nr_nodes               : 1
cores_per_socket       : 8
threads_per_core       : 2
cpu_mhz                : 2400
hw_caps                : b7ebfbff:77fef3ff:2c100800:00000021:00000001:000037ab:00000000:00000100
virt_caps              : hvm hvm_directio
total_memory           : 130959
free_memory            : 125188
sharing_freed_memory   : 0
sharing_used_memory    : 0
outstanding_claims     : 0
free_cpus              : 0
xen_major              : 4
xen_minor              : 8
xen_extra              : .0
xen_version            : 4.8.0
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler          : credit
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          :
xen_commandline        : /boot/xen-4.8.0.gz dom0_mem=4096M,max:4096M dom0_max_vcpus=4 dom0_vcpus_pin xsave=1
cc_compiler            : gcc (GCC) 6.3.1 20170306
cc_compile_by          : reinism
cc_compile_domain      :
cc_compile_date        : Fri Apr 21 21:11:59 EEST 2017
build_id               : 9798821599c96a0b16875250823f389a03079823
xend_config_format     : 4

[-- Attachment #3: DomD.cfg --]
[-- Type: text/plain, Size: 326 bytes --]

vcpus       = '4'
memory      = '32768'
bootloader = "pygrub"
disk        = ['phy:/dev/VG_ssd/TEST_ARCH,xvda,w']
name        = 'arch-zfs-test'
vif         = [ 'mac=00:16:3E:AA:BB:CC,bridge=xenbr0' ]
on_poweroff = 'destroy'
on_reboot   = 'restart'
on_crash    = 'restart'
pci         = [ '01:00.0' ]
driver_domain=1

[-- Attachment #4: journalctl (domD).txt --]
[-- Type: text/plain, Size: 5455 bytes --]

[root@arch-zfs-test ~]# journalctl -f
-- Logs begin at Sat 2017-04-15 01:20:58 EEST. --
May 03 02:18:05 arch-zfs-test systemd[1493]: Starting D-Bus User Message Bus Socket.
May 03 02:18:05 arch-zfs-test systemd[1493]: Reached target Timers.
May 03 02:18:05 arch-zfs-test systemd[1493]: Listening on D-Bus User Message Bus Socket.
May 03 02:18:05 arch-zfs-test systemd[1493]: Reached target Sockets.
May 03 02:18:05 arch-zfs-test systemd[1493]: Reached target Basic System.
May 03 02:18:05 arch-zfs-test systemd[1493]: Reached target Default.
May 03 02:18:05 arch-zfs-test systemd[1493]: Startup finished in 25ms.
May 03 02:18:05 arch-zfs-test systemd[1]: Started User Manager for UID 0.
May 03 02:18:05 arch-zfs-test login[1489]: ROOT LOGIN ON hvc0
May 03 02:18:06 arch-zfs-test dhcpcd[1486]: eth0: no IPv6 Routers available

# After the 1st `xl block-attach` command:

May 03 02:25:53 arch-zfs-test kernel: xen-blkback: backend/vbd/0/51712: using 4 queues, protocol 1 (x86_64-abi) persistent grants
May 03 02:25:53 arch-zfs-test root[1550]: /etc/xen/scripts/block: add XENBUS_PATH=backend/vbd/0/51712
May 03 02:25:53 arch-zfs-test root[1602]: /etc/xen/scripts/block: Writing backend/vbd/0/51712/physical-device e6:0 to xenstore.
May 03 02:25:53 arch-zfs-test root[1604]: /etc/xen/scripts/block: Writing backend/vbd/0/51712/physical-device-path /dev/zd0 to xenstore.
May 03 02:25:53 arch-zfs-test root[1611]: /etc/xen/scripts/block: Writing backend/vbd/0/51712/hotplug-status connected to xenstore.

# After the 2nd `xl block-attach` command:

May 03 02:28:12 arch-zfs-test kernel: xen-blkback: backend/vbd/0/51728: using 1 queues, protocol 1 (x86_64-abi) persistent grants
May 03 02:28:12 arch-zfs-test kernel: xen-blkback: backend/vbd/0/51728: using 1 queues, protocol 1 (x86_64-abi) persistent grants
May 03 02:28:12 arch-zfs-test root[1637]: /etc/xen/scripts/block: add XENBUS_PATH=backend/vbd/0/51728
May 03 02:28:12 arch-zfs-test root[1691]: /etc/xen/scripts/block: Writing backend/vbd/0/51728/physical-device e6:20 to xenstore.
May 03 02:28:12 arch-zfs-test root[1693]: /etc/xen/scripts/block: Writing backend/vbd/0/51728/physical-device-path /dev/zd32 to xenstore.
May 03 02:28:12 arch-zfs-test root[1697]: /etc/xen/scripts/block: Writing backend/vbd/0/51728/hotplug-status connected to xenstore.

# After the 1st `xl block-detach` command:

May 03 02:29:21 arch-zfs-test root[1712]: /etc/xen/scripts/block: remove XENBUS_PATH=backend/vbd/0/51712

# After the 2nd `xl block-detach` command:

May 03 02:30:28 arch-zfs-test kernel: traps: xl[1403] general protection ip:7f49bf42519d sp:7ffc601e6dd0 error:0
May 03 02:30:28 arch-zfs-test kernel:  in libxenlight.so.4.8.0[7f49bf3f8000+dd000]
May 03 02:30:28 arch-zfs-test systemd[1]: Created slice system-systemd\x2dcoredump.slice.
May 03 02:30:28 arch-zfs-test systemd[1]: Started Process Core Dump (PID 1722/UID 0).
May 03 02:30:28 arch-zfs-test systemd[1]: xendriverdomain.service: Main process exited, code=dumped, status=11/SEGV
May 03 02:30:28 arch-zfs-test systemd[1]: xendriverdomain.service: Unit entered failed state.
May 03 02:30:28 arch-zfs-test systemd[1]: xendriverdomain.service: Failed with result 'core-dump'.
May 03 02:30:28 arch-zfs-test systemd-coredump[1725]: Process 1403 (xl) of user 0 dumped core.

                                                      Stack trace of thread 1403:
                                                      #0  0x00007f49bf42519d search_for_guest (libxenlight.so.4.8)
                                                      #1  0x00007f49bf425931 backend_watch_callback (libxenlight.so.4.8)
                                                      #2  0x00007f49bf4629da watchfd_callback (libxenlight.so.4.8)
                                                      #3  0x00007f49bf464612 fd_occurs (libxenlight.so.4.8)
                                                      #4  0x00007f49bf4646c4 afterpoll_internal (libxenlight.so.4.8)
                                                      #5  0x00007f49bf465dfd eventloop_iteration (libxenlight.so.4.8)
                                                      #6  0x00007f49bf466bb1 libxl__ao_inprogress (libxenlight.so.4.8)
                                                      #7  0x00007f49bf4261dc libxl_device_events_handler (libxenlight.so.4.8)
                                                      #8  0x0000000000423258 main_devd (xl)
                                                      #9  0x0000000000408e05 main (xl)
                                                      #10 0x00007f49bea49511 __libc_start_main (libc.so.6)
                                                      #11 0x000000000040800a _start (xl)

                                                      Stack trace of thread 1404:
                                                      #0  0x00007f49bedddf7d read (libpthread.so.0)
                                                      #1  0x00007f49be1b5c3d read_all (libxenstore.so.3.0)
                                                      #2  0x00007f49be1b76ca read_message (libxenstore.so.3.0)
                                                      #3  0x00007f49be1b7a1f read_thread (libxenstore.so.3.0)
                                                      #4  0x00007f49bedd42e7 start_thread (libpthread.so.0)
                                                      #5  0x00007f49beb1554f __clone (libc.so.6)

[-- Attachment #5: xenstored-access.log --]
[-- Type: text/plain, Size: 45580 bytes --]

# After the 1st `xl block-attach` command:

[20170502T23:25:53.081Z]  A31          newconn   
[20170502T23:25:53.083Z]  A31.1        rm        /libxl/0/device/vbd/51712 
[20170502T23:25:53.084Z]  A31.1        write     /libxl/0/device/vbd/51712/frontend /local/domain/0/device/vbd/51712
[20170502T23:25:53.084Z]  A31.1        write     /libxl/0/device/vbd/51712/backend /local/domain/1/backend/vbd/0/51712
[20170502T23:25:53.084Z]  A31.1        rm        /local/domain/0/device/vbd/51712 
[20170502T23:25:53.084Z]  A31.1        mkdir     /local/domain/0/device/vbd/51712 
[20170502T23:25:53.085Z]  A31.1        setperms  /local/domain/0/device/vbd/51712 n0 r1 
[20170502T23:25:53.085Z]  A31.1        write     /local/domain/0/device/vbd/51712/backend /local/domain/1/backend/vbd/0/51712
[20170502T23:25:53.085Z]  A31.1        write     /local/domain/0/device/vbd/51712/backend-id 1
[20170502T23:25:53.085Z]  A31.1        setperms  /local/domain/0/device/vbd/51712/backend-id n0 r1 
[20170502T23:25:53.085Z]  A31.1        write     /local/domain/0/device/vbd/51712/state 1
[20170502T23:25:53.085Z]  A31.1        setperms  /local/domain/0/device/vbd/51712/state n0 r1 
[20170502T23:25:53.086Z]  A31.1        write     /local/domain/0/device/vbd/51712/virtual-device 51712
[20170502T23:25:53.086Z]  A31.1        setperms  /local/domain/0/device/vbd/51712/virtual-device n0 r1 
[20170502T23:25:53.086Z]  A31.1        write     /local/domain/0/device/vbd/51712/device-type disk
[20170502T23:25:53.086Z]  A31.1        setperms  /local/domain/0/device/vbd/51712/device-type n0 r1 
[20170502T23:25:53.086Z]  A31.1        write     /local/domain/0/device/vbd/51712/protocol x86_64-abi
[20170502T23:25:53.087Z]  A31.1        setperms  /local/domain/0/device/vbd/51712/protocol n0 r1 
[20170502T23:25:53.087Z]  A31.1        rm        /local/domain/1/backend/vbd/0/51712 
[20170502T23:25:53.087Z]  A31.1        mkdir     /local/domain/1/backend/vbd/0/51712 
[20170502T23:25:53.087Z]  A31.1        setperms  /local/domain/1/backend/vbd/0/51712 n1 r0 
[20170502T23:25:53.087Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/frontend /local/domain/0/device/vbd/51712
[20170502T23:25:53.088Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/params /dev/zvol/test_pool/test1
[20170502T23:25:53.088Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/script /etc/xen/scripts/block
[20170502T23:25:53.088Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/frontend-id 0
[20170502T23:25:53.088Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/online 1
[20170502T23:25:53.088Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/removable 0
[20170502T23:25:53.088Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/bootable 1
[20170502T23:25:53.089Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/state 1
[20170502T23:25:53.089Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/dev xvda
[20170502T23:25:53.089Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/type phy
[20170502T23:25:53.089Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/mode w
[20170502T23:25:53.089Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/device-type disk
[20170502T23:25:53.089Z]  A31.1        write     /local/domain/1/backend/vbd/0/51712/discard-enable 1
[20170502T23:25:53.090Z]  A31.1        write     /libxl/0/device/vbd/51712/params /dev/zvol/test_pool/test1
[20170502T23:25:53.090Z]  A31.1        write     /libxl/0/device/vbd/51712/script /etc/xen/scripts/block
[20170502T23:25:53.090Z]  A31.1        write     /libxl/0/device/vbd/51712/frontend-id 0
[20170502T23:25:53.090Z]  A31.1        write     /libxl/0/device/vbd/51712/online 1
[20170502T23:25:53.090Z]  A31.1        write     /libxl/0/device/vbd/51712/removable 0
[20170502T23:25:53.091Z]  A31.1        write     /libxl/0/device/vbd/51712/bootable 1
[20170502T23:25:53.091Z]  A31.1        write     /libxl/0/device/vbd/51712/state 1
[20170502T23:25:53.091Z]  A31.1        write     /libxl/0/device/vbd/51712/dev xvda
[20170502T23:25:53.091Z]  A31.1        write     /libxl/0/device/vbd/51712/type phy
[20170502T23:25:53.091Z]  A31.1        write     /libxl/0/device/vbd/51712/mode w
[20170502T23:25:53.091Z]  A31.1        write     /libxl/0/device/vbd/51712/device-type disk
[20170502T23:25:53.092Z]  A31.1        write     /libxl/0/device/vbd/51712/discard-enable 1
[20170502T23:25:53.092Z]  A31.1        commit    
[20170502T23:25:53.092Z]  D0           w event   device/vbd/51712 FFFFFFFF81AA8180 
[20170502T23:25:53.092Z]  D1           w event   /local/domain/1/backend/vbd/0/51712 FFFF88087AE46910 
[20170502T23:25:53.092Z]  D0           w event   device/vbd/51712 FFFFFFFF81AA8180 
[20170502T23:25:53.092Z]  D1           w event   backend/vbd/0/51712 FFFFFFFF81AA7FA0 
[20170502T23:25:53.092Z]  D0           w event   device/vbd/51712/backend FFFFFFFF81AA8180 
[20170502T23:25:53.092Z]  D1           w event   /local/domain/1/backend/vbd/0/51712 FFFF88087AE46910 
[20170502T23:25:53.092Z]  D0           w event   device/vbd/51712/backend-id FFFFFFFF81AA8180 
[20170502T23:25:53.092Z]  D1           w event   backend/vbd/0/51712 FFFFFFFF81AA7FA0 
[20170502T23:25:53.092Z]  D0           w event   device/vbd/51712/backend-id FFFFFFFF81AA8180 
[20170502T23:25:53.092Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/frontend FFFF88087AE46910 
[20170502T23:25:53.093Z]  D0           w event   device/vbd/51712/state FFFFFFFF81AA8180 
[20170502T23:25:53.093Z]  D1           w event   backend/vbd/0/51712/frontend FFFFFFFF81AA7FA0 
[20170502T23:25:53.093Z]  A31          watch     /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170502T23:25:53.093Z]  D0           w event   device/vbd/51712/state FFFFFFFF81AA8180 
[20170502T23:25:53.093Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/params FFFF88087AE46910 
[20170502T23:25:53.093Z]  D0           w event   device/vbd/51712/virtual-device FFFFFFFF81AA8180 
[20170502T23:25:53.093Z]  D1           w event   backend/vbd/0/51712/params FFFFFFFF81AA7FA0 
[20170502T23:25:53.093Z]  A31          w event   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170502T23:25:53.093Z]  D0           w event   device/vbd/51712/virtual-device FFFFFFFF81AA8180 
[20170502T23:25:53.093Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/script FFFF88087AE46910 
[20170502T23:25:53.093Z]  D0           w event   device/vbd/51712/device-type FFFFFFFF81AA8180 
[20170502T23:25:53.093Z]  D1           w event   backend/vbd/0/51712/script FFFFFFFF81AA7FA0 
[20170502T23:25:53.093Z]  D0           w event   device/vbd/51712/device-type FFFFFFFF81AA8180 
[20170502T23:25:53.093Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/frontend-id FFFF88087AE46910 
[20170502T23:25:53.093Z]  D0           w event   device/vbd/51712/protocol FFFFFFFF81AA8180 
[20170502T23:25:53.093Z]  D1           w event   backend/vbd/0/51712/frontend-id FFFFFFFF81AA7FA0 
[20170502T23:25:53.093Z]  D0           w event   device/vbd/51712/protocol FFFFFFFF81AA8180 
[20170502T23:25:53.093Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/online FFFF88087AE46910 
[20170502T23:25:53.093Z]  D1           w event   backend/vbd/0/51712/online FFFFFFFF81AA7FA0 
[20170502T23:25:53.093Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/removable FFFF88087AE46910 
[20170502T23:25:53.093Z]  D1           w event   backend/vbd/0/51712/removable FFFFFFFF81AA7FA0 
[20170502T23:25:53.094Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/bootable FFFF88087AE46910 
[20170502T23:25:53.094Z]  D1           w event   backend/vbd/0/51712/bootable FFFFFFFF81AA7FA0 
[20170502T23:25:53.094Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF88087AE46910 
[20170502T23:25:53.094Z]  D1           w event   backend/vbd/0/51712/state FFFFFFFF81AA7FA0 
[20170502T23:25:53.094Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/dev FFFF88087AE46910 
[20170502T23:25:53.094Z]  D1           w event   backend/vbd/0/51712/dev FFFFFFFF81AA7FA0 
[20170502T23:25:53.094Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/type FFFF88087AE46910 
[20170502T23:25:53.094Z]  D1           w event   backend/vbd/0/51712/type FFFFFFFF81AA7FA0 
[20170502T23:25:53.094Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/mode FFFF88087AE46910 
[20170502T23:25:53.094Z]  D1           w event   backend/vbd/0/51712/mode FFFFFFFF81AA7FA0 
[20170502T23:25:53.094Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/device-type FFFF88087AE46910 
[20170502T23:25:53.094Z]  D1           w event   backend/vbd/0/51712/device-type FFFFFFFF81AA7FA0 
[20170502T23:25:53.094Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/discard-enable FFFF88087AE46910 
[20170502T23:25:53.094Z]  D1           w event   backend/vbd/0/51712/discard-enable FFFFFFFF81AA7FA0 
[20170502T23:25:53.095Z]  D1           write     backend/vbd/0/51712/feature-max-indirect-segments 256
[20170502T23:25:53.095Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/feature-max-indirect-segments FFFF88087AE46910 
[20170502T23:25:53.095Z]  D1           w event   backend/vbd/0/51712/feature-max-indirect-segments FFFFFFFF81AA7FA0 
[20170502T23:25:53.095Z]  D1           write     backend/vbd/0/51712/multi-queue-max-queues 4
[20170502T23:25:53.095Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/multi-queue-max-queues FFFF88087AE46910 
[20170502T23:25:53.095Z]  D1           watch     backend/vbd/0/51712/physical-device FFFF88087512C310 
[20170502T23:25:53.095Z]  D1           w event   backend/vbd/0/51712/multi-queue-max-queues FFFFFFFF81AA7FA0 
[20170502T23:25:53.095Z]  D1           w event   backend/vbd/0/51712/physical-device FFFF88087512C310 
[20170502T23:25:53.096Z]  D1           write     backend/vbd/0/51712/max-ring-page-order 4
[20170502T23:25:53.096Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/max-ring-page-order FFFF88087AE46910 
[20170502T23:25:53.096Z]  D1           w event   backend/vbd/0/51712/max-ring-page-order FFFFFFFF81AA7FA0 
[20170502T23:25:53.096Z]  D1.11        write     backend/vbd/0/51712/state 2
[20170502T23:25:53.096Z]  D1.11        commit    
[20170502T23:25:53.096Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF88087AE46910 
[20170502T23:25:53.096Z]  A31          w event   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170502T23:25:53.096Z]  D1           w event   backend/vbd/0/51712/state FFFFFFFF81AA7FA0 
[20170502T23:25:53.097Z]  D1           watch     /local/domain/0/device/vbd/51712/state FFFF8808752B2420 
[20170502T23:25:53.097Z]  D1           w event   /local/domain/0/device/vbd/51712/state FFFF8808752B2420 
[20170502T23:25:53.097Z]  A31          unwatch   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170502T23:25:53.098Z]  D0           watch     /local/domain/1/backend/vbd/0/51712/state FFFF88017FA58020 
[20170502T23:25:53.098Z]  A31          endconn   
[20170502T23:25:53.098Z]  D0           w event   /local/domain/1/backend/vbd/0/51712/state FFFF88017FA58020 
[20170502T23:25:53.099Z]  D0.12        write     device/vbd/51712/multi-queue-num-queues 4
[20170502T23:25:53.099Z]  D0.12        write     device/vbd/51712/queue-0/ring-ref 8
[20170502T23:25:53.099Z]  D0.12        write     device/vbd/51712/queue-0/event-channel 79
[20170502T23:25:53.099Z]  D0.12        write     device/vbd/51712/queue-1/ring-ref 9
[20170502T23:25:53.100Z]  D0.12        write     device/vbd/51712/queue-1/event-channel 80
[20170502T23:25:53.100Z]  D0.12        write     device/vbd/51712/queue-2/ring-ref 10
[20170502T23:25:53.100Z]  D0.12        write     device/vbd/51712/queue-2/event-channel 81
[20170502T23:25:53.100Z]  D0.12        write     device/vbd/51712/queue-3/ring-ref 11
[20170502T23:25:53.100Z]  D0.12        write     device/vbd/51712/queue-3/event-channel 82
[20170502T23:25:53.100Z]  D0.12        write     device/vbd/51712/protocol x86_64-abi
[20170502T23:25:53.101Z]  D0.12        write     device/vbd/51712/feature-persistent 1
[20170502T23:25:53.101Z]  D1           watch     /local/domain/1/backend/vbd/0/51712/state FFFF880881C43D90 
[20170502T23:25:53.101Z]  D0.12        commit    
[20170502T23:25:53.101Z]  D0           w event   device/vbd/51712/multi-queue-num-queues FFFFFFFF81AA8180 
[20170502T23:25:53.101Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880881C43D90 
[20170502T23:25:53.101Z]  D0           w event   device/vbd/51712/queue-0/ring-ref FFFFFFFF81AA8180 
[20170502T23:25:53.101Z]  D0           w event   device/vbd/51712/queue-0/event-channel FFFFFFFF81AA8180 
[20170502T23:25:53.101Z]  D0           w event   device/vbd/51712/queue-1/ring-ref FFFFFFFF81AA8180 
[20170502T23:25:53.101Z]  D0           w event   device/vbd/51712/queue-1/event-channel FFFFFFFF81AA8180 
[20170502T23:25:53.101Z]  D0           w event   device/vbd/51712/queue-2/ring-ref FFFFFFFF81AA8180 
[20170502T23:25:53.101Z]  D0           w event   device/vbd/51712/queue-2/event-channel FFFFFFFF81AA8180 
[20170502T23:25:53.101Z]  D0           w event   device/vbd/51712/queue-3/ring-ref FFFFFFFF81AA8180 
[20170502T23:25:53.101Z]  D0           w event   device/vbd/51712/queue-3/event-channel FFFFFFFF81AA8180 
[20170502T23:25:53.101Z]  D0           w event   device/vbd/51712/protocol FFFFFFFF81AA8180 
[20170502T23:25:53.101Z]  D0           w event   device/vbd/51712/feature-persistent FFFFFFFF81AA8180 
[20170502T23:25:53.102Z]  D0.13        write     device/vbd/51712/state 3
[20170502T23:25:53.102Z]  D0.13        commit    
[20170502T23:25:53.102Z]  D0           w event   device/vbd/51712/state FFFFFFFF81AA8180 
[20170502T23:25:53.102Z]  D1           w event   /local/domain/0/device/vbd/51712/state FFFF8808752B2420 
[20170502T23:25:53.102Z]  D1           unwatch   /local/domain/1/backend/vbd/0/51712/state FFFF880881C43D90 
[20170502T23:25:53.323Z]  D1.12        commit    
[20170502T23:25:53.331Z]  D1.13        commit    
[20170502T23:25:53.359Z]  D1           write     backend/vbd/0/51712/physical-device e6:0
[20170502T23:25:53.359Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/physical-device FFFF88087AE46910 
[20170502T23:25:53.359Z]  D1           w event   backend/vbd/0/51712/physical-device FFFFFFFF81AA7FA0 
[20170502T23:25:53.359Z]  D1           w event   backend/vbd/0/51712/physical-device FFFF88087512C310 
[20170502T23:25:53.362Z]  D1.14        write     backend/vbd/0/51712/feature-flush-cache 1
[20170502T23:25:53.362Z]  D1.14        write     backend/vbd/0/51712/discard-granularity 8192
[20170502T23:25:53.362Z]  D1.14        write     backend/vbd/0/51712/discard-alignment 0
[20170502T23:25:53.362Z]  D1.14        write     backend/vbd/0/51712/discard-secure 0
[20170502T23:25:53.362Z]  D1.14        write     backend/vbd/0/51712/feature-discard 1
[20170502T23:25:53.362Z]  D1.14        write     backend/vbd/0/51712/feature-barrier 1
[20170502T23:25:53.363Z]  D1.14        write     backend/vbd/0/51712/feature-persistent 1
[20170502T23:25:53.363Z]  D1.14        write     backend/vbd/0/51712/sectors 419430400
[20170502T23:25:53.363Z]  D1.14        write     backend/vbd/0/51712/info 0
[20170502T23:25:53.363Z]  D1.14        write     backend/vbd/0/51712/sector-size 512
[20170502T23:25:53.363Z]  D1.14        write     backend/vbd/0/51712/physical-sector-size 8192
[20170502T23:25:53.363Z]  D1.14        commit    
[20170502T23:25:53.363Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/feature-flush-cache FFFF88087AE46910 
[20170502T23:25:53.363Z]  D1           w event   backend/vbd/0/51712/feature-flush-cache FFFFFFFF81AA7FA0 
[20170502T23:25:53.363Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/discard-granularity FFFF88087AE46910 
[20170502T23:25:53.363Z]  D1           w event   backend/vbd/0/51712/discard-granularity FFFFFFFF81AA7FA0 
[20170502T23:25:53.363Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/discard-alignment FFFF88087AE46910 
[20170502T23:25:53.364Z]  D1           w event   backend/vbd/0/51712/discard-alignment FFFFFFFF81AA7FA0 
[20170502T23:25:53.364Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/discard-secure FFFF88087AE46910 
[20170502T23:25:53.364Z]  D1           w event   backend/vbd/0/51712/discard-secure FFFFFFFF81AA7FA0 
[20170502T23:25:53.364Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/feature-discard FFFF88087AE46910 
[20170502T23:25:53.364Z]  D1           w event   backend/vbd/0/51712/feature-discard FFFFFFFF81AA7FA0 
[20170502T23:25:53.364Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/feature-barrier FFFF88087AE46910 
[20170502T23:25:53.364Z]  D1           w event   backend/vbd/0/51712/feature-barrier FFFFFFFF81AA7FA0 
[20170502T23:25:53.364Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/feature-persistent FFFF88087AE46910 
[20170502T23:25:53.364Z]  D1           w event   backend/vbd/0/51712/feature-persistent FFFFFFFF81AA7FA0 
[20170502T23:25:53.364Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/sectors FFFF88087AE46910 
[20170502T23:25:53.364Z]  D1           w event   backend/vbd/0/51712/sectors FFFFFFFF81AA7FA0 
[20170502T23:25:53.364Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/info FFFF88087AE46910 
[20170502T23:25:53.364Z]  D1           w event   backend/vbd/0/51712/info FFFFFFFF81AA7FA0 
[20170502T23:25:53.364Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/sector-size FFFF88087AE46910 
[20170502T23:25:53.364Z]  D1           w event   backend/vbd/0/51712/sector-size FFFFFFFF81AA7FA0 
[20170502T23:25:53.364Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/physical-sector-size FFFF88087AE46910 
[20170502T23:25:53.364Z]  D1           w event   backend/vbd/0/51712/physical-sector-size FFFFFFFF81AA7FA0 
[20170502T23:25:53.365Z]  D1.15        write     backend/vbd/0/51712/state 4
[20170502T23:25:53.365Z]  D1.15        commit    
[20170502T23:25:53.365Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF88087AE46910 
[20170502T23:25:53.365Z]  D0           w event   /local/domain/1/backend/vbd/0/51712/state FFFF88017FA58020 
[20170502T23:25:53.365Z]  D1           w event   backend/vbd/0/51712/state FFFFFFFF81AA7FA0 
[20170502T23:25:53.368Z]  D0.14        write     device/vbd/51712/state 4
[20170502T23:25:53.368Z]  D0.14        commit    
[20170502T23:25:53.368Z]  D0           w event   device/vbd/51712/state FFFFFFFF81AA8180 
[20170502T23:25:53.368Z]  D1           w event   /local/domain/0/device/vbd/51712/state FFFF8808752B2420 
[20170502T23:25:53.372Z]  D1           write     backend/vbd/0/51712/physical-device-path /dev/zd0
[20170502T23:25:53.372Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/physical-device-path FFFF88087AE46910 
[20170502T23:25:53.372Z]  D1           w event   backend/vbd/0/51712/physical-device-path FFFFFFFF81AA7FA0 
[20170502T23:25:53.384Z]  D1           write     backend/vbd/0/51712/hotplug-status connected
[20170502T23:25:53.384Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/hotplug-status FFFF88087AE46910 
[20170502T23:25:53.384Z]  D1           w event   backend/vbd/0/51712/hotplug-status FFFFFFFF81AA7FA0 
[20170502T23:27:50.316Z]  A32          newconn   
[20170502T23:27:50.410Z]  A32          endconn   

# After the 2nd `xl block-attach` command:

[20170502T23:28:12.104Z]  A33          newconn   
[20170502T23:28:12.108Z]  A33.1        rm        /libxl/0/device/vbd/51728 
[20170502T23:28:12.108Z]  A33.1        write     /libxl/0/device/vbd/51728/frontend /local/domain/0/device/vbd/51728
[20170502T23:28:12.108Z]  A33.1        write     /libxl/0/device/vbd/51728/backend /local/domain/1/backend/vbd/0/51728
[20170502T23:28:12.108Z]  A33.1        rm        /local/domain/0/device/vbd/51728 
[20170502T23:28:12.108Z]  A33.1        mkdir     /local/domain/0/device/vbd/51728 
[20170502T23:28:12.109Z]  A33.1        setperms  /local/domain/0/device/vbd/51728 n0 r1 
[20170502T23:28:12.109Z]  A33.1        write     /local/domain/0/device/vbd/51728/backend /local/domain/1/backend/vbd/0/51728
[20170502T23:28:12.109Z]  A33.1        write     /local/domain/0/device/vbd/51728/backend-id 1
[20170502T23:28:12.109Z]  A33.1        setperms  /local/domain/0/device/vbd/51728/backend-id n0 r1 
[20170502T23:28:12.109Z]  A33.1        write     /local/domain/0/device/vbd/51728/state 1
[20170502T23:28:12.109Z]  A33.1        setperms  /local/domain/0/device/vbd/51728/state n0 r1 
[20170502T23:28:12.110Z]  A33.1        write     /local/domain/0/device/vbd/51728/virtual-device 51728
[20170502T23:28:12.110Z]  A33.1        setperms  /local/domain/0/device/vbd/51728/virtual-device n0 r1 
[20170502T23:28:12.110Z]  A33.1        write     /local/domain/0/device/vbd/51728/device-type disk
[20170502T23:28:12.110Z]  A33.1        setperms  /local/domain/0/device/vbd/51728/device-type n0 r1 
[20170502T23:28:12.111Z]  A33.1        write     /local/domain/0/device/vbd/51728/protocol x86_64-abi
[20170502T23:28:12.111Z]  A33.1        setperms  /local/domain/0/device/vbd/51728/protocol n0 r1 
[20170502T23:28:12.111Z]  A33.1        rm        /local/domain/1/backend/vbd/0/51728 
[20170502T23:28:12.111Z]  A33.1        mkdir     /local/domain/1/backend/vbd/0/51728 
[20170502T23:28:12.111Z]  A33.1        setperms  /local/domain/1/backend/vbd/0/51728 n1 r0 
[20170502T23:28:12.111Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/frontend /local/domain/0/device/vbd/51728
[20170502T23:28:12.112Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/params /dev/zvol/test_pool/test2
[20170502T23:28:12.112Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/script /etc/xen/scripts/block
[20170502T23:28:12.112Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/frontend-id 0
[20170502T23:28:12.112Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/online 1
[20170502T23:28:12.112Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/removable 0
[20170502T23:28:12.112Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/bootable 1
[20170502T23:28:12.113Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/state 1
[20170502T23:28:12.113Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/dev xvdb
[20170502T23:28:12.113Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/type phy
[20170502T23:28:12.113Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/mode w
[20170502T23:28:12.113Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/device-type disk
[20170502T23:28:12.114Z]  A33.1        write     /local/domain/1/backend/vbd/0/51728/discard-enable 1
[20170502T23:28:12.114Z]  A33.1        write     /libxl/0/device/vbd/51728/params /dev/zvol/test_pool/test2
[20170502T23:28:12.114Z]  A33.1        write     /libxl/0/device/vbd/51728/script /etc/xen/scripts/block
[20170502T23:28:12.114Z]  A33.1        write     /libxl/0/device/vbd/51728/frontend-id 0
[20170502T23:28:12.114Z]  A33.1        write     /libxl/0/device/vbd/51728/online 1
[20170502T23:28:12.114Z]  A33.1        write     /libxl/0/device/vbd/51728/removable 0
[20170502T23:28:12.115Z]  A33.1        write     /libxl/0/device/vbd/51728/bootable 1
[20170502T23:28:12.115Z]  A33.1        write     /libxl/0/device/vbd/51728/state 1
[20170502T23:28:12.115Z]  A33.1        write     /libxl/0/device/vbd/51728/dev xvdb
[20170502T23:28:12.115Z]  A33.1        write     /libxl/0/device/vbd/51728/type phy
[20170502T23:28:12.115Z]  A33.1        write     /libxl/0/device/vbd/51728/mode w
[20170502T23:28:12.115Z]  A33.1        write     /libxl/0/device/vbd/51728/device-type disk
[20170502T23:28:12.116Z]  A33.1        write     /libxl/0/device/vbd/51728/discard-enable 1
[20170502T23:28:12.116Z]  A33.1        commit    
[20170502T23:28:12.116Z]  D0           w event   device/vbd/51728 FFFFFFFF81AA8180 
[20170502T23:28:12.116Z]  D1           w event   /local/domain/1/backend/vbd/0/51728 FFFF88087AE46910 
[20170502T23:28:12.116Z]  D0           w event   device/vbd/51728 FFFFFFFF81AA8180 
[20170502T23:28:12.116Z]  D1           w event   backend/vbd/0/51728 FFFFFFFF81AA7FA0 
[20170502T23:28:12.116Z]  D0           w event   device/vbd/51728/backend FFFFFFFF81AA8180 
[20170502T23:28:12.116Z]  D1           w event   /local/domain/1/backend/vbd/0/51728 FFFF88087AE46910 
[20170502T23:28:12.116Z]  D0           w event   device/vbd/51728/backend-id FFFFFFFF81AA8180 
[20170502T23:28:12.116Z]  D1           w event   backend/vbd/0/51728 FFFFFFFF81AA7FA0 
[20170502T23:28:12.116Z]  D0           w event   device/vbd/51728/backend-id FFFFFFFF81AA8180 
[20170502T23:28:12.116Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/frontend FFFF88087AE46910 
[20170502T23:28:12.117Z]  D0           w event   device/vbd/51728/state FFFFFFFF81AA8180 
[20170502T23:28:12.117Z]  D1           w event   backend/vbd/0/51728/frontend FFFFFFFF81AA7FA0 
[20170502T23:28:12.117Z]  D0           w event   device/vbd/51728/state FFFFFFFF81AA8180 
[20170502T23:28:12.117Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/params FFFF88087AE46910 
[20170502T23:28:12.117Z]  D0           w event   device/vbd/51728/virtual-device FFFFFFFF81AA8180 
[20170502T23:28:12.117Z]  D1           w event   backend/vbd/0/51728/params FFFFFFFF81AA7FA0 
[20170502T23:28:12.117Z]  D0           w event   device/vbd/51728/virtual-device FFFFFFFF81AA8180 
[20170502T23:28:12.117Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/script FFFF88087AE46910 
[20170502T23:28:12.117Z]  D0           w event   device/vbd/51728/device-type FFFFFFFF81AA8180 
[20170502T23:28:12.117Z]  D1           w event   backend/vbd/0/51728/script FFFFFFFF81AA7FA0 
[20170502T23:28:12.117Z]  D0           w event   device/vbd/51728/device-type FFFFFFFF81AA8180 
[20170502T23:28:12.117Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/frontend-id FFFF88087AE46910 
[20170502T23:28:12.117Z]  D0           w event   device/vbd/51728/protocol FFFFFFFF81AA8180 
[20170502T23:28:12.117Z]  D1           w event   backend/vbd/0/51728/frontend-id FFFFFFFF81AA7FA0 
[20170502T23:28:12.117Z]  D0           w event   device/vbd/51728/protocol FFFFFFFF81AA8180 
[20170502T23:28:12.117Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/online FFFF88087AE46910 
[20170502T23:28:12.117Z]  D1           w event   backend/vbd/0/51728/online FFFFFFFF81AA7FA0 
[20170502T23:28:12.117Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/removable FFFF88087AE46910 
[20170502T23:28:12.117Z]  D1           w event   backend/vbd/0/51728/removable FFFFFFFF81AA7FA0 
[20170502T23:28:12.117Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/bootable FFFF88087AE46910 
[20170502T23:28:12.118Z]  D1           w event   backend/vbd/0/51728/bootable FFFFFFFF81AA7FA0 
[20170502T23:28:12.118Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88087AE46910 
[20170502T23:28:12.118Z]  D1           w event   backend/vbd/0/51728/state FFFFFFFF81AA7FA0 
[20170502T23:28:12.118Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/dev FFFF88087AE46910 
[20170502T23:28:12.118Z]  D1           w event   backend/vbd/0/51728/dev FFFFFFFF81AA7FA0 
[20170502T23:28:12.118Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/type FFFF88087AE46910 
[20170502T23:28:12.118Z]  D1           w event   backend/vbd/0/51728/type FFFFFFFF81AA7FA0 
[20170502T23:28:12.118Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/mode FFFF88087AE46910 
[20170502T23:28:12.118Z]  D1           w event   backend/vbd/0/51728/mode FFFFFFFF81AA7FA0 
[20170502T23:28:12.118Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/device-type FFFF88087AE46910 
[20170502T23:28:12.118Z]  D1           w event   backend/vbd/0/51728/device-type FFFFFFFF81AA7FA0 
[20170502T23:28:12.118Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/discard-enable FFFF88087AE46910 
[20170502T23:28:12.118Z]  D1           w event   backend/vbd/0/51728/discard-enable FFFFFFFF81AA7FA0 
[20170502T23:28:12.119Z]  A33          watch     /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170502T23:28:12.119Z]  A33          w event   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170502T23:28:12.120Z]  D1           write     backend/vbd/0/51728/feature-max-indirect-segments 256
[20170502T23:28:12.120Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/feature-max-indirect-segments FFFF88087AE46910 
[20170502T23:28:12.120Z]  D0           watch     /local/domain/1/backend/vbd/0/51728/state FFFF88017F40CC20 
[20170502T23:28:12.120Z]  D1           w event   backend/vbd/0/51728/feature-max-indirect-segments FFFFFFFF81AA7FA0 
[20170502T23:28:12.120Z]  D0           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88017F40CC20 
[20170502T23:28:12.120Z]  D1           write     backend/vbd/0/51728/multi-queue-max-queues 4
[20170502T23:28:12.120Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/multi-queue-max-queues FFFF88087AE46910 
[20170502T23:28:12.120Z]  D1           w event   backend/vbd/0/51728/multi-queue-max-queues FFFFFFFF81AA7FA0 
[20170502T23:28:12.120Z]  D1           watch     backend/vbd/0/51728/physical-device FFFF88087512C3D0 
[20170502T23:28:12.120Z]  D1           w event   backend/vbd/0/51728/physical-device FFFF88087512C3D0 
[20170502T23:28:12.121Z]  D1           write     backend/vbd/0/51728/max-ring-page-order 4
[20170502T23:28:12.121Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/max-ring-page-order FFFF88087AE46910 
[20170502T23:28:12.121Z]  D1           w event   backend/vbd/0/51728/max-ring-page-order FFFFFFFF81AA7FA0 
[20170502T23:28:12.121Z]  D1.16        write     backend/vbd/0/51728/state 2
[20170502T23:28:12.121Z]  D1.16        commit    
[20170502T23:28:12.121Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88087AE46910 
[20170502T23:28:12.121Z]  A33          w event   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170502T23:28:12.121Z]  D0           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88017F40CC20 
[20170502T23:28:12.121Z]  D1           w event   backend/vbd/0/51728/state FFFFFFFF81AA7FA0 
[20170502T23:28:12.122Z]  D1           watch     /local/domain/0/device/vbd/51728/state FFFF880874D07020 
[20170502T23:28:12.122Z]  D1           w event   /local/domain/0/device/vbd/51728/state FFFF880874D07020 
[20170502T23:28:12.122Z]  A33          unwatch   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170502T23:28:12.122Z]  D0.15        write     device/vbd/51728/ring-ref 80
[20170502T23:28:12.122Z]  D0.15        write     device/vbd/51728/event-channel 83
[20170502T23:28:12.123Z]  D0.15        write     device/vbd/51728/protocol x86_64-abi
[20170502T23:28:12.123Z]  D0.15        write     device/vbd/51728/feature-persistent 1
[20170502T23:28:12.123Z]  D0.15        commit    
[20170502T23:28:12.123Z]  D0           w event   device/vbd/51728/ring-ref FFFFFFFF81AA8180 
[20170502T23:28:12.123Z]  A33          endconn   
[20170502T23:28:12.123Z]  D0           w event   device/vbd/51728/event-channel FFFFFFFF81AA8180 
[20170502T23:28:12.123Z]  D0           w event   device/vbd/51728/protocol FFFFFFFF81AA8180 
[20170502T23:28:12.123Z]  D0           w event   device/vbd/51728/feature-persistent FFFFFFFF81AA8180 
[20170502T23:28:12.124Z]  D0.16        write     device/vbd/51728/state 3
[20170502T23:28:12.124Z]  D0.16        commit    
[20170502T23:28:12.124Z]  D0           w event   device/vbd/51728/state FFFFFFFF81AA8180 
[20170502T23:28:12.124Z]  D1           w event   /local/domain/0/device/vbd/51728/state FFFF880874D07020 
[20170502T23:28:12.124Z]  D1           watch     /local/domain/1/backend/vbd/0/51728/state FFFF880872F7D090 
[20170502T23:28:12.125Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/state FFFF880872F7D090 
[20170502T23:28:12.130Z]  D1           unwatch   /local/domain/1/backend/vbd/0/51728/state FFFF880872F7D090 
[20170502T23:28:12.324Z]  D1.17        commit    
[20170502T23:28:12.333Z]  D1.18        commit    
[20170502T23:28:12.369Z]  D1           write     backend/vbd/0/51728/physical-device e6:20
[20170502T23:28:12.369Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/physical-device FFFF88087AE46910 
[20170502T23:28:12.369Z]  D1           w event   backend/vbd/0/51728/physical-device FFFFFFFF81AA7FA0 
[20170502T23:28:12.369Z]  D1           w event   backend/vbd/0/51728/physical-device FFFF88087512C3D0 
[20170502T23:28:12.371Z]  D1.19        write     backend/vbd/0/51728/feature-flush-cache 1
[20170502T23:28:12.371Z]  D1.19        write     backend/vbd/0/51728/discard-granularity 8192
[20170502T23:28:12.371Z]  D1.19        write     backend/vbd/0/51728/discard-alignment 0
[20170502T23:28:12.371Z]  D1.19        write     backend/vbd/0/51728/discard-secure 0
[20170502T23:28:12.371Z]  D1.19        write     backend/vbd/0/51728/feature-discard 1
[20170502T23:28:12.372Z]  D1.19        write     backend/vbd/0/51728/feature-barrier 1
[20170502T23:28:12.372Z]  D1.19        write     backend/vbd/0/51728/feature-persistent 1
[20170502T23:28:12.372Z]  D1.19        write     backend/vbd/0/51728/sectors 209715200
[20170502T23:28:12.372Z]  D1.19        write     backend/vbd/0/51728/info 0
[20170502T23:28:12.372Z]  D1.19        write     backend/vbd/0/51728/sector-size 512
[20170502T23:28:12.372Z]  D1.19        write     backend/vbd/0/51728/physical-sector-size 8192
[20170502T23:28:12.372Z]  D1.19        commit    
[20170502T23:28:12.372Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/feature-flush-cache FFFF88087AE46910 
[20170502T23:28:12.373Z]  D1           w event   backend/vbd/0/51728/feature-flush-cache FFFFFFFF81AA7FA0 
[20170502T23:28:12.373Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/discard-granularity FFFF88087AE46910 
[20170502T23:28:12.373Z]  D1           w event   backend/vbd/0/51728/discard-granularity FFFFFFFF81AA7FA0 
[20170502T23:28:12.373Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/discard-alignment FFFF88087AE46910 
[20170502T23:28:12.373Z]  D1           w event   backend/vbd/0/51728/discard-alignment FFFFFFFF81AA7FA0 
[20170502T23:28:12.373Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/discard-secure FFFF88087AE46910 
[20170502T23:28:12.373Z]  D1           w event   backend/vbd/0/51728/discard-secure FFFFFFFF81AA7FA0 
[20170502T23:28:12.373Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/feature-discard FFFF88087AE46910 
[20170502T23:28:12.373Z]  D1           w event   backend/vbd/0/51728/feature-discard FFFFFFFF81AA7FA0 
[20170502T23:28:12.373Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/feature-barrier FFFF88087AE46910 
[20170502T23:28:12.373Z]  D1           w event   backend/vbd/0/51728/feature-barrier FFFFFFFF81AA7FA0 
[20170502T23:28:12.373Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/feature-persistent FFFF88087AE46910 
[20170502T23:28:12.373Z]  D1           w event   backend/vbd/0/51728/feature-persistent FFFFFFFF81AA7FA0 
[20170502T23:28:12.373Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/sectors FFFF88087AE46910 
[20170502T23:28:12.373Z]  D1           w event   backend/vbd/0/51728/sectors FFFFFFFF81AA7FA0 
[20170502T23:28:12.373Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/info FFFF88087AE46910 
[20170502T23:28:12.373Z]  D1           w event   backend/vbd/0/51728/info FFFFFFFF81AA7FA0 
[20170502T23:28:12.373Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/sector-size FFFF88087AE46910 
[20170502T23:28:12.373Z]  D1           w event   backend/vbd/0/51728/sector-size FFFFFFFF81AA7FA0 
[20170502T23:28:12.374Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/physical-sector-size FFFF88087AE46910 
[20170502T23:28:12.374Z]  D1           w event   backend/vbd/0/51728/physical-sector-size FFFFFFFF81AA7FA0 
[20170502T23:28:12.374Z]  D1.20        write     backend/vbd/0/51728/state 4
[20170502T23:28:12.374Z]  D1.20        commit    
[20170502T23:28:12.374Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88087AE46910 
[20170502T23:28:12.374Z]  D0           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88017F40CC20 
[20170502T23:28:12.374Z]  D1           w event   backend/vbd/0/51728/state FFFFFFFF81AA7FA0 
[20170502T23:28:12.378Z]  D0.17        write     device/vbd/51728/state 4
[20170502T23:28:12.378Z]  D0.17        commit    
[20170502T23:28:12.378Z]  D0           w event   device/vbd/51728/state FFFFFFFF81AA8180 
[20170502T23:28:12.378Z]  D1           w event   /local/domain/0/device/vbd/51728/state FFFF880874D07020 
[20170502T23:28:12.380Z]  D1           write     backend/vbd/0/51728/physical-device-path /dev/zd32
[20170502T23:28:12.380Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/physical-device-path FFFF88087AE46910 
[20170502T23:28:12.381Z]  D1           w event   backend/vbd/0/51728/physical-device-path FFFFFFFF81AA7FA0 
[20170502T23:28:12.392Z]  D1           write     backend/vbd/0/51728/hotplug-status connected
[20170502T23:28:12.392Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/hotplug-status FFFF88087AE46910 
[20170502T23:28:12.392Z]  D1           w event   backend/vbd/0/51728/hotplug-status FFFFFFFF81AA7FA0 
[20170502T23:28:58.238Z]  A34          newconn   
[20170502T23:28:58.334Z]  A34          endconn   

# After the 1st `xl block-detach` command:

[20170502T23:29:21.711Z]  A35          newconn   
[20170502T23:29:21.713Z]  A35.1        write     /local/domain/1/backend/vbd/0/51712/online 0
[20170502T23:29:21.714Z]  A35.1        write     /local/domain/1/backend/vbd/0/51712/state 5
[20170502T23:29:21.714Z]  A35.1        commit    
[20170502T23:29:21.714Z]  D0           w event   /local/domain/1/backend/vbd/0/51712/state FFFF88017FA58020 
[20170502T23:29:21.714Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/online FFFF88087AE46910 
[20170502T23:29:21.714Z]  D1           w event   backend/vbd/0/51712/online FFFFFFFF81AA7FA0 
[20170502T23:29:21.714Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF88087AE46910 
[20170502T23:29:21.714Z]  D1           w event   backend/vbd/0/51712/state FFFFFFFF81AA7FA0 
[20170502T23:29:21.714Z]  A35          watch     /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170502T23:29:21.714Z]  A35          w event   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170502T23:29:21.744Z]  D0.18        write     device/vbd/51712/state 6
[20170502T23:29:21.744Z]  D0.18        commit    
[20170502T23:29:21.744Z]  D0           w event   device/vbd/51712/state FFFFFFFF81AA8180 
[20170502T23:29:21.744Z]  D1           w event   /local/domain/0/device/vbd/51712/state FFFF8808752B2420 
[20170502T23:29:21.749Z]  D1.21        write     backend/vbd/0/51712/state 6
[20170502T23:29:21.749Z]  D1.21        commit    
[20170502T23:29:21.749Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF88087AE46910 
[20170502T23:29:21.749Z]  A35          w event   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170502T23:29:21.749Z]  D0           w event   /local/domain/1/backend/vbd/0/51712/state FFFF88017FA58020 
[20170502T23:29:21.749Z]  D1           w event   backend/vbd/0/51712/state FFFFFFFF81AA7FA0 
[20170502T23:29:21.750Z]  D1           unwatch   /local/domain/0/device/vbd/51712/state FFFF8808752B2420 
[20170502T23:29:21.750Z]  A35          unwatch   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170502T23:29:21.750Z]  D1           unwatch   backend/vbd/0/51712/physical-device FFFF88087512C310 
[20170502T23:29:21.751Z]  A35          watch     /local/domain/1/backend/vbd/0/51712 3/1 
[20170502T23:29:21.751Z]  A35          w event   /local/domain/1/backend/vbd/0/51712 3/1 
[20170502T23:29:21.753Z]  D1.22        write     /local/domain/1/backend/vbd/0/51712/online 0
[20170502T23:29:21.753Z]  D1.22        commit    
[20170502T23:29:21.753Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/online FFFF88087AE46910 
[20170502T23:29:21.753Z]  A35          w event   /local/domain/1/backend/vbd/0/51712/online 3/1 
[20170502T23:29:21.753Z]  D1           w event   backend/vbd/0/51712/online FFFFFFFF81AA7FA0 
[20170502T23:29:21.754Z]  D1           watch     /local/domain/1/backend/vbd/0/51712/state FFFF880881C43210 
[20170502T23:29:21.754Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880881C43210 
[20170502T23:29:21.754Z]  D1           unwatch   /local/domain/1/backend/vbd/0/51712/state FFFF880881C43210 
[20170502T23:29:21.833Z]  D1.23        rm        /local/domain/1/backend/vbd/0/51712 
[20170502T23:29:21.833Z]  D1.23        commit    
[20170502T23:29:21.833Z]  D1           w event   /local/domain/1/backend/vbd/0/51712 FFFF88087AE46910 
[20170502T23:29:21.833Z]  A35          w event   /local/domain/1/backend/vbd/0/51712 3/1 
[20170502T23:29:21.833Z]  D0           w event   /local/domain/1/backend/vbd/0/51712/state FFFF88017FA58020 
[20170502T23:29:21.834Z]  D1           w event   backend/vbd/0/51712 FFFFFFFF81AA7FA0 
[20170502T23:29:21.834Z]  A35          unwatch   /local/domain/1/backend/vbd/0/51712 3/1 
[20170502T23:29:21.835Z]  A35.2        rm        /local/domain/0/device/vbd/51712 
[20170502T23:29:21.836Z]  A35.2        rm        /libxl/0/device/vbd/51712 
[20170502T23:29:21.836Z]  A35.2        commit    
[20170502T23:29:21.836Z]  D0           w event   device/vbd/51712 FFFFFFFF81AA8180 
[20170502T23:29:21.837Z]  D0           unwatch   /local/domain/1/backend/vbd/0/51712/state FFFF88017FA58020 
[20170502T23:29:21.838Z]  A35          endconn   
[20170502T23:29:55.903Z]  A36          newconn   
[20170502T23:29:55.972Z]  A36          endconn   

# After the 2nd `xl block-detach` command:

[20170502T23:30:28.125Z]  A37          newconn   
[20170502T23:30:28.127Z]  A37.1        write     /local/domain/1/backend/vbd/0/51728/online 0
[20170502T23:30:28.127Z]  A37.1        write     /local/domain/1/backend/vbd/0/51728/state 5
[20170502T23:30:28.128Z]  A37.1        commit    
[20170502T23:30:28.128Z]  D0           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88017F40CC20 
[20170502T23:30:28.128Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/online FFFF88087AE46910 
[20170502T23:30:28.128Z]  D1           w event   backend/vbd/0/51728/online FFFFFFFF81AA7FA0 
[20170502T23:30:28.128Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88087AE46910 
[20170502T23:30:28.128Z]  D1           w event   backend/vbd/0/51728/state FFFFFFFF81AA7FA0 
[20170502T23:30:28.128Z]  A37          watch     /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170502T23:30:28.128Z]  A37          w event   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170502T23:30:28.161Z]  D0.19        write     device/vbd/51728/state 6
[20170502T23:30:28.161Z]  D0.19        commit    
[20170502T23:30:28.161Z]  D0           w event   device/vbd/51728/state FFFFFFFF81AA8180 
[20170502T23:30:28.161Z]  D1           unwatch   /local/domain/1/backend FFFF88087AE46910 
[20170502T23:30:28.161Z]  D1           w event   /local/domain/0/device/vbd/51728/state FFFF880874D07020 
[20170502T23:30:28.163Z]  D1.24        write     backend/vbd/0/51728/state 6
[20170502T23:30:28.163Z]  D1.24        commit    
[20170502T23:30:28.163Z]  D1           w event   backend/vbd/0/51728/state FFFFFFFF81AA7FA0 
[20170502T23:30:28.163Z]  A37          w event   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170502T23:30:28.163Z]  D0           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88017F40CC20 
[20170502T23:30:28.163Z]  D1           unwatch   /local/domain/0/device/vbd/51728/state FFFF880874D07020 
[20170502T23:30:28.163Z]  A37          unwatch   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170502T23:30:28.163Z]  D1           unwatch   backend/vbd/0/51728/physical-device FFFF88087512C3D0 
[20170502T23:30:28.164Z]  A37          watch     /local/domain/1/backend/vbd/0/51728 3/1 
[20170502T23:30:28.164Z]  A37          w event   /local/domain/1/backend/vbd/0/51728 3/1 
[20170502T23:30:29.260Z]  D1           watch     /local/domain/1/backend FFFF88087622D110 
[20170502T23:30:29.260Z]  D1           w event   /local/domain/1/backend FFFF88087622D110 
[20170502T23:30:38.175Z]  A37          unwatch   /local/domain/1/backend/vbd/0/51728 3/1 
[20170502T23:30:38.176Z]  A37.2        rm        /local/domain/0/device/vbd/51728 
[20170502T23:30:38.177Z]  A37.2        rm        /local/domain/0/device/vbd 
[20170502T23:30:38.177Z]  A37.2        rm        /local/domain/0/device 
[20170502T23:30:38.178Z]  A37.2        rm        /libxl/0/device/vbd/51728 
[20170502T23:30:38.178Z]  A37.2        rm        /libxl/0/device/vbd 
[20170502T23:30:38.179Z]  A37.2        rm        /libxl/0/device 
[20170502T23:30:38.179Z]  A37.2        rm        /libxl/0 
[20170502T23:30:38.180Z]  A37.2        commit    
[20170502T23:30:38.180Z]  D0           w event   device/vbd/51728 FFFFFFFF81AA8180 
[20170502T23:30:38.180Z]  D0           w event   device/vbd FFFFFFFF81AA8180 
[20170502T23:30:38.180Z]  D0           w event   device FFFFFFFF81AA8180 
[20170502T23:30:38.181Z]  D0           unwatch   /local/domain/1/backend/vbd/0/51728/state FFFF88017F40CC20 
[20170502T23:30:38.181Z]  A37          endconn   
[20170502T23:31:17.867Z]  A38          newconn   
[20170502T23:31:17.957Z]  A38          endconn   

[-- Attachment #6: xenstore-ls.txt --]
[-- Type: text/plain, Size: 99771 bytes --]

# Before the 1st `xl block-attach` command:

/local = ""   (n0)
/local/domain = ""   (n0)
/local/domain/0 = ""   (n0)
/local/domain/0/control = ""   (n0)
/local/domain/0/control/feature-poweroff = "1"   (n0)
/local/domain/0/control/feature-reboot = "1"   (n0)
/local/domain/0/control/feature-suspend = "1"   (n0)
/local/domain/0/domid = "0"   (n0)
/local/domain/0/name = "Domain-0"   (n0)
/local/domain/0/device-model = ""   (n0)
/local/domain/0/device-model/0 = ""   (n0)
/local/domain/0/device-model/0/backends = ""   (n0)
/local/domain/0/device-model/0/backends/console = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vkbd = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qdisk = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qusb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vfb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qnic = ""   (n0,n0)
/local/domain/0/device-model/0/state = "running"   (n0)
/local/domain/0/backend = ""   (n0)
/local/domain/0/backend/vbd = ""   (n0)
/local/domain/0/backend/vbd/1 = ""   (n0)
/local/domain/0/backend/vbd/1/51712 = ""   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/script = "/etc/xen/scripts/block"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/online = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/removable = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/bootable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/state = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/dev = "xvda"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/type = "phy"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/mode = "w"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/device-type = "disk"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-enable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-max-indirect-segments = "256"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/max-ring-page-order = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device = "fe:22"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device-path = "/dev/dm-34"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-flush-cache = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-granularity = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-alignment = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-secure = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-discard = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-barrier = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sectors = "16777216"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/info = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sector-size = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-sector-size = "512"   (n0,r1)
/local/domain/0/backend/console = ""   (n0)
/local/domain/0/backend/console/1 = ""   (n0)
/local/domain/0/backend/console/1/0 = ""   (n0,r1)
/local/domain/0/backend/console/1/0/frontend = "/local/domain/1/console"   (n0,r1)
/local/domain/0/backend/console/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/state = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/protocol = "vt100"   (n0,r1)
/local/domain/0/backend/vif = ""   (n0)
/local/domain/0/backend/vif/1 = ""   (n0)
/local/domain/0/backend/vif/1/0 = ""   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend = "/local/domain/1/device/vif/0"   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/script = "/etc/xen/scripts/vif-bridge"   (n0,r1)
/local/domain/0/backend/vif/1/0/mac = "00:16:3e:aa:bb:cc"   (n0,r1)
/local/domain/0/backend/vif/1/0/bridge = "xenbr0"   (n0,r1)
/local/domain/0/backend/vif/1/0/handle = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/type = "vif"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-sg = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv4 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv6 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ipv6-csum-offload = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-copy = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-flip = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-dynamic-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-split-event-channels = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ctrl-ring = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/pci = ""   (n0)
/local/domain/0/backend/pci/1 = ""   (n0)
/local/domain/0/backend/pci/1/0 = ""   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend = "/local/domain/1/device/pci/0"   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/pci/1/0/domain = "arch-zfs-test"   (n0,r1)
/local/domain/0/backend/pci/1/0/key-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/dev-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0,r1)
/local/domain/0/backend/pci/1/0/state-0 = "3"   (n0,r1)
/local/domain/0/backend/pci/1/0/num_devs = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/vdev-0 = "0000:00:00.00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root-0 = "0000:00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root_num = "1"   (n0,r1)
/local/domain/1 = ""   (n0,r1)
/local/domain/1/vm = "/vm/59f752d2-7d5f-4aba-9411-302221c4e188"   (n0,r1)
/local/domain/1/name = "arch-zfs-test"   (n0,r1)
/local/domain/1/cpu = ""   (n0,r1)
/local/domain/1/cpu/0 = ""   (n0,r1)
/local/domain/1/cpu/0/availability = "online"   (n0,r1)
/local/domain/1/cpu/1 = ""   (n0,r1)
/local/domain/1/cpu/1/availability = "online"   (n0,r1)
/local/domain/1/cpu/2 = ""   (n0,r1)
/local/domain/1/cpu/2/availability = "online"   (n0,r1)
/local/domain/1/cpu/3 = ""   (n0,r1)
/local/domain/1/cpu/3/availability = "online"   (n0,r1)
/local/domain/1/memory = ""   (n0,r1)
/local/domain/1/memory/static-max = "33554432"   (n0,r1)
/local/domain/1/memory/target = "33554432"   (n0,r1)
/local/domain/1/memory/videoram = "0"   (n0,r1)
/local/domain/1/device = ""   (n0,r1)
/local/domain/1/device/suspend = ""   (n0,r1)
/local/domain/1/device/suspend/event-channel = ""   (n1)
/local/domain/1/device/vbd = ""   (n0,r1)
/local/domain/1/device/vbd/51712 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n1,r0)
/local/domain/1/device/vbd/51712/backend-id = "0"   (n1,r0)
/local/domain/1/device/vbd/51712/state = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/virtual-device = "51712"   (n1,r0)
/local/domain/1/device/vbd/51712/device-type = "disk"   (n1,r0)
/local/domain/1/device/vbd/51712/protocol = "x86_64-abi"   (n1,r0)
/local/domain/1/device/vbd/51712/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/ring-ref = "8"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/event-channel = "31"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/ring-ref = "9"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/event-channel = "32"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/ring-ref = "10"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/event-channel = "33"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/ring-ref = "11"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/event-channel = "34"   (n1,r0)
/local/domain/1/device/vbd/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/device/vif = ""   (n0,r1)
/local/domain/1/device/vif/0 = ""   (n1,r0)
/local/domain/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n1,r0)
/local/domain/1/device/vif/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/vif/0/state = "4"   (n1,r0)
/local/domain/1/device/vif/0/handle = "0"   (n1,r0)
/local/domain/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n1,r0)
/local/domain/1/device/vif/0/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vif/0/queue-0 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-0/tx-ring-ref = "2304"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/rx-ring-ref = "2305"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-tx = "35"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-rx = "36"   (n1,r0)
/local/domain/1/device/vif/0/queue-1 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-1/tx-ring-ref = "2306"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/rx-ring-ref = "2307"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-tx = "37"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-rx = "38"   (n1,r0)
/local/domain/1/device/vif/0/queue-2 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-2/tx-ring-ref = "2308"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/rx-ring-ref = "2309"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-tx = "39"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-rx = "40"   (n1,r0)
/local/domain/1/device/vif/0/queue-3 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-3/tx-ring-ref = "2310"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/rx-ring-ref = "2311"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-tx = "41"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-rx = "42"   (n1,r0)
/local/domain/1/device/vif/0/request-rx-copy = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-rx-notify = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-sg = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv4 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv6 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-ipv6-csum-offload = "1"   (n1,r0)
/local/domain/1/device/pci = ""   (n0,r1)
/local/domain/1/device/pci/0 = ""   (n1,r0)
/local/domain/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n1,r0)
/local/domain/1/device/pci/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/pci/0/state = "4"   (n1,r0)
/local/domain/1/device/pci/0/pci-op-ref = "361"   (n1,r0)
/local/domain/1/device/pci/0/event-channel = "43"   (n1,r0)
/local/domain/1/device/pci/0/magic = "7"   (n1,r0)
/local/domain/1/control = ""   (n0,r1)
/local/domain/1/control/shutdown = ""   (n1)
/local/domain/1/control/feature-poweroff = "1"   (n1)
/local/domain/1/control/feature-reboot = "1"   (n1)
/local/domain/1/control/feature-suspend = "1"   (n1)
/local/domain/1/control/platform-feature-multiprocessor-suspend = "1"   (n0,r1)
/local/domain/1/control/platform-feature-xs_reset_watches = "1"   (n0,r1)
/local/domain/1/data = ""   (n1)
/local/domain/1/drivers = ""   (n1)
/local/domain/1/feature = ""   (n1)
/local/domain/1/attr = ""   (n1)
/local/domain/1/libxl = ""   (n1)
/local/domain/1/device-model = ""   (n1)
/local/domain/1/domid = "1"   (n0,r1)
/local/domain/1/store = ""   (n0,r1)
/local/domain/1/store/port = "1"   (n0,r1)
/local/domain/1/store/ring-ref = "20014470"   (n0,r1)
/local/domain/1/console = ""   (n0,r1)
/local/domain/1/console/backend = "/local/domain/0/backend/console/1/0"   (n0,r1)
/local/domain/1/console/backend-id = "0"   (n1,r0)
/local/domain/1/console/limit = "1048576"   (n0,r1)
/local/domain/1/console/type = "xenconsoled"   (n0,r1)
/local/domain/1/console/output = "pty"   (n0,r1)
/local/domain/1/console/tty = "/dev/pts/1"   (n0,r1)
/local/domain/1/console/port = "2"   (n0,r1)
/local/domain/1/console/ring-ref = "20014471"   (n0,r1)
/libxl = ""   (n0)
/libxl/pciback = ""   (n0)
/libxl/pciback/0000-00-1f-2 = ""   (n0)
/libxl/pciback/0000-00-1f-2/driver_path = "/sys/bus/pci/drivers/ahci"   (n0)
/libxl/pciback/0000-01-00-0 = ""   (n0)
/libxl/pciback/0000-01-00-0/driver_path = "/sys/bus/pci/drivers/mpt3sas"   (n0)
/libxl/pciback/0000-06-00-0 = ""   (n0)
/libxl/pciback/0000-06-00-0/driver_path = "/sys/bus/pci/drivers/serial"   (n0)
/libxl/1 = ""   (n0)
/libxl/1/device = ""   (n0)
/libxl/1/device/vbd = ""   (n0)
/libxl/1/device/vbd/51712 = ""   (n0)
/libxl/1/device/vbd/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0)
/libxl/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n0)
/libxl/1/device/vbd/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0)
/libxl/1/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/1/device/vbd/51712/frontend-id = "1"   (n0)
/libxl/1/device/vbd/51712/online = "1"   (n0)
/libxl/1/device/vbd/51712/removable = "0"   (n0)
/libxl/1/device/vbd/51712/bootable = "1"   (n0)
/libxl/1/device/vbd/51712/state = "1"   (n0)
/libxl/1/device/vbd/51712/dev = "xvda"   (n0)
/libxl/1/device/vbd/51712/type = "phy"   (n0)
/libxl/1/device/vbd/51712/mode = "w"   (n0)
/libxl/1/device/vbd/51712/device-type = "disk"   (n0)
/libxl/1/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/1/device/console = ""   (n0)
/libxl/1/device/console/0 = ""   (n0)
/libxl/1/device/console/0/frontend = "/local/domain/1/console"   (n0)
/libxl/1/device/console/0/backend = "/local/domain/0/backend/console/1/0"   (n0)
/libxl/1/device/console/0/frontend-id = "1"   (n0)
/libxl/1/device/console/0/online = "1"   (n0)
/libxl/1/device/console/0/state = "1"   (n0)
/libxl/1/device/console/0/protocol = "vt100"   (n0)
/libxl/1/device/vif = ""   (n0)
/libxl/1/device/vif/0 = ""   (n0)
/libxl/1/device/vif/0/frontend = "/local/domain/1/device/vif/0"   (n0)
/libxl/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n0)
/libxl/1/device/vif/0/frontend-id = "1"   (n0)
/libxl/1/device/vif/0/online = "1"   (n0)
/libxl/1/device/vif/0/state = "1"   (n0)
/libxl/1/device/vif/0/script = "/etc/xen/scripts/vif-bridge"   (n0)
/libxl/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n0)
/libxl/1/device/vif/0/bridge = "xenbr0"   (n0)
/libxl/1/device/vif/0/handle = "0"   (n0)
/libxl/1/device/vif/0/type = "vif"   (n0)
/libxl/1/device/pci = ""   (n0)
/libxl/1/device/pci/0 = ""   (n0)
/libxl/1/device/pci/0/frontend = "/local/domain/1/device/pci/0"   (n0)
/libxl/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n0)
/libxl/1/device/pci/0/frontend-id = "1"   (n0)
/libxl/1/device/pci/0/online = "1"   (n0)
/libxl/1/device/pci/0/state = "1"   (n0)
/libxl/1/device/pci/0/domain = "arch-zfs-test"   (n0)
/libxl/1/device/pci/0/key-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/dev-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0)
/libxl/1/device/pci/0/state-0 = "1"   (n0)
/libxl/1/device/pci/0/num_devs = "1"   (n0)
/libxl/1/dm-version = "qemu_xen"   (n0)
/vm = ""   (n0)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188 = ""   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/name = "arch-zfs-test"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/uuid = "59f752d2-7d5f-4aba-9411-302221c4e188"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image = ""   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/ostype = "linux"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/kernel = "/run/xen/bootloader.1.d/boot_kernel.M1Zoy1"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/ramdisk = "/run/xen/bootloader.1.d/boot_ramdisk.4o1QjN"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/cmdline = "root=UUID=c4e5bb0c-5638-45f6-a90a-0107cc97506b ro"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/start_time = "1493767063.02"   (n0,r1)

# After the 1st `xl block-attach` command:

/local = ""   (n0)
/local/domain = ""   (n0)
/local/domain/0 = ""   (n0)
/local/domain/0/control = ""   (n0)
/local/domain/0/control/feature-poweroff = "1"   (n0)
/local/domain/0/control/feature-reboot = "1"   (n0)
/local/domain/0/control/feature-suspend = "1"   (n0)
/local/domain/0/domid = "0"   (n0)
/local/domain/0/name = "Domain-0"   (n0)
/local/domain/0/device-model = ""   (n0)
/local/domain/0/device-model/0 = ""   (n0)
/local/domain/0/device-model/0/backends = ""   (n0)
/local/domain/0/device-model/0/backends/console = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vkbd = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qdisk = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qusb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vfb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qnic = ""   (n0,n0)
/local/domain/0/device-model/0/state = "running"   (n0)
/local/domain/0/backend = ""   (n0)
/local/domain/0/backend/vbd = ""   (n0)
/local/domain/0/backend/vbd/1 = ""   (n0)
/local/domain/0/backend/vbd/1/51712 = ""   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/script = "/etc/xen/scripts/block"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/online = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/removable = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/bootable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/state = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/dev = "xvda"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/type = "phy"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/mode = "w"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/device-type = "disk"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-enable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-max-indirect-segments = "256"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/max-ring-page-order = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device = "fe:22"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device-path = "/dev/dm-34"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-flush-cache = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-granularity = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-alignment = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-secure = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-discard = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-barrier = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sectors = "16777216"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/info = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sector-size = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-sector-size = "512"   (n0,r1)
/local/domain/0/backend/console = ""   (n0)
/local/domain/0/backend/console/1 = ""   (n0)
/local/domain/0/backend/console/1/0 = ""   (n0,r1)
/local/domain/0/backend/console/1/0/frontend = "/local/domain/1/console"   (n0,r1)
/local/domain/0/backend/console/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/state = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/protocol = "vt100"   (n0,r1)
/local/domain/0/backend/vif = ""   (n0)
/local/domain/0/backend/vif/1 = ""   (n0)
/local/domain/0/backend/vif/1/0 = ""   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend = "/local/domain/1/device/vif/0"   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/script = "/etc/xen/scripts/vif-bridge"   (n0,r1)
/local/domain/0/backend/vif/1/0/mac = "00:16:3e:aa:bb:cc"   (n0,r1)
/local/domain/0/backend/vif/1/0/bridge = "xenbr0"   (n0,r1)
/local/domain/0/backend/vif/1/0/handle = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/type = "vif"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-sg = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv4 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv6 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ipv6-csum-offload = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-copy = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-flip = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-dynamic-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-split-event-channels = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ctrl-ring = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/pci = ""   (n0)
/local/domain/0/backend/pci/1 = ""   (n0)
/local/domain/0/backend/pci/1/0 = ""   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend = "/local/domain/1/device/pci/0"   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/pci/1/0/domain = "arch-zfs-test"   (n0,r1)
/local/domain/0/backend/pci/1/0/key-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/dev-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0,r1)
/local/domain/0/backend/pci/1/0/state-0 = "3"   (n0,r1)
/local/domain/0/backend/pci/1/0/num_devs = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/vdev-0 = "0000:00:00.00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root-0 = "0000:00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root_num = "1"   (n0,r1)
/local/domain/0/device = ""   (n0)
/local/domain/0/device/vbd = ""   (n0)
/local/domain/0/device/vbd/51712 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/backend = "/local/domain/1/backend/vbd/0/51712"   (n0,r1)
/local/domain/0/device/vbd/51712/backend-id = "1"   (n0,r1)
/local/domain/0/device/vbd/51712/state = "4"   (n0,r1)
/local/domain/0/device/vbd/51712/virtual-device = "51712"   (n0,r1)
/local/domain/0/device/vbd/51712/device-type = "disk"   (n0,r1)
/local/domain/0/device/vbd/51712/protocol = "x86_64-abi"   (n0,r1)
/local/domain/0/device/vbd/51712/multi-queue-num-queues = "4"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0/ring-ref = "8"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0/event-channel = "79"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1/ring-ref = "9"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1/event-channel = "80"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2/ring-ref = "10"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2/event-channel = "81"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3/ring-ref = "11"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3/event-channel = "82"   (n0,r1)
/local/domain/0/device/vbd/51712/feature-persistent = "1"   (n0,r1)
/local/domain/1 = ""   (n0,r1)
/local/domain/1/vm = "/vm/59f752d2-7d5f-4aba-9411-302221c4e188"   (n0,r1)
/local/domain/1/name = "arch-zfs-test"   (n0,r1)
/local/domain/1/cpu = ""   (n0,r1)
/local/domain/1/cpu/0 = ""   (n0,r1)
/local/domain/1/cpu/0/availability = "online"   (n0,r1)
/local/domain/1/cpu/1 = ""   (n0,r1)
/local/domain/1/cpu/1/availability = "online"   (n0,r1)
/local/domain/1/cpu/2 = ""   (n0,r1)
/local/domain/1/cpu/2/availability = "online"   (n0,r1)
/local/domain/1/cpu/3 = ""   (n0,r1)
/local/domain/1/cpu/3/availability = "online"   (n0,r1)
/local/domain/1/memory = ""   (n0,r1)
/local/domain/1/memory/static-max = "33554432"   (n0,r1)
/local/domain/1/memory/target = "33554432"   (n0,r1)
/local/domain/1/memory/videoram = "0"   (n0,r1)
/local/domain/1/device = ""   (n0,r1)
/local/domain/1/device/suspend = ""   (n0,r1)
/local/domain/1/device/suspend/event-channel = ""   (n1)
/local/domain/1/device/vbd = ""   (n0,r1)
/local/domain/1/device/vbd/51712 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n1,r0)
/local/domain/1/device/vbd/51712/backend-id = "0"   (n1,r0)
/local/domain/1/device/vbd/51712/state = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/virtual-device = "51712"   (n1,r0)
/local/domain/1/device/vbd/51712/device-type = "disk"   (n1,r0)
/local/domain/1/device/vbd/51712/protocol = "x86_64-abi"   (n1,r0)
/local/domain/1/device/vbd/51712/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/ring-ref = "8"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/event-channel = "31"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/ring-ref = "9"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/event-channel = "32"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/ring-ref = "10"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/event-channel = "33"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/ring-ref = "11"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/event-channel = "34"   (n1,r0)
/local/domain/1/device/vbd/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/device/vif = ""   (n0,r1)
/local/domain/1/device/vif/0 = ""   (n1,r0)
/local/domain/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n1,r0)
/local/domain/1/device/vif/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/vif/0/state = "4"   (n1,r0)
/local/domain/1/device/vif/0/handle = "0"   (n1,r0)
/local/domain/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n1,r0)
/local/domain/1/device/vif/0/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vif/0/queue-0 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-0/tx-ring-ref = "2304"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/rx-ring-ref = "2305"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-tx = "35"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-rx = "36"   (n1,r0)
/local/domain/1/device/vif/0/queue-1 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-1/tx-ring-ref = "2306"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/rx-ring-ref = "2307"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-tx = "37"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-rx = "38"   (n1,r0)
/local/domain/1/device/vif/0/queue-2 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-2/tx-ring-ref = "2308"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/rx-ring-ref = "2309"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-tx = "39"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-rx = "40"   (n1,r0)
/local/domain/1/device/vif/0/queue-3 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-3/tx-ring-ref = "2310"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/rx-ring-ref = "2311"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-tx = "41"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-rx = "42"   (n1,r0)
/local/domain/1/device/vif/0/request-rx-copy = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-rx-notify = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-sg = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv4 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv6 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-ipv6-csum-offload = "1"   (n1,r0)
/local/domain/1/device/pci = ""   (n0,r1)
/local/domain/1/device/pci/0 = ""   (n1,r0)
/local/domain/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n1,r0)
/local/domain/1/device/pci/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/pci/0/state = "4"   (n1,r0)
/local/domain/1/device/pci/0/pci-op-ref = "361"   (n1,r0)
/local/domain/1/device/pci/0/event-channel = "43"   (n1,r0)
/local/domain/1/device/pci/0/magic = "7"   (n1,r0)
/local/domain/1/control = ""   (n0,r1)
/local/domain/1/control/shutdown = ""   (n1)
/local/domain/1/control/feature-poweroff = "1"   (n1)
/local/domain/1/control/feature-reboot = "1"   (n1)
/local/domain/1/control/feature-suspend = "1"   (n1)
/local/domain/1/control/platform-feature-multiprocessor-suspend = "1"   (n0,r1)
/local/domain/1/control/platform-feature-xs_reset_watches = "1"   (n0,r1)
/local/domain/1/data = ""   (n1)
/local/domain/1/drivers = ""   (n1)
/local/domain/1/feature = ""   (n1)
/local/domain/1/attr = ""   (n1)
/local/domain/1/libxl = ""   (n1)
/local/domain/1/device-model = ""   (n1)
/local/domain/1/domid = "1"   (n0,r1)
/local/domain/1/store = ""   (n0,r1)
/local/domain/1/store/port = "1"   (n0,r1)
/local/domain/1/store/ring-ref = "20014470"   (n0,r1)
/local/domain/1/console = ""   (n0,r1)
/local/domain/1/console/backend = "/local/domain/0/backend/console/1/0"   (n0,r1)
/local/domain/1/console/backend-id = "0"   (n1,r0)
/local/domain/1/console/limit = "1048576"   (n0,r1)
/local/domain/1/console/type = "xenconsoled"   (n0,r1)
/local/domain/1/console/output = "pty"   (n0,r1)
/local/domain/1/console/tty = "/dev/pts/1"   (n0,r1)
/local/domain/1/console/port = "2"   (n0,r1)
/local/domain/1/console/ring-ref = "20014471"   (n0,r1)
/local/domain/1/backend = ""   (n0,r1)
/local/domain/1/backend/vbd = ""   (n0,r1)
/local/domain/1/backend/vbd/0 = ""   (n0,r1)
/local/domain/1/backend/vbd/0/51712 = ""   (n1,r0)
/local/domain/1/backend/vbd/0/51712/frontend = "/local/domain/0/device/vbd/51712"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/params = "/dev/zvol/test_pool/test1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/script = "/etc/xen/scripts/block"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/frontend-id = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/online = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/removable = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/bootable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/state = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/dev = "xvda"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/type = "phy"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/mode = "w"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/device-type = "disk"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-enable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-max-indirect-segments = "256"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/multi-queue-max-queues = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/max-ring-page-order = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-device = "e6:0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-flush-cache = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-granularity = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-alignment = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-secure = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-discard = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-barrier = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/sectors = "419430400"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/info = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/sector-size = "512"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-sector-size = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-device-path = "/dev/zd0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/hotplug-status = "connected"   (n1,r0)
/libxl = ""   (n0)
/libxl/pciback = ""   (n0)
/libxl/pciback/0000-00-1f-2 = ""   (n0)
/libxl/pciback/0000-00-1f-2/driver_path = "/sys/bus/pci/drivers/ahci"   (n0)
/libxl/pciback/0000-01-00-0 = ""   (n0)
/libxl/pciback/0000-01-00-0/driver_path = "/sys/bus/pci/drivers/mpt3sas"   (n0)
/libxl/pciback/0000-06-00-0 = ""   (n0)
/libxl/pciback/0000-06-00-0/driver_path = "/sys/bus/pci/drivers/serial"   (n0)
/libxl/1 = ""   (n0)
/libxl/1/device = ""   (n0)
/libxl/1/device/vbd = ""   (n0)
/libxl/1/device/vbd/51712 = ""   (n0)
/libxl/1/device/vbd/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0)
/libxl/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n0)
/libxl/1/device/vbd/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0)
/libxl/1/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/1/device/vbd/51712/frontend-id = "1"   (n0)
/libxl/1/device/vbd/51712/online = "1"   (n0)
/libxl/1/device/vbd/51712/removable = "0"   (n0)
/libxl/1/device/vbd/51712/bootable = "1"   (n0)
/libxl/1/device/vbd/51712/state = "1"   (n0)
/libxl/1/device/vbd/51712/dev = "xvda"   (n0)
/libxl/1/device/vbd/51712/type = "phy"   (n0)
/libxl/1/device/vbd/51712/mode = "w"   (n0)
/libxl/1/device/vbd/51712/device-type = "disk"   (n0)
/libxl/1/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/1/device/console = ""   (n0)
/libxl/1/device/console/0 = ""   (n0)
/libxl/1/device/console/0/frontend = "/local/domain/1/console"   (n0)
/libxl/1/device/console/0/backend = "/local/domain/0/backend/console/1/0"   (n0)
/libxl/1/device/console/0/frontend-id = "1"   (n0)
/libxl/1/device/console/0/online = "1"   (n0)
/libxl/1/device/console/0/state = "1"   (n0)
/libxl/1/device/console/0/protocol = "vt100"   (n0)
/libxl/1/device/vif = ""   (n0)
/libxl/1/device/vif/0 = ""   (n0)
/libxl/1/device/vif/0/frontend = "/local/domain/1/device/vif/0"   (n0)
/libxl/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n0)
/libxl/1/device/vif/0/frontend-id = "1"   (n0)
/libxl/1/device/vif/0/online = "1"   (n0)
/libxl/1/device/vif/0/state = "1"   (n0)
/libxl/1/device/vif/0/script = "/etc/xen/scripts/vif-bridge"   (n0)
/libxl/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n0)
/libxl/1/device/vif/0/bridge = "xenbr0"   (n0)
/libxl/1/device/vif/0/handle = "0"   (n0)
/libxl/1/device/vif/0/type = "vif"   (n0)
/libxl/1/device/pci = ""   (n0)
/libxl/1/device/pci/0 = ""   (n0)
/libxl/1/device/pci/0/frontend = "/local/domain/1/device/pci/0"   (n0)
/libxl/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n0)
/libxl/1/device/pci/0/frontend-id = "1"   (n0)
/libxl/1/device/pci/0/online = "1"   (n0)
/libxl/1/device/pci/0/state = "1"   (n0)
/libxl/1/device/pci/0/domain = "arch-zfs-test"   (n0)
/libxl/1/device/pci/0/key-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/dev-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0)
/libxl/1/device/pci/0/state-0 = "1"   (n0)
/libxl/1/device/pci/0/num_devs = "1"   (n0)
/libxl/1/dm-version = "qemu_xen"   (n0)
/libxl/0 = ""   (n0)
/libxl/0/device = ""   (n0)
/libxl/0/device/vbd = ""   (n0)
/libxl/0/device/vbd/51712 = ""   (n0)
/libxl/0/device/vbd/51712/frontend = "/local/domain/0/device/vbd/51712"   (n0)
/libxl/0/device/vbd/51712/backend = "/local/domain/1/backend/vbd/0/51712"   (n0)
/libxl/0/device/vbd/51712/params = "/dev/zvol/test_pool/test1"   (n0)
/libxl/0/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/0/device/vbd/51712/frontend-id = "0"   (n0)
/libxl/0/device/vbd/51712/online = "1"   (n0)
/libxl/0/device/vbd/51712/removable = "0"   (n0)
/libxl/0/device/vbd/51712/bootable = "1"   (n0)
/libxl/0/device/vbd/51712/state = "1"   (n0)
/libxl/0/device/vbd/51712/dev = "xvda"   (n0)
/libxl/0/device/vbd/51712/type = "phy"   (n0)
/libxl/0/device/vbd/51712/mode = "w"   (n0)
/libxl/0/device/vbd/51712/device-type = "disk"   (n0)
/libxl/0/device/vbd/51712/discard-enable = "1"   (n0)
/vm = ""   (n0)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188 = ""   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/name = "arch-zfs-test"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/uuid = "59f752d2-7d5f-4aba-9411-302221c4e188"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image = ""   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/ostype = "linux"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/kernel = "/run/xen/bootloader.1.d/boot_kernel.M1Zoy1"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/ramdisk = "/run/xen/bootloader.1.d/boot_ramdisk.4o1QjN"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/cmdline = "root=UUID=c4e5bb0c-5638-45f6-a90a-0107cc97506b ro"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/start_time = "1493767063.02"   (n0,r1)

# After the 2nd `xl block-attach` command:

/local = ""   (n0)
/local/domain = ""   (n0)
/local/domain/0 = ""   (n0)
/local/domain/0/control = ""   (n0)
/local/domain/0/control/feature-poweroff = "1"   (n0)
/local/domain/0/control/feature-reboot = "1"   (n0)
/local/domain/0/control/feature-suspend = "1"   (n0)
/local/domain/0/domid = "0"   (n0)
/local/domain/0/name = "Domain-0"   (n0)
/local/domain/0/device-model = ""   (n0)
/local/domain/0/device-model/0 = ""   (n0)
/local/domain/0/device-model/0/backends = ""   (n0)
/local/domain/0/device-model/0/backends/console = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vkbd = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qdisk = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qusb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vfb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qnic = ""   (n0,n0)
/local/domain/0/device-model/0/state = "running"   (n0)
/local/domain/0/backend = ""   (n0)
/local/domain/0/backend/vbd = ""   (n0)
/local/domain/0/backend/vbd/1 = ""   (n0)
/local/domain/0/backend/vbd/1/51712 = ""   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/script = "/etc/xen/scripts/block"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/online = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/removable = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/bootable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/state = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/dev = "xvda"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/type = "phy"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/mode = "w"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/device-type = "disk"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-enable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-max-indirect-segments = "256"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/max-ring-page-order = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device = "fe:22"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device-path = "/dev/dm-34"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-flush-cache = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-granularity = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-alignment = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-secure = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-discard = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-barrier = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sectors = "16777216"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/info = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sector-size = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-sector-size = "512"   (n0,r1)
/local/domain/0/backend/console = ""   (n0)
/local/domain/0/backend/console/1 = ""   (n0)
/local/domain/0/backend/console/1/0 = ""   (n0,r1)
/local/domain/0/backend/console/1/0/frontend = "/local/domain/1/console"   (n0,r1)
/local/domain/0/backend/console/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/state = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/protocol = "vt100"   (n0,r1)
/local/domain/0/backend/vif = ""   (n0)
/local/domain/0/backend/vif/1 = ""   (n0)
/local/domain/0/backend/vif/1/0 = ""   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend = "/local/domain/1/device/vif/0"   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/script = "/etc/xen/scripts/vif-bridge"   (n0,r1)
/local/domain/0/backend/vif/1/0/mac = "00:16:3e:aa:bb:cc"   (n0,r1)
/local/domain/0/backend/vif/1/0/bridge = "xenbr0"   (n0,r1)
/local/domain/0/backend/vif/1/0/handle = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/type = "vif"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-sg = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv4 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv6 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ipv6-csum-offload = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-copy = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-flip = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-dynamic-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-split-event-channels = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ctrl-ring = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/pci = ""   (n0)
/local/domain/0/backend/pci/1 = ""   (n0)
/local/domain/0/backend/pci/1/0 = ""   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend = "/local/domain/1/device/pci/0"   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/pci/1/0/domain = "arch-zfs-test"   (n0,r1)
/local/domain/0/backend/pci/1/0/key-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/dev-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0,r1)
/local/domain/0/backend/pci/1/0/state-0 = "3"   (n0,r1)
/local/domain/0/backend/pci/1/0/num_devs = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/vdev-0 = "0000:00:00.00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root-0 = "0000:00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root_num = "1"   (n0,r1)
/local/domain/0/device = ""   (n0)
/local/domain/0/device/vbd = ""   (n0)
/local/domain/0/device/vbd/51712 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/backend = "/local/domain/1/backend/vbd/0/51712"   (n0,r1)
/local/domain/0/device/vbd/51712/backend-id = "1"   (n0,r1)
/local/domain/0/device/vbd/51712/state = "4"   (n0,r1)
/local/domain/0/device/vbd/51712/virtual-device = "51712"   (n0,r1)
/local/domain/0/device/vbd/51712/device-type = "disk"   (n0,r1)
/local/domain/0/device/vbd/51712/protocol = "x86_64-abi"   (n0,r1)
/local/domain/0/device/vbd/51712/multi-queue-num-queues = "4"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0/ring-ref = "8"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0/event-channel = "79"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1/ring-ref = "9"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1/event-channel = "80"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2/ring-ref = "10"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2/event-channel = "81"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3/ring-ref = "11"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3/event-channel = "82"   (n0,r1)
/local/domain/0/device/vbd/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/device/vbd/51728 = ""   (n0,r1)
/local/domain/0/device/vbd/51728/backend = "/local/domain/1/backend/vbd/0/51728"   (n0,r1)
/local/domain/0/device/vbd/51728/backend-id = "1"   (n0,r1)
/local/domain/0/device/vbd/51728/state = "4"   (n0,r1)
/local/domain/0/device/vbd/51728/virtual-device = "51728"   (n0,r1)
/local/domain/0/device/vbd/51728/device-type = "disk"   (n0,r1)
/local/domain/0/device/vbd/51728/protocol = "x86_64-abi"   (n0,r1)
/local/domain/0/device/vbd/51728/ring-ref = "80"   (n0,r1)
/local/domain/0/device/vbd/51728/event-channel = "83"   (n0,r1)
/local/domain/0/device/vbd/51728/feature-persistent = "1"   (n0,r1)
/local/domain/1 = ""   (n0,r1)
/local/domain/1/vm = "/vm/59f752d2-7d5f-4aba-9411-302221c4e188"   (n0,r1)
/local/domain/1/name = "arch-zfs-test"   (n0,r1)
/local/domain/1/cpu = ""   (n0,r1)
/local/domain/1/cpu/0 = ""   (n0,r1)
/local/domain/1/cpu/0/availability = "online"   (n0,r1)
/local/domain/1/cpu/1 = ""   (n0,r1)
/local/domain/1/cpu/1/availability = "online"   (n0,r1)
/local/domain/1/cpu/2 = ""   (n0,r1)
/local/domain/1/cpu/2/availability = "online"   (n0,r1)
/local/domain/1/cpu/3 = ""   (n0,r1)
/local/domain/1/cpu/3/availability = "online"   (n0,r1)
/local/domain/1/memory = ""   (n0,r1)
/local/domain/1/memory/static-max = "33554432"   (n0,r1)
/local/domain/1/memory/target = "33554432"   (n0,r1)
/local/domain/1/memory/videoram = "0"   (n0,r1)
/local/domain/1/device = ""   (n0,r1)
/local/domain/1/device/suspend = ""   (n0,r1)
/local/domain/1/device/suspend/event-channel = ""   (n1)
/local/domain/1/device/vbd = ""   (n0,r1)
/local/domain/1/device/vbd/51712 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n1,r0)
/local/domain/1/device/vbd/51712/backend-id = "0"   (n1,r0)
/local/domain/1/device/vbd/51712/state = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/virtual-device = "51712"   (n1,r0)
/local/domain/1/device/vbd/51712/device-type = "disk"   (n1,r0)
/local/domain/1/device/vbd/51712/protocol = "x86_64-abi"   (n1,r0)
/local/domain/1/device/vbd/51712/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/ring-ref = "8"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/event-channel = "31"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/ring-ref = "9"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/event-channel = "32"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/ring-ref = "10"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/event-channel = "33"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/ring-ref = "11"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/event-channel = "34"   (n1,r0)
/local/domain/1/device/vbd/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/device/vif = ""   (n0,r1)
/local/domain/1/device/vif/0 = ""   (n1,r0)
/local/domain/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n1,r0)
/local/domain/1/device/vif/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/vif/0/state = "4"   (n1,r0)
/local/domain/1/device/vif/0/handle = "0"   (n1,r0)
/local/domain/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n1,r0)
/local/domain/1/device/vif/0/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vif/0/queue-0 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-0/tx-ring-ref = "2304"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/rx-ring-ref = "2305"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-tx = "35"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-rx = "36"   (n1,r0)
/local/domain/1/device/vif/0/queue-1 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-1/tx-ring-ref = "2306"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/rx-ring-ref = "2307"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-tx = "37"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-rx = "38"   (n1,r0)
/local/domain/1/device/vif/0/queue-2 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-2/tx-ring-ref = "2308"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/rx-ring-ref = "2309"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-tx = "39"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-rx = "40"   (n1,r0)
/local/domain/1/device/vif/0/queue-3 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-3/tx-ring-ref = "2310"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/rx-ring-ref = "2311"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-tx = "41"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-rx = "42"   (n1,r0)
/local/domain/1/device/vif/0/request-rx-copy = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-rx-notify = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-sg = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv4 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv6 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-ipv6-csum-offload = "1"   (n1,r0)
/local/domain/1/device/pci = ""   (n0,r1)
/local/domain/1/device/pci/0 = ""   (n1,r0)
/local/domain/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n1,r0)
/local/domain/1/device/pci/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/pci/0/state = "4"   (n1,r0)
/local/domain/1/device/pci/0/pci-op-ref = "361"   (n1,r0)
/local/domain/1/device/pci/0/event-channel = "43"   (n1,r0)
/local/domain/1/device/pci/0/magic = "7"   (n1,r0)
/local/domain/1/control = ""   (n0,r1)
/local/domain/1/control/shutdown = ""   (n1)
/local/domain/1/control/feature-poweroff = "1"   (n1)
/local/domain/1/control/feature-reboot = "1"   (n1)
/local/domain/1/control/feature-suspend = "1"   (n1)
/local/domain/1/control/platform-feature-multiprocessor-suspend = "1"   (n0,r1)
/local/domain/1/control/platform-feature-xs_reset_watches = "1"   (n0,r1)
/local/domain/1/data = ""   (n1)
/local/domain/1/drivers = ""   (n1)
/local/domain/1/feature = ""   (n1)
/local/domain/1/attr = ""   (n1)
/local/domain/1/libxl = ""   (n1)
/local/domain/1/device-model = ""   (n1)
/local/domain/1/domid = "1"   (n0,r1)
/local/domain/1/store = ""   (n0,r1)
/local/domain/1/store/port = "1"   (n0,r1)
/local/domain/1/store/ring-ref = "20014470"   (n0,r1)
/local/domain/1/console = ""   (n0,r1)
/local/domain/1/console/backend = "/local/domain/0/backend/console/1/0"   (n0,r1)
/local/domain/1/console/backend-id = "0"   (n1,r0)
/local/domain/1/console/limit = "1048576"   (n0,r1)
/local/domain/1/console/type = "xenconsoled"   (n0,r1)
/local/domain/1/console/output = "pty"   (n0,r1)
/local/domain/1/console/tty = "/dev/pts/1"   (n0,r1)
/local/domain/1/console/port = "2"   (n0,r1)
/local/domain/1/console/ring-ref = "20014471"   (n0,r1)
/local/domain/1/backend = ""   (n0,r1)
/local/domain/1/backend/vbd = ""   (n0,r1)
/local/domain/1/backend/vbd/0 = ""   (n0,r1)
/local/domain/1/backend/vbd/0/51712 = ""   (n1,r0)
/local/domain/1/backend/vbd/0/51712/frontend = "/local/domain/0/device/vbd/51712"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/params = "/dev/zvol/test_pool/test1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/script = "/etc/xen/scripts/block"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/frontend-id = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/online = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/removable = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/bootable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/state = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/dev = "xvda"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/type = "phy"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/mode = "w"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/device-type = "disk"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-enable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-max-indirect-segments = "256"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/multi-queue-max-queues = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/max-ring-page-order = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-device = "e6:0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-flush-cache = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-granularity = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-alignment = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-secure = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-discard = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-barrier = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/sectors = "419430400"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/info = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/sector-size = "512"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-sector-size = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-device-path = "/dev/zd0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/hotplug-status = "connected"   (n1,r0)
/local/domain/1/backend/vbd/0/51728 = ""   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend = "/local/domain/0/device/vbd/51728"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/params = "/dev/zvol/test_pool/test2"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/script = "/etc/xen/scripts/block"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend-id = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/online = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/removable = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/bootable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/state = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/dev = "xvdb"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/type = "phy"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/mode = "w"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/device-type = "disk"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-enable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-max-indirect-segments = "256"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/multi-queue-max-queues = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/max-ring-page-order = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device = "e6:20"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-flush-cache = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-granularity = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-alignment = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-secure = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-discard = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-barrier = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-persistent = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sectors = "209715200"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/info = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sector-size = "512"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-sector-size = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device-path = "/dev/zd32"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/hotplug-status = "connected"   (n1,r0)
/libxl = ""   (n0)
/libxl/pciback = ""   (n0)
/libxl/pciback/0000-00-1f-2 = ""   (n0)
/libxl/pciback/0000-00-1f-2/driver_path = "/sys/bus/pci/drivers/ahci"   (n0)
/libxl/pciback/0000-01-00-0 = ""   (n0)
/libxl/pciback/0000-01-00-0/driver_path = "/sys/bus/pci/drivers/mpt3sas"   (n0)
/libxl/pciback/0000-06-00-0 = ""   (n0)
/libxl/pciback/0000-06-00-0/driver_path = "/sys/bus/pci/drivers/serial"   (n0)
/libxl/1 = ""   (n0)
/libxl/1/device = ""   (n0)
/libxl/1/device/vbd = ""   (n0)
/libxl/1/device/vbd/51712 = ""   (n0)
/libxl/1/device/vbd/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0)
/libxl/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n0)
/libxl/1/device/vbd/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0)
/libxl/1/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/1/device/vbd/51712/frontend-id = "1"   (n0)
/libxl/1/device/vbd/51712/online = "1"   (n0)
/libxl/1/device/vbd/51712/removable = "0"   (n0)
/libxl/1/device/vbd/51712/bootable = "1"   (n0)
/libxl/1/device/vbd/51712/state = "1"   (n0)
/libxl/1/device/vbd/51712/dev = "xvda"   (n0)
/libxl/1/device/vbd/51712/type = "phy"   (n0)
/libxl/1/device/vbd/51712/mode = "w"   (n0)
/libxl/1/device/vbd/51712/device-type = "disk"   (n0)
/libxl/1/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/1/device/console = ""   (n0)
/libxl/1/device/console/0 = ""   (n0)
/libxl/1/device/console/0/frontend = "/local/domain/1/console"   (n0)
/libxl/1/device/console/0/backend = "/local/domain/0/backend/console/1/0"   (n0)
/libxl/1/device/console/0/frontend-id = "1"   (n0)
/libxl/1/device/console/0/online = "1"   (n0)
/libxl/1/device/console/0/state = "1"   (n0)
/libxl/1/device/console/0/protocol = "vt100"   (n0)
/libxl/1/device/vif = ""   (n0)
/libxl/1/device/vif/0 = ""   (n0)
/libxl/1/device/vif/0/frontend = "/local/domain/1/device/vif/0"   (n0)
/libxl/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n0)
/libxl/1/device/vif/0/frontend-id = "1"   (n0)
/libxl/1/device/vif/0/online = "1"   (n0)
/libxl/1/device/vif/0/state = "1"   (n0)
/libxl/1/device/vif/0/script = "/etc/xen/scripts/vif-bridge"   (n0)
/libxl/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n0)
/libxl/1/device/vif/0/bridge = "xenbr0"   (n0)
/libxl/1/device/vif/0/handle = "0"   (n0)
/libxl/1/device/vif/0/type = "vif"   (n0)
/libxl/1/device/pci = ""   (n0)
/libxl/1/device/pci/0 = ""   (n0)
/libxl/1/device/pci/0/frontend = "/local/domain/1/device/pci/0"   (n0)
/libxl/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n0)
/libxl/1/device/pci/0/frontend-id = "1"   (n0)
/libxl/1/device/pci/0/online = "1"   (n0)
/libxl/1/device/pci/0/state = "1"   (n0)
/libxl/1/device/pci/0/domain = "arch-zfs-test"   (n0)
/libxl/1/device/pci/0/key-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/dev-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0)
/libxl/1/device/pci/0/state-0 = "1"   (n0)
/libxl/1/device/pci/0/num_devs = "1"   (n0)
/libxl/1/dm-version = "qemu_xen"   (n0)
/libxl/0 = ""   (n0)
/libxl/0/device = ""   (n0)
/libxl/0/device/vbd = ""   (n0)
/libxl/0/device/vbd/51712 = ""   (n0)
/libxl/0/device/vbd/51712/frontend = "/local/domain/0/device/vbd/51712"   (n0)
/libxl/0/device/vbd/51712/backend = "/local/domain/1/backend/vbd/0/51712"   (n0)
/libxl/0/device/vbd/51712/params = "/dev/zvol/test_pool/test1"   (n0)
/libxl/0/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/0/device/vbd/51712/frontend-id = "0"   (n0)
/libxl/0/device/vbd/51712/online = "1"   (n0)
/libxl/0/device/vbd/51712/removable = "0"   (n0)
/libxl/0/device/vbd/51712/bootable = "1"   (n0)
/libxl/0/device/vbd/51712/state = "1"   (n0)
/libxl/0/device/vbd/51712/dev = "xvda"   (n0)
/libxl/0/device/vbd/51712/type = "phy"   (n0)
/libxl/0/device/vbd/51712/mode = "w"   (n0)
/libxl/0/device/vbd/51712/device-type = "disk"   (n0)
/libxl/0/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/0/device/vbd/51728 = ""   (n0)
/libxl/0/device/vbd/51728/frontend = "/local/domain/0/device/vbd/51728"   (n0)
/libxl/0/device/vbd/51728/backend = "/local/domain/1/backend/vbd/0/51728"   (n0)
/libxl/0/device/vbd/51728/params = "/dev/zvol/test_pool/test2"   (n0)
/libxl/0/device/vbd/51728/script = "/etc/xen/scripts/block"   (n0)
/libxl/0/device/vbd/51728/frontend-id = "0"   (n0)
/libxl/0/device/vbd/51728/online = "1"   (n0)
/libxl/0/device/vbd/51728/removable = "0"   (n0)
/libxl/0/device/vbd/51728/bootable = "1"   (n0)
/libxl/0/device/vbd/51728/state = "1"   (n0)
/libxl/0/device/vbd/51728/dev = "xvdb"   (n0)
/libxl/0/device/vbd/51728/type = "phy"   (n0)
/libxl/0/device/vbd/51728/mode = "w"   (n0)
/libxl/0/device/vbd/51728/device-type = "disk"   (n0)
/libxl/0/device/vbd/51728/discard-enable = "1"   (n0)
/vm = ""   (n0)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188 = ""   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/name = "arch-zfs-test"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/uuid = "59f752d2-7d5f-4aba-9411-302221c4e188"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image = ""   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/ostype = "linux"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/kernel = "/run/xen/bootloader.1.d/boot_kernel.M1Zoy1"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/ramdisk = "/run/xen/bootloader.1.d/boot_ramdisk.4o1QjN"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/cmdline = "root=UUID=c4e5bb0c-5638-45f6-a90a-0107cc97506b ro"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/start_time = "1493767063.02"   (n0,r1)

# After the 1st `xl block-detach` command:

/local = ""   (n0)
/local/domain = ""   (n0)
/local/domain/0 = ""   (n0)
/local/domain/0/control = ""   (n0)
/local/domain/0/control/feature-poweroff = "1"   (n0)
/local/domain/0/control/feature-reboot = "1"   (n0)
/local/domain/0/control/feature-suspend = "1"   (n0)
/local/domain/0/domid = "0"   (n0)
/local/domain/0/name = "Domain-0"   (n0)
/local/domain/0/device-model = ""   (n0)
/local/domain/0/device-model/0 = ""   (n0)
/local/domain/0/device-model/0/backends = ""   (n0)
/local/domain/0/device-model/0/backends/console = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vkbd = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qdisk = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qusb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vfb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qnic = ""   (n0,n0)
/local/domain/0/device-model/0/state = "running"   (n0)
/local/domain/0/backend = ""   (n0)
/local/domain/0/backend/vbd = ""   (n0)
/local/domain/0/backend/vbd/1 = ""   (n0)
/local/domain/0/backend/vbd/1/51712 = ""   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/script = "/etc/xen/scripts/block"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/online = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/removable = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/bootable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/state = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/dev = "xvda"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/type = "phy"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/mode = "w"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/device-type = "disk"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-enable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-max-indirect-segments = "256"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/max-ring-page-order = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device = "fe:22"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device-path = "/dev/dm-34"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-flush-cache = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-granularity = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-alignment = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-secure = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-discard = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-barrier = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sectors = "16777216"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/info = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sector-size = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-sector-size = "512"   (n0,r1)
/local/domain/0/backend/console = ""   (n0)
/local/domain/0/backend/console/1 = ""   (n0)
/local/domain/0/backend/console/1/0 = ""   (n0,r1)
/local/domain/0/backend/console/1/0/frontend = "/local/domain/1/console"   (n0,r1)
/local/domain/0/backend/console/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/state = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/protocol = "vt100"   (n0,r1)
/local/domain/0/backend/vif = ""   (n0)
/local/domain/0/backend/vif/1 = ""   (n0)
/local/domain/0/backend/vif/1/0 = ""   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend = "/local/domain/1/device/vif/0"   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/script = "/etc/xen/scripts/vif-bridge"   (n0,r1)
/local/domain/0/backend/vif/1/0/mac = "00:16:3e:aa:bb:cc"   (n0,r1)
/local/domain/0/backend/vif/1/0/bridge = "xenbr0"   (n0,r1)
/local/domain/0/backend/vif/1/0/handle = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/type = "vif"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-sg = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv4 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv6 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ipv6-csum-offload = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-copy = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-flip = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-dynamic-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-split-event-channels = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ctrl-ring = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/pci = ""   (n0)
/local/domain/0/backend/pci/1 = ""   (n0)
/local/domain/0/backend/pci/1/0 = ""   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend = "/local/domain/1/device/pci/0"   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/pci/1/0/domain = "arch-zfs-test"   (n0,r1)
/local/domain/0/backend/pci/1/0/key-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/dev-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0,r1)
/local/domain/0/backend/pci/1/0/state-0 = "3"   (n0,r1)
/local/domain/0/backend/pci/1/0/num_devs = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/vdev-0 = "0000:00:00.00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root-0 = "0000:00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root_num = "1"   (n0,r1)
/local/domain/0/device = ""   (n0)
/local/domain/0/device/vbd = ""   (n0)
/local/domain/0/device/vbd/51728 = ""   (n0,r1)
/local/domain/0/device/vbd/51728/backend = "/local/domain/1/backend/vbd/0/51728"   (n0,r1)
/local/domain/0/device/vbd/51728/backend-id = "1"   (n0,r1)
/local/domain/0/device/vbd/51728/state = "4"   (n0,r1)
/local/domain/0/device/vbd/51728/virtual-device = "51728"   (n0,r1)
/local/domain/0/device/vbd/51728/device-type = "disk"   (n0,r1)
/local/domain/0/device/vbd/51728/protocol = "x86_64-abi"   (n0,r1)
/local/domain/0/device/vbd/51728/ring-ref = "80"   (n0,r1)
/local/domain/0/device/vbd/51728/event-channel = "83"   (n0,r1)
/local/domain/0/device/vbd/51728/feature-persistent = "1"   (n0,r1)
/local/domain/1 = ""   (n0,r1)
/local/domain/1/vm = "/vm/59f752d2-7d5f-4aba-9411-302221c4e188"   (n0,r1)
/local/domain/1/name = "arch-zfs-test"   (n0,r1)
/local/domain/1/cpu = ""   (n0,r1)
/local/domain/1/cpu/0 = ""   (n0,r1)
/local/domain/1/cpu/0/availability = "online"   (n0,r1)
/local/domain/1/cpu/1 = ""   (n0,r1)
/local/domain/1/cpu/1/availability = "online"   (n0,r1)
/local/domain/1/cpu/2 = ""   (n0,r1)
/local/domain/1/cpu/2/availability = "online"   (n0,r1)
/local/domain/1/cpu/3 = ""   (n0,r1)
/local/domain/1/cpu/3/availability = "online"   (n0,r1)
/local/domain/1/memory = ""   (n0,r1)
/local/domain/1/memory/static-max = "33554432"   (n0,r1)
/local/domain/1/memory/target = "33554432"   (n0,r1)
/local/domain/1/memory/videoram = "0"   (n0,r1)
/local/domain/1/device = ""   (n0,r1)
/local/domain/1/device/suspend = ""   (n0,r1)
/local/domain/1/device/suspend/event-channel = ""   (n1)
/local/domain/1/device/vbd = ""   (n0,r1)
/local/domain/1/device/vbd/51712 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n1,r0)
/local/domain/1/device/vbd/51712/backend-id = "0"   (n1,r0)
/local/domain/1/device/vbd/51712/state = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/virtual-device = "51712"   (n1,r0)
/local/domain/1/device/vbd/51712/device-type = "disk"   (n1,r0)
/local/domain/1/device/vbd/51712/protocol = "x86_64-abi"   (n1,r0)
/local/domain/1/device/vbd/51712/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/ring-ref = "8"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/event-channel = "31"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/ring-ref = "9"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/event-channel = "32"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/ring-ref = "10"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/event-channel = "33"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/ring-ref = "11"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/event-channel = "34"   (n1,r0)
/local/domain/1/device/vbd/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/device/vif = ""   (n0,r1)
/local/domain/1/device/vif/0 = ""   (n1,r0)
/local/domain/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n1,r0)
/local/domain/1/device/vif/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/vif/0/state = "4"   (n1,r0)
/local/domain/1/device/vif/0/handle = "0"   (n1,r0)
/local/domain/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n1,r0)
/local/domain/1/device/vif/0/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vif/0/queue-0 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-0/tx-ring-ref = "2304"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/rx-ring-ref = "2305"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-tx = "35"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-rx = "36"   (n1,r0)
/local/domain/1/device/vif/0/queue-1 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-1/tx-ring-ref = "2306"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/rx-ring-ref = "2307"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-tx = "37"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-rx = "38"   (n1,r0)
/local/domain/1/device/vif/0/queue-2 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-2/tx-ring-ref = "2308"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/rx-ring-ref = "2309"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-tx = "39"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-rx = "40"   (n1,r0)
/local/domain/1/device/vif/0/queue-3 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-3/tx-ring-ref = "2310"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/rx-ring-ref = "2311"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-tx = "41"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-rx = "42"   (n1,r0)
/local/domain/1/device/vif/0/request-rx-copy = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-rx-notify = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-sg = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv4 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv6 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-ipv6-csum-offload = "1"   (n1,r0)
/local/domain/1/device/pci = ""   (n0,r1)
/local/domain/1/device/pci/0 = ""   (n1,r0)
/local/domain/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n1,r0)
/local/domain/1/device/pci/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/pci/0/state = "4"   (n1,r0)
/local/domain/1/device/pci/0/pci-op-ref = "361"   (n1,r0)
/local/domain/1/device/pci/0/event-channel = "43"   (n1,r0)
/local/domain/1/device/pci/0/magic = "7"   (n1,r0)
/local/domain/1/control = ""   (n0,r1)
/local/domain/1/control/shutdown = ""   (n1)
/local/domain/1/control/feature-poweroff = "1"   (n1)
/local/domain/1/control/feature-reboot = "1"   (n1)
/local/domain/1/control/feature-suspend = "1"   (n1)
/local/domain/1/control/platform-feature-multiprocessor-suspend = "1"   (n0,r1)
/local/domain/1/control/platform-feature-xs_reset_watches = "1"   (n0,r1)
/local/domain/1/data = ""   (n1)
/local/domain/1/drivers = ""   (n1)
/local/domain/1/feature = ""   (n1)
/local/domain/1/attr = ""   (n1)
/local/domain/1/libxl = ""   (n1)
/local/domain/1/device-model = ""   (n1)
/local/domain/1/domid = "1"   (n0,r1)
/local/domain/1/store = ""   (n0,r1)
/local/domain/1/store/port = "1"   (n0,r1)
/local/domain/1/store/ring-ref = "20014470"   (n0,r1)
/local/domain/1/console = ""   (n0,r1)
/local/domain/1/console/backend = "/local/domain/0/backend/console/1/0"   (n0,r1)
/local/domain/1/console/backend-id = "0"   (n1,r0)
/local/domain/1/console/limit = "1048576"   (n0,r1)
/local/domain/1/console/type = "xenconsoled"   (n0,r1)
/local/domain/1/console/output = "pty"   (n0,r1)
/local/domain/1/console/tty = "/dev/pts/1"   (n0,r1)
/local/domain/1/console/port = "2"   (n0,r1)
/local/domain/1/console/ring-ref = "20014471"   (n0,r1)
/local/domain/1/backend = ""   (n0,r1)
/local/domain/1/backend/vbd = ""   (n0,r1)
/local/domain/1/backend/vbd/0 = ""   (n0,r1)
/local/domain/1/backend/vbd/0/51728 = ""   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend = "/local/domain/0/device/vbd/51728"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/params = "/dev/zvol/test_pool/test2"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/script = "/etc/xen/scripts/block"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend-id = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/online = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/removable = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/bootable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/state = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/dev = "xvdb"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/type = "phy"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/mode = "w"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/device-type = "disk"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-enable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-max-indirect-segments = "256"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/multi-queue-max-queues = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/max-ring-page-order = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device = "e6:20"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-flush-cache = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-granularity = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-alignment = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-secure = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-discard = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-barrier = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-persistent = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sectors = "209715200"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/info = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sector-size = "512"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-sector-size = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device-path = "/dev/zd32"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/hotplug-status = "connected"   (n1,r0)
/libxl = ""   (n0)
/libxl/pciback = ""   (n0)
/libxl/pciback/0000-00-1f-2 = ""   (n0)
/libxl/pciback/0000-00-1f-2/driver_path = "/sys/bus/pci/drivers/ahci"   (n0)
/libxl/pciback/0000-01-00-0 = ""   (n0)
/libxl/pciback/0000-01-00-0/driver_path = "/sys/bus/pci/drivers/mpt3sas"   (n0)
/libxl/pciback/0000-06-00-0 = ""   (n0)
/libxl/pciback/0000-06-00-0/driver_path = "/sys/bus/pci/drivers/serial"   (n0)
/libxl/1 = ""   (n0)
/libxl/1/device = ""   (n0)
/libxl/1/device/vbd = ""   (n0)
/libxl/1/device/vbd/51712 = ""   (n0)
/libxl/1/device/vbd/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0)
/libxl/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n0)
/libxl/1/device/vbd/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0)
/libxl/1/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/1/device/vbd/51712/frontend-id = "1"   (n0)
/libxl/1/device/vbd/51712/online = "1"   (n0)
/libxl/1/device/vbd/51712/removable = "0"   (n0)
/libxl/1/device/vbd/51712/bootable = "1"   (n0)
/libxl/1/device/vbd/51712/state = "1"   (n0)
/libxl/1/device/vbd/51712/dev = "xvda"   (n0)
/libxl/1/device/vbd/51712/type = "phy"   (n0)
/libxl/1/device/vbd/51712/mode = "w"   (n0)
/libxl/1/device/vbd/51712/device-type = "disk"   (n0)
/libxl/1/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/1/device/console = ""   (n0)
/libxl/1/device/console/0 = ""   (n0)
/libxl/1/device/console/0/frontend = "/local/domain/1/console"   (n0)
/libxl/1/device/console/0/backend = "/local/domain/0/backend/console/1/0"   (n0)
/libxl/1/device/console/0/frontend-id = "1"   (n0)
/libxl/1/device/console/0/online = "1"   (n0)
/libxl/1/device/console/0/state = "1"   (n0)
/libxl/1/device/console/0/protocol = "vt100"   (n0)
/libxl/1/device/vif = ""   (n0)
/libxl/1/device/vif/0 = ""   (n0)
/libxl/1/device/vif/0/frontend = "/local/domain/1/device/vif/0"   (n0)
/libxl/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n0)
/libxl/1/device/vif/0/frontend-id = "1"   (n0)
/libxl/1/device/vif/0/online = "1"   (n0)
/libxl/1/device/vif/0/state = "1"   (n0)
/libxl/1/device/vif/0/script = "/etc/xen/scripts/vif-bridge"   (n0)
/libxl/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n0)
/libxl/1/device/vif/0/bridge = "xenbr0"   (n0)
/libxl/1/device/vif/0/handle = "0"   (n0)
/libxl/1/device/vif/0/type = "vif"   (n0)
/libxl/1/device/pci = ""   (n0)
/libxl/1/device/pci/0 = ""   (n0)
/libxl/1/device/pci/0/frontend = "/local/domain/1/device/pci/0"   (n0)
/libxl/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n0)
/libxl/1/device/pci/0/frontend-id = "1"   (n0)
/libxl/1/device/pci/0/online = "1"   (n0)
/libxl/1/device/pci/0/state = "1"   (n0)
/libxl/1/device/pci/0/domain = "arch-zfs-test"   (n0)
/libxl/1/device/pci/0/key-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/dev-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0)
/libxl/1/device/pci/0/state-0 = "1"   (n0)
/libxl/1/device/pci/0/num_devs = "1"   (n0)
/libxl/1/dm-version = "qemu_xen"   (n0)
/libxl/0 = ""   (n0)
/libxl/0/device = ""   (n0)
/libxl/0/device/vbd = ""   (n0)
/libxl/0/device/vbd/51728 = ""   (n0)
/libxl/0/device/vbd/51728/frontend = "/local/domain/0/device/vbd/51728"   (n0)
/libxl/0/device/vbd/51728/backend = "/local/domain/1/backend/vbd/0/51728"   (n0)
/libxl/0/device/vbd/51728/params = "/dev/zvol/test_pool/test2"   (n0)
/libxl/0/device/vbd/51728/script = "/etc/xen/scripts/block"   (n0)
/libxl/0/device/vbd/51728/frontend-id = "0"   (n0)
/libxl/0/device/vbd/51728/online = "1"   (n0)
/libxl/0/device/vbd/51728/removable = "0"   (n0)
/libxl/0/device/vbd/51728/bootable = "1"   (n0)
/libxl/0/device/vbd/51728/state = "1"   (n0)
/libxl/0/device/vbd/51728/dev = "xvdb"   (n0)
/libxl/0/device/vbd/51728/type = "phy"   (n0)
/libxl/0/device/vbd/51728/mode = "w"   (n0)
/libxl/0/device/vbd/51728/device-type = "disk"   (n0)
/libxl/0/device/vbd/51728/discard-enable = "1"   (n0)
/vm = ""   (n0)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188 = ""   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/name = "arch-zfs-test"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/uuid = "59f752d2-7d5f-4aba-9411-302221c4e188"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image = ""   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/ostype = "linux"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/kernel = "/run/xen/bootloader.1.d/boot_kernel.M1Zoy1"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/ramdisk = "/run/xen/bootloader.1.d/boot_ramdisk.4o1QjN"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/cmdline = "root=UUID=c4e5bb0c-5638-45f6-a90a-0107cc97506b ro"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/start_time = "1493767063.02"   (n0,r1)

# After the 2nd `xl block-detach` command:

/local = ""   (n0)
/local/domain = ""   (n0)
/local/domain/0 = ""   (n0)
/local/domain/0/control = ""   (n0)
/local/domain/0/control/feature-poweroff = "1"   (n0)
/local/domain/0/control/feature-reboot = "1"   (n0)
/local/domain/0/control/feature-suspend = "1"   (n0)
/local/domain/0/domid = "0"   (n0)
/local/domain/0/name = "Domain-0"   (n0)
/local/domain/0/device-model = ""   (n0)
/local/domain/0/device-model/0 = ""   (n0)
/local/domain/0/device-model/0/backends = ""   (n0)
/local/domain/0/device-model/0/backends/console = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vkbd = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qdisk = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qusb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vfb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qnic = ""   (n0,n0)
/local/domain/0/device-model/0/state = "running"   (n0)
/local/domain/0/backend = ""   (n0)
/local/domain/0/backend/vbd = ""   (n0)
/local/domain/0/backend/vbd/1 = ""   (n0)
/local/domain/0/backend/vbd/1/51712 = ""   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/script = "/etc/xen/scripts/block"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/online = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/removable = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/bootable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/state = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/dev = "xvda"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/type = "phy"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/mode = "w"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/device-type = "disk"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-enable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-max-indirect-segments = "256"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/max-ring-page-order = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device = "fe:22"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device-path = "/dev/dm-34"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-flush-cache = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-granularity = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-alignment = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-secure = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-discard = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-barrier = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sectors = "16777216"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/info = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sector-size = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-sector-size = "512"   (n0,r1)
/local/domain/0/backend/console = ""   (n0)
/local/domain/0/backend/console/1 = ""   (n0)
/local/domain/0/backend/console/1/0 = ""   (n0,r1)
/local/domain/0/backend/console/1/0/frontend = "/local/domain/1/console"   (n0,r1)
/local/domain/0/backend/console/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/state = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/protocol = "vt100"   (n0,r1)
/local/domain/0/backend/vif = ""   (n0)
/local/domain/0/backend/vif/1 = ""   (n0)
/local/domain/0/backend/vif/1/0 = ""   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend = "/local/domain/1/device/vif/0"   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/script = "/etc/xen/scripts/vif-bridge"   (n0,r1)
/local/domain/0/backend/vif/1/0/mac = "00:16:3e:aa:bb:cc"   (n0,r1)
/local/domain/0/backend/vif/1/0/bridge = "xenbr0"   (n0,r1)
/local/domain/0/backend/vif/1/0/handle = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/type = "vif"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-sg = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv4 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv6 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ipv6-csum-offload = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-copy = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-flip = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-dynamic-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-split-event-channels = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ctrl-ring = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/pci = ""   (n0)
/local/domain/0/backend/pci/1 = ""   (n0)
/local/domain/0/backend/pci/1/0 = ""   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend = "/local/domain/1/device/pci/0"   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/pci/1/0/domain = "arch-zfs-test"   (n0,r1)
/local/domain/0/backend/pci/1/0/key-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/dev-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0,r1)
/local/domain/0/backend/pci/1/0/state-0 = "3"   (n0,r1)
/local/domain/0/backend/pci/1/0/num_devs = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/vdev-0 = "0000:00:00.00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root-0 = "0000:00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root_num = "1"   (n0,r1)
/local/domain/1 = ""   (n0,r1)
/local/domain/1/vm = "/vm/59f752d2-7d5f-4aba-9411-302221c4e188"   (n0,r1)
/local/domain/1/name = "arch-zfs-test"   (n0,r1)
/local/domain/1/cpu = ""   (n0,r1)
/local/domain/1/cpu/0 = ""   (n0,r1)
/local/domain/1/cpu/0/availability = "online"   (n0,r1)
/local/domain/1/cpu/1 = ""   (n0,r1)
/local/domain/1/cpu/1/availability = "online"   (n0,r1)
/local/domain/1/cpu/2 = ""   (n0,r1)
/local/domain/1/cpu/2/availability = "online"   (n0,r1)
/local/domain/1/cpu/3 = ""   (n0,r1)
/local/domain/1/cpu/3/availability = "online"   (n0,r1)
/local/domain/1/memory = ""   (n0,r1)
/local/domain/1/memory/static-max = "33554432"   (n0,r1)
/local/domain/1/memory/target = "33554432"   (n0,r1)
/local/domain/1/memory/videoram = "0"   (n0,r1)
/local/domain/1/device = ""   (n0,r1)
/local/domain/1/device/suspend = ""   (n0,r1)
/local/domain/1/device/suspend/event-channel = ""   (n1)
/local/domain/1/device/vbd = ""   (n0,r1)
/local/domain/1/device/vbd/51712 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n1,r0)
/local/domain/1/device/vbd/51712/backend-id = "0"   (n1,r0)
/local/domain/1/device/vbd/51712/state = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/virtual-device = "51712"   (n1,r0)
/local/domain/1/device/vbd/51712/device-type = "disk"   (n1,r0)
/local/domain/1/device/vbd/51712/protocol = "x86_64-abi"   (n1,r0)
/local/domain/1/device/vbd/51712/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/ring-ref = "8"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/event-channel = "31"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/ring-ref = "9"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/event-channel = "32"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/ring-ref = "10"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/event-channel = "33"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/ring-ref = "11"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/event-channel = "34"   (n1,r0)
/local/domain/1/device/vbd/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/device/vif = ""   (n0,r1)
/local/domain/1/device/vif/0 = ""   (n1,r0)
/local/domain/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n1,r0)
/local/domain/1/device/vif/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/vif/0/state = "4"   (n1,r0)
/local/domain/1/device/vif/0/handle = "0"   (n1,r0)
/local/domain/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n1,r0)
/local/domain/1/device/vif/0/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vif/0/queue-0 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-0/tx-ring-ref = "2304"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/rx-ring-ref = "2305"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-tx = "35"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-rx = "36"   (n1,r0)
/local/domain/1/device/vif/0/queue-1 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-1/tx-ring-ref = "2306"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/rx-ring-ref = "2307"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-tx = "37"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-rx = "38"   (n1,r0)
/local/domain/1/device/vif/0/queue-2 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-2/tx-ring-ref = "2308"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/rx-ring-ref = "2309"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-tx = "39"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-rx = "40"   (n1,r0)
/local/domain/1/device/vif/0/queue-3 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-3/tx-ring-ref = "2310"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/rx-ring-ref = "2311"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-tx = "41"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-rx = "42"   (n1,r0)
/local/domain/1/device/vif/0/request-rx-copy = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-rx-notify = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-sg = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv4 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv6 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-ipv6-csum-offload = "1"   (n1,r0)
/local/domain/1/device/pci = ""   (n0,r1)
/local/domain/1/device/pci/0 = ""   (n1,r0)
/local/domain/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n1,r0)
/local/domain/1/device/pci/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/pci/0/state = "4"   (n1,r0)
/local/domain/1/device/pci/0/pci-op-ref = "361"   (n1,r0)
/local/domain/1/device/pci/0/event-channel = "43"   (n1,r0)
/local/domain/1/device/pci/0/magic = "7"   (n1,r0)
/local/domain/1/control = ""   (n0,r1)
/local/domain/1/control/shutdown = ""   (n1)
/local/domain/1/control/feature-poweroff = "1"   (n1)
/local/domain/1/control/feature-reboot = "1"   (n1)
/local/domain/1/control/feature-suspend = "1"   (n1)
/local/domain/1/control/platform-feature-multiprocessor-suspend = "1"   (n0,r1)
/local/domain/1/control/platform-feature-xs_reset_watches = "1"   (n0,r1)
/local/domain/1/data = ""   (n1)
/local/domain/1/drivers = ""   (n1)
/local/domain/1/feature = ""   (n1)
/local/domain/1/attr = ""   (n1)
/local/domain/1/libxl = ""   (n1)
/local/domain/1/device-model = ""   (n1)
/local/domain/1/domid = "1"   (n0,r1)
/local/domain/1/store = ""   (n0,r1)
/local/domain/1/store/port = "1"   (n0,r1)
/local/domain/1/store/ring-ref = "20014470"   (n0,r1)
/local/domain/1/console = ""   (n0,r1)
/local/domain/1/console/backend = "/local/domain/0/backend/console/1/0"   (n0,r1)
/local/domain/1/console/backend-id = "0"   (n1,r0)
/local/domain/1/console/limit = "1048576"   (n0,r1)
/local/domain/1/console/type = "xenconsoled"   (n0,r1)
/local/domain/1/console/output = "pty"   (n0,r1)
/local/domain/1/console/tty = "/dev/pts/1"   (n0,r1)
/local/domain/1/console/port = "2"   (n0,r1)
/local/domain/1/console/ring-ref = "20014471"   (n0,r1)
/local/domain/1/backend = ""   (n0,r1)
/local/domain/1/backend/vbd = ""   (n0,r1)
/local/domain/1/backend/vbd/0 = ""   (n0,r1)
/local/domain/1/backend/vbd/0/51728 = ""   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend = "/local/domain/0/device/vbd/51728"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/params = "/dev/zvol/test_pool/test2"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/script = "/etc/xen/scripts/block"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend-id = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/online = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/removable = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/bootable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/state = "6"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/dev = "xvdb"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/type = "phy"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/mode = "w"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/device-type = "disk"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-enable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-max-indirect-segments = "256"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/multi-queue-max-queues = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/max-ring-page-order = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device = "e6:20"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-flush-cache = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-granularity = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-alignment = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-secure = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-discard = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-barrier = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-persistent = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sectors = "209715200"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/info = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sector-size = "512"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-sector-size = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device-path = "/dev/zd32"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/hotplug-status = "connected"   (n1,r0)
/libxl = ""   (n0)
/libxl/pciback = ""   (n0)
/libxl/pciback/0000-00-1f-2 = ""   (n0)
/libxl/pciback/0000-00-1f-2/driver_path = "/sys/bus/pci/drivers/ahci"   (n0)
/libxl/pciback/0000-01-00-0 = ""   (n0)
/libxl/pciback/0000-01-00-0/driver_path = "/sys/bus/pci/drivers/mpt3sas"   (n0)
/libxl/pciback/0000-06-00-0 = ""   (n0)
/libxl/pciback/0000-06-00-0/driver_path = "/sys/bus/pci/drivers/serial"   (n0)
/libxl/1 = ""   (n0)
/libxl/1/device = ""   (n0)
/libxl/1/device/vbd = ""   (n0)
/libxl/1/device/vbd/51712 = ""   (n0)
/libxl/1/device/vbd/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0)
/libxl/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n0)
/libxl/1/device/vbd/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0)
/libxl/1/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/1/device/vbd/51712/frontend-id = "1"   (n0)
/libxl/1/device/vbd/51712/online = "1"   (n0)
/libxl/1/device/vbd/51712/removable = "0"   (n0)
/libxl/1/device/vbd/51712/bootable = "1"   (n0)
/libxl/1/device/vbd/51712/state = "1"   (n0)
/libxl/1/device/vbd/51712/dev = "xvda"   (n0)
/libxl/1/device/vbd/51712/type = "phy"   (n0)
/libxl/1/device/vbd/51712/mode = "w"   (n0)
/libxl/1/device/vbd/51712/device-type = "disk"   (n0)
/libxl/1/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/1/device/console = ""   (n0)
/libxl/1/device/console/0 = ""   (n0)
/libxl/1/device/console/0/frontend = "/local/domain/1/console"   (n0)
/libxl/1/device/console/0/backend = "/local/domain/0/backend/console/1/0"   (n0)
/libxl/1/device/console/0/frontend-id = "1"   (n0)
/libxl/1/device/console/0/online = "1"   (n0)
/libxl/1/device/console/0/state = "1"   (n0)
/libxl/1/device/console/0/protocol = "vt100"   (n0)
/libxl/1/device/vif = ""   (n0)
/libxl/1/device/vif/0 = ""   (n0)
/libxl/1/device/vif/0/frontend = "/local/domain/1/device/vif/0"   (n0)
/libxl/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n0)
/libxl/1/device/vif/0/frontend-id = "1"   (n0)
/libxl/1/device/vif/0/online = "1"   (n0)
/libxl/1/device/vif/0/state = "1"   (n0)
/libxl/1/device/vif/0/script = "/etc/xen/scripts/vif-bridge"   (n0)
/libxl/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n0)
/libxl/1/device/vif/0/bridge = "xenbr0"   (n0)
/libxl/1/device/vif/0/handle = "0"   (n0)
/libxl/1/device/vif/0/type = "vif"   (n0)
/libxl/1/device/pci = ""   (n0)
/libxl/1/device/pci/0 = ""   (n0)
/libxl/1/device/pci/0/frontend = "/local/domain/1/device/pci/0"   (n0)
/libxl/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n0)
/libxl/1/device/pci/0/frontend-id = "1"   (n0)
/libxl/1/device/pci/0/online = "1"   (n0)
/libxl/1/device/pci/0/state = "1"   (n0)
/libxl/1/device/pci/0/domain = "arch-zfs-test"   (n0)
/libxl/1/device/pci/0/key-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/dev-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0)
/libxl/1/device/pci/0/state-0 = "1"   (n0)
/libxl/1/device/pci/0/num_devs = "1"   (n0)
/libxl/1/dm-version = "qemu_xen"   (n0)
/vm = ""   (n0)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188 = ""   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/name = "arch-zfs-test"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/uuid = "59f752d2-7d5f-4aba-9411-302221c4e188"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image = ""   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/ostype = "linux"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/kernel = "/run/xen/bootloader.1.d/boot_kernel.M1Zoy1"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/ramdisk = "/run/xen/bootloader.1.d/boot_ramdisk.4o1QjN"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/image/cmdline = "root=UUID=c4e5bb0c-5638-45f6-a90a-0107cc97506b ro"   (n0,r1)
/vm/59f752d2-7d5f-4aba-9411-302221c4e188/start_time = "1493767063.02"   (n0,r1)

[-- Attachment #7: coredumpctl gdb.txt --]
[-- Type: text/plain, Size: 8171 bytes --]

[root@arch-zfs-test ~]# coredumpctl gdb 1403
           PID: 1403 (xl)
           UID: 0 (root)
           GID: 0 (root)
        Signal: 11 (SEGV)
     Timestamp: Wed 2017-05-03 02:30:28 EEST (13min ago)
  Command Line: /usr/bin/xl devd
    Executable: /usr/bin/xl
 Control Group: /system.slice/xendriverdomain.service
          Unit: xendriverdomain.service
         Slice: system.slice
       Boot ID: 563263b57f1245c9b4266b42d5ca3dc5
    Machine ID: c0f2ee0d91c44644a2ea229db2047149
      Hostname: arch-zfs-test
       Storage: /var/lib/systemd/coredump/core.xl.0.563263b57f1245c9b4266b42d5ca3dc5.1403.1493767828000000000000.lz4
       Message: Process 1403 (xl) of user 0 dumped core.

                Stack trace of thread 1403:
                #0  0x00007f49bf42519d search_for_guest (libxenlight.so.4.8)
                #1  0x00007f49bf425931 backend_watch_callback (libxenlight.so.4.8)
                #2  0x00007f49bf4629da watchfd_callback (libxenlight.so.4.8)
                #3  0x00007f49bf464612 fd_occurs (libxenlight.so.4.8)
                #4  0x00007f49bf4646c4 afterpoll_internal (libxenlight.so.4.8)
                #5  0x00007f49bf465dfd eventloop_iteration (libxenlight.so.4.8)
                #6  0x00007f49bf466bb1 libxl__ao_inprogress (libxenlight.so.4.8)
                #7  0x00007f49bf4261dc libxl_device_events_handler (libxenlight.so.4.8)
                #8  0x0000000000423258 main_devd (xl)
                #9  0x0000000000408e05 main (xl)
                #10 0x00007f49bea49511 __libc_start_main (libc.so.6)
                #11 0x000000000040800a _start (xl)

                Stack trace of thread 1404:
                #0  0x00007f49bedddf7d read (libpthread.so.0)
                #1  0x00007f49be1b5c3d read_all (libxenstore.so.3.0)
                #2  0x00007f49be1b76ca read_message (libxenstore.so.3.0)
                #3  0x00007f49be1b7a1f read_thread (libxenstore.so.3.0)
                #4  0x00007f49bedd42e7 start_thread (libpthread.so.0)
                #5  0x00007f49beb1554f __clone (libc.so.6)

GNU gdb (GDB) 7.12.1
Copyright (C) 2017 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /usr/bin/xl...done.
[New LWP 1403]
[New LWP 1404]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
Core was generated by `/usr/bin/xl devd'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00007f49bf42519d in search_for_guest (ddomain=0x7ffc601e7130, domid=0)
    at libxl.c:3688
3688            if (dguest->domid == domid)
[Current thread is 1 (Thread 0x7f49bfa75fc0 (LWP 1403))]
(gdb) backtrace full
#0  0x00007f49bf42519d in search_for_guest (ddomain=0x7ffc601e7130, domid=0)
    at libxl.c:3688
        dguest = 0x31352f302f646276
#1  0x00007f49bf425931 in backend_watch_callback (egc=0x7ffc601e7060,
    watch=0x7ffc601e7138, watch_path=0x2188560 "/local/domain/1/backend",
    event_path=0x218ac90 "/local/domain/1/backend/vbd/0/51728/online")
    at libxl.c:3874
        ddomain = 0x7ffc601e7130
        nested_ao = 0x218ab80
        ao = 0x218ab80
        gc = 0x218abc0
        p = 0x218ac33 ""
        path = 0x218ac10 "/local/domain/1/backend/vbd/0/51728"
        sstate = 0x7f49b40012b0 "5"
        sonline = 0x7f49b4001290 "0"
        state = 5
        online = 0
        rc = 0
        num_devs = 0
        dev = 0x2188bf0
        ddev = 0x0
        dguest = 0x0
        free_ao = false
---Type <return> to continue, or q <return> to quit---
        __func__ = "backend_watch_callback"
#2  0x00007f49bf4629da in watchfd_callback (egc=0x7ffc601e7060, ev=0x218a8a8,
    fd=16, events=1, revents=1) at libxl_event.c:574
        token = 0x218acbb "3/0"
        w = 0x7ffc601e7138
        event = 0x218ac80
        epath = 0x218ac90 "/local/domain/1/backend/vbd/0/51728/online"
        slotnum = 3
        counterval = 0
        rc = 2
        gc = 0x7ffc601e7060
        __func__ = "watchfd_callback"
#3  0x00007f49bf464612 in fd_occurs (egc=0x7ffc601e7060, efd=0x218a8a8,
    revents_ign=1) at libxl_event.c:1200
        revents_current = 1
#4  0x00007f49bf4646c4 in afterpoll_internal (egc=0x7ffc601e7060,
    poller=0x2189da0, nfds=2, fds=0x218a0e0, now=...) at libxl_event.c:1265
        revents = 1
        gc = 0x7ffc601e7060
        efd = 0x218a8a8
        __func__ = "afterpoll_internal"
        __PRETTY_FUNCTION__ = "afterpoll_internal"
#5  0x00007f49bf465dfd in eventloop_iteration (egc=0x7ffc601e7060,
---Type <return> to continue, or q <return> to quit---
    poller=0x2189da0) at libxl_event.c:1711
        gc = 0x7ffc601e7060
        rc = 0
        nfds = 2
        now = {tv_sec = 1493767828, tv_usec = 93099}
        timeout = -1
        __func__ = "eventloop_iteration"
#6  0x00007f49bf466bb1 in libxl__ao_inprogress (ao=0x2188350,
    file=0x7f49bf4a979b "libxl.c", line=4014,
    func=0x7f49bf4acd00 <__func__.21414> "libxl_device_events_handler")
    at libxl_event.c:1997
        egc = {gc = {alloc_maxsize = 0, alloc_ptrs = 0x0, owner = 0x218a7b0},
          occurred_for_callback = {tqh_first = 0x0,
            tqh_last = 0x7ffc601e7078}, aos_for_callback = {tqh_first = 0x0,
            tqh_last = 0x7ffc601e7088}, aops_for_callback = {tqh_first = 0x0,
            tqh_last = 0x7ffc601e7098}}
        gc = 0x2188390
        rc = 0
        __PRETTY_FUNCTION__ = "libxl__ao_inprogress"
        __func__ = "libxl__ao_inprogress"
#7  0x00007f49bf4261dc in libxl_device_events_handler (ctx=0x218a7b0,
    ao_how=0x0) at libxl.c:4014
        ao__ctx = 0x218a7b0
---Type <return> to continue, or q <return> to quit---
        ao__rc = 0
        ao = 0x2188350
        __func__ = "libxl_device_events_handler"
        egc = {{gc = {alloc_maxsize = 0, alloc_ptrs = 0x0, owner = 0x218a7b0},
            occurred_for_callback = {tqh_first = 0x0,
              tqh_last = 0x7ffc601e7178}, aos_for_callback = {tqh_first = 0x0,
              tqh_last = 0x7ffc601e7188}, aops_for_callback = {
              tqh_first = 0x0, tqh_last = 0x7ffc601e7198}}}
        gc = 0x2188390
        rc = 0
        domid = 1
        ddomain = {ao = 0x2188350, watch = {
            path = 0x2188560 "/local/domain/1/backend",
            callback = 0x7f49bf425703 <backend_watch_callback>, slotnum = 3,
            counterval = 0}, guests = {slh_first = 0x2189f70}}
        be_path = 0x2189d80 "/local/domain/1/backend"
        kinds = 0x0
        domains = 0x0
        devs = 0x0
        sstate = 0xffff000000000000 <error: Cannot access memory at address 0xffff000000000000>
        state_path = 0x0
        state = 0
---Type <return> to continue, or q <return> to quit---
        nkinds = 4294967295
        ndomains = 4294901760
        ndevs = 6778732
        i = -1078873872
        j = 0
        k = 0
        __PRETTY_FUNCTION__ = "libxl_device_events_handler"
#8  0x0000000000423258 in main_devd (argc=1, argv=0x7ffc601e7390)
    at xl_cmdimpl.c:9059
        ret = 0
        opt = -1
        daemonize = 1
        pidfile = 0x0
        opts = {{name = 0x42d3e5 "pidfile", has_arg = 1, flag = 0x0,
            val = 112}, {name = 0x429059 "help", has_arg = 0, flag = 0x0,
            val = 104}, {name = 0x0, has_arg = 0, flag = 0x0, val = 0}, {
            name = 0x0, has_arg = 0, flag = 0x0, val = 0}}
#9  0x0000000000408e05 in main (argc=1, argv=0x7ffc601e7390) at xl.c:364
        opt = -1
        cmd = 0x7ffc601e8f5b "devd"
        cspec = 0x6363d0 <cmd_table+3504>
        ret = 0
        config_data = 0x2187f20
---Type <return> to continue, or q <return> to quit---
        config_len = 1303

[-- Attachment #8: Type: text/plain, Size: 127 bytes --]

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [BUG] xl devd segmentation fault on xl block-detach
  2017-05-03  0:04 [BUG] xl devd segmentation fault on xl block-detach Reinis Martinsons
@ 2017-05-03 10:27 ` Wei Liu
  2017-05-03 13:27   ` Reinis Martinsons
  0 siblings, 1 reply; 8+ messages in thread
From: Wei Liu @ 2017-05-03 10:27 UTC (permalink / raw)
  To: Reinis Martinsons; +Cc: Ian Jackson, Wei Liu, xen-devel

CC Ian

On Wed, May 03, 2017 at 03:04:44AM +0300, Reinis Martinsons wrote:
> Hi,
> 
> I would like to report a problem with storage driver domain. When detaching
> 2 virtual block devices from the same domain provided by the same driver
> domain, this generates a segmentation fault in the driver domain `xl devd`
> process. I observed the same problem both when manually detaching block
> devices from Dom0 and when shutting down guest domains with several block
> devices.
> 
> For ease of demonstration I am sharing my test results on a simple scenario
> where virtual block devices are provided from a storage driver domain (DomD)
> back to Dom0, but I observed identical results for other DomUs.
> 
> Both of my Dom0 and DomD are Arch Linux (kernel 4.10.11-1-ARCH). I built xen
> from Arch Linux User Repository (https://aur.archlinux.org/xen.git) latest
> commit 16894c15a19bfef23550ba09d58e097fe16c4792, which is using Xen 4.8.0
> (commit b03cee73197f4a37bf2941b9367105187355e638). Please see the output of
> `xl info` attached in "xl info (Dom0).txt". When building xen for DomD, I
> enabled debugging symbols (`debug ?= y` in /Config.mk). I enabled
> xendriverdomain.service in DomD. DomD configuration file is attached in
> "DomD.cfg".
> 
> After 2 consecutive `xl block-attach` and `xl block-detach` commands in Dom0
> I am observing the following output:
> 
> [root@arch-test-dom0 ~]# xl block-attach 0 'format=raw,backendtype=phy,backend=arch-zfs-test,vdev=xvda,target=/dev/zvol/test_pool/test1'
> [root@arch-test-dom0 ~]# xl block-attach 0 'format=raw,backendtype=phy,backend=arch-zfs-test,vdev=xvdb,target=/dev/zvol/test_pool/test2'
> [root@arch-test-dom0 ~]# xl block-detach 0 51712
> [root@arch-test-dom0 ~]# xl block-detach 0 51728
> libxl: error: libxl_device.c:1264:device_destroy_be_watch_cb: timed out
> while waiting for /local/domain/1/backend/vbd/0/51728 to be removed
> libxl: error: libxl.c:2009:device_addrm_aocomplete: unable to remove vbd
> with id 51728
> libxl_device_disk_remove failed.
> 
> The 2nd `xl block-detach` command is generating segmentation fault in DomD
> `xl devd` process (search_for_guest (libxenlight.so.4.8)) - please see full
> DomD log output attached in "journalctl (domD).txt".
> 
> I am also attaching "xenstored-access.log" and output of `xenstore-ls -fp`
> in "xenstore-ls.txt". In addition, I am attaching output of gdb `backtrace
> full` command on the generated coredump in DomD as "coredumpctl gdb
> (DomD).txt"
> 
> Please let me know if I should provide any other information for debugging
> this problem.
> 
> Kind regards
> 
> Reinis Martinsons


[...]
> # After the 2nd `xl block-detach` command:
> 
[...]
> [20170502T23:30:38.176Z]  A37.2        rm        /local/domain/0/device/vbd/51728 
> [20170502T23:30:38.177Z]  A37.2        rm        /local/domain/0/device/vbd 
> [20170502T23:30:38.177Z]  A37.2        rm        /local/domain/0/device 
> [20170502T23:30:38.178Z]  A37.2        rm        /libxl/0/device/vbd/51728 
> [20170502T23:30:38.178Z]  A37.2        rm        /libxl/0/device/vbd 
> [20170502T23:30:38.179Z]  A37.2        rm        /libxl/0/device 
> [20170502T23:30:38.179Z]  A37.2        rm        /libxl/0 
> [20170502T23:30:38.180Z]  A37.2        commit    
> [20170502T23:30:38.180Z]  D0           w event   device/vbd/51728 FFFFFFFF81AA8180 
> [20170502T23:30:38.180Z]  D0           w event   device/vbd FFFFFFFF81AA8180 
> [20170502T23:30:38.180Z]  D0           w event   device FFFFFFFF81AA8180 
> [20170502T23:30:38.181Z]  D0           unwatch   /local/domain/1/backend/vbd/0/51728/state FFFF88017F40CC20 
> [20170502T23:30:38.181Z]  A37          endconn   
> [20170502T23:31:17.867Z]  A38          newconn   
> [20170502T23:31:17.957Z]  A38          endconn   
[...]
> Core was generated by `/usr/bin/xl devd'.
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0  0x00007f49bf42519d in search_for_guest (ddomain=0x7ffc601e7130, domid=0)
>     at libxl.c:3688
> 3688            if (dguest->domid == domid)
> [Current thread is 1 (Thread 0x7f49bfa75fc0 (LWP 1403))]
> (gdb) backtrace full
> #0  0x00007f49bf42519d in search_for_guest (ddomain=0x7ffc601e7130, domid=0)
>     at libxl.c:3688
>         dguest = 0x31352f302f646276

This seems to suggest dguest is used after freed.

But looking at the code of backend_watch_callback, dguest shouldn't be
on the list.

3927         /* If this was the last device in the domain, remove it from the list */
3928         num_devs = dguest->num_vifs + dguest->num_vbds + dguest->num_qdisks;
3929         if (num_devs == 0) {
3930             LIBXL_SLIST_REMOVE(&ddomain->guests, dguest, libxl__ddomain_guest,
3931                                next);
3932             LOG(DEBUG, "removed domain %u from the list of active guests",
3933                        dguest->domid);
3934             /* Clear any leftovers in libxl/<domid> */
3935             libxl__xs_rm_checked(gc, XBT_NULL,
3936                                  GCSPRINTF("libxl/%u", dguest->domid));
3937             free(dguest);
3938         }
3939     }

There is no logging unfortunately. But the xenstore log suggests this
path is taken. Can you do a quick retest? Modify the unit file for xl
devd to make it `xl -vvv devd` to grab more output.

Wei.

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [BUG] xl devd segmentation fault on xl block-detach
  2017-05-03 10:27 ` Wei Liu
@ 2017-05-03 13:27   ` Reinis Martinsons
  2017-05-03 14:31     ` Wei Liu
  0 siblings, 1 reply; 8+ messages in thread
From: Reinis Martinsons @ 2017-05-03 13:27 UTC (permalink / raw)
  To: Wei Liu; +Cc: Ian Jackson, xen-devel

[-- Attachment #1: Type: text/plain, Size: 6305 bytes --]

On 03.05.2017 13:27, Wei Liu wrote:
> CC Ian
> 
> On Wed, May 03, 2017 at 03:04:44AM +0300, Reinis Martinsons wrote:
>> Hi,
>>
>> I would like to report a problem with storage driver domain. When detaching
>> 2 virtual block devices from the same domain provided by the same driver
>> domain, this generates a segmentation fault in the driver domain `xl devd`
>> process. I observed the same problem both when manually detaching block
>> devices from Dom0 and when shutting down guest domains with several block
>> devices.
>>
>> For ease of demonstration I am sharing my test results on a simple scenario
>> where virtual block devices are provided from a storage driver domain (DomD)
>> back to Dom0, but I observed identical results for other DomUs.
>>
>> Both of my Dom0 and DomD are Arch Linux (kernel 4.10.11-1-ARCH). I built xen
>> from Arch Linux User Repository (https://aur.archlinux.org/xen.git) latest
>> commit 16894c15a19bfef23550ba09d58e097fe16c4792, which is using Xen 4.8.0
>> (commit b03cee73197f4a37bf2941b9367105187355e638). Please see the output of
>> `xl info` attached in "xl info (Dom0).txt". When building xen for DomD, I
>> enabled debugging symbols (`debug ?= y` in /Config.mk). I enabled
>> xendriverdomain.service in DomD. DomD configuration file is attached in
>> "DomD.cfg".
>>
>> After 2 consecutive `xl block-attach` and `xl block-detach` commands in Dom0
>> I am observing the following output:
>>
>> [root@arch-test-dom0 ~]# xl block-attach 0 'format=raw,backendtype=phy,backend=arch-zfs-test,vdev=xvda,target=/dev/zvol/test_pool/test1'
>> [root@arch-test-dom0 ~]# xl block-attach 0 'format=raw,backendtype=phy,backend=arch-zfs-test,vdev=xvdb,target=/dev/zvol/test_pool/test2'
>> [root@arch-test-dom0 ~]# xl block-detach 0 51712
>> [root@arch-test-dom0 ~]# xl block-detach 0 51728
>> libxl: error: libxl_device.c:1264:device_destroy_be_watch_cb: timed out
>> while waiting for /local/domain/1/backend/vbd/0/51728 to be removed
>> libxl: error: libxl.c:2009:device_addrm_aocomplete: unable to remove vbd
>> with id 51728
>> libxl_device_disk_remove failed.
>>
>> The 2nd `xl block-detach` command is generating segmentation fault in DomD
>> `xl devd` process (search_for_guest (libxenlight.so.4.8)) - please see full
>> DomD log output attached in "journalctl (domD).txt".
>>
>> I am also attaching "xenstored-access.log" and output of `xenstore-ls -fp`
>> in "xenstore-ls.txt". In addition, I am attaching output of gdb `backtrace
>> full` command on the generated coredump in DomD as "coredumpctl gdb
>> (DomD).txt"
>>
>> Please let me know if I should provide any other information for debugging
>> this problem.
>>
>> Kind regards
>>
>> Reinis Martinsons
> 
> 
> [...]
>> # After the 2nd `xl block-detach` command:
>>
> [...]
>> [20170502T23:30:38.176Z]  A37.2        rm        /local/domain/0/device/vbd/51728
>> [20170502T23:30:38.177Z]  A37.2        rm        /local/domain/0/device/vbd
>> [20170502T23:30:38.177Z]  A37.2        rm        /local/domain/0/device
>> [20170502T23:30:38.178Z]  A37.2        rm        /libxl/0/device/vbd/51728
>> [20170502T23:30:38.178Z]  A37.2        rm        /libxl/0/device/vbd
>> [20170502T23:30:38.179Z]  A37.2        rm        /libxl/0/device
>> [20170502T23:30:38.179Z]  A37.2        rm        /libxl/0
>> [20170502T23:30:38.180Z]  A37.2        commit
>> [20170502T23:30:38.180Z]  D0           w event   device/vbd/51728 FFFFFFFF81AA8180
>> [20170502T23:30:38.180Z]  D0           w event   device/vbd FFFFFFFF81AA8180
>> [20170502T23:30:38.180Z]  D0           w event   device FFFFFFFF81AA8180
>> [20170502T23:30:38.181Z]  D0           unwatch   /local/domain/1/backend/vbd/0/51728/state FFFF88017F40CC20
>> [20170502T23:30:38.181Z]  A37          endconn
>> [20170502T23:31:17.867Z]  A38          newconn
>> [20170502T23:31:17.957Z]  A38          endconn
> [...]
>> Core was generated by `/usr/bin/xl devd'.
>> Program terminated with signal SIGSEGV, Segmentation fault.
>> #0  0x00007f49bf42519d in search_for_guest (ddomain=0x7ffc601e7130, domid=0)
>>      at libxl.c:3688
>> 3688            if (dguest->domid == domid)
>> [Current thread is 1 (Thread 0x7f49bfa75fc0 (LWP 1403))]
>> (gdb) backtrace full
>> #0  0x00007f49bf42519d in search_for_guest (ddomain=0x7ffc601e7130, domid=0)
>>      at libxl.c:3688
>>          dguest = 0x31352f302f646276
> 
> This seems to suggest dguest is used after freed.
> 
> But looking at the code of backend_watch_callback, dguest shouldn't be
> on the list.
> 
> 3927         /* If this was the last device in the domain, remove it from the list */
> 3928         num_devs = dguest->num_vifs + dguest->num_vbds + dguest->num_qdisks;
> 3929         if (num_devs == 0) {
> 3930             LIBXL_SLIST_REMOVE(&ddomain->guests, dguest, libxl__ddomain_guest,
> 3931                                next);
> 3932             LOG(DEBUG, "removed domain %u from the list of active guests",
> 3933                        dguest->domid);
> 3934             /* Clear any leftovers in libxl/<domid> */
> 3935             libxl__xs_rm_checked(gc, XBT_NULL,
> 3936                                  GCSPRINTF("libxl/%u", dguest->domid));
> 3937             free(dguest);
> 3938         }
> 3939     }
> 
> There is no logging unfortunately. But the xenstore log suggests this
> path is taken. Can you do a quick retest? Modify the unit file for xl
> devd to make it `xl -vvv devd` to grab more output.

I modified xendriverdomain.service unit file to execute `xl -vvv devd`. 
This provided following output from journalctl when the service was started:

[root@arch-zfs-test ~]# journalctl -b 
"_SYSTEMD_UNIT=xendriverdomain.service"
-- Logs begin at Sat 2017-04-15 01:20:58 EEST, end at Wed 2017-05-03 
15:32:12 EEST. --
May 03 14:53:46 arch-zfs-test xl[1396]: xencall:buffer: debug: total 
allocations:7 total releases:7
May 03 14:53:46 arch-zfs-test xl[1396]: xencall:buffer: debug: current 
allocations:0 maximum allocations:1
May 03 14:53:46 arch-zfs-test xl[1396]: xencall:buffer: debug: cache 
current size:1
May 03 14:53:46 arch-zfs-test xl[1396]: xencall:buffer: debug: cache 
hits:6 misses:1 toobig:0

In addition, full xldevd log was generated - please see "xldevd.log.1" 
from the respective session attached.

> 
> Wei.
> 

I also attach the repeated test results similar as before.

Reinis

[-- Attachment #2: xldevd.log.1 --]
[-- Type: text/plain, Size: 32377 bytes --]

libxl: debug: libxl.c:3957:libxl_device_events_handler: ao 0x206e350: create: how=(nil) callback=(nil) poller=0x206fda0
libxl: debug: libxl_event.c:636:libxl__ev_xswatch_register: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: register slotnum=3
libxl: debug: libxl.c:4014:libxl_device_events_handler: ao 0x206e350: inprogress: poller=0x206fda0, flags=i
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/frontend
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/params
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/script
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/frontend-id
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/online
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl.c:3889:backend_watch_callback: added domain 0 to the list of active guests
libxl: debug: libxl.c:3906:backend_watch_callback: added device /local/domain/1/backend/vbd/0/51712 to the list of active devices
libxl: debug: libxl_event.c:636:libxl__ev_xswatch_register: watch w=0x2070af0 wpath=/local/domain/1/backend/vbd/0/51712/state token=2/1: register slotnum=2
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/removable
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070470: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070470: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/bootable
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070470: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070470: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/state
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070470: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/dev
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070dd0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070dd0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/type
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070dd0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070dd0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/mode
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070dd0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070dd0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/device-type
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070dd0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070dd0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/discard-enable
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070dd0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070dd0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/feature-max-indirect-segments
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070ea0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070ea0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/multi-queue-max-queues
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070ea0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070ea0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/max-ring-page-order
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070ea0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070ea0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/state
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070ea0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x2070af0 wpath=/local/domain/1/backend/vbd/0/51712/state token=2/1: event epath=/local/domain/1/backend/vbd/0/51712/state
libxl: debug: libxl_event.c:874:devstate_callback: backend /local/domain/1/backend/vbd/0/51712/state wanted state 2 ok
libxl: debug: libxl_event.c:673:libxl__ev_xswatch_deregister: watch w=0x2070af0 wpath=/local/domain/1/backend/vbd/0/51712/state token=2/1: deregister slotnum=2
libxl: debug: libxl_device.c:1059:device_backend_callback: calling device_backend_cleanup
libxl: debug: libxl_event.c:686:libxl__ev_xswatch_deregister: watch w=0x2070af0: deregister unregistered
libxl: debug: libxl_linux.c:183:libxl__hotplug_disk: Args and environment ready
libxl: debug: libxl_device.c:1157:device_hotplug: calling hotplug script: /etc/xen/scripts/block add
libxl: debug: libxl_device.c:1158:device_hotplug: extra args:
libxl: debug: libxl_device.c:1166:device_hotplug: env:
libxl: debug: libxl_device.c:1173:device_hotplug: 	script: /etc/xen/scripts/block
libxl: debug: libxl_device.c:1173:device_hotplug: 	XENBUS_TYPE: vbd
libxl: debug: libxl_device.c:1173:device_hotplug: 	XENBUS_PATH: backend/vbd/0/51712
libxl: debug: libxl_device.c:1173:device_hotplug: 	XENBUS_BASE_PATH: backend
libxl: debug: libxl_aoutils.c:593:libxl__async_exec_start: forking to execute: /etc/xen/scripts/block add 
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/physical-device
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/feature-flush-cache
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/discard-granularity
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/discard-alignment
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/discard-secure
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/feature-discard
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/feature-barrier
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/feature-persistent
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/sectors
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/info
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/sector-size
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/physical-sector-size
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20710a0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/state
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20710a0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/physical-device-path
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20713b0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20713b0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/hotplug-status
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20713b0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20713b0: destroy
libxl: debug: libxl_event.c:686:libxl__ev_xswatch_deregister: watch w=0x2070bf0: deregister unregistered
libxl: debug: libxl_linux.c:200:libxl__get_hotplug_script_info: num_exec 1, not running hotplug scripts
libxl: debug: libxl_device.c:1143:device_hotplug: No hotplug script to execute
libxl: debug: libxl_event.c:686:libxl__ev_xswatch_deregister: watch w=0x2070bf0: deregister unregistered
libxl: debug: libxl.c:3721:device_complete: device /local/domain/1/backend/vbd/0/51712 add succeed
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20713b0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20713b0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/frontend
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/params
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20713b0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20713b0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/script
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/frontend-id
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/online
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20713b0: nested ao, parent 0x206e350
libxl: debug: libxl.c:3906:backend_watch_callback: added device /local/domain/1/backend/vbd/0/51728 to the list of active devices
libxl: debug: libxl_event.c:636:libxl__ev_xswatch_register: watch w=0x2070af0 wpath=/local/domain/1/backend/vbd/0/51728/state token=2/2: register slotnum=2
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/removable
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/bootable
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070250: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/state
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070250: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/dev
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2071680: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2071680: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/type
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2071680: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2071680: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/mode
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2071680: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2071680: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/device-type
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2071680: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2071680: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/discard-enable
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2071680: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2071680: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/feature-max-indirect-segments
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2071680: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2071680: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/multi-queue-max-queues
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2071680: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2071680: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/max-ring-page-order
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2071680: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2071680: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/state
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2071680: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x2070af0 wpath=/local/domain/1/backend/vbd/0/51728/state token=2/2: event epath=/local/domain/1/backend/vbd/0/51728/state
libxl: debug: libxl_event.c:874:devstate_callback: backend /local/domain/1/backend/vbd/0/51728/state wanted state 2 ok
libxl: debug: libxl_event.c:673:libxl__ev_xswatch_deregister: watch w=0x2070af0 wpath=/local/domain/1/backend/vbd/0/51728/state token=2/2: deregister slotnum=2
libxl: debug: libxl_device.c:1059:device_backend_callback: calling device_backend_cleanup
libxl: debug: libxl_event.c:686:libxl__ev_xswatch_deregister: watch w=0x2070af0: deregister unregistered
libxl: debug: libxl_linux.c:183:libxl__hotplug_disk: Args and environment ready
libxl: debug: libxl_device.c:1157:device_hotplug: calling hotplug script: /etc/xen/scripts/block add
libxl: debug: libxl_device.c:1158:device_hotplug: extra args:
libxl: debug: libxl_device.c:1166:device_hotplug: env:
libxl: debug: libxl_device.c:1173:device_hotplug: 	script: /etc/xen/scripts/block
libxl: debug: libxl_device.c:1173:device_hotplug: 	XENBUS_TYPE: vbd
libxl: debug: libxl_device.c:1173:device_hotplug: 	XENBUS_PATH: backend/vbd/0/51728
libxl: debug: libxl_device.c:1173:device_hotplug: 	XENBUS_BASE_PATH: backend
libxl: debug: libxl_aoutils.c:593:libxl__async_exec_start: forking to execute: /etc/xen/scripts/block add 
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/physical-device
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/feature-flush-cache
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/discard-granularity
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/discard-alignment
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/discard-secure
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/feature-discard
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/feature-barrier
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/feature-persistent
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/sectors
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/info
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/sector-size
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/physical-sector-size
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20718c0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/state
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20718c0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/physical-device-path
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2071be0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2071be0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/hotplug-status
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2071be0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2071be0: destroy
libxl: debug: libxl_event.c:686:libxl__ev_xswatch_deregister: watch w=0x2070bf0: deregister unregistered
libxl: debug: libxl_linux.c:200:libxl__get_hotplug_script_info: num_exec 1, not running hotplug scripts
libxl: debug: libxl_device.c:1143:device_hotplug: No hotplug script to execute
libxl: debug: libxl_event.c:686:libxl__ev_xswatch_deregister: watch w=0x2070bf0: deregister unregistered
libxl: debug: libxl.c:3721:device_complete: device /local/domain/1/backend/vbd/0/51728 add succeed
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x20713b0: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/online
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x20713b0: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/state
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070a20: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/state
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070b80: nested ao, parent 0x206e350
libxl: debug: libxl.c:3920:backend_watch_callback: removed device /local/domain/1/backend/vbd/0/51712 from the list of active devices
libxl: debug: libxl_event.c:636:libxl__ev_xswatch_register: watch w=0x206e8a0 wpath=/local/domain/1/backend/vbd/0/51712/state token=2/3: register slotnum=2
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712/online
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x206eb80: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x206eb80: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x206e8a0 wpath=/local/domain/1/backend/vbd/0/51712/state token=2/3: event epath=/local/domain/1/backend/vbd/0/51712/state
libxl: debug: libxl_event.c:874:devstate_callback: backend /local/domain/1/backend/vbd/0/51712/state wanted state 6 ok
libxl: debug: libxl_event.c:673:libxl__ev_xswatch_deregister: watch w=0x206e8a0 wpath=/local/domain/1/backend/vbd/0/51712/state token=2/3: deregister slotnum=2
libxl: debug: libxl_device.c:1059:device_backend_callback: calling device_backend_cleanup
libxl: debug: libxl_event.c:686:libxl__ev_xswatch_deregister: watch w=0x206e8a0: deregister unregistered
libxl: debug: libxl_linux.c:183:libxl__hotplug_disk: Args and environment ready
libxl: debug: libxl_device.c:1157:device_hotplug: calling hotplug script: /etc/xen/scripts/block remove
libxl: debug: libxl_device.c:1158:device_hotplug: extra args:
libxl: debug: libxl_device.c:1166:device_hotplug: env:
libxl: debug: libxl_device.c:1173:device_hotplug: 	script: /etc/xen/scripts/block
libxl: debug: libxl_device.c:1173:device_hotplug: 	XENBUS_TYPE: vbd
libxl: debug: libxl_device.c:1173:device_hotplug: 	XENBUS_PATH: backend/vbd/0/51712
libxl: debug: libxl_device.c:1173:device_hotplug: 	XENBUS_BASE_PATH: backend
libxl: debug: libxl_aoutils.c:593:libxl__async_exec_start: forking to execute: /etc/xen/scripts/block remove 
libxl: debug: libxl_event.c:686:libxl__ev_xswatch_deregister: watch w=0x206e9a0: deregister unregistered
libxl: debug: libxl_linux.c:200:libxl__get_hotplug_script_info: num_exec 1, not running hotplug scripts
libxl: debug: libxl_device.c:1143:device_hotplug: No hotplug script to execute
libxl: debug: libxl_event.c:686:libxl__ev_xswatch_deregister: watch w=0x206e9a0: deregister unregistered
libxl: debug: libxl.c:3721:device_complete: device /local/domain/1/backend/vbd/0/51712 remove succeed
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070b80: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070b80: nested ao, parent 0x206e350
libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070b80: destroy
libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/online
libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070b80: nested ao, parent 0x206e350

[-- Attachment #3: journalctl (domD).txt --]
[-- Type: text/plain, Size: 5577 bytes --]

[root@arch-zfs-test ~]# journalctl -f
-- Logs begin at Sat 2017-04-15 01:20:58 EEST. --
May 03 14:54:03 arch-zfs-test systemd[1496]: Starting D-Bus User Message Bus Socket.
May 03 14:54:03 arch-zfs-test systemd[1496]: Reached target Timers.
May 03 14:54:03 arch-zfs-test systemd[1496]: Reached target Paths.
May 03 14:54:03 arch-zfs-test systemd[1496]: Listening on D-Bus User Message Bus Socket.
May 03 14:54:03 arch-zfs-test systemd[1496]: Reached target Sockets.
May 03 14:54:03 arch-zfs-test systemd[1496]: Reached target Basic System.
May 03 14:54:03 arch-zfs-test systemd[1496]: Reached target Default.
May 03 14:54:03 arch-zfs-test systemd[1496]: Startup finished in 32ms.
May 03 14:54:03 arch-zfs-test systemd[1]: Started User Manager for UID 0.
May 03 14:54:03 arch-zfs-test login[1491]: ROOT LOGIN ON hvc0

# After the 1st `xl block-attach` command:

May 03 15:03:44 arch-zfs-test kernel: xen-blkback: backend/vbd/0/51712: using 4 queues, protocol 1 (x86_64-abi) persistent grants
May 03 15:03:44 arch-zfs-test kernel: xen-blkback: backend/vbd/0/51712: using 4 queues, protocol 1 (x86_64-abi) persistent grants
May 03 15:03:44 arch-zfs-test root[1569]: /etc/xen/scripts/block: add XENBUS_PATH=backend/vbd/0/51712
May 03 15:03:44 arch-zfs-test root[1621]: /etc/xen/scripts/block: Writing backend/vbd/0/51712/physical-device e6:0 to xenstore.
May 03 15:03:44 arch-zfs-test root[1623]: /etc/xen/scripts/block: Writing backend/vbd/0/51712/physical-device-path /dev/zd0 to xenstore.
May 03 15:03:44 arch-zfs-test root[1630]: /etc/xen/scripts/block: Writing backend/vbd/0/51712/hotplug-status connected to xenstore.

# After the 2nd `xl block-attach` command:

May 03 15:05:37 arch-zfs-test kernel: xen-blkback: backend/vbd/0/51728: using 1 queues, protocol 1 (x86_64-abi) persistent grants
May 03 15:05:37 arch-zfs-test kernel: xen-blkback: backend/vbd/0/51728: using 1 queues, protocol 1 (x86_64-abi) persistent grants
May 03 15:05:37 arch-zfs-test root[1655]: /etc/xen/scripts/block: add XENBUS_PATH=backend/vbd/0/51728
May 03 15:05:37 arch-zfs-test root[1709]: /etc/xen/scripts/block: Writing backend/vbd/0/51728/physical-device e6:20 to xenstore.
May 03 15:05:37 arch-zfs-test root[1711]: /etc/xen/scripts/block: Writing backend/vbd/0/51728/physical-device-path /dev/zd32 to xenstore.
May 03 15:05:37 arch-zfs-test root[1715]: /etc/xen/scripts/block: Writing backend/vbd/0/51728/hotplug-status connected to xenstore.

# After the 1st `xl block-detach` command:

May 03 15:06:43 arch-zfs-test root[1730]: /etc/xen/scripts/block: remove XENBUS_PATH=backend/vbd/0/51712

# After the 2nd `xl block-detach` command:

May 03 15:08:09 arch-zfs-test kernel: traps: xl[1400] general protection ip:7f00df92b19d sp:7fff97ba7040 error:0
May 03 15:08:09 arch-zfs-test kernel:  in libxenlight.so.4.8.0[7f00df8fe000+dd000]
May 03 15:08:09 arch-zfs-test systemd[1]: Created slice system-systemd\x2dcoredump.slice.
May 03 15:08:09 arch-zfs-test systemd[1]: Started Process Core Dump (PID 1740/UID 0).
May 03 15:08:09 arch-zfs-test systemd[1]: xendriverdomain.service: Main process exited, code=dumped, status=11/SEGV
May 03 15:08:09 arch-zfs-test systemd[1]: xendriverdomain.service: Unit entered failed state.
May 03 15:08:09 arch-zfs-test systemd[1]: xendriverdomain.service: Failed with result 'core-dump'.
May 03 15:08:09 arch-zfs-test systemd-coredump[1742]: Process 1400 (xl) of user 0 dumped core.

                                                      Stack trace of thread 1400:
                                                      #0  0x00007f00df92b19d search_for_guest (libxenlight.so.4.8)
                                                      #1  0x00007f00df92b931 backend_watch_callback (libxenlight.so.4.8)
                                                      #2  0x00007f00df9689da watchfd_callback (libxenlight.so.4.8)
                                                      #3  0x00007f00df96a612 fd_occurs (libxenlight.so.4.8)
                                                      #4  0x00007f00df96a6c4 afterpoll_internal (libxenlight.so.4.8)
                                                      #5  0x00007f00df96bdfd eventloop_iteration (libxenlight.so.4.8)
                                                      #6  0x00007f00df96cbb1 libxl__ao_inprogress (libxenlight.so.4.8)
                                                      #7  0x00007f00df92c1dc libxl_device_events_handler (libxenlight.so.4.8)
                                                      #8  0x0000000000423258 main_devd (xl)
                                                      #9  0x0000000000408e05 main (xl)
                                                      #10 0x00007f00def4f511 __libc_start_main (libc.so.6)
                                                      #11 0x000000000040800a _start (xl)

                                                      Stack trace of thread 1401:
                                                      #0  0x00007f00df2e3f7d read (libpthread.so.0)
                                                      #1  0x00007f00de6bbc3d read_all (libxenstore.so.3.0)
                                                      #2  0x00007f00de6bd6ca read_message (libxenstore.so.3.0)
                                                      #3  0x00007f00de6bda1f read_thread (libxenstore.so.3.0)
                                                      #4  0x00007f00df2da2e7 start_thread (libpthread.so.0)
                                                      #5  0x00007f00df01b54f __clone (libc.so.6)

[-- Attachment #4: xenstored-access.log --]
[-- Type: text/plain, Size: 45789 bytes --]

# After the 1st `xl block-attach` command:

[20170503T12:03:06.422Z]  A28          newconn   
[20170503T12:03:06.505Z]  A28          endconn   
[20170503T12:03:44.134Z]  A29          newconn   
[20170503T12:03:44.136Z]  A29.1        rm        /libxl/0/device/vbd/51712 
[20170503T12:03:44.136Z]  A29.1        write     /libxl/0/device/vbd/51712/frontend /local/domain/0/device/vbd/51712
[20170503T12:03:44.136Z]  A29.1        write     /libxl/0/device/vbd/51712/backend /local/domain/1/backend/vbd/0/51712
[20170503T12:03:44.136Z]  A29.1        rm        /local/domain/0/device/vbd/51712 
[20170503T12:03:44.136Z]  A29.1        mkdir     /local/domain/0/device/vbd/51712 
[20170503T12:03:44.137Z]  A29.1        setperms  /local/domain/0/device/vbd/51712 n0 r1 
[20170503T12:03:44.137Z]  A29.1        write     /local/domain/0/device/vbd/51712/backend /local/domain/1/backend/vbd/0/51712
[20170503T12:03:44.137Z]  A29.1        write     /local/domain/0/device/vbd/51712/backend-id 1
[20170503T12:03:44.137Z]  A29.1        setperms  /local/domain/0/device/vbd/51712/backend-id n0 r1 
[20170503T12:03:44.137Z]  A29.1        write     /local/domain/0/device/vbd/51712/state 1
[20170503T12:03:44.137Z]  A29.1        setperms  /local/domain/0/device/vbd/51712/state n0 r1 
[20170503T12:03:44.137Z]  A29.1        write     /local/domain/0/device/vbd/51712/virtual-device 51712
[20170503T12:03:44.137Z]  A29.1        setperms  /local/domain/0/device/vbd/51712/virtual-device n0 r1 
[20170503T12:03:44.138Z]  A29.1        write     /local/domain/0/device/vbd/51712/device-type disk
[20170503T12:03:44.138Z]  A29.1        setperms  /local/domain/0/device/vbd/51712/device-type n0 r1 
[20170503T12:03:44.138Z]  A29.1        write     /local/domain/0/device/vbd/51712/protocol x86_64-abi
[20170503T12:03:44.138Z]  A29.1        setperms  /local/domain/0/device/vbd/51712/protocol n0 r1 
[20170503T12:03:44.138Z]  A29.1        rm        /local/domain/1/backend/vbd/0/51712 
[20170503T12:03:44.138Z]  A29.1        mkdir     /local/domain/1/backend/vbd/0/51712 
[20170503T12:03:44.138Z]  A29.1        setperms  /local/domain/1/backend/vbd/0/51712 n1 r0 
[20170503T12:03:44.138Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/frontend /local/domain/0/device/vbd/51712
[20170503T12:03:44.138Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/params /dev/zvol/test_pool/test1
[20170503T12:03:44.139Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/script /etc/xen/scripts/block
[20170503T12:03:44.139Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/frontend-id 0
[20170503T12:03:44.139Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/online 1
[20170503T12:03:44.139Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/removable 0
[20170503T12:03:44.139Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/bootable 1
[20170503T12:03:44.139Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/state 1
[20170503T12:03:44.139Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/dev xvda
[20170503T12:03:44.139Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/type phy
[20170503T12:03:44.140Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/mode w
[20170503T12:03:44.140Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/device-type disk
[20170503T12:03:44.140Z]  A29.1        write     /local/domain/1/backend/vbd/0/51712/discard-enable 1
[20170503T12:03:44.140Z]  A29.1        write     /libxl/0/device/vbd/51712/params /dev/zvol/test_pool/test1
[20170503T12:03:44.140Z]  A29.1        write     /libxl/0/device/vbd/51712/script /etc/xen/scripts/block
[20170503T12:03:44.140Z]  A29.1        write     /libxl/0/device/vbd/51712/frontend-id 0
[20170503T12:03:44.140Z]  A29.1        write     /libxl/0/device/vbd/51712/online 1
[20170503T12:03:44.141Z]  A29.1        write     /libxl/0/device/vbd/51712/removable 0
[20170503T12:03:44.141Z]  A29.1        write     /libxl/0/device/vbd/51712/bootable 1
[20170503T12:03:44.141Z]  A29.1        write     /libxl/0/device/vbd/51712/state 1
[20170503T12:03:44.141Z]  A29.1        write     /libxl/0/device/vbd/51712/dev xvda
[20170503T12:03:44.141Z]  A29.1        write     /libxl/0/device/vbd/51712/type phy
[20170503T12:03:44.141Z]  A29.1        write     /libxl/0/device/vbd/51712/mode w
[20170503T12:03:44.141Z]  A29.1        write     /libxl/0/device/vbd/51712/device-type disk
[20170503T12:03:44.141Z]  A29.1        write     /libxl/0/device/vbd/51712/discard-enable 1
[20170503T12:03:44.141Z]  A29.1        commit    
[20170503T12:03:44.142Z]  D0           w event   device/vbd/51712 FFFFFFFF81AA8180 
[20170503T12:03:44.142Z]  D1           w event   /local/domain/1/backend/vbd/0/51712 FFFF880881C8F250 
[20170503T12:03:44.142Z]  D0           w event   device/vbd/51712 FFFFFFFF81AA8180 
[20170503T12:03:44.142Z]  D1           w event   backend/vbd/0/51712 FFFFFFFF81AA7FA0 
[20170503T12:03:44.142Z]  D0           w event   device/vbd/51712/backend FFFFFFFF81AA8180 
[20170503T12:03:44.142Z]  D1           w event   /local/domain/1/backend/vbd/0/51712 FFFF880881C8F250 
[20170503T12:03:44.142Z]  D0           w event   device/vbd/51712/backend-id FFFFFFFF81AA8180 
[20170503T12:03:44.142Z]  D1           w event   backend/vbd/0/51712 FFFFFFFF81AA7FA0 
[20170503T12:03:44.142Z]  D0           w event   device/vbd/51712/backend-id FFFFFFFF81AA8180 
[20170503T12:03:44.142Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/frontend FFFF880881C8F250 
[20170503T12:03:44.142Z]  D0           w event   device/vbd/51712/state FFFFFFFF81AA8180 
[20170503T12:03:44.142Z]  D1           w event   backend/vbd/0/51712/frontend FFFFFFFF81AA7FA0 
[20170503T12:03:44.142Z]  A29          watch     /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170503T12:03:44.142Z]  D0           w event   device/vbd/51712/state FFFFFFFF81AA8180 
[20170503T12:03:44.142Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/params FFFF880881C8F250 
[20170503T12:03:44.142Z]  D0           w event   device/vbd/51712/virtual-device FFFFFFFF81AA8180 
[20170503T12:03:44.142Z]  D1           w event   backend/vbd/0/51712/params FFFFFFFF81AA7FA0 
[20170503T12:03:44.142Z]  A29          w event   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170503T12:03:44.142Z]  D0           w event   device/vbd/51712/virtual-device FFFFFFFF81AA8180 
[20170503T12:03:44.142Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/script FFFF880881C8F250 
[20170503T12:03:44.143Z]  D0           w event   device/vbd/51712/device-type FFFFFFFF81AA8180 
[20170503T12:03:44.143Z]  D1           w event   backend/vbd/0/51712/script FFFFFFFF81AA7FA0 
[20170503T12:03:44.143Z]  D0           w event   device/vbd/51712/device-type FFFFFFFF81AA8180 
[20170503T12:03:44.143Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/frontend-id FFFF880881C8F250 
[20170503T12:03:44.143Z]  D0           w event   device/vbd/51712/protocol FFFFFFFF81AA8180 
[20170503T12:03:44.143Z]  D1           w event   backend/vbd/0/51712/frontend-id FFFFFFFF81AA7FA0 
[20170503T12:03:44.143Z]  D0           w event   device/vbd/51712/protocol FFFFFFFF81AA8180 
[20170503T12:03:44.143Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/online FFFF880881C8F250 
[20170503T12:03:44.143Z]  D1           w event   backend/vbd/0/51712/online FFFFFFFF81AA7FA0 
[20170503T12:03:44.143Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/removable FFFF880881C8F250 
[20170503T12:03:44.143Z]  D1           w event   backend/vbd/0/51712/removable FFFFFFFF81AA7FA0 
[20170503T12:03:44.143Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/bootable FFFF880881C8F250 
[20170503T12:03:44.143Z]  D1           w event   backend/vbd/0/51712/bootable FFFFFFFF81AA7FA0 
[20170503T12:03:44.143Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880881C8F250 
[20170503T12:03:44.143Z]  D1           w event   backend/vbd/0/51712/state FFFFFFFF81AA7FA0 
[20170503T12:03:44.143Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/dev FFFF880881C8F250 
[20170503T12:03:44.143Z]  D1           w event   backend/vbd/0/51712/dev FFFFFFFF81AA7FA0 
[20170503T12:03:44.143Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/type FFFF880881C8F250 
[20170503T12:03:44.144Z]  D1           w event   backend/vbd/0/51712/type FFFFFFFF81AA7FA0 
[20170503T12:03:44.144Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/mode FFFF880881C8F250 
[20170503T12:03:44.144Z]  D1           w event   backend/vbd/0/51712/mode FFFFFFFF81AA7FA0 
[20170503T12:03:44.144Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/device-type FFFF880881C8F250 
[20170503T12:03:44.144Z]  D1           w event   backend/vbd/0/51712/device-type FFFFFFFF81AA7FA0 
[20170503T12:03:44.144Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/discard-enable FFFF880881C8F250 
[20170503T12:03:44.146Z]  D1           w event   backend/vbd/0/51712/discard-enable FFFFFFFF81AA7FA0 
[20170503T12:03:44.147Z]  D1           write     backend/vbd/0/51712/feature-max-indirect-segments 256
[20170503T12:03:44.147Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/feature-max-indirect-segments FFFF880881C8F250 
[20170503T12:03:44.147Z]  D1           w event   backend/vbd/0/51712/feature-max-indirect-segments FFFFFFFF81AA7FA0 
[20170503T12:03:44.147Z]  D1           write     backend/vbd/0/51712/multi-queue-max-queues 4
[20170503T12:03:44.147Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/multi-queue-max-queues FFFF880881C8F250 
[20170503T12:03:44.147Z]  D1           watch     backend/vbd/0/51712/physical-device FFFF88087665D190 
[20170503T12:03:44.147Z]  D1           w event   backend/vbd/0/51712/multi-queue-max-queues FFFFFFFF81AA7FA0 
[20170503T12:03:44.148Z]  D1           w event   backend/vbd/0/51712/physical-device FFFF88087665D190 
[20170503T12:03:44.148Z]  D1           write     backend/vbd/0/51712/max-ring-page-order 4
[20170503T12:03:44.148Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/max-ring-page-order FFFF880881C8F250 
[20170503T12:03:44.148Z]  D1           w event   backend/vbd/0/51712/max-ring-page-order FFFFFFFF81AA7FA0 
[20170503T12:03:44.148Z]  D0           watch     /local/domain/1/backend/vbd/0/51712/state FFFF880180A24C20 
[20170503T12:03:44.148Z]  D0           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880180A24C20 
[20170503T12:03:44.148Z]  D1.11        write     backend/vbd/0/51712/state 2
[20170503T12:03:44.149Z]  D1.11        commit    
[20170503T12:03:44.149Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880881C8F250 
[20170503T12:03:44.149Z]  A29          w event   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170503T12:03:44.149Z]  D0           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880180A24C20 
[20170503T12:03:44.149Z]  D1           w event   backend/vbd/0/51712/state FFFFFFFF81AA7FA0 
[20170503T12:03:44.149Z]  D1           watch     /local/domain/0/device/vbd/51712/state FFFF880874281820 
[20170503T12:03:44.149Z]  D1           w event   /local/domain/0/device/vbd/51712/state FFFF880874281820 
[20170503T12:03:44.150Z]  D0.12        write     device/vbd/51712/multi-queue-num-queues 4
[20170503T12:03:44.150Z]  D0.12        write     device/vbd/51712/queue-0/ring-ref 8
[20170503T12:03:44.150Z]  D0.12        write     device/vbd/51712/queue-0/event-channel 79
[20170503T12:03:44.150Z]  A29          unwatch   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170503T12:03:44.150Z]  D0.12        write     device/vbd/51712/queue-1/ring-ref 9
[20170503T12:03:44.151Z]  D0.12        write     device/vbd/51712/queue-1/event-channel 80
[20170503T12:03:44.151Z]  D0.12        write     device/vbd/51712/queue-2/ring-ref 10
[20170503T12:03:44.151Z]  D0.12        write     device/vbd/51712/queue-2/event-channel 81
[20170503T12:03:44.151Z]  D0.12        write     device/vbd/51712/queue-3/ring-ref 11
[20170503T12:03:44.151Z]  D0.12        write     device/vbd/51712/queue-3/event-channel 82
[20170503T12:03:44.151Z]  D0.12        write     device/vbd/51712/protocol x86_64-abi
[20170503T12:03:44.151Z]  D0.12        write     device/vbd/51712/feature-persistent 1
[20170503T12:03:44.152Z]  A29          endconn   
[20170503T12:03:44.152Z]  D0.12        commit    
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/multi-queue-num-queues FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/queue-0/ring-ref FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/queue-0/event-channel FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/queue-1/ring-ref FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/queue-1/event-channel FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/queue-2/ring-ref FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/queue-2/event-channel FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/queue-3/ring-ref FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/queue-3/event-channel FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/protocol FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/feature-persistent FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D0.13        write     device/vbd/51712/state 3
[20170503T12:03:44.152Z]  D0.13        commit    
[20170503T12:03:44.152Z]  D0           w event   device/vbd/51712/state FFFFFFFF81AA8180 
[20170503T12:03:44.152Z]  D1           w event   /local/domain/0/device/vbd/51712/state FFFF880874281820 
[20170503T12:03:44.152Z]  D1           watch     /local/domain/1/backend/vbd/0/51712/state FFFF880874F60FD0 
[20170503T12:03:44.153Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880874F60FD0 
[20170503T12:03:44.164Z]  D1           unwatch   /local/domain/1/backend/vbd/0/51712/state FFFF880874F60FD0 
[20170503T12:03:44.377Z]  D1.12        commit    
[20170503T12:03:44.385Z]  D1.13        commit    
[20170503T12:03:44.413Z]  D1           write     backend/vbd/0/51712/physical-device e6:0
[20170503T12:03:44.413Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/physical-device FFFF880881C8F250 
[20170503T12:03:44.413Z]  D1           w event   backend/vbd/0/51712/physical-device FFFFFFFF81AA7FA0 
[20170503T12:03:44.413Z]  D1           w event   backend/vbd/0/51712/physical-device FFFF88087665D190 
[20170503T12:03:44.415Z]  D1.14        write     backend/vbd/0/51712/feature-flush-cache 1
[20170503T12:03:44.415Z]  D1.14        write     backend/vbd/0/51712/discard-granularity 8192
[20170503T12:03:44.415Z]  D1.14        write     backend/vbd/0/51712/discard-alignment 0
[20170503T12:03:44.416Z]  D1.14        write     backend/vbd/0/51712/discard-secure 0
[20170503T12:03:44.416Z]  D1.14        write     backend/vbd/0/51712/feature-discard 1
[20170503T12:03:44.416Z]  D1.14        write     backend/vbd/0/51712/feature-barrier 1
[20170503T12:03:44.416Z]  D1.14        write     backend/vbd/0/51712/feature-persistent 1
[20170503T12:03:44.416Z]  D1.14        write     backend/vbd/0/51712/sectors 419430400
[20170503T12:03:44.416Z]  D1.14        write     backend/vbd/0/51712/info 0
[20170503T12:03:44.416Z]  D1.14        write     backend/vbd/0/51712/sector-size 512
[20170503T12:03:44.416Z]  D1.14        write     backend/vbd/0/51712/physical-sector-size 8192
[20170503T12:03:44.416Z]  D1.14        commit    
[20170503T12:03:44.417Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/feature-flush-cache FFFF880881C8F250 
[20170503T12:03:44.417Z]  D1           w event   backend/vbd/0/51712/feature-flush-cache FFFFFFFF81AA7FA0 
[20170503T12:03:44.417Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/discard-granularity FFFF880881C8F250 
[20170503T12:03:44.417Z]  D1           w event   backend/vbd/0/51712/discard-granularity FFFFFFFF81AA7FA0 
[20170503T12:03:44.417Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/discard-alignment FFFF880881C8F250 
[20170503T12:03:44.417Z]  D1           w event   backend/vbd/0/51712/discard-alignment FFFFFFFF81AA7FA0 
[20170503T12:03:44.417Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/discard-secure FFFF880881C8F250 
[20170503T12:03:44.417Z]  D1           w event   backend/vbd/0/51712/discard-secure FFFFFFFF81AA7FA0 
[20170503T12:03:44.417Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/feature-discard FFFF880881C8F250 
[20170503T12:03:44.417Z]  D1           w event   backend/vbd/0/51712/feature-discard FFFFFFFF81AA7FA0 
[20170503T12:03:44.417Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/feature-barrier FFFF880881C8F250 
[20170503T12:03:44.417Z]  D1           w event   backend/vbd/0/51712/feature-barrier FFFFFFFF81AA7FA0 
[20170503T12:03:44.417Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/feature-persistent FFFF880881C8F250 
[20170503T12:03:44.417Z]  D1           w event   backend/vbd/0/51712/feature-persistent FFFFFFFF81AA7FA0 
[20170503T12:03:44.417Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/sectors FFFF880881C8F250 
[20170503T12:03:44.417Z]  D1           w event   backend/vbd/0/51712/sectors FFFFFFFF81AA7FA0 
[20170503T12:03:44.417Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/info FFFF880881C8F250 
[20170503T12:03:44.417Z]  D1           w event   backend/vbd/0/51712/info FFFFFFFF81AA7FA0 
[20170503T12:03:44.417Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/sector-size FFFF880881C8F250 
[20170503T12:03:44.417Z]  D1           w event   backend/vbd/0/51712/sector-size FFFFFFFF81AA7FA0 
[20170503T12:03:44.417Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/physical-sector-size FFFF880881C8F250 
[20170503T12:03:44.417Z]  D1           w event   backend/vbd/0/51712/physical-sector-size FFFFFFFF81AA7FA0 
[20170503T12:03:44.418Z]  D1.15        write     backend/vbd/0/51712/state 4
[20170503T12:03:44.418Z]  D1.15        commit    
[20170503T12:03:44.418Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880881C8F250 
[20170503T12:03:44.418Z]  D0           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880180A24C20 
[20170503T12:03:44.418Z]  D1           w event   backend/vbd/0/51712/state FFFFFFFF81AA7FA0 
[20170503T12:03:44.421Z]  D0.14        write     device/vbd/51712/state 4
[20170503T12:03:44.421Z]  D0.14        commit    
[20170503T12:03:44.421Z]  D0           w event   device/vbd/51712/state FFFFFFFF81AA8180 
[20170503T12:03:44.421Z]  D1           w event   /local/domain/0/device/vbd/51712/state FFFF880874281820 
[20170503T12:03:44.425Z]  D1           write     backend/vbd/0/51712/physical-device-path /dev/zd0
[20170503T12:03:44.425Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/physical-device-path FFFF880881C8F250 
[20170503T12:03:44.425Z]  D1           w event   backend/vbd/0/51712/physical-device-path FFFFFFFF81AA7FA0 
[20170503T12:03:44.436Z]  D1           write     backend/vbd/0/51712/hotplug-status connected
[20170503T12:03:44.436Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/hotplug-status FFFF880881C8F250 
[20170503T12:03:44.436Z]  D1           w event   backend/vbd/0/51712/hotplug-status FFFFFFFF81AA7FA0 
[20170503T12:05:21.323Z]  A30          newconn   
[20170503T12:05:21.407Z]  A30          endconn   

# After the 2nd `xl block-attach` command:

[20170503T12:05:37.131Z]  A31          newconn   
[20170503T12:05:37.133Z]  A31.1        rm        /libxl/0/device/vbd/51728 
[20170503T12:05:37.134Z]  A31.1        write     /libxl/0/device/vbd/51728/frontend /local/domain/0/device/vbd/51728
[20170503T12:05:37.134Z]  A31.1        write     /libxl/0/device/vbd/51728/backend /local/domain/1/backend/vbd/0/51728
[20170503T12:05:37.134Z]  A31.1        rm        /local/domain/0/device/vbd/51728 
[20170503T12:05:37.134Z]  A31.1        mkdir     /local/domain/0/device/vbd/51728 
[20170503T12:05:37.134Z]  A31.1        setperms  /local/domain/0/device/vbd/51728 n0 r1 
[20170503T12:05:37.134Z]  A31.1        write     /local/domain/0/device/vbd/51728/backend /local/domain/1/backend/vbd/0/51728
[20170503T12:05:37.134Z]  A31.1        write     /local/domain/0/device/vbd/51728/backend-id 1
[20170503T12:05:37.134Z]  A31.1        setperms  /local/domain/0/device/vbd/51728/backend-id n0 r1 
[20170503T12:05:37.134Z]  A31.1        write     /local/domain/0/device/vbd/51728/state 1
[20170503T12:05:37.135Z]  A31.1        setperms  /local/domain/0/device/vbd/51728/state n0 r1 
[20170503T12:05:37.135Z]  A31.1        write     /local/domain/0/device/vbd/51728/virtual-device 51728
[20170503T12:05:37.135Z]  A31.1        setperms  /local/domain/0/device/vbd/51728/virtual-device n0 r1 
[20170503T12:05:37.135Z]  A31.1        write     /local/domain/0/device/vbd/51728/device-type disk
[20170503T12:05:37.135Z]  A31.1        setperms  /local/domain/0/device/vbd/51728/device-type n0 r1 
[20170503T12:05:37.135Z]  A31.1        write     /local/domain/0/device/vbd/51728/protocol x86_64-abi
[20170503T12:05:37.135Z]  A31.1        setperms  /local/domain/0/device/vbd/51728/protocol n0 r1 
[20170503T12:05:37.135Z]  A31.1        rm        /local/domain/1/backend/vbd/0/51728 
[20170503T12:05:37.135Z]  A31.1        mkdir     /local/domain/1/backend/vbd/0/51728 
[20170503T12:05:37.135Z]  A31.1        setperms  /local/domain/1/backend/vbd/0/51728 n1 r0 
[20170503T12:05:37.136Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/frontend /local/domain/0/device/vbd/51728
[20170503T12:05:37.136Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/params /dev/zvol/test_pool/test2
[20170503T12:05:37.136Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/script /etc/xen/scripts/block
[20170503T12:05:37.136Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/frontend-id 0
[20170503T12:05:37.136Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/online 1
[20170503T12:05:37.136Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/removable 0
[20170503T12:05:37.136Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/bootable 1
[20170503T12:05:37.136Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/state 1
[20170503T12:05:37.136Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/dev xvdb
[20170503T12:05:37.136Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/type phy
[20170503T12:05:37.137Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/mode w
[20170503T12:05:37.137Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/device-type disk
[20170503T12:05:37.137Z]  A31.1        write     /local/domain/1/backend/vbd/0/51728/discard-enable 1
[20170503T12:05:37.137Z]  A31.1        write     /libxl/0/device/vbd/51728/params /dev/zvol/test_pool/test2
[20170503T12:05:37.137Z]  A31.1        write     /libxl/0/device/vbd/51728/script /etc/xen/scripts/block
[20170503T12:05:37.137Z]  A31.1        write     /libxl/0/device/vbd/51728/frontend-id 0
[20170503T12:05:37.137Z]  A31.1        write     /libxl/0/device/vbd/51728/online 1
[20170503T12:05:37.137Z]  A31.1        write     /libxl/0/device/vbd/51728/removable 0
[20170503T12:05:37.137Z]  A31.1        write     /libxl/0/device/vbd/51728/bootable 1
[20170503T12:05:37.138Z]  A31.1        write     /libxl/0/device/vbd/51728/state 1
[20170503T12:05:37.138Z]  A31.1        write     /libxl/0/device/vbd/51728/dev xvdb
[20170503T12:05:37.138Z]  A31.1        write     /libxl/0/device/vbd/51728/type phy
[20170503T12:05:37.138Z]  A31.1        write     /libxl/0/device/vbd/51728/mode w
[20170503T12:05:37.138Z]  A31.1        write     /libxl/0/device/vbd/51728/device-type disk
[20170503T12:05:37.138Z]  A31.1        write     /libxl/0/device/vbd/51728/discard-enable 1
[20170503T12:05:37.138Z]  A31.1        commit    
[20170503T12:05:37.138Z]  D0           w event   device/vbd/51728 FFFFFFFF81AA8180 
[20170503T12:05:37.138Z]  D1           w event   /local/domain/1/backend/vbd/0/51728 FFFF880881C8F250 
[20170503T12:05:37.138Z]  D0           w event   device/vbd/51728 FFFFFFFF81AA8180 
[20170503T12:05:37.138Z]  D1           w event   backend/vbd/0/51728 FFFFFFFF81AA7FA0 
[20170503T12:05:37.138Z]  D0           w event   device/vbd/51728/backend FFFFFFFF81AA8180 
[20170503T12:05:37.138Z]  D1           w event   /local/domain/1/backend/vbd/0/51728 FFFF880881C8F250 
[20170503T12:05:37.138Z]  D0           w event   device/vbd/51728/backend-id FFFFFFFF81AA8180 
[20170503T12:05:37.138Z]  D1           w event   backend/vbd/0/51728 FFFFFFFF81AA7FA0 
[20170503T12:05:37.138Z]  D0           w event   device/vbd/51728/backend-id FFFFFFFF81AA8180 
[20170503T12:05:37.138Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/frontend FFFF880881C8F250 
[20170503T12:05:37.138Z]  D0           w event   device/vbd/51728/state FFFFFFFF81AA8180 
[20170503T12:05:37.138Z]  D1           w event   backend/vbd/0/51728/frontend FFFFFFFF81AA7FA0 
[20170503T12:05:37.138Z]  D0           w event   device/vbd/51728/state FFFFFFFF81AA8180 
[20170503T12:05:37.138Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/params FFFF880881C8F250 
[20170503T12:05:37.139Z]  D0           w event   device/vbd/51728/virtual-device FFFFFFFF81AA8180 
[20170503T12:05:37.139Z]  D1           w event   backend/vbd/0/51728/params FFFFFFFF81AA7FA0 
[20170503T12:05:37.139Z]  D0           w event   device/vbd/51728/virtual-device FFFFFFFF81AA8180 
[20170503T12:05:37.139Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/script FFFF880881C8F250 
[20170503T12:05:37.139Z]  D0           w event   device/vbd/51728/device-type FFFFFFFF81AA8180 
[20170503T12:05:37.139Z]  D1           w event   backend/vbd/0/51728/script FFFFFFFF81AA7FA0 
[20170503T12:05:37.139Z]  D0           w event   device/vbd/51728/device-type FFFFFFFF81AA8180 
[20170503T12:05:37.139Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/frontend-id FFFF880881C8F250 
[20170503T12:05:37.139Z]  A31          watch     /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170503T12:05:37.139Z]  D0           w event   device/vbd/51728/protocol FFFFFFFF81AA8180 
[20170503T12:05:37.139Z]  D1           w event   backend/vbd/0/51728/frontend-id FFFFFFFF81AA7FA0 
[20170503T12:05:37.139Z]  D0           w event   device/vbd/51728/protocol FFFFFFFF81AA8180 
[20170503T12:05:37.139Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/online FFFF880881C8F250 
[20170503T12:05:37.139Z]  A31          w event   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170503T12:05:37.139Z]  D1           w event   backend/vbd/0/51728/online FFFFFFFF81AA7FA0 
[20170503T12:05:37.139Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/removable FFFF880881C8F250 
[20170503T12:05:37.139Z]  D1           w event   backend/vbd/0/51728/removable FFFFFFFF81AA7FA0 
[20170503T12:05:37.139Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/bootable FFFF880881C8F250 
[20170503T12:05:37.139Z]  D1           w event   backend/vbd/0/51728/bootable FFFFFFFF81AA7FA0 
[20170503T12:05:37.139Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/state FFFF880881C8F250 
[20170503T12:05:37.139Z]  D1           w event   backend/vbd/0/51728/state FFFFFFFF81AA7FA0 
[20170503T12:05:37.139Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/dev FFFF880881C8F250 
[20170503T12:05:37.139Z]  D1           w event   backend/vbd/0/51728/dev FFFFFFFF81AA7FA0 
[20170503T12:05:37.139Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/type FFFF880881C8F250 
[20170503T12:05:37.139Z]  D1           w event   backend/vbd/0/51728/type FFFFFFFF81AA7FA0 
[20170503T12:05:37.139Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/mode FFFF880881C8F250 
[20170503T12:05:37.139Z]  D1           w event   backend/vbd/0/51728/mode FFFFFFFF81AA7FA0 
[20170503T12:05:37.139Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/device-type FFFF880881C8F250 
[20170503T12:05:37.139Z]  D1           w event   backend/vbd/0/51728/device-type FFFFFFFF81AA7FA0 
[20170503T12:05:37.140Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/discard-enable FFFF880881C8F250 
[20170503T12:05:37.140Z]  D1           w event   backend/vbd/0/51728/discard-enable FFFFFFFF81AA7FA0 
[20170503T12:05:37.140Z]  D0           watch     /local/domain/1/backend/vbd/0/51728/state FFFF88017BA5FC20 
[20170503T12:05:37.140Z]  D0           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88017BA5FC20 
[20170503T12:05:37.140Z]  D1           write     backend/vbd/0/51728/feature-max-indirect-segments 256
[20170503T12:05:37.140Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/feature-max-indirect-segments FFFF880881C8F250 
[20170503T12:05:37.141Z]  D1           w event   backend/vbd/0/51728/feature-max-indirect-segments FFFFFFFF81AA7FA0 
[20170503T12:05:37.141Z]  D1           write     backend/vbd/0/51728/multi-queue-max-queues 4
[20170503T12:05:37.141Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/multi-queue-max-queues FFFF880881C8F250 
[20170503T12:05:37.141Z]  D1           watch     backend/vbd/0/51728/physical-device FFFF88087665DA90 
[20170503T12:05:37.141Z]  D1           w event   backend/vbd/0/51728/multi-queue-max-queues FFFFFFFF81AA7FA0 
[20170503T12:05:37.141Z]  D1           w event   backend/vbd/0/51728/physical-device FFFF88087665DA90 
[20170503T12:05:37.141Z]  D1           write     backend/vbd/0/51728/max-ring-page-order 4
[20170503T12:05:37.141Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/max-ring-page-order FFFF880881C8F250 
[20170503T12:05:37.141Z]  D1           w event   backend/vbd/0/51728/max-ring-page-order FFFFFFFF81AA7FA0 
[20170503T12:05:37.141Z]  D1.16        write     backend/vbd/0/51728/state 2
[20170503T12:05:37.141Z]  D1.16        commit    
[20170503T12:05:37.141Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/state FFFF880881C8F250 
[20170503T12:05:37.141Z]  A31          w event   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170503T12:05:37.141Z]  D0           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88017BA5FC20 
[20170503T12:05:37.141Z]  D1           w event   backend/vbd/0/51728/state FFFFFFFF81AA7FA0 
[20170503T12:05:37.141Z]  D1           watch     /local/domain/0/device/vbd/51728/state FFFF880876742420 
[20170503T12:05:37.141Z]  D1           w event   /local/domain/0/device/vbd/51728/state FFFF880876742420 
[20170503T12:05:37.142Z]  D0.15        write     device/vbd/51728/ring-ref 79
[20170503T12:05:37.142Z]  A31          unwatch   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170503T12:05:37.142Z]  D0.15        write     device/vbd/51728/event-channel 83
[20170503T12:05:37.142Z]  D0.15        write     device/vbd/51728/protocol x86_64-abi
[20170503T12:05:37.142Z]  D0.15        write     device/vbd/51728/feature-persistent 1
[20170503T12:05:37.142Z]  D0.15        commit    
[20170503T12:05:37.142Z]  D0           w event   device/vbd/51728/ring-ref FFFFFFFF81AA8180 
[20170503T12:05:37.142Z]  D0           w event   device/vbd/51728/event-channel FFFFFFFF81AA8180 
[20170503T12:05:37.142Z]  D0           w event   device/vbd/51728/protocol FFFFFFFF81AA8180 
[20170503T12:05:37.142Z]  D0           w event   device/vbd/51728/feature-persistent FFFFFFFF81AA8180 
[20170503T12:05:37.143Z]  D0.16        write     device/vbd/51728/state 3
[20170503T12:05:37.143Z]  D0.16        commit    
[20170503T12:05:37.143Z]  D0           w event   device/vbd/51728/state FFFFFFFF81AA8180 
[20170503T12:05:37.143Z]  D1           w event   /local/domain/0/device/vbd/51728/state FFFF880876742420 
[20170503T12:05:37.143Z]  A31          endconn   
[20170503T12:05:37.143Z]  D1           watch     /local/domain/1/backend/vbd/0/51728/state FFFF880872DA3110 
[20170503T12:05:37.143Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/state FFFF880872DA3110 
[20170503T12:05:37.148Z]  D1           unwatch   /local/domain/1/backend/vbd/0/51728/state FFFF880872DA3110 
[20170503T12:05:37.345Z]  D1.17        commit    
[20170503T12:05:37.353Z]  D1.18        commit    
[20170503T12:05:37.389Z]  D1           write     backend/vbd/0/51728/physical-device e6:20
[20170503T12:05:37.389Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/physical-device FFFF880881C8F250 
[20170503T12:05:37.390Z]  D1           w event   backend/vbd/0/51728/physical-device FFFFFFFF81AA7FA0 
[20170503T12:05:37.390Z]  D1           w event   backend/vbd/0/51728/physical-device FFFF88087665DA90 
[20170503T12:05:37.392Z]  D1.19        write     backend/vbd/0/51728/feature-flush-cache 1
[20170503T12:05:37.392Z]  D1.19        write     backend/vbd/0/51728/discard-granularity 8192
[20170503T12:05:37.392Z]  D1.19        write     backend/vbd/0/51728/discard-alignment 0
[20170503T12:05:37.392Z]  D1.19        write     backend/vbd/0/51728/discard-secure 0
[20170503T12:05:37.392Z]  D1.19        write     backend/vbd/0/51728/feature-discard 1
[20170503T12:05:37.392Z]  D1.19        write     backend/vbd/0/51728/feature-barrier 1
[20170503T12:05:37.392Z]  D1.19        write     backend/vbd/0/51728/feature-persistent 1
[20170503T12:05:37.392Z]  D1.19        write     backend/vbd/0/51728/sectors 209715200
[20170503T12:05:37.393Z]  D1.19        write     backend/vbd/0/51728/info 0
[20170503T12:05:37.393Z]  D1.19        write     backend/vbd/0/51728/sector-size 512
[20170503T12:05:37.393Z]  D1.19        write     backend/vbd/0/51728/physical-sector-size 8192
[20170503T12:05:37.393Z]  D1.19        commit    
[20170503T12:05:37.393Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/feature-flush-cache FFFF880881C8F250 
[20170503T12:05:37.393Z]  D1           w event   backend/vbd/0/51728/feature-flush-cache FFFFFFFF81AA7FA0 
[20170503T12:05:37.393Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/discard-granularity FFFF880881C8F250 
[20170503T12:05:37.393Z]  D1           w event   backend/vbd/0/51728/discard-granularity FFFFFFFF81AA7FA0 
[20170503T12:05:37.393Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/discard-alignment FFFF880881C8F250 
[20170503T12:05:37.393Z]  D1           w event   backend/vbd/0/51728/discard-alignment FFFFFFFF81AA7FA0 
[20170503T12:05:37.393Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/discard-secure FFFF880881C8F250 
[20170503T12:05:37.393Z]  D1           w event   backend/vbd/0/51728/discard-secure FFFFFFFF81AA7FA0 
[20170503T12:05:37.393Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/feature-discard FFFF880881C8F250 
[20170503T12:05:37.393Z]  D1           w event   backend/vbd/0/51728/feature-discard FFFFFFFF81AA7FA0 
[20170503T12:05:37.393Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/feature-barrier FFFF880881C8F250 
[20170503T12:05:37.393Z]  D1           w event   backend/vbd/0/51728/feature-barrier FFFFFFFF81AA7FA0 
[20170503T12:05:37.393Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/feature-persistent FFFF880881C8F250 
[20170503T12:05:37.393Z]  D1           w event   backend/vbd/0/51728/feature-persistent FFFFFFFF81AA7FA0 
[20170503T12:05:37.393Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/sectors FFFF880881C8F250 
[20170503T12:05:37.393Z]  D1           w event   backend/vbd/0/51728/sectors FFFFFFFF81AA7FA0 
[20170503T12:05:37.393Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/info FFFF880881C8F250 
[20170503T12:05:37.393Z]  D1           w event   backend/vbd/0/51728/info FFFFFFFF81AA7FA0 
[20170503T12:05:37.393Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/sector-size FFFF880881C8F250 
[20170503T12:05:37.394Z]  D1           w event   backend/vbd/0/51728/sector-size FFFFFFFF81AA7FA0 
[20170503T12:05:37.394Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/physical-sector-size FFFF880881C8F250 
[20170503T12:05:37.394Z]  D1           w event   backend/vbd/0/51728/physical-sector-size FFFFFFFF81AA7FA0 
[20170503T12:05:37.394Z]  D1.20        write     backend/vbd/0/51728/state 4
[20170503T12:05:37.394Z]  D1.20        commit    
[20170503T12:05:37.394Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/state FFFF880881C8F250 
[20170503T12:05:37.394Z]  D0           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88017BA5FC20 
[20170503T12:05:37.394Z]  D1           w event   backend/vbd/0/51728/state FFFFFFFF81AA7FA0 
[20170503T12:05:37.398Z]  D0.17        write     device/vbd/51728/state 4
[20170503T12:05:37.398Z]  D0.17        commit    
[20170503T12:05:37.398Z]  D0           w event   device/vbd/51728/state FFFFFFFF81AA8180 
[20170503T12:05:37.398Z]  D1           w event   /local/domain/0/device/vbd/51728/state FFFF880876742420 
[20170503T12:05:37.402Z]  D1           write     backend/vbd/0/51728/physical-device-path /dev/zd32
[20170503T12:05:37.402Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/physical-device-path FFFF880881C8F250 
[20170503T12:05:37.402Z]  D1           w event   backend/vbd/0/51728/physical-device-path FFFFFFFF81AA7FA0 
[20170503T12:05:37.414Z]  D1           write     backend/vbd/0/51728/hotplug-status connected
[20170503T12:05:37.414Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/hotplug-status FFFF880881C8F250 
[20170503T12:05:37.414Z]  D1           w event   backend/vbd/0/51728/hotplug-status FFFFFFFF81AA7FA0 
[20170503T12:06:18.149Z]  A32          newconn   
[20170503T12:06:18.260Z]  A32          endconn   

# After the 1st `xl block-detach` command:

[20170503T12:06:43.580Z]  A33          newconn   
[20170503T12:06:43.583Z]  A33.1        write     /local/domain/1/backend/vbd/0/51712/online 0
[20170503T12:06:43.583Z]  A33.1        write     /local/domain/1/backend/vbd/0/51712/state 5
[20170503T12:06:43.583Z]  A33.1        commit    
[20170503T12:06:43.583Z]  D0           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880180A24C20 
[20170503T12:06:43.583Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/online FFFF880881C8F250 
[20170503T12:06:43.583Z]  D1           w event   backend/vbd/0/51712/online FFFFFFFF81AA7FA0 
[20170503T12:06:43.584Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880881C8F250 
[20170503T12:06:43.584Z]  D1           w event   backend/vbd/0/51712/state FFFFFFFF81AA7FA0 
[20170503T12:06:43.584Z]  A33          watch     /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170503T12:06:43.584Z]  A33          w event   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170503T12:06:43.624Z]  D0.18        write     device/vbd/51712/state 6
[20170503T12:06:43.624Z]  D0.18        commit    
[20170503T12:06:43.624Z]  D0           w event   device/vbd/51712/state FFFFFFFF81AA8180 
[20170503T12:06:43.624Z]  D1           w event   /local/domain/0/device/vbd/51712/state FFFF880874281820 
[20170503T12:06:43.629Z]  D1.21        write     backend/vbd/0/51712/state 6
[20170503T12:06:43.629Z]  D1.21        commit    
[20170503T12:06:43.629Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880881C8F250 
[20170503T12:06:43.629Z]  A33          w event   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170503T12:06:43.629Z]  D0           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880180A24C20 
[20170503T12:06:43.629Z]  D1           w event   backend/vbd/0/51712/state FFFFFFFF81AA7FA0 
[20170503T12:06:43.629Z]  D1           unwatch   /local/domain/0/device/vbd/51712/state FFFF880874281820 
[20170503T12:06:43.629Z]  A33          unwatch   /local/domain/1/backend/vbd/0/51712/state 3/0 
[20170503T12:06:43.629Z]  D1           unwatch   backend/vbd/0/51712/physical-device FFFF88087665D190 
[20170503T12:06:43.630Z]  A33          watch     /local/domain/1/backend/vbd/0/51712 3/1 
[20170503T12:06:43.630Z]  A33          w event   /local/domain/1/backend/vbd/0/51712 3/1 
[20170503T12:06:43.632Z]  D1.22        write     /local/domain/1/backend/vbd/0/51712/online 0
[20170503T12:06:43.632Z]  D1.22        commit    
[20170503T12:06:43.632Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/online FFFF880881C8F250 
[20170503T12:06:43.633Z]  A33          w event   /local/domain/1/backend/vbd/0/51712/online 3/1 
[20170503T12:06:43.633Z]  D1           w event   backend/vbd/0/51712/online FFFFFFFF81AA7FA0 
[20170503T12:06:43.633Z]  D1           watch     /local/domain/1/backend/vbd/0/51712/state FFFF8808725C8950 
[20170503T12:06:43.633Z]  D1           w event   /local/domain/1/backend/vbd/0/51712/state FFFF8808725C8950 
[20170503T12:06:43.634Z]  D1           unwatch   /local/domain/1/backend/vbd/0/51712/state FFFF8808725C8950 
[20170503T12:06:43.714Z]  D1.23        rm        /local/domain/1/backend/vbd/0/51712 
[20170503T12:06:43.714Z]  D1.23        commit    
[20170503T12:06:43.715Z]  D1           w event   /local/domain/1/backend/vbd/0/51712 FFFF880881C8F250 
[20170503T12:06:43.715Z]  A33          w event   /local/domain/1/backend/vbd/0/51712 3/1 
[20170503T12:06:43.715Z]  D0           w event   /local/domain/1/backend/vbd/0/51712/state FFFF880180A24C20 
[20170503T12:06:43.715Z]  D1           w event   backend/vbd/0/51712 FFFFFFFF81AA7FA0 
[20170503T12:06:43.715Z]  A33          unwatch   /local/domain/1/backend/vbd/0/51712 3/1 
[20170503T12:06:43.716Z]  A33.2        rm        /local/domain/0/device/vbd/51712 
[20170503T12:06:43.717Z]  A33.2        rm        /libxl/0/device/vbd/51712 
[20170503T12:06:43.717Z]  A33.2        commit    
[20170503T12:06:43.717Z]  D0           w event   device/vbd/51712 FFFFFFFF81AA8180 
[20170503T12:06:43.717Z]  D0           unwatch   /local/domain/1/backend/vbd/0/51712/state FFFF880180A24C20 
[20170503T12:06:43.718Z]  A33          endconn   
[20170503T12:07:44.578Z]  A34          newconn   
[20170503T12:07:44.660Z]  A34          endconn   

# After the 2nd `xl block-detach` command:

[20170503T12:08:09.743Z]  A35          newconn   
[20170503T12:08:09.746Z]  A35.1        write     /local/domain/1/backend/vbd/0/51728/online 0
[20170503T12:08:09.746Z]  A35.1        write     /local/domain/1/backend/vbd/0/51728/state 5
[20170503T12:08:09.746Z]  A35.1        commit    
[20170503T12:08:09.746Z]  D0           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88017BA5FC20 
[20170503T12:08:09.746Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/online FFFF880881C8F250 
[20170503T12:08:09.746Z]  D1           w event   backend/vbd/0/51728/online FFFFFFFF81AA7FA0 
[20170503T12:08:09.746Z]  D1           w event   /local/domain/1/backend/vbd/0/51728/state FFFF880881C8F250 
[20170503T12:08:09.746Z]  D1           w event   backend/vbd/0/51728/state FFFFFFFF81AA7FA0 
[20170503T12:08:09.746Z]  A35          watch     /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170503T12:08:09.747Z]  A35          w event   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170503T12:08:09.782Z]  D1           unwatch   /local/domain/1/backend FFFF880881C8F250 
[20170503T12:08:09.794Z]  D0.19        write     device/vbd/51728/state 6
[20170503T12:08:09.794Z]  D0.19        commit    
[20170503T12:08:09.794Z]  D0           w event   device/vbd/51728/state FFFFFFFF81AA8180 
[20170503T12:08:09.794Z]  D1           w event   /local/domain/0/device/vbd/51728/state FFFF880876742420 
[20170503T12:08:09.796Z]  D1.24        write     backend/vbd/0/51728/state 6
[20170503T12:08:09.796Z]  D1.24        commit    
[20170503T12:08:09.796Z]  D1           w event   backend/vbd/0/51728/state FFFFFFFF81AA7FA0 
[20170503T12:08:09.796Z]  A35          w event   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170503T12:08:09.796Z]  D0           w event   /local/domain/1/backend/vbd/0/51728/state FFFF88017BA5FC20 
[20170503T12:08:09.796Z]  D1           unwatch   /local/domain/0/device/vbd/51728/state FFFF880876742420 
[20170503T12:08:09.796Z]  D1           unwatch   backend/vbd/0/51728/physical-device FFFF88087665DA90 
[20170503T12:08:09.796Z]  A35          unwatch   /local/domain/1/backend/vbd/0/51728/state 3/0 
[20170503T12:08:09.797Z]  A35          watch     /local/domain/1/backend/vbd/0/51728 3/1 
[20170503T12:08:09.797Z]  A35          w event   /local/domain/1/backend/vbd/0/51728 3/1 
[20170503T12:08:10.919Z]  D1           watch     /local/domain/1/backend FFFF8808743D01D0 
[20170503T12:08:10.919Z]  D1           w event   /local/domain/1/backend FFFF8808743D01D0 
[20170503T12:08:19.808Z]  A35          unwatch   /local/domain/1/backend/vbd/0/51728 3/1 
[20170503T12:08:19.809Z]  A35.2        rm        /local/domain/0/device/vbd/51728 
[20170503T12:08:19.809Z]  A35.2        rm        /local/domain/0/device/vbd 
[20170503T12:08:19.809Z]  A35.2        rm        /local/domain/0/device 
[20170503T12:08:19.810Z]  A35.2        rm        /libxl/0/device/vbd/51728 
[20170503T12:08:19.810Z]  A35.2        rm        /libxl/0/device/vbd 
[20170503T12:08:19.811Z]  A35.2        rm        /libxl/0/device 
[20170503T12:08:19.811Z]  A35.2        rm        /libxl/0 
[20170503T12:08:19.811Z]  A35.2        commit    
[20170503T12:08:19.812Z]  D0           w event   device/vbd/51728 FFFFFFFF81AA8180 
[20170503T12:08:19.812Z]  D0           w event   device/vbd FFFFFFFF81AA8180 
[20170503T12:08:19.812Z]  D0           w event   device FFFFFFFF81AA8180 
[20170503T12:08:19.812Z]  D0           unwatch   /local/domain/1/backend/vbd/0/51728/state FFFF88017BA5FC20 
[20170503T12:08:19.812Z]  A35          endconn   
[20170503T12:09:19.769Z]  A36          newconn   
[20170503T12:09:19.839Z]  A36          endconn   

[-- Attachment #5: xenstore-ls.txt --]
[-- Type: text/plain, Size: 99771 bytes --]

# Before the 1st `xl block-attach` command:

/local = ""   (n0)
/local/domain = ""   (n0)
/local/domain/0 = ""   (n0)
/local/domain/0/control = ""   (n0)
/local/domain/0/control/feature-poweroff = "1"   (n0)
/local/domain/0/control/feature-reboot = "1"   (n0)
/local/domain/0/control/feature-suspend = "1"   (n0)
/local/domain/0/domid = "0"   (n0)
/local/domain/0/name = "Domain-0"   (n0)
/local/domain/0/device-model = ""   (n0)
/local/domain/0/device-model/0 = ""   (n0)
/local/domain/0/device-model/0/backends = ""   (n0)
/local/domain/0/device-model/0/backends/console = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vkbd = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qdisk = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qusb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vfb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qnic = ""   (n0,n0)
/local/domain/0/device-model/0/state = "running"   (n0)
/local/domain/0/backend = ""   (n0)
/local/domain/0/backend/vbd = ""   (n0)
/local/domain/0/backend/vbd/1 = ""   (n0)
/local/domain/0/backend/vbd/1/51712 = ""   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/script = "/etc/xen/scripts/block"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/online = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/removable = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/bootable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/state = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/dev = "xvda"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/type = "phy"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/mode = "w"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/device-type = "disk"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-enable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-max-indirect-segments = "256"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/max-ring-page-order = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device = "fe:22"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device-path = "/dev/dm-34"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-flush-cache = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-granularity = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-alignment = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-secure = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-discard = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-barrier = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sectors = "16777216"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/info = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sector-size = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-sector-size = "512"   (n0,r1)
/local/domain/0/backend/console = ""   (n0)
/local/domain/0/backend/console/1 = ""   (n0)
/local/domain/0/backend/console/1/0 = ""   (n0,r1)
/local/domain/0/backend/console/1/0/frontend = "/local/domain/1/console"   (n0,r1)
/local/domain/0/backend/console/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/state = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/protocol = "vt100"   (n0,r1)
/local/domain/0/backend/vif = ""   (n0)
/local/domain/0/backend/vif/1 = ""   (n0)
/local/domain/0/backend/vif/1/0 = ""   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend = "/local/domain/1/device/vif/0"   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/script = "/etc/xen/scripts/vif-bridge"   (n0,r1)
/local/domain/0/backend/vif/1/0/mac = "00:16:3e:aa:bb:cc"   (n0,r1)
/local/domain/0/backend/vif/1/0/bridge = "xenbr0"   (n0,r1)
/local/domain/0/backend/vif/1/0/handle = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/type = "vif"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-sg = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv4 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv6 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ipv6-csum-offload = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-copy = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-flip = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-dynamic-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-split-event-channels = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ctrl-ring = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/pci = ""   (n0)
/local/domain/0/backend/pci/1 = ""   (n0)
/local/domain/0/backend/pci/1/0 = ""   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend = "/local/domain/1/device/pci/0"   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/pci/1/0/domain = "arch-zfs-test"   (n0,r1)
/local/domain/0/backend/pci/1/0/key-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/dev-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0,r1)
/local/domain/0/backend/pci/1/0/state-0 = "3"   (n0,r1)
/local/domain/0/backend/pci/1/0/num_devs = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/vdev-0 = "0000:00:00.00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root-0 = "0000:00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root_num = "1"   (n0,r1)
/local/domain/1 = ""   (n0,r1)
/local/domain/1/vm = "/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e"   (n0,r1)
/local/domain/1/name = "arch-zfs-test"   (n0,r1)
/local/domain/1/cpu = ""   (n0,r1)
/local/domain/1/cpu/0 = ""   (n0,r1)
/local/domain/1/cpu/0/availability = "online"   (n0,r1)
/local/domain/1/cpu/1 = ""   (n0,r1)
/local/domain/1/cpu/1/availability = "online"   (n0,r1)
/local/domain/1/cpu/2 = ""   (n0,r1)
/local/domain/1/cpu/2/availability = "online"   (n0,r1)
/local/domain/1/cpu/3 = ""   (n0,r1)
/local/domain/1/cpu/3/availability = "online"   (n0,r1)
/local/domain/1/memory = ""   (n0,r1)
/local/domain/1/memory/static-max = "33554432"   (n0,r1)
/local/domain/1/memory/target = "33554432"   (n0,r1)
/local/domain/1/memory/videoram = "0"   (n0,r1)
/local/domain/1/device = ""   (n0,r1)
/local/domain/1/device/suspend = ""   (n0,r1)
/local/domain/1/device/suspend/event-channel = ""   (n1)
/local/domain/1/device/vbd = ""   (n0,r1)
/local/domain/1/device/vbd/51712 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n1,r0)
/local/domain/1/device/vbd/51712/backend-id = "0"   (n1,r0)
/local/domain/1/device/vbd/51712/state = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/virtual-device = "51712"   (n1,r0)
/local/domain/1/device/vbd/51712/device-type = "disk"   (n1,r0)
/local/domain/1/device/vbd/51712/protocol = "x86_64-abi"   (n1,r0)
/local/domain/1/device/vbd/51712/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/ring-ref = "8"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/event-channel = "31"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/ring-ref = "9"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/event-channel = "32"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/ring-ref = "10"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/event-channel = "33"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/ring-ref = "11"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/event-channel = "34"   (n1,r0)
/local/domain/1/device/vbd/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/device/vif = ""   (n0,r1)
/local/domain/1/device/vif/0 = ""   (n1,r0)
/local/domain/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n1,r0)
/local/domain/1/device/vif/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/vif/0/state = "4"   (n1,r0)
/local/domain/1/device/vif/0/handle = "0"   (n1,r0)
/local/domain/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n1,r0)
/local/domain/1/device/vif/0/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vif/0/queue-0 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-0/tx-ring-ref = "2304"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/rx-ring-ref = "2305"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-tx = "35"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-rx = "36"   (n1,r0)
/local/domain/1/device/vif/0/queue-1 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-1/tx-ring-ref = "2306"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/rx-ring-ref = "2307"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-tx = "37"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-rx = "38"   (n1,r0)
/local/domain/1/device/vif/0/queue-2 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-2/tx-ring-ref = "2308"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/rx-ring-ref = "2309"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-tx = "39"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-rx = "40"   (n1,r0)
/local/domain/1/device/vif/0/queue-3 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-3/tx-ring-ref = "2310"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/rx-ring-ref = "2311"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-tx = "41"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-rx = "42"   (n1,r0)
/local/domain/1/device/vif/0/request-rx-copy = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-rx-notify = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-sg = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv4 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv6 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-ipv6-csum-offload = "1"   (n1,r0)
/local/domain/1/device/pci = ""   (n0,r1)
/local/domain/1/device/pci/0 = ""   (n1,r0)
/local/domain/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n1,r0)
/local/domain/1/device/pci/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/pci/0/state = "4"   (n1,r0)
/local/domain/1/device/pci/0/pci-op-ref = "362"   (n1,r0)
/local/domain/1/device/pci/0/event-channel = "43"   (n1,r0)
/local/domain/1/device/pci/0/magic = "7"   (n1,r0)
/local/domain/1/control = ""   (n0,r1)
/local/domain/1/control/shutdown = ""   (n1)
/local/domain/1/control/feature-poweroff = "1"   (n1)
/local/domain/1/control/feature-reboot = "1"   (n1)
/local/domain/1/control/feature-suspend = "1"   (n1)
/local/domain/1/control/platform-feature-multiprocessor-suspend = "1"   (n0,r1)
/local/domain/1/control/platform-feature-xs_reset_watches = "1"   (n0,r1)
/local/domain/1/data = ""   (n1)
/local/domain/1/drivers = ""   (n1)
/local/domain/1/feature = ""   (n1)
/local/domain/1/attr = ""   (n1)
/local/domain/1/libxl = ""   (n1)
/local/domain/1/device-model = ""   (n1)
/local/domain/1/domid = "1"   (n0,r1)
/local/domain/1/store = ""   (n0,r1)
/local/domain/1/store/port = "1"   (n0,r1)
/local/domain/1/store/ring-ref = "20014982"   (n0,r1)
/local/domain/1/console = ""   (n0,r1)
/local/domain/1/console/backend = "/local/domain/0/backend/console/1/0"   (n0,r1)
/local/domain/1/console/backend-id = "0"   (n1,r0)
/local/domain/1/console/limit = "1048576"   (n0,r1)
/local/domain/1/console/type = "xenconsoled"   (n0,r1)
/local/domain/1/console/output = "pty"   (n0,r1)
/local/domain/1/console/tty = "/dev/pts/1"   (n0,r1)
/local/domain/1/console/port = "2"   (n0,r1)
/local/domain/1/console/ring-ref = "20014983"   (n0,r1)
/libxl = ""   (n0)
/libxl/pciback = ""   (n0)
/libxl/pciback/0000-00-1f-2 = ""   (n0)
/libxl/pciback/0000-00-1f-2/driver_path = "/sys/bus/pci/drivers/ahci"   (n0)
/libxl/pciback/0000-01-00-0 = ""   (n0)
/libxl/pciback/0000-01-00-0/driver_path = "/sys/bus/pci/drivers/mpt3sas"   (n0)
/libxl/pciback/0000-06-00-0 = ""   (n0)
/libxl/pciback/0000-06-00-0/driver_path = "/sys/bus/pci/drivers/serial"   (n0)
/libxl/1 = ""   (n0)
/libxl/1/device = ""   (n0)
/libxl/1/device/vbd = ""   (n0)
/libxl/1/device/vbd/51712 = ""   (n0)
/libxl/1/device/vbd/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0)
/libxl/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n0)
/libxl/1/device/vbd/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0)
/libxl/1/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/1/device/vbd/51712/frontend-id = "1"   (n0)
/libxl/1/device/vbd/51712/online = "1"   (n0)
/libxl/1/device/vbd/51712/removable = "0"   (n0)
/libxl/1/device/vbd/51712/bootable = "1"   (n0)
/libxl/1/device/vbd/51712/state = "1"   (n0)
/libxl/1/device/vbd/51712/dev = "xvda"   (n0)
/libxl/1/device/vbd/51712/type = "phy"   (n0)
/libxl/1/device/vbd/51712/mode = "w"   (n0)
/libxl/1/device/vbd/51712/device-type = "disk"   (n0)
/libxl/1/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/1/device/console = ""   (n0)
/libxl/1/device/console/0 = ""   (n0)
/libxl/1/device/console/0/frontend = "/local/domain/1/console"   (n0)
/libxl/1/device/console/0/backend = "/local/domain/0/backend/console/1/0"   (n0)
/libxl/1/device/console/0/frontend-id = "1"   (n0)
/libxl/1/device/console/0/online = "1"   (n0)
/libxl/1/device/console/0/state = "1"   (n0)
/libxl/1/device/console/0/protocol = "vt100"   (n0)
/libxl/1/device/vif = ""   (n0)
/libxl/1/device/vif/0 = ""   (n0)
/libxl/1/device/vif/0/frontend = "/local/domain/1/device/vif/0"   (n0)
/libxl/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n0)
/libxl/1/device/vif/0/frontend-id = "1"   (n0)
/libxl/1/device/vif/0/online = "1"   (n0)
/libxl/1/device/vif/0/state = "1"   (n0)
/libxl/1/device/vif/0/script = "/etc/xen/scripts/vif-bridge"   (n0)
/libxl/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n0)
/libxl/1/device/vif/0/bridge = "xenbr0"   (n0)
/libxl/1/device/vif/0/handle = "0"   (n0)
/libxl/1/device/vif/0/type = "vif"   (n0)
/libxl/1/device/pci = ""   (n0)
/libxl/1/device/pci/0 = ""   (n0)
/libxl/1/device/pci/0/frontend = "/local/domain/1/device/pci/0"   (n0)
/libxl/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n0)
/libxl/1/device/pci/0/frontend-id = "1"   (n0)
/libxl/1/device/pci/0/online = "1"   (n0)
/libxl/1/device/pci/0/state = "1"   (n0)
/libxl/1/device/pci/0/domain = "arch-zfs-test"   (n0)
/libxl/1/device/pci/0/key-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/dev-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0)
/libxl/1/device/pci/0/state-0 = "1"   (n0)
/libxl/1/device/pci/0/num_devs = "1"   (n0)
/libxl/1/dm-version = "qemu_xen"   (n0)
/vm = ""   (n0)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e = ""   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/name = "arch-zfs-test"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/uuid = "ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image = ""   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/ostype = "linux"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/kernel = "/run/xen/bootloader.1.d/boot_kernel.DD1934"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/ramdisk = "/run/xen/bootloader.1.d/boot_ramdisk._HBmJ1"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/cmdline = "root=UUID=c4e5bb0c-5638-45f6-a90a-0107cc97506b ro"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/start_time = "1493812417.09"   (n0,r1)

# After the 1st `xl block-attach` command:

/local = ""   (n0)
/local/domain = ""   (n0)
/local/domain/0 = ""   (n0)
/local/domain/0/control = ""   (n0)
/local/domain/0/control/feature-poweroff = "1"   (n0)
/local/domain/0/control/feature-reboot = "1"   (n0)
/local/domain/0/control/feature-suspend = "1"   (n0)
/local/domain/0/domid = "0"   (n0)
/local/domain/0/name = "Domain-0"   (n0)
/local/domain/0/device-model = ""   (n0)
/local/domain/0/device-model/0 = ""   (n0)
/local/domain/0/device-model/0/backends = ""   (n0)
/local/domain/0/device-model/0/backends/console = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vkbd = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qdisk = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qusb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vfb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qnic = ""   (n0,n0)
/local/domain/0/device-model/0/state = "running"   (n0)
/local/domain/0/backend = ""   (n0)
/local/domain/0/backend/vbd = ""   (n0)
/local/domain/0/backend/vbd/1 = ""   (n0)
/local/domain/0/backend/vbd/1/51712 = ""   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/script = "/etc/xen/scripts/block"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/online = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/removable = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/bootable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/state = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/dev = "xvda"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/type = "phy"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/mode = "w"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/device-type = "disk"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-enable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-max-indirect-segments = "256"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/max-ring-page-order = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device = "fe:22"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device-path = "/dev/dm-34"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-flush-cache = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-granularity = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-alignment = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-secure = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-discard = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-barrier = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sectors = "16777216"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/info = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sector-size = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-sector-size = "512"   (n0,r1)
/local/domain/0/backend/console = ""   (n0)
/local/domain/0/backend/console/1 = ""   (n0)
/local/domain/0/backend/console/1/0 = ""   (n0,r1)
/local/domain/0/backend/console/1/0/frontend = "/local/domain/1/console"   (n0,r1)
/local/domain/0/backend/console/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/state = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/protocol = "vt100"   (n0,r1)
/local/domain/0/backend/vif = ""   (n0)
/local/domain/0/backend/vif/1 = ""   (n0)
/local/domain/0/backend/vif/1/0 = ""   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend = "/local/domain/1/device/vif/0"   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/script = "/etc/xen/scripts/vif-bridge"   (n0,r1)
/local/domain/0/backend/vif/1/0/mac = "00:16:3e:aa:bb:cc"   (n0,r1)
/local/domain/0/backend/vif/1/0/bridge = "xenbr0"   (n0,r1)
/local/domain/0/backend/vif/1/0/handle = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/type = "vif"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-sg = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv4 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv6 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ipv6-csum-offload = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-copy = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-flip = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-dynamic-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-split-event-channels = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ctrl-ring = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/pci = ""   (n0)
/local/domain/0/backend/pci/1 = ""   (n0)
/local/domain/0/backend/pci/1/0 = ""   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend = "/local/domain/1/device/pci/0"   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/pci/1/0/domain = "arch-zfs-test"   (n0,r1)
/local/domain/0/backend/pci/1/0/key-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/dev-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0,r1)
/local/domain/0/backend/pci/1/0/state-0 = "3"   (n0,r1)
/local/domain/0/backend/pci/1/0/num_devs = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/vdev-0 = "0000:00:00.00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root-0 = "0000:00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root_num = "1"   (n0,r1)
/local/domain/0/device = ""   (n0)
/local/domain/0/device/vbd = ""   (n0)
/local/domain/0/device/vbd/51712 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/backend = "/local/domain/1/backend/vbd/0/51712"   (n0,r1)
/local/domain/0/device/vbd/51712/backend-id = "1"   (n0,r1)
/local/domain/0/device/vbd/51712/state = "4"   (n0,r1)
/local/domain/0/device/vbd/51712/virtual-device = "51712"   (n0,r1)
/local/domain/0/device/vbd/51712/device-type = "disk"   (n0,r1)
/local/domain/0/device/vbd/51712/protocol = "x86_64-abi"   (n0,r1)
/local/domain/0/device/vbd/51712/multi-queue-num-queues = "4"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0/ring-ref = "8"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0/event-channel = "79"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1/ring-ref = "9"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1/event-channel = "80"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2/ring-ref = "10"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2/event-channel = "81"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3/ring-ref = "11"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3/event-channel = "82"   (n0,r1)
/local/domain/0/device/vbd/51712/feature-persistent = "1"   (n0,r1)
/local/domain/1 = ""   (n0,r1)
/local/domain/1/vm = "/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e"   (n0,r1)
/local/domain/1/name = "arch-zfs-test"   (n0,r1)
/local/domain/1/cpu = ""   (n0,r1)
/local/domain/1/cpu/0 = ""   (n0,r1)
/local/domain/1/cpu/0/availability = "online"   (n0,r1)
/local/domain/1/cpu/1 = ""   (n0,r1)
/local/domain/1/cpu/1/availability = "online"   (n0,r1)
/local/domain/1/cpu/2 = ""   (n0,r1)
/local/domain/1/cpu/2/availability = "online"   (n0,r1)
/local/domain/1/cpu/3 = ""   (n0,r1)
/local/domain/1/cpu/3/availability = "online"   (n0,r1)
/local/domain/1/memory = ""   (n0,r1)
/local/domain/1/memory/static-max = "33554432"   (n0,r1)
/local/domain/1/memory/target = "33554432"   (n0,r1)
/local/domain/1/memory/videoram = "0"   (n0,r1)
/local/domain/1/device = ""   (n0,r1)
/local/domain/1/device/suspend = ""   (n0,r1)
/local/domain/1/device/suspend/event-channel = ""   (n1)
/local/domain/1/device/vbd = ""   (n0,r1)
/local/domain/1/device/vbd/51712 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n1,r0)
/local/domain/1/device/vbd/51712/backend-id = "0"   (n1,r0)
/local/domain/1/device/vbd/51712/state = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/virtual-device = "51712"   (n1,r0)
/local/domain/1/device/vbd/51712/device-type = "disk"   (n1,r0)
/local/domain/1/device/vbd/51712/protocol = "x86_64-abi"   (n1,r0)
/local/domain/1/device/vbd/51712/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/ring-ref = "8"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/event-channel = "31"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/ring-ref = "9"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/event-channel = "32"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/ring-ref = "10"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/event-channel = "33"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/ring-ref = "11"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/event-channel = "34"   (n1,r0)
/local/domain/1/device/vbd/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/device/vif = ""   (n0,r1)
/local/domain/1/device/vif/0 = ""   (n1,r0)
/local/domain/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n1,r0)
/local/domain/1/device/vif/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/vif/0/state = "4"   (n1,r0)
/local/domain/1/device/vif/0/handle = "0"   (n1,r0)
/local/domain/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n1,r0)
/local/domain/1/device/vif/0/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vif/0/queue-0 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-0/tx-ring-ref = "2304"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/rx-ring-ref = "2305"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-tx = "35"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-rx = "36"   (n1,r0)
/local/domain/1/device/vif/0/queue-1 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-1/tx-ring-ref = "2306"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/rx-ring-ref = "2307"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-tx = "37"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-rx = "38"   (n1,r0)
/local/domain/1/device/vif/0/queue-2 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-2/tx-ring-ref = "2308"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/rx-ring-ref = "2309"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-tx = "39"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-rx = "40"   (n1,r0)
/local/domain/1/device/vif/0/queue-3 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-3/tx-ring-ref = "2310"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/rx-ring-ref = "2311"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-tx = "41"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-rx = "42"   (n1,r0)
/local/domain/1/device/vif/0/request-rx-copy = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-rx-notify = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-sg = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv4 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv6 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-ipv6-csum-offload = "1"   (n1,r0)
/local/domain/1/device/pci = ""   (n0,r1)
/local/domain/1/device/pci/0 = ""   (n1,r0)
/local/domain/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n1,r0)
/local/domain/1/device/pci/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/pci/0/state = "4"   (n1,r0)
/local/domain/1/device/pci/0/pci-op-ref = "362"   (n1,r0)
/local/domain/1/device/pci/0/event-channel = "43"   (n1,r0)
/local/domain/1/device/pci/0/magic = "7"   (n1,r0)
/local/domain/1/control = ""   (n0,r1)
/local/domain/1/control/shutdown = ""   (n1)
/local/domain/1/control/feature-poweroff = "1"   (n1)
/local/domain/1/control/feature-reboot = "1"   (n1)
/local/domain/1/control/feature-suspend = "1"   (n1)
/local/domain/1/control/platform-feature-multiprocessor-suspend = "1"   (n0,r1)
/local/domain/1/control/platform-feature-xs_reset_watches = "1"   (n0,r1)
/local/domain/1/data = ""   (n1)
/local/domain/1/drivers = ""   (n1)
/local/domain/1/feature = ""   (n1)
/local/domain/1/attr = ""   (n1)
/local/domain/1/libxl = ""   (n1)
/local/domain/1/device-model = ""   (n1)
/local/domain/1/domid = "1"   (n0,r1)
/local/domain/1/store = ""   (n0,r1)
/local/domain/1/store/port = "1"   (n0,r1)
/local/domain/1/store/ring-ref = "20014982"   (n0,r1)
/local/domain/1/console = ""   (n0,r1)
/local/domain/1/console/backend = "/local/domain/0/backend/console/1/0"   (n0,r1)
/local/domain/1/console/backend-id = "0"   (n1,r0)
/local/domain/1/console/limit = "1048576"   (n0,r1)
/local/domain/1/console/type = "xenconsoled"   (n0,r1)
/local/domain/1/console/output = "pty"   (n0,r1)
/local/domain/1/console/tty = "/dev/pts/1"   (n0,r1)
/local/domain/1/console/port = "2"   (n0,r1)
/local/domain/1/console/ring-ref = "20014983"   (n0,r1)
/local/domain/1/backend = ""   (n0,r1)
/local/domain/1/backend/vbd = ""   (n0,r1)
/local/domain/1/backend/vbd/0 = ""   (n0,r1)
/local/domain/1/backend/vbd/0/51712 = ""   (n1,r0)
/local/domain/1/backend/vbd/0/51712/frontend = "/local/domain/0/device/vbd/51712"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/params = "/dev/zvol/test_pool/test1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/script = "/etc/xen/scripts/block"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/frontend-id = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/online = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/removable = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/bootable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/state = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/dev = "xvda"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/type = "phy"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/mode = "w"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/device-type = "disk"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-enable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-max-indirect-segments = "256"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/multi-queue-max-queues = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/max-ring-page-order = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-device = "e6:0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-flush-cache = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-granularity = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-alignment = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-secure = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-discard = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-barrier = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/sectors = "419430400"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/info = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/sector-size = "512"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-sector-size = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-device-path = "/dev/zd0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/hotplug-status = "connected"   (n1,r0)
/libxl = ""   (n0)
/libxl/pciback = ""   (n0)
/libxl/pciback/0000-00-1f-2 = ""   (n0)
/libxl/pciback/0000-00-1f-2/driver_path = "/sys/bus/pci/drivers/ahci"   (n0)
/libxl/pciback/0000-01-00-0 = ""   (n0)
/libxl/pciback/0000-01-00-0/driver_path = "/sys/bus/pci/drivers/mpt3sas"   (n0)
/libxl/pciback/0000-06-00-0 = ""   (n0)
/libxl/pciback/0000-06-00-0/driver_path = "/sys/bus/pci/drivers/serial"   (n0)
/libxl/1 = ""   (n0)
/libxl/1/device = ""   (n0)
/libxl/1/device/vbd = ""   (n0)
/libxl/1/device/vbd/51712 = ""   (n0)
/libxl/1/device/vbd/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0)
/libxl/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n0)
/libxl/1/device/vbd/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0)
/libxl/1/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/1/device/vbd/51712/frontend-id = "1"   (n0)
/libxl/1/device/vbd/51712/online = "1"   (n0)
/libxl/1/device/vbd/51712/removable = "0"   (n0)
/libxl/1/device/vbd/51712/bootable = "1"   (n0)
/libxl/1/device/vbd/51712/state = "1"   (n0)
/libxl/1/device/vbd/51712/dev = "xvda"   (n0)
/libxl/1/device/vbd/51712/type = "phy"   (n0)
/libxl/1/device/vbd/51712/mode = "w"   (n0)
/libxl/1/device/vbd/51712/device-type = "disk"   (n0)
/libxl/1/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/1/device/console = ""   (n0)
/libxl/1/device/console/0 = ""   (n0)
/libxl/1/device/console/0/frontend = "/local/domain/1/console"   (n0)
/libxl/1/device/console/0/backend = "/local/domain/0/backend/console/1/0"   (n0)
/libxl/1/device/console/0/frontend-id = "1"   (n0)
/libxl/1/device/console/0/online = "1"   (n0)
/libxl/1/device/console/0/state = "1"   (n0)
/libxl/1/device/console/0/protocol = "vt100"   (n0)
/libxl/1/device/vif = ""   (n0)
/libxl/1/device/vif/0 = ""   (n0)
/libxl/1/device/vif/0/frontend = "/local/domain/1/device/vif/0"   (n0)
/libxl/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n0)
/libxl/1/device/vif/0/frontend-id = "1"   (n0)
/libxl/1/device/vif/0/online = "1"   (n0)
/libxl/1/device/vif/0/state = "1"   (n0)
/libxl/1/device/vif/0/script = "/etc/xen/scripts/vif-bridge"   (n0)
/libxl/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n0)
/libxl/1/device/vif/0/bridge = "xenbr0"   (n0)
/libxl/1/device/vif/0/handle = "0"   (n0)
/libxl/1/device/vif/0/type = "vif"   (n0)
/libxl/1/device/pci = ""   (n0)
/libxl/1/device/pci/0 = ""   (n0)
/libxl/1/device/pci/0/frontend = "/local/domain/1/device/pci/0"   (n0)
/libxl/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n0)
/libxl/1/device/pci/0/frontend-id = "1"   (n0)
/libxl/1/device/pci/0/online = "1"   (n0)
/libxl/1/device/pci/0/state = "1"   (n0)
/libxl/1/device/pci/0/domain = "arch-zfs-test"   (n0)
/libxl/1/device/pci/0/key-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/dev-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0)
/libxl/1/device/pci/0/state-0 = "1"   (n0)
/libxl/1/device/pci/0/num_devs = "1"   (n0)
/libxl/1/dm-version = "qemu_xen"   (n0)
/libxl/0 = ""   (n0)
/libxl/0/device = ""   (n0)
/libxl/0/device/vbd = ""   (n0)
/libxl/0/device/vbd/51712 = ""   (n0)
/libxl/0/device/vbd/51712/frontend = "/local/domain/0/device/vbd/51712"   (n0)
/libxl/0/device/vbd/51712/backend = "/local/domain/1/backend/vbd/0/51712"   (n0)
/libxl/0/device/vbd/51712/params = "/dev/zvol/test_pool/test1"   (n0)
/libxl/0/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/0/device/vbd/51712/frontend-id = "0"   (n0)
/libxl/0/device/vbd/51712/online = "1"   (n0)
/libxl/0/device/vbd/51712/removable = "0"   (n0)
/libxl/0/device/vbd/51712/bootable = "1"   (n0)
/libxl/0/device/vbd/51712/state = "1"   (n0)
/libxl/0/device/vbd/51712/dev = "xvda"   (n0)
/libxl/0/device/vbd/51712/type = "phy"   (n0)
/libxl/0/device/vbd/51712/mode = "w"   (n0)
/libxl/0/device/vbd/51712/device-type = "disk"   (n0)
/libxl/0/device/vbd/51712/discard-enable = "1"   (n0)
/vm = ""   (n0)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e = ""   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/name = "arch-zfs-test"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/uuid = "ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image = ""   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/ostype = "linux"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/kernel = "/run/xen/bootloader.1.d/boot_kernel.DD1934"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/ramdisk = "/run/xen/bootloader.1.d/boot_ramdisk._HBmJ1"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/cmdline = "root=UUID=c4e5bb0c-5638-45f6-a90a-0107cc97506b ro"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/start_time = "1493812417.09"   (n0,r1)

# After the 2nd `xl block-attach` command:

/local = ""   (n0)
/local/domain = ""   (n0)
/local/domain/0 = ""   (n0)
/local/domain/0/control = ""   (n0)
/local/domain/0/control/feature-poweroff = "1"   (n0)
/local/domain/0/control/feature-reboot = "1"   (n0)
/local/domain/0/control/feature-suspend = "1"   (n0)
/local/domain/0/domid = "0"   (n0)
/local/domain/0/name = "Domain-0"   (n0)
/local/domain/0/device-model = ""   (n0)
/local/domain/0/device-model/0 = ""   (n0)
/local/domain/0/device-model/0/backends = ""   (n0)
/local/domain/0/device-model/0/backends/console = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vkbd = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qdisk = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qusb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vfb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qnic = ""   (n0,n0)
/local/domain/0/device-model/0/state = "running"   (n0)
/local/domain/0/backend = ""   (n0)
/local/domain/0/backend/vbd = ""   (n0)
/local/domain/0/backend/vbd/1 = ""   (n0)
/local/domain/0/backend/vbd/1/51712 = ""   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/script = "/etc/xen/scripts/block"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/online = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/removable = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/bootable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/state = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/dev = "xvda"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/type = "phy"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/mode = "w"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/device-type = "disk"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-enable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-max-indirect-segments = "256"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/max-ring-page-order = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device = "fe:22"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device-path = "/dev/dm-34"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-flush-cache = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-granularity = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-alignment = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-secure = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-discard = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-barrier = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sectors = "16777216"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/info = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sector-size = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-sector-size = "512"   (n0,r1)
/local/domain/0/backend/console = ""   (n0)
/local/domain/0/backend/console/1 = ""   (n0)
/local/domain/0/backend/console/1/0 = ""   (n0,r1)
/local/domain/0/backend/console/1/0/frontend = "/local/domain/1/console"   (n0,r1)
/local/domain/0/backend/console/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/state = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/protocol = "vt100"   (n0,r1)
/local/domain/0/backend/vif = ""   (n0)
/local/domain/0/backend/vif/1 = ""   (n0)
/local/domain/0/backend/vif/1/0 = ""   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend = "/local/domain/1/device/vif/0"   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/script = "/etc/xen/scripts/vif-bridge"   (n0,r1)
/local/domain/0/backend/vif/1/0/mac = "00:16:3e:aa:bb:cc"   (n0,r1)
/local/domain/0/backend/vif/1/0/bridge = "xenbr0"   (n0,r1)
/local/domain/0/backend/vif/1/0/handle = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/type = "vif"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-sg = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv4 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv6 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ipv6-csum-offload = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-copy = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-flip = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-dynamic-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-split-event-channels = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ctrl-ring = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/pci = ""   (n0)
/local/domain/0/backend/pci/1 = ""   (n0)
/local/domain/0/backend/pci/1/0 = ""   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend = "/local/domain/1/device/pci/0"   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/pci/1/0/domain = "arch-zfs-test"   (n0,r1)
/local/domain/0/backend/pci/1/0/key-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/dev-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0,r1)
/local/domain/0/backend/pci/1/0/state-0 = "3"   (n0,r1)
/local/domain/0/backend/pci/1/0/num_devs = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/vdev-0 = "0000:00:00.00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root-0 = "0000:00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root_num = "1"   (n0,r1)
/local/domain/0/device = ""   (n0)
/local/domain/0/device/vbd = ""   (n0)
/local/domain/0/device/vbd/51712 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/backend = "/local/domain/1/backend/vbd/0/51712"   (n0,r1)
/local/domain/0/device/vbd/51712/backend-id = "1"   (n0,r1)
/local/domain/0/device/vbd/51712/state = "4"   (n0,r1)
/local/domain/0/device/vbd/51712/virtual-device = "51712"   (n0,r1)
/local/domain/0/device/vbd/51712/device-type = "disk"   (n0,r1)
/local/domain/0/device/vbd/51712/protocol = "x86_64-abi"   (n0,r1)
/local/domain/0/device/vbd/51712/multi-queue-num-queues = "4"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0/ring-ref = "8"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-0/event-channel = "79"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1/ring-ref = "9"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-1/event-channel = "80"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2/ring-ref = "10"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-2/event-channel = "81"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3 = ""   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3/ring-ref = "11"   (n0,r1)
/local/domain/0/device/vbd/51712/queue-3/event-channel = "82"   (n0,r1)
/local/domain/0/device/vbd/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/device/vbd/51728 = ""   (n0,r1)
/local/domain/0/device/vbd/51728/backend = "/local/domain/1/backend/vbd/0/51728"   (n0,r1)
/local/domain/0/device/vbd/51728/backend-id = "1"   (n0,r1)
/local/domain/0/device/vbd/51728/state = "4"   (n0,r1)
/local/domain/0/device/vbd/51728/virtual-device = "51728"   (n0,r1)
/local/domain/0/device/vbd/51728/device-type = "disk"   (n0,r1)
/local/domain/0/device/vbd/51728/protocol = "x86_64-abi"   (n0,r1)
/local/domain/0/device/vbd/51728/ring-ref = "79"   (n0,r1)
/local/domain/0/device/vbd/51728/event-channel = "83"   (n0,r1)
/local/domain/0/device/vbd/51728/feature-persistent = "1"   (n0,r1)
/local/domain/1 = ""   (n0,r1)
/local/domain/1/vm = "/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e"   (n0,r1)
/local/domain/1/name = "arch-zfs-test"   (n0,r1)
/local/domain/1/cpu = ""   (n0,r1)
/local/domain/1/cpu/0 = ""   (n0,r1)
/local/domain/1/cpu/0/availability = "online"   (n0,r1)
/local/domain/1/cpu/1 = ""   (n0,r1)
/local/domain/1/cpu/1/availability = "online"   (n0,r1)
/local/domain/1/cpu/2 = ""   (n0,r1)
/local/domain/1/cpu/2/availability = "online"   (n0,r1)
/local/domain/1/cpu/3 = ""   (n0,r1)
/local/domain/1/cpu/3/availability = "online"   (n0,r1)
/local/domain/1/memory = ""   (n0,r1)
/local/domain/1/memory/static-max = "33554432"   (n0,r1)
/local/domain/1/memory/target = "33554432"   (n0,r1)
/local/domain/1/memory/videoram = "0"   (n0,r1)
/local/domain/1/device = ""   (n0,r1)
/local/domain/1/device/suspend = ""   (n0,r1)
/local/domain/1/device/suspend/event-channel = ""   (n1)
/local/domain/1/device/vbd = ""   (n0,r1)
/local/domain/1/device/vbd/51712 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n1,r0)
/local/domain/1/device/vbd/51712/backend-id = "0"   (n1,r0)
/local/domain/1/device/vbd/51712/state = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/virtual-device = "51712"   (n1,r0)
/local/domain/1/device/vbd/51712/device-type = "disk"   (n1,r0)
/local/domain/1/device/vbd/51712/protocol = "x86_64-abi"   (n1,r0)
/local/domain/1/device/vbd/51712/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/ring-ref = "8"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/event-channel = "31"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/ring-ref = "9"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/event-channel = "32"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/ring-ref = "10"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/event-channel = "33"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/ring-ref = "11"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/event-channel = "34"   (n1,r0)
/local/domain/1/device/vbd/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/device/vif = ""   (n0,r1)
/local/domain/1/device/vif/0 = ""   (n1,r0)
/local/domain/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n1,r0)
/local/domain/1/device/vif/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/vif/0/state = "4"   (n1,r0)
/local/domain/1/device/vif/0/handle = "0"   (n1,r0)
/local/domain/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n1,r0)
/local/domain/1/device/vif/0/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vif/0/queue-0 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-0/tx-ring-ref = "2304"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/rx-ring-ref = "2305"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-tx = "35"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-rx = "36"   (n1,r0)
/local/domain/1/device/vif/0/queue-1 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-1/tx-ring-ref = "2306"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/rx-ring-ref = "2307"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-tx = "37"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-rx = "38"   (n1,r0)
/local/domain/1/device/vif/0/queue-2 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-2/tx-ring-ref = "2308"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/rx-ring-ref = "2309"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-tx = "39"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-rx = "40"   (n1,r0)
/local/domain/1/device/vif/0/queue-3 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-3/tx-ring-ref = "2310"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/rx-ring-ref = "2311"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-tx = "41"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-rx = "42"   (n1,r0)
/local/domain/1/device/vif/0/request-rx-copy = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-rx-notify = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-sg = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv4 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv6 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-ipv6-csum-offload = "1"   (n1,r0)
/local/domain/1/device/pci = ""   (n0,r1)
/local/domain/1/device/pci/0 = ""   (n1,r0)
/local/domain/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n1,r0)
/local/domain/1/device/pci/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/pci/0/state = "4"   (n1,r0)
/local/domain/1/device/pci/0/pci-op-ref = "362"   (n1,r0)
/local/domain/1/device/pci/0/event-channel = "43"   (n1,r0)
/local/domain/1/device/pci/0/magic = "7"   (n1,r0)
/local/domain/1/control = ""   (n0,r1)
/local/domain/1/control/shutdown = ""   (n1)
/local/domain/1/control/feature-poweroff = "1"   (n1)
/local/domain/1/control/feature-reboot = "1"   (n1)
/local/domain/1/control/feature-suspend = "1"   (n1)
/local/domain/1/control/platform-feature-multiprocessor-suspend = "1"   (n0,r1)
/local/domain/1/control/platform-feature-xs_reset_watches = "1"   (n0,r1)
/local/domain/1/data = ""   (n1)
/local/domain/1/drivers = ""   (n1)
/local/domain/1/feature = ""   (n1)
/local/domain/1/attr = ""   (n1)
/local/domain/1/libxl = ""   (n1)
/local/domain/1/device-model = ""   (n1)
/local/domain/1/domid = "1"   (n0,r1)
/local/domain/1/store = ""   (n0,r1)
/local/domain/1/store/port = "1"   (n0,r1)
/local/domain/1/store/ring-ref = "20014982"   (n0,r1)
/local/domain/1/console = ""   (n0,r1)
/local/domain/1/console/backend = "/local/domain/0/backend/console/1/0"   (n0,r1)
/local/domain/1/console/backend-id = "0"   (n1,r0)
/local/domain/1/console/limit = "1048576"   (n0,r1)
/local/domain/1/console/type = "xenconsoled"   (n0,r1)
/local/domain/1/console/output = "pty"   (n0,r1)
/local/domain/1/console/tty = "/dev/pts/1"   (n0,r1)
/local/domain/1/console/port = "2"   (n0,r1)
/local/domain/1/console/ring-ref = "20014983"   (n0,r1)
/local/domain/1/backend = ""   (n0,r1)
/local/domain/1/backend/vbd = ""   (n0,r1)
/local/domain/1/backend/vbd/0 = ""   (n0,r1)
/local/domain/1/backend/vbd/0/51712 = ""   (n1,r0)
/local/domain/1/backend/vbd/0/51712/frontend = "/local/domain/0/device/vbd/51712"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/params = "/dev/zvol/test_pool/test1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/script = "/etc/xen/scripts/block"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/frontend-id = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/online = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/removable = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/bootable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/state = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/dev = "xvda"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/type = "phy"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/mode = "w"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/device-type = "disk"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-enable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-max-indirect-segments = "256"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/multi-queue-max-queues = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/max-ring-page-order = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-device = "e6:0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-flush-cache = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-granularity = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-alignment = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/discard-secure = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-discard = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-barrier = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/sectors = "419430400"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/info = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/sector-size = "512"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-sector-size = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/physical-device-path = "/dev/zd0"   (n1,r0)
/local/domain/1/backend/vbd/0/51712/hotplug-status = "connected"   (n1,r0)
/local/domain/1/backend/vbd/0/51728 = ""   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend = "/local/domain/0/device/vbd/51728"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/params = "/dev/zvol/test_pool/test2"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/script = "/etc/xen/scripts/block"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend-id = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/online = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/removable = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/bootable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/state = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/dev = "xvdb"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/type = "phy"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/mode = "w"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/device-type = "disk"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-enable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-max-indirect-segments = "256"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/multi-queue-max-queues = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/max-ring-page-order = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device = "e6:20"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-flush-cache = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-granularity = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-alignment = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-secure = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-discard = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-barrier = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-persistent = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sectors = "209715200"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/info = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sector-size = "512"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-sector-size = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device-path = "/dev/zd32"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/hotplug-status = "connected"   (n1,r0)
/libxl = ""   (n0)
/libxl/pciback = ""   (n0)
/libxl/pciback/0000-00-1f-2 = ""   (n0)
/libxl/pciback/0000-00-1f-2/driver_path = "/sys/bus/pci/drivers/ahci"   (n0)
/libxl/pciback/0000-01-00-0 = ""   (n0)
/libxl/pciback/0000-01-00-0/driver_path = "/sys/bus/pci/drivers/mpt3sas"   (n0)
/libxl/pciback/0000-06-00-0 = ""   (n0)
/libxl/pciback/0000-06-00-0/driver_path = "/sys/bus/pci/drivers/serial"   (n0)
/libxl/1 = ""   (n0)
/libxl/1/device = ""   (n0)
/libxl/1/device/vbd = ""   (n0)
/libxl/1/device/vbd/51712 = ""   (n0)
/libxl/1/device/vbd/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0)
/libxl/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n0)
/libxl/1/device/vbd/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0)
/libxl/1/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/1/device/vbd/51712/frontend-id = "1"   (n0)
/libxl/1/device/vbd/51712/online = "1"   (n0)
/libxl/1/device/vbd/51712/removable = "0"   (n0)
/libxl/1/device/vbd/51712/bootable = "1"   (n0)
/libxl/1/device/vbd/51712/state = "1"   (n0)
/libxl/1/device/vbd/51712/dev = "xvda"   (n0)
/libxl/1/device/vbd/51712/type = "phy"   (n0)
/libxl/1/device/vbd/51712/mode = "w"   (n0)
/libxl/1/device/vbd/51712/device-type = "disk"   (n0)
/libxl/1/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/1/device/console = ""   (n0)
/libxl/1/device/console/0 = ""   (n0)
/libxl/1/device/console/0/frontend = "/local/domain/1/console"   (n0)
/libxl/1/device/console/0/backend = "/local/domain/0/backend/console/1/0"   (n0)
/libxl/1/device/console/0/frontend-id = "1"   (n0)
/libxl/1/device/console/0/online = "1"   (n0)
/libxl/1/device/console/0/state = "1"   (n0)
/libxl/1/device/console/0/protocol = "vt100"   (n0)
/libxl/1/device/vif = ""   (n0)
/libxl/1/device/vif/0 = ""   (n0)
/libxl/1/device/vif/0/frontend = "/local/domain/1/device/vif/0"   (n0)
/libxl/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n0)
/libxl/1/device/vif/0/frontend-id = "1"   (n0)
/libxl/1/device/vif/0/online = "1"   (n0)
/libxl/1/device/vif/0/state = "1"   (n0)
/libxl/1/device/vif/0/script = "/etc/xen/scripts/vif-bridge"   (n0)
/libxl/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n0)
/libxl/1/device/vif/0/bridge = "xenbr0"   (n0)
/libxl/1/device/vif/0/handle = "0"   (n0)
/libxl/1/device/vif/0/type = "vif"   (n0)
/libxl/1/device/pci = ""   (n0)
/libxl/1/device/pci/0 = ""   (n0)
/libxl/1/device/pci/0/frontend = "/local/domain/1/device/pci/0"   (n0)
/libxl/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n0)
/libxl/1/device/pci/0/frontend-id = "1"   (n0)
/libxl/1/device/pci/0/online = "1"   (n0)
/libxl/1/device/pci/0/state = "1"   (n0)
/libxl/1/device/pci/0/domain = "arch-zfs-test"   (n0)
/libxl/1/device/pci/0/key-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/dev-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0)
/libxl/1/device/pci/0/state-0 = "1"   (n0)
/libxl/1/device/pci/0/num_devs = "1"   (n0)
/libxl/1/dm-version = "qemu_xen"   (n0)
/libxl/0 = ""   (n0)
/libxl/0/device = ""   (n0)
/libxl/0/device/vbd = ""   (n0)
/libxl/0/device/vbd/51712 = ""   (n0)
/libxl/0/device/vbd/51712/frontend = "/local/domain/0/device/vbd/51712"   (n0)
/libxl/0/device/vbd/51712/backend = "/local/domain/1/backend/vbd/0/51712"   (n0)
/libxl/0/device/vbd/51712/params = "/dev/zvol/test_pool/test1"   (n0)
/libxl/0/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/0/device/vbd/51712/frontend-id = "0"   (n0)
/libxl/0/device/vbd/51712/online = "1"   (n0)
/libxl/0/device/vbd/51712/removable = "0"   (n0)
/libxl/0/device/vbd/51712/bootable = "1"   (n0)
/libxl/0/device/vbd/51712/state = "1"   (n0)
/libxl/0/device/vbd/51712/dev = "xvda"   (n0)
/libxl/0/device/vbd/51712/type = "phy"   (n0)
/libxl/0/device/vbd/51712/mode = "w"   (n0)
/libxl/0/device/vbd/51712/device-type = "disk"   (n0)
/libxl/0/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/0/device/vbd/51728 = ""   (n0)
/libxl/0/device/vbd/51728/frontend = "/local/domain/0/device/vbd/51728"   (n0)
/libxl/0/device/vbd/51728/backend = "/local/domain/1/backend/vbd/0/51728"   (n0)
/libxl/0/device/vbd/51728/params = "/dev/zvol/test_pool/test2"   (n0)
/libxl/0/device/vbd/51728/script = "/etc/xen/scripts/block"   (n0)
/libxl/0/device/vbd/51728/frontend-id = "0"   (n0)
/libxl/0/device/vbd/51728/online = "1"   (n0)
/libxl/0/device/vbd/51728/removable = "0"   (n0)
/libxl/0/device/vbd/51728/bootable = "1"   (n0)
/libxl/0/device/vbd/51728/state = "1"   (n0)
/libxl/0/device/vbd/51728/dev = "xvdb"   (n0)
/libxl/0/device/vbd/51728/type = "phy"   (n0)
/libxl/0/device/vbd/51728/mode = "w"   (n0)
/libxl/0/device/vbd/51728/device-type = "disk"   (n0)
/libxl/0/device/vbd/51728/discard-enable = "1"   (n0)
/vm = ""   (n0)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e = ""   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/name = "arch-zfs-test"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/uuid = "ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image = ""   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/ostype = "linux"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/kernel = "/run/xen/bootloader.1.d/boot_kernel.DD1934"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/ramdisk = "/run/xen/bootloader.1.d/boot_ramdisk._HBmJ1"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/cmdline = "root=UUID=c4e5bb0c-5638-45f6-a90a-0107cc97506b ro"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/start_time = "1493812417.09"   (n0,r1)

# After the 1st `xl block-detach` command:

/local = ""   (n0)
/local/domain = ""   (n0)
/local/domain/0 = ""   (n0)
/local/domain/0/control = ""   (n0)
/local/domain/0/control/feature-poweroff = "1"   (n0)
/local/domain/0/control/feature-reboot = "1"   (n0)
/local/domain/0/control/feature-suspend = "1"   (n0)
/local/domain/0/domid = "0"   (n0)
/local/domain/0/name = "Domain-0"   (n0)
/local/domain/0/device-model = ""   (n0)
/local/domain/0/device-model/0 = ""   (n0)
/local/domain/0/device-model/0/backends = ""   (n0)
/local/domain/0/device-model/0/backends/console = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vkbd = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qdisk = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qusb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vfb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qnic = ""   (n0,n0)
/local/domain/0/device-model/0/state = "running"   (n0)
/local/domain/0/backend = ""   (n0)
/local/domain/0/backend/vbd = ""   (n0)
/local/domain/0/backend/vbd/1 = ""   (n0)
/local/domain/0/backend/vbd/1/51712 = ""   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/script = "/etc/xen/scripts/block"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/online = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/removable = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/bootable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/state = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/dev = "xvda"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/type = "phy"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/mode = "w"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/device-type = "disk"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-enable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-max-indirect-segments = "256"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/max-ring-page-order = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device = "fe:22"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device-path = "/dev/dm-34"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-flush-cache = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-granularity = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-alignment = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-secure = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-discard = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-barrier = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sectors = "16777216"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/info = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sector-size = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-sector-size = "512"   (n0,r1)
/local/domain/0/backend/console = ""   (n0)
/local/domain/0/backend/console/1 = ""   (n0)
/local/domain/0/backend/console/1/0 = ""   (n0,r1)
/local/domain/0/backend/console/1/0/frontend = "/local/domain/1/console"   (n0,r1)
/local/domain/0/backend/console/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/state = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/protocol = "vt100"   (n0,r1)
/local/domain/0/backend/vif = ""   (n0)
/local/domain/0/backend/vif/1 = ""   (n0)
/local/domain/0/backend/vif/1/0 = ""   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend = "/local/domain/1/device/vif/0"   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/script = "/etc/xen/scripts/vif-bridge"   (n0,r1)
/local/domain/0/backend/vif/1/0/mac = "00:16:3e:aa:bb:cc"   (n0,r1)
/local/domain/0/backend/vif/1/0/bridge = "xenbr0"   (n0,r1)
/local/domain/0/backend/vif/1/0/handle = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/type = "vif"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-sg = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv4 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv6 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ipv6-csum-offload = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-copy = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-flip = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-dynamic-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-split-event-channels = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ctrl-ring = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/pci = ""   (n0)
/local/domain/0/backend/pci/1 = ""   (n0)
/local/domain/0/backend/pci/1/0 = ""   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend = "/local/domain/1/device/pci/0"   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/pci/1/0/domain = "arch-zfs-test"   (n0,r1)
/local/domain/0/backend/pci/1/0/key-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/dev-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0,r1)
/local/domain/0/backend/pci/1/0/state-0 = "3"   (n0,r1)
/local/domain/0/backend/pci/1/0/num_devs = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/vdev-0 = "0000:00:00.00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root-0 = "0000:00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root_num = "1"   (n0,r1)
/local/domain/0/device = ""   (n0)
/local/domain/0/device/vbd = ""   (n0)
/local/domain/0/device/vbd/51728 = ""   (n0,r1)
/local/domain/0/device/vbd/51728/backend = "/local/domain/1/backend/vbd/0/51728"   (n0,r1)
/local/domain/0/device/vbd/51728/backend-id = "1"   (n0,r1)
/local/domain/0/device/vbd/51728/state = "4"   (n0,r1)
/local/domain/0/device/vbd/51728/virtual-device = "51728"   (n0,r1)
/local/domain/0/device/vbd/51728/device-type = "disk"   (n0,r1)
/local/domain/0/device/vbd/51728/protocol = "x86_64-abi"   (n0,r1)
/local/domain/0/device/vbd/51728/ring-ref = "79"   (n0,r1)
/local/domain/0/device/vbd/51728/event-channel = "83"   (n0,r1)
/local/domain/0/device/vbd/51728/feature-persistent = "1"   (n0,r1)
/local/domain/1 = ""   (n0,r1)
/local/domain/1/vm = "/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e"   (n0,r1)
/local/domain/1/name = "arch-zfs-test"   (n0,r1)
/local/domain/1/cpu = ""   (n0,r1)
/local/domain/1/cpu/0 = ""   (n0,r1)
/local/domain/1/cpu/0/availability = "online"   (n0,r1)
/local/domain/1/cpu/1 = ""   (n0,r1)
/local/domain/1/cpu/1/availability = "online"   (n0,r1)
/local/domain/1/cpu/2 = ""   (n0,r1)
/local/domain/1/cpu/2/availability = "online"   (n0,r1)
/local/domain/1/cpu/3 = ""   (n0,r1)
/local/domain/1/cpu/3/availability = "online"   (n0,r1)
/local/domain/1/memory = ""   (n0,r1)
/local/domain/1/memory/static-max = "33554432"   (n0,r1)
/local/domain/1/memory/target = "33554432"   (n0,r1)
/local/domain/1/memory/videoram = "0"   (n0,r1)
/local/domain/1/device = ""   (n0,r1)
/local/domain/1/device/suspend = ""   (n0,r1)
/local/domain/1/device/suspend/event-channel = ""   (n1)
/local/domain/1/device/vbd = ""   (n0,r1)
/local/domain/1/device/vbd/51712 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n1,r0)
/local/domain/1/device/vbd/51712/backend-id = "0"   (n1,r0)
/local/domain/1/device/vbd/51712/state = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/virtual-device = "51712"   (n1,r0)
/local/domain/1/device/vbd/51712/device-type = "disk"   (n1,r0)
/local/domain/1/device/vbd/51712/protocol = "x86_64-abi"   (n1,r0)
/local/domain/1/device/vbd/51712/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/ring-ref = "8"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/event-channel = "31"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/ring-ref = "9"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/event-channel = "32"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/ring-ref = "10"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/event-channel = "33"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/ring-ref = "11"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/event-channel = "34"   (n1,r0)
/local/domain/1/device/vbd/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/device/vif = ""   (n0,r1)
/local/domain/1/device/vif/0 = ""   (n1,r0)
/local/domain/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n1,r0)
/local/domain/1/device/vif/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/vif/0/state = "4"   (n1,r0)
/local/domain/1/device/vif/0/handle = "0"   (n1,r0)
/local/domain/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n1,r0)
/local/domain/1/device/vif/0/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vif/0/queue-0 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-0/tx-ring-ref = "2304"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/rx-ring-ref = "2305"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-tx = "35"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-rx = "36"   (n1,r0)
/local/domain/1/device/vif/0/queue-1 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-1/tx-ring-ref = "2306"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/rx-ring-ref = "2307"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-tx = "37"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-rx = "38"   (n1,r0)
/local/domain/1/device/vif/0/queue-2 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-2/tx-ring-ref = "2308"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/rx-ring-ref = "2309"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-tx = "39"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-rx = "40"   (n1,r0)
/local/domain/1/device/vif/0/queue-3 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-3/tx-ring-ref = "2310"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/rx-ring-ref = "2311"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-tx = "41"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-rx = "42"   (n1,r0)
/local/domain/1/device/vif/0/request-rx-copy = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-rx-notify = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-sg = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv4 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv6 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-ipv6-csum-offload = "1"   (n1,r0)
/local/domain/1/device/pci = ""   (n0,r1)
/local/domain/1/device/pci/0 = ""   (n1,r0)
/local/domain/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n1,r0)
/local/domain/1/device/pci/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/pci/0/state = "4"   (n1,r0)
/local/domain/1/device/pci/0/pci-op-ref = "362"   (n1,r0)
/local/domain/1/device/pci/0/event-channel = "43"   (n1,r0)
/local/domain/1/device/pci/0/magic = "7"   (n1,r0)
/local/domain/1/control = ""   (n0,r1)
/local/domain/1/control/shutdown = ""   (n1)
/local/domain/1/control/feature-poweroff = "1"   (n1)
/local/domain/1/control/feature-reboot = "1"   (n1)
/local/domain/1/control/feature-suspend = "1"   (n1)
/local/domain/1/control/platform-feature-multiprocessor-suspend = "1"   (n0,r1)
/local/domain/1/control/platform-feature-xs_reset_watches = "1"   (n0,r1)
/local/domain/1/data = ""   (n1)
/local/domain/1/drivers = ""   (n1)
/local/domain/1/feature = ""   (n1)
/local/domain/1/attr = ""   (n1)
/local/domain/1/libxl = ""   (n1)
/local/domain/1/device-model = ""   (n1)
/local/domain/1/domid = "1"   (n0,r1)
/local/domain/1/store = ""   (n0,r1)
/local/domain/1/store/port = "1"   (n0,r1)
/local/domain/1/store/ring-ref = "20014982"   (n0,r1)
/local/domain/1/console = ""   (n0,r1)
/local/domain/1/console/backend = "/local/domain/0/backend/console/1/0"   (n0,r1)
/local/domain/1/console/backend-id = "0"   (n1,r0)
/local/domain/1/console/limit = "1048576"   (n0,r1)
/local/domain/1/console/type = "xenconsoled"   (n0,r1)
/local/domain/1/console/output = "pty"   (n0,r1)
/local/domain/1/console/tty = "/dev/pts/1"   (n0,r1)
/local/domain/1/console/port = "2"   (n0,r1)
/local/domain/1/console/ring-ref = "20014983"   (n0,r1)
/local/domain/1/backend = ""   (n0,r1)
/local/domain/1/backend/vbd = ""   (n0,r1)
/local/domain/1/backend/vbd/0 = ""   (n0,r1)
/local/domain/1/backend/vbd/0/51728 = ""   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend = "/local/domain/0/device/vbd/51728"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/params = "/dev/zvol/test_pool/test2"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/script = "/etc/xen/scripts/block"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend-id = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/online = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/removable = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/bootable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/state = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/dev = "xvdb"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/type = "phy"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/mode = "w"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/device-type = "disk"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-enable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-max-indirect-segments = "256"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/multi-queue-max-queues = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/max-ring-page-order = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device = "e6:20"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-flush-cache = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-granularity = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-alignment = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-secure = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-discard = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-barrier = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-persistent = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sectors = "209715200"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/info = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sector-size = "512"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-sector-size = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device-path = "/dev/zd32"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/hotplug-status = "connected"   (n1,r0)
/libxl = ""   (n0)
/libxl/pciback = ""   (n0)
/libxl/pciback/0000-00-1f-2 = ""   (n0)
/libxl/pciback/0000-00-1f-2/driver_path = "/sys/bus/pci/drivers/ahci"   (n0)
/libxl/pciback/0000-01-00-0 = ""   (n0)
/libxl/pciback/0000-01-00-0/driver_path = "/sys/bus/pci/drivers/mpt3sas"   (n0)
/libxl/pciback/0000-06-00-0 = ""   (n0)
/libxl/pciback/0000-06-00-0/driver_path = "/sys/bus/pci/drivers/serial"   (n0)
/libxl/1 = ""   (n0)
/libxl/1/device = ""   (n0)
/libxl/1/device/vbd = ""   (n0)
/libxl/1/device/vbd/51712 = ""   (n0)
/libxl/1/device/vbd/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0)
/libxl/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n0)
/libxl/1/device/vbd/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0)
/libxl/1/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/1/device/vbd/51712/frontend-id = "1"   (n0)
/libxl/1/device/vbd/51712/online = "1"   (n0)
/libxl/1/device/vbd/51712/removable = "0"   (n0)
/libxl/1/device/vbd/51712/bootable = "1"   (n0)
/libxl/1/device/vbd/51712/state = "1"   (n0)
/libxl/1/device/vbd/51712/dev = "xvda"   (n0)
/libxl/1/device/vbd/51712/type = "phy"   (n0)
/libxl/1/device/vbd/51712/mode = "w"   (n0)
/libxl/1/device/vbd/51712/device-type = "disk"   (n0)
/libxl/1/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/1/device/console = ""   (n0)
/libxl/1/device/console/0 = ""   (n0)
/libxl/1/device/console/0/frontend = "/local/domain/1/console"   (n0)
/libxl/1/device/console/0/backend = "/local/domain/0/backend/console/1/0"   (n0)
/libxl/1/device/console/0/frontend-id = "1"   (n0)
/libxl/1/device/console/0/online = "1"   (n0)
/libxl/1/device/console/0/state = "1"   (n0)
/libxl/1/device/console/0/protocol = "vt100"   (n0)
/libxl/1/device/vif = ""   (n0)
/libxl/1/device/vif/0 = ""   (n0)
/libxl/1/device/vif/0/frontend = "/local/domain/1/device/vif/0"   (n0)
/libxl/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n0)
/libxl/1/device/vif/0/frontend-id = "1"   (n0)
/libxl/1/device/vif/0/online = "1"   (n0)
/libxl/1/device/vif/0/state = "1"   (n0)
/libxl/1/device/vif/0/script = "/etc/xen/scripts/vif-bridge"   (n0)
/libxl/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n0)
/libxl/1/device/vif/0/bridge = "xenbr0"   (n0)
/libxl/1/device/vif/0/handle = "0"   (n0)
/libxl/1/device/vif/0/type = "vif"   (n0)
/libxl/1/device/pci = ""   (n0)
/libxl/1/device/pci/0 = ""   (n0)
/libxl/1/device/pci/0/frontend = "/local/domain/1/device/pci/0"   (n0)
/libxl/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n0)
/libxl/1/device/pci/0/frontend-id = "1"   (n0)
/libxl/1/device/pci/0/online = "1"   (n0)
/libxl/1/device/pci/0/state = "1"   (n0)
/libxl/1/device/pci/0/domain = "arch-zfs-test"   (n0)
/libxl/1/device/pci/0/key-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/dev-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0)
/libxl/1/device/pci/0/state-0 = "1"   (n0)
/libxl/1/device/pci/0/num_devs = "1"   (n0)
/libxl/1/dm-version = "qemu_xen"   (n0)
/libxl/0 = ""   (n0)
/libxl/0/device = ""   (n0)
/libxl/0/device/vbd = ""   (n0)
/libxl/0/device/vbd/51728 = ""   (n0)
/libxl/0/device/vbd/51728/frontend = "/local/domain/0/device/vbd/51728"   (n0)
/libxl/0/device/vbd/51728/backend = "/local/domain/1/backend/vbd/0/51728"   (n0)
/libxl/0/device/vbd/51728/params = "/dev/zvol/test_pool/test2"   (n0)
/libxl/0/device/vbd/51728/script = "/etc/xen/scripts/block"   (n0)
/libxl/0/device/vbd/51728/frontend-id = "0"   (n0)
/libxl/0/device/vbd/51728/online = "1"   (n0)
/libxl/0/device/vbd/51728/removable = "0"   (n0)
/libxl/0/device/vbd/51728/bootable = "1"   (n0)
/libxl/0/device/vbd/51728/state = "1"   (n0)
/libxl/0/device/vbd/51728/dev = "xvdb"   (n0)
/libxl/0/device/vbd/51728/type = "phy"   (n0)
/libxl/0/device/vbd/51728/mode = "w"   (n0)
/libxl/0/device/vbd/51728/device-type = "disk"   (n0)
/libxl/0/device/vbd/51728/discard-enable = "1"   (n0)
/vm = ""   (n0)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e = ""   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/name = "arch-zfs-test"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/uuid = "ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image = ""   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/ostype = "linux"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/kernel = "/run/xen/bootloader.1.d/boot_kernel.DD1934"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/ramdisk = "/run/xen/bootloader.1.d/boot_ramdisk._HBmJ1"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/cmdline = "root=UUID=c4e5bb0c-5638-45f6-a90a-0107cc97506b ro"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/start_time = "1493812417.09"   (n0,r1)

# After the 2nd `xl block-detach` command:

/local = ""   (n0)
/local/domain = ""   (n0)
/local/domain/0 = ""   (n0)
/local/domain/0/control = ""   (n0)
/local/domain/0/control/feature-poweroff = "1"   (n0)
/local/domain/0/control/feature-reboot = "1"   (n0)
/local/domain/0/control/feature-suspend = "1"   (n0)
/local/domain/0/domid = "0"   (n0)
/local/domain/0/name = "Domain-0"   (n0)
/local/domain/0/device-model = ""   (n0)
/local/domain/0/device-model/0 = ""   (n0)
/local/domain/0/device-model/0/backends = ""   (n0)
/local/domain/0/device-model/0/backends/console = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vkbd = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qdisk = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qusb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/vfb = ""   (n0,n0)
/local/domain/0/device-model/0/backends/qnic = ""   (n0,n0)
/local/domain/0/device-model/0/state = "running"   (n0)
/local/domain/0/backend = ""   (n0)
/local/domain/0/backend/vbd = ""   (n0)
/local/domain/0/backend/vbd/1 = ""   (n0)
/local/domain/0/backend/vbd/1/51712 = ""   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/script = "/etc/xen/scripts/block"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/online = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/removable = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/bootable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/state = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/dev = "xvda"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/type = "phy"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/mode = "w"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/device-type = "disk"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-enable = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-max-indirect-segments = "256"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/max-ring-page-order = "4"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device = "fe:22"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-device-path = "/dev/dm-34"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-flush-cache = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-granularity = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-alignment = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/discard-secure = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-discard = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-barrier = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/feature-persistent = "1"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sectors = "16777216"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/info = "0"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/sector-size = "512"   (n0,r1)
/local/domain/0/backend/vbd/1/51712/physical-sector-size = "512"   (n0,r1)
/local/domain/0/backend/console = ""   (n0)
/local/domain/0/backend/console/1 = ""   (n0)
/local/domain/0/backend/console/1/0 = ""   (n0,r1)
/local/domain/0/backend/console/1/0/frontend = "/local/domain/1/console"   (n0,r1)
/local/domain/0/backend/console/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/state = "1"   (n0,r1)
/local/domain/0/backend/console/1/0/protocol = "vt100"   (n0,r1)
/local/domain/0/backend/vif = ""   (n0)
/local/domain/0/backend/vif/1 = ""   (n0)
/local/domain/0/backend/vif/1/0 = ""   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend = "/local/domain/1/device/vif/0"   (n0,r1)
/local/domain/0/backend/vif/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/script = "/etc/xen/scripts/vif-bridge"   (n0,r1)
/local/domain/0/backend/vif/1/0/mac = "00:16:3e:aa:bb:cc"   (n0,r1)
/local/domain/0/backend/vif/1/0/bridge = "xenbr0"   (n0,r1)
/local/domain/0/backend/vif/1/0/handle = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/type = "vif"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-sg = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv4 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-gso-tcpv6 = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ipv6-csum-offload = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-copy = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-rx-flip = "0"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-dynamic-multicast-control = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-split-event-channels = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/multi-queue-max-queues = "4"   (n0,r1)
/local/domain/0/backend/vif/1/0/feature-ctrl-ring = "1"   (n0,r1)
/local/domain/0/backend/vif/1/0/hotplug-status = "connected"   (n0,r1)
/local/domain/0/backend/pci = ""   (n0)
/local/domain/0/backend/pci/1 = ""   (n0)
/local/domain/0/backend/pci/1/0 = ""   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend = "/local/domain/1/device/pci/0"   (n0,r1)
/local/domain/0/backend/pci/1/0/frontend-id = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/online = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/state = "4"   (n0,r1)
/local/domain/0/backend/pci/1/0/domain = "arch-zfs-test"   (n0,r1)
/local/domain/0/backend/pci/1/0/key-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/dev-0 = "0000:01:00.0"   (n0,r1)
/local/domain/0/backend/pci/1/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0,r1)
/local/domain/0/backend/pci/1/0/state-0 = "3"   (n0,r1)
/local/domain/0/backend/pci/1/0/num_devs = "1"   (n0,r1)
/local/domain/0/backend/pci/1/0/vdev-0 = "0000:00:00.00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root-0 = "0000:00"   (n0,r1)
/local/domain/0/backend/pci/1/0/root_num = "1"   (n0,r1)
/local/domain/1 = ""   (n0,r1)
/local/domain/1/vm = "/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e"   (n0,r1)
/local/domain/1/name = "arch-zfs-test"   (n0,r1)
/local/domain/1/cpu = ""   (n0,r1)
/local/domain/1/cpu/0 = ""   (n0,r1)
/local/domain/1/cpu/0/availability = "online"   (n0,r1)
/local/domain/1/cpu/1 = ""   (n0,r1)
/local/domain/1/cpu/1/availability = "online"   (n0,r1)
/local/domain/1/cpu/2 = ""   (n0,r1)
/local/domain/1/cpu/2/availability = "online"   (n0,r1)
/local/domain/1/cpu/3 = ""   (n0,r1)
/local/domain/1/cpu/3/availability = "online"   (n0,r1)
/local/domain/1/memory = ""   (n0,r1)
/local/domain/1/memory/static-max = "33554432"   (n0,r1)
/local/domain/1/memory/target = "33554432"   (n0,r1)
/local/domain/1/memory/videoram = "0"   (n0,r1)
/local/domain/1/device = ""   (n0,r1)
/local/domain/1/device/suspend = ""   (n0,r1)
/local/domain/1/device/suspend/event-channel = ""   (n1)
/local/domain/1/device/vbd = ""   (n0,r1)
/local/domain/1/device/vbd/51712 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n1,r0)
/local/domain/1/device/vbd/51712/backend-id = "0"   (n1,r0)
/local/domain/1/device/vbd/51712/state = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/virtual-device = "51712"   (n1,r0)
/local/domain/1/device/vbd/51712/device-type = "disk"   (n1,r0)
/local/domain/1/device/vbd/51712/protocol = "x86_64-abi"   (n1,r0)
/local/domain/1/device/vbd/51712/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/ring-ref = "8"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-0/event-channel = "31"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/ring-ref = "9"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-1/event-channel = "32"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/ring-ref = "10"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-2/event-channel = "33"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3 = ""   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/ring-ref = "11"   (n1,r0)
/local/domain/1/device/vbd/51712/queue-3/event-channel = "34"   (n1,r0)
/local/domain/1/device/vbd/51712/feature-persistent = "1"   (n1,r0)
/local/domain/1/device/vif = ""   (n0,r1)
/local/domain/1/device/vif/0 = ""   (n1,r0)
/local/domain/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n1,r0)
/local/domain/1/device/vif/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/vif/0/state = "4"   (n1,r0)
/local/domain/1/device/vif/0/handle = "0"   (n1,r0)
/local/domain/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n1,r0)
/local/domain/1/device/vif/0/multi-queue-num-queues = "4"   (n1,r0)
/local/domain/1/device/vif/0/queue-0 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-0/tx-ring-ref = "2304"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/rx-ring-ref = "2305"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-tx = "35"   (n1,r0)
/local/domain/1/device/vif/0/queue-0/event-channel-rx = "36"   (n1,r0)
/local/domain/1/device/vif/0/queue-1 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-1/tx-ring-ref = "2306"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/rx-ring-ref = "2307"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-tx = "37"   (n1,r0)
/local/domain/1/device/vif/0/queue-1/event-channel-rx = "38"   (n1,r0)
/local/domain/1/device/vif/0/queue-2 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-2/tx-ring-ref = "2308"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/rx-ring-ref = "2309"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-tx = "39"   (n1,r0)
/local/domain/1/device/vif/0/queue-2/event-channel-rx = "40"   (n1,r0)
/local/domain/1/device/vif/0/queue-3 = ""   (n1,r0)
/local/domain/1/device/vif/0/queue-3/tx-ring-ref = "2310"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/rx-ring-ref = "2311"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-tx = "41"   (n1,r0)
/local/domain/1/device/vif/0/queue-3/event-channel-rx = "42"   (n1,r0)
/local/domain/1/device/vif/0/request-rx-copy = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-rx-notify = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-sg = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv4 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-gso-tcpv6 = "1"   (n1,r0)
/local/domain/1/device/vif/0/feature-ipv6-csum-offload = "1"   (n1,r0)
/local/domain/1/device/pci = ""   (n0,r1)
/local/domain/1/device/pci/0 = ""   (n1,r0)
/local/domain/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n1,r0)
/local/domain/1/device/pci/0/backend-id = "0"   (n1,r0)
/local/domain/1/device/pci/0/state = "4"   (n1,r0)
/local/domain/1/device/pci/0/pci-op-ref = "362"   (n1,r0)
/local/domain/1/device/pci/0/event-channel = "43"   (n1,r0)
/local/domain/1/device/pci/0/magic = "7"   (n1,r0)
/local/domain/1/control = ""   (n0,r1)
/local/domain/1/control/shutdown = ""   (n1)
/local/domain/1/control/feature-poweroff = "1"   (n1)
/local/domain/1/control/feature-reboot = "1"   (n1)
/local/domain/1/control/feature-suspend = "1"   (n1)
/local/domain/1/control/platform-feature-multiprocessor-suspend = "1"   (n0,r1)
/local/domain/1/control/platform-feature-xs_reset_watches = "1"   (n0,r1)
/local/domain/1/data = ""   (n1)
/local/domain/1/drivers = ""   (n1)
/local/domain/1/feature = ""   (n1)
/local/domain/1/attr = ""   (n1)
/local/domain/1/libxl = ""   (n1)
/local/domain/1/device-model = ""   (n1)
/local/domain/1/domid = "1"   (n0,r1)
/local/domain/1/store = ""   (n0,r1)
/local/domain/1/store/port = "1"   (n0,r1)
/local/domain/1/store/ring-ref = "20014982"   (n0,r1)
/local/domain/1/console = ""   (n0,r1)
/local/domain/1/console/backend = "/local/domain/0/backend/console/1/0"   (n0,r1)
/local/domain/1/console/backend-id = "0"   (n1,r0)
/local/domain/1/console/limit = "1048576"   (n0,r1)
/local/domain/1/console/type = "xenconsoled"   (n0,r1)
/local/domain/1/console/output = "pty"   (n0,r1)
/local/domain/1/console/tty = "/dev/pts/1"   (n0,r1)
/local/domain/1/console/port = "2"   (n0,r1)
/local/domain/1/console/ring-ref = "20014983"   (n0,r1)
/local/domain/1/backend = ""   (n0,r1)
/local/domain/1/backend/vbd = ""   (n0,r1)
/local/domain/1/backend/vbd/0 = ""   (n0,r1)
/local/domain/1/backend/vbd/0/51728 = ""   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend = "/local/domain/0/device/vbd/51728"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/params = "/dev/zvol/test_pool/test2"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/script = "/etc/xen/scripts/block"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/frontend-id = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/online = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/removable = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/bootable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/state = "6"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/dev = "xvdb"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/type = "phy"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/mode = "w"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/device-type = "disk"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-enable = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-max-indirect-segments = "256"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/multi-queue-max-queues = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/max-ring-page-order = "4"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device = "e6:20"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-flush-cache = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-granularity = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-alignment = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/discard-secure = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-discard = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-barrier = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/feature-persistent = "1"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sectors = "209715200"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/info = "0"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/sector-size = "512"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-sector-size = "8192"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/physical-device-path = "/dev/zd32"   (n1,r0)
/local/domain/1/backend/vbd/0/51728/hotplug-status = "connected"   (n1,r0)
/libxl = ""   (n0)
/libxl/pciback = ""   (n0)
/libxl/pciback/0000-00-1f-2 = ""   (n0)
/libxl/pciback/0000-00-1f-2/driver_path = "/sys/bus/pci/drivers/ahci"   (n0)
/libxl/pciback/0000-01-00-0 = ""   (n0)
/libxl/pciback/0000-01-00-0/driver_path = "/sys/bus/pci/drivers/mpt3sas"   (n0)
/libxl/pciback/0000-06-00-0 = ""   (n0)
/libxl/pciback/0000-06-00-0/driver_path = "/sys/bus/pci/drivers/serial"   (n0)
/libxl/1 = ""   (n0)
/libxl/1/device = ""   (n0)
/libxl/1/device/vbd = ""   (n0)
/libxl/1/device/vbd/51712 = ""   (n0)
/libxl/1/device/vbd/51712/frontend = "/local/domain/1/device/vbd/51712"   (n0)
/libxl/1/device/vbd/51712/backend = "/local/domain/0/backend/vbd/1/51712"   (n0)
/libxl/1/device/vbd/51712/params = "/dev/VG_ssd/TEST_ARCH"   (n0)
/libxl/1/device/vbd/51712/script = "/etc/xen/scripts/block"   (n0)
/libxl/1/device/vbd/51712/frontend-id = "1"   (n0)
/libxl/1/device/vbd/51712/online = "1"   (n0)
/libxl/1/device/vbd/51712/removable = "0"   (n0)
/libxl/1/device/vbd/51712/bootable = "1"   (n0)
/libxl/1/device/vbd/51712/state = "1"   (n0)
/libxl/1/device/vbd/51712/dev = "xvda"   (n0)
/libxl/1/device/vbd/51712/type = "phy"   (n0)
/libxl/1/device/vbd/51712/mode = "w"   (n0)
/libxl/1/device/vbd/51712/device-type = "disk"   (n0)
/libxl/1/device/vbd/51712/discard-enable = "1"   (n0)
/libxl/1/device/console = ""   (n0)
/libxl/1/device/console/0 = ""   (n0)
/libxl/1/device/console/0/frontend = "/local/domain/1/console"   (n0)
/libxl/1/device/console/0/backend = "/local/domain/0/backend/console/1/0"   (n0)
/libxl/1/device/console/0/frontend-id = "1"   (n0)
/libxl/1/device/console/0/online = "1"   (n0)
/libxl/1/device/console/0/state = "1"   (n0)
/libxl/1/device/console/0/protocol = "vt100"   (n0)
/libxl/1/device/vif = ""   (n0)
/libxl/1/device/vif/0 = ""   (n0)
/libxl/1/device/vif/0/frontend = "/local/domain/1/device/vif/0"   (n0)
/libxl/1/device/vif/0/backend = "/local/domain/0/backend/vif/1/0"   (n0)
/libxl/1/device/vif/0/frontend-id = "1"   (n0)
/libxl/1/device/vif/0/online = "1"   (n0)
/libxl/1/device/vif/0/state = "1"   (n0)
/libxl/1/device/vif/0/script = "/etc/xen/scripts/vif-bridge"   (n0)
/libxl/1/device/vif/0/mac = "00:16:3e:aa:bb:cc"   (n0)
/libxl/1/device/vif/0/bridge = "xenbr0"   (n0)
/libxl/1/device/vif/0/handle = "0"   (n0)
/libxl/1/device/vif/0/type = "vif"   (n0)
/libxl/1/device/pci = ""   (n0)
/libxl/1/device/pci/0 = ""   (n0)
/libxl/1/device/pci/0/frontend = "/local/domain/1/device/pci/0"   (n0)
/libxl/1/device/pci/0/backend = "/local/domain/0/backend/pci/1/0"   (n0)
/libxl/1/device/pci/0/frontend-id = "1"   (n0)
/libxl/1/device/pci/0/online = "1"   (n0)
/libxl/1/device/pci/0/state = "1"   (n0)
/libxl/1/device/pci/0/domain = "arch-zfs-test"   (n0)
/libxl/1/device/pci/0/key-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/dev-0 = "0000:01:00.0"   (n0)
/libxl/1/device/pci/0/opts-0 = "msitranslate=0,power_mgmt=0,permissive=0"   (n0)
/libxl/1/device/pci/0/state-0 = "1"   (n0)
/libxl/1/device/pci/0/num_devs = "1"   (n0)
/libxl/1/dm-version = "qemu_xen"   (n0)
/vm = ""   (n0)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e = ""   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/name = "arch-zfs-test"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/uuid = "ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image = ""   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/ostype = "linux"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/kernel = "/run/xen/bootloader.1.d/boot_kernel.DD1934"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/ramdisk = "/run/xen/bootloader.1.d/boot_ramdisk._HBmJ1"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/image/cmdline = "root=UUID=c4e5bb0c-5638-45f6-a90a-0107cc97506b ro"   (n0,r1)
/vm/ae4f37d1-1d35-4c48-8fe3-32d8dcdb130e/start_time = "1493812417.09"   (n0,r1)

[-- Attachment #6: coredumpctl gdb.txt --]
[-- Type: text/plain, Size: 8181 bytes --]

[root@arch-zfs-test ~]# coredumpctl gdb 1400
           PID: 1400 (xl)
           UID: 0 (root)
           GID: 0 (root)
        Signal: 11 (SEGV)
     Timestamp: Wed 2017-05-03 15:08:09 EEST (12min ago)
  Command Line: /usr/bin/xl -vvv devd
    Executable: /usr/bin/xl
 Control Group: /system.slice/xendriverdomain.service
          Unit: xendriverdomain.service
         Slice: system.slice
       Boot ID: e11f9f8063b24ba6abb709f76694a202
    Machine ID: c0f2ee0d91c44644a2ea229db2047149
      Hostname: arch-zfs-test
       Storage: /var/lib/systemd/coredump/core.xl.0.e11f9f8063b24ba6abb709f76694a202.1400.1493813289000000000000.lz4
       Message: Process 1400 (xl) of user 0 dumped core.

                Stack trace of thread 1400:
                #0  0x00007f00df92b19d search_for_guest (libxenlight.so.4.8)
                #1  0x00007f00df92b931 backend_watch_callback (libxenlight.so.4.8)
                #2  0x00007f00df9689da watchfd_callback (libxenlight.so.4.8)
                #3  0x00007f00df96a612 fd_occurs (libxenlight.so.4.8)
                #4  0x00007f00df96a6c4 afterpoll_internal (libxenlight.so.4.8)
                #5  0x00007f00df96bdfd eventloop_iteration (libxenlight.so.4.8)
                #6  0x00007f00df96cbb1 libxl__ao_inprogress (libxenlight.so.4.8)
                #7  0x00007f00df92c1dc libxl_device_events_handler (libxenlight.so.4.8)
                #8  0x0000000000423258 main_devd (xl)
                #9  0x0000000000408e05 main (xl)
                #10 0x00007f00def4f511 __libc_start_main (libc.so.6)
                #11 0x000000000040800a _start (xl)

                Stack trace of thread 1401:
                #0  0x00007f00df2e3f7d read (libpthread.so.0)
                #1  0x00007f00de6bbc3d read_all (libxenstore.so.3.0)
                #2  0x00007f00de6bd6ca read_message (libxenstore.so.3.0)
                #3  0x00007f00de6bda1f read_thread (libxenstore.so.3.0)
                #4  0x00007f00df2da2e7 start_thread (libpthread.so.0)
                #5  0x00007f00df01b54f __clone (libc.so.6)

GNU gdb (GDB) 7.12.1
Copyright (C) 2017 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /usr/bin/xl...done.
[New LWP 1400]
[New LWP 1401]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
Core was generated by `/usr/bin/xl -vvv devd'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00007f00df92b19d in search_for_guest (ddomain=0x7fff97ba73a0, domid=0)
    at libxl.c:3688
3688            if (dguest->domid == domid)
[Current thread is 1 (Thread 0x7f00dff7bfc0 (LWP 1400))]
(gdb) backtrace full
#0  0x00007f00df92b19d in search_for_guest (ddomain=0x7fff97ba73a0, domid=0)
    at libxl.c:3688
        dguest = 0x31352f302f646276
#1  0x00007f00df92b931 in backend_watch_callback (egc=0x7fff97ba72d0,
    watch=0x7fff97ba73a8, watch_path=0x206e560 "/local/domain/1/backend",
    event_path=0x2070c90 "/local/domain/1/backend/vbd/0/51728/online")
    at libxl.c:3874
        ddomain = 0x7fff97ba73a0
        nested_ao = 0x2070b80
        ao = 0x2070b80
        gc = 0x2070bc0
        p = 0x2070c33 ""
        path = 0x2070c10 "/local/domain/1/backend/vbd/0/51728"
        sstate = 0x7f00d40012b0 "5"
        sonline = 0x7f00d4001290 "0"
        state = 5
        online = 0
        rc = 0
        num_devs = 0
        dev = 0x206ebf0
        ddev = 0x0
        dguest = 0x0
        free_ao = false
---Type <return> to continue, or q <return> to quit---
        __func__ = "backend_watch_callback"
#2  0x00007f00df9689da in watchfd_callback (egc=0x7fff97ba72d0, ev=0x20708a8,
    fd=16, events=1, revents=1) at libxl_event.c:574
        token = 0x2070cbb "3/0"
        w = 0x7fff97ba73a8
        event = 0x2070c80
        epath = 0x2070c90 "/local/domain/1/backend/vbd/0/51728/online"
        slotnum = 3
        counterval = 0
        rc = 2
        gc = 0x7fff97ba72d0
        __func__ = "watchfd_callback"
#3  0x00007f00df96a612 in fd_occurs (egc=0x7fff97ba72d0, efd=0x20708a8,
    revents_ign=1) at libxl_event.c:1200
        revents_current = 1
#4  0x00007f00df96a6c4 in afterpoll_internal (egc=0x7fff97ba72d0,
    poller=0x206fda0, nfds=2, fds=0x20700e0, now=...) at libxl_event.c:1265
        revents = 1
        gc = 0x7fff97ba72d0
        efd = 0x20708a8
        __func__ = "afterpoll_internal"
        __PRETTY_FUNCTION__ = "afterpoll_internal"
#5  0x00007f00df96bdfd in eventloop_iteration (egc=0x7fff97ba72d0,
---Type <return> to continue, or q <return> to quit---
    poller=0x206fda0) at libxl_event.c:1711
        gc = 0x7fff97ba72d0
        rc = 0
        nfds = 2
        now = {tv_sec = 1493813289, tv_usec = 710596}
        timeout = -1
        __func__ = "eventloop_iteration"
#6  0x00007f00df96cbb1 in libxl__ao_inprogress (ao=0x206e350,
    file=0x7f00df9af79b "libxl.c", line=4014,
    func=0x7f00df9b2d00 <__func__.21414> "libxl_device_events_handler")
    at libxl_event.c:1997
        egc = {gc = {alloc_maxsize = 0, alloc_ptrs = 0x0, owner = 0x20707b0},
          occurred_for_callback = {tqh_first = 0x0,
            tqh_last = 0x7fff97ba72e8}, aos_for_callback = {tqh_first = 0x0,
            tqh_last = 0x7fff97ba72f8}, aops_for_callback = {tqh_first = 0x0,
            tqh_last = 0x7fff97ba7308}}
        gc = 0x206e390
        rc = 0
        __PRETTY_FUNCTION__ = "libxl__ao_inprogress"
        __func__ = "libxl__ao_inprogress"
#7  0x00007f00df92c1dc in libxl_device_events_handler (ctx=0x20707b0,
    ao_how=0x0) at libxl.c:4014
        ao__ctx = 0x20707b0
---Type <return> to continue, or q <return> to quit---
        ao__rc = 0
        ao = 0x206e350
        __func__ = "libxl_device_events_handler"
        egc = {{gc = {alloc_maxsize = 0, alloc_ptrs = 0x0, owner = 0x20707b0},
            occurred_for_callback = {tqh_first = 0x0,
              tqh_last = 0x7fff97ba73e8}, aos_for_callback = {tqh_first = 0x0,
              tqh_last = 0x7fff97ba73f8}, aops_for_callback = {
              tqh_first = 0x0, tqh_last = 0x7fff97ba7408}}}
        gc = 0x206e390
        rc = 0
        domid = 1
        ddomain = {ao = 0x206e350, watch = {
            path = 0x206e560 "/local/domain/1/backend",
            callback = 0x7f00df92b703 <backend_watch_callback>, slotnum = 3,
            counterval = 0}, guests = {slh_first = 0x206ff70}}
        be_path = 0x206fd80 "/local/domain/1/backend"
        kinds = 0x0
        domains = 0x0
        devs = 0x0
        sstate = 0xffff00ff00000000 <error: Cannot access memory at address 0xffff00ff00000000>
        state_path = 0x0
        state = 0
---Type <return> to continue, or q <return> to quit---
        nkinds = 4294967295
        ndomains = 4294901760
        ndevs = 6778732
        i = -536735504
        j = 0
        k = 0
        __PRETTY_FUNCTION__ = "libxl_device_events_handler"
#8  0x0000000000423258 in main_devd (argc=1, argv=0x7fff97ba7608)
    at xl_cmdimpl.c:9059
        ret = 0
        opt = -1
        daemonize = 1
        pidfile = 0x0
        opts = {{name = 0x42d3e5 "pidfile", has_arg = 1, flag = 0x0,
            val = 112}, {name = 0x429059 "help", has_arg = 0, flag = 0x0,
            val = 104}, {name = 0x0, has_arg = 0, flag = 0x0, val = 0}, {
            name = 0x0, has_arg = 0, flag = 0x0, val = 0}}
#9  0x0000000000408e05 in main (argc=1, argv=0x7fff97ba7608) at xl.c:364
        opt = -1
        cmd = 0x7fff97ba8f59 "devd"
        cspec = 0x6363d0 <cmd_table+3504>
        ret = 0
        config_data = 0x206df20
---Type <return> to continue, or q <return> to quit---
        config_len = 1303

[-- Attachment #7: Type: text/plain, Size: 127 bytes --]

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [BUG] xl devd segmentation fault on xl block-detach
  2017-05-03 13:27   ` Reinis Martinsons
@ 2017-05-03 14:31     ` Wei Liu
  2017-05-03 17:02       ` Wei Liu
  0 siblings, 1 reply; 8+ messages in thread
From: Wei Liu @ 2017-05-03 14:31 UTC (permalink / raw)
  To: Reinis Martinsons; +Cc: Ian Jackson, Wei Liu, xen-devel

On Wed, May 03, 2017 at 04:27:41PM +0300, Reinis Martinsons wrote:
> On 03.05.2017 13:27, Wei Liu wrote:
> libxl: debug: libxl_linux.c:200:libxl__get_hotplug_script_info: num_exec 1, not running hotplug scripts
> libxl: debug: libxl_device.c:1143:device_hotplug: No hotplug script to execute
> libxl: debug: libxl_event.c:686:libxl__ev_xswatch_deregister: watch w=0x206e9a0: deregister unregistered
> libxl: debug: libxl.c:3721:device_complete: device /local/domain/1/backend/vbd/0/51712 remove succeed
> libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070b80: destroy
> libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712
> libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070b80: nested ao, parent 0x206e350
> libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070b80: destroy
> libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/online
> libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070b80: nested ao, parent 0x206e350

Interesting, so it seems xl devd never removed dguest from the list.

I wonder what else could go wrong.

I've managed to reproduce this locally. I will try to fix it for 4.9.

Wei.

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [BUG] xl devd segmentation fault on xl block-detach
  2017-05-03 14:31     ` Wei Liu
@ 2017-05-03 17:02       ` Wei Liu
  2017-05-04  9:23         ` Reinis Martinsons
  2017-05-04  9:51         ` Ian Jackson
  0 siblings, 2 replies; 8+ messages in thread
From: Wei Liu @ 2017-05-03 17:02 UTC (permalink / raw)
  To: Reinis Martinsons; +Cc: Ian Jackson, Roger Pau Monné, Wei Liu, xen-devel

On Wed, May 03, 2017 at 03:31:58PM +0100, Wei Liu wrote:
> On Wed, May 03, 2017 at 04:27:41PM +0300, Reinis Martinsons wrote:
> > On 03.05.2017 13:27, Wei Liu wrote:
> > libxl: debug: libxl_linux.c:200:libxl__get_hotplug_script_info: num_exec 1, not running hotplug scripts
> > libxl: debug: libxl_device.c:1143:device_hotplug: No hotplug script to execute
> > libxl: debug: libxl_event.c:686:libxl__ev_xswatch_deregister: watch w=0x206e9a0: deregister unregistered
> > libxl: debug: libxl.c:3721:device_complete: device /local/domain/1/backend/vbd/0/51712 remove succeed
> > libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070b80: destroy
> > libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51712
> > libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070b80: nested ao, parent 0x206e350
> > libxl: debug: libxl_event.c:1838:libxl__ao__destroy: ao 0x2070b80: destroy
> > libxl: debug: libxl_event.c:573:watchfd_callback: watch w=0x7fff97ba73a8 wpath=/local/domain/1/backend token=3/0: event epath=/local/domain/1/backend/vbd/0/51728/online
> > libxl: debug: libxl_event.c:2223:libxl__nested_ao_create: ao 0x2070b80: nested ao, parent 0x206e350
> 
> Interesting, so it seems xl devd never removed dguest from the list.
> 
> I wonder what else could go wrong.
> 
> I've managed to reproduce this locally. I will try to fix it for 4.9.
> 
> Wei.

Can you give the following patch a try? This applies to 4.8.

Not sure if there is a better way to fix it though. Ian and Roger?

---8<---
From 8542a1d4f537cb5719ebd245872d0256df816670 Mon Sep 17 00:00:00 2001
From: Wei Liu <wei.liu2@citrix.com>
Date: Wed, 3 May 2017 17:55:42 +0100
Subject: [PATCH] libxl: fix backend_watch_callback

That function needs to cope with spurious events. The original "skip"
path blindly freed dguest even when it needed to stay in ddomain list.

Free dguest iff it is newly added to the list. That way we don't free
the one that should stay on the list and we don't unnecessarily add a
stale dguest entry to ddomain list.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
 tools/libxl/libxl.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index acf714e1f9..ed542c0977 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -3842,6 +3842,7 @@ static void backend_watch_callback(libxl__egc *egc, libxl__ev_xswatch *watch,
     libxl__device *dev = NULL;
     libxl__ddomain_device *ddev = NULL;
     libxl__ddomain_guest *dguest = NULL;
+    bool new_dguest = false;
     bool free_ao = false;
 
     /* Check if event_path ends with "state" or "online" and truncate it. */
@@ -3888,6 +3889,7 @@ static void backend_watch_callback(libxl__egc *egc, libxl__ev_xswatch *watch,
         LIBXL_SLIST_INSERT_HEAD(&ddomain->guests, dguest, next);
         LOG(DEBUG, "added domain %u to the list of active guests",
                    dguest->domid);
+        new_dguest = true;
     }
     ddev = search_for_device(dguest, dev);
     if (ddev == NULL && state == XenbusStateClosed) {
@@ -3947,7 +3949,13 @@ skip:
     libxl__nested_ao_free(nested_ao);
     free(dev);
     free(ddev);
-    free(dguest);
+    if (new_dguest) {
+        LIBXL_SLIST_REMOVE(&ddomain->guests, dguest, libxl__ddomain_guest,
+                           next);
+        LOG(DEBUG, "removed domain %u from the list of active guests",
+                   dguest->domid);
+        free(dguest);
+    }
     return;
 }
 
-- 
2.11.0


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^ permalink raw reply related	[flat|nested] 8+ messages in thread

* Re: [BUG] xl devd segmentation fault on xl block-detach
  2017-05-03 17:02       ` Wei Liu
@ 2017-05-04  9:23         ` Reinis Martinsons
  2017-05-04  9:51         ` Ian Jackson
  1 sibling, 0 replies; 8+ messages in thread
From: Reinis Martinsons @ 2017-05-04  9:23 UTC (permalink / raw)
  To: Wei Liu; +Cc: Roger Pau Monné, Ian Jackson, xen-devel

On 03.05.2017 20:02, Wei Liu wrote:
> 
> Can you give the following patch a try? This applies to 4.8.
> 
> Not sure if there is a better way to fix it though. Ian and Roger?
> 
> ---8<---
>  From 8542a1d4f537cb5719ebd245872d0256df816670 Mon Sep 17 00:00:00 2001
> From: Wei Liu <wei.liu2@citrix.com>
> Date: Wed, 3 May 2017 17:55:42 +0100
> Subject: [PATCH] libxl: fix backend_watch_callback
> 
> That function needs to cope with spurious events. The original "skip"
> path blindly freed dguest even when it needed to stay in ddomain list.
> 
> Free dguest iff it is newly added to the list. That way we don't free
> the one that should stay on the list and we don't unnecessarily add a
> stale dguest entry to ddomain list.
> 
> Signed-off-by: Wei Liu <wei.liu2@citrix.com>
> ---
>   tools/libxl/libxl.c | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index acf714e1f9..ed542c0977 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -3842,6 +3842,7 @@ static void backend_watch_callback(libxl__egc *egc, libxl__ev_xswatch *watch,
>       libxl__device *dev = NULL;
>       libxl__ddomain_device *ddev = NULL;
>       libxl__ddomain_guest *dguest = NULL;
> +    bool new_dguest = false;
>       bool free_ao = false;
>   
>       /* Check if event_path ends with "state" or "online" and truncate it. */
> @@ -3888,6 +3889,7 @@ static void backend_watch_callback(libxl__egc *egc, libxl__ev_xswatch *watch,
>           LIBXL_SLIST_INSERT_HEAD(&ddomain->guests, dguest, next);
>           LOG(DEBUG, "added domain %u to the list of active guests",
>                      dguest->domid);
> +        new_dguest = true;
>       }
>       ddev = search_for_device(dguest, dev);
>       if (ddev == NULL && state == XenbusStateClosed) {
> @@ -3947,7 +3949,13 @@ skip:
>       libxl__nested_ao_free(nested_ao);
>       free(dev);
>       free(ddev);
> -    free(dguest);
> +    if (new_dguest) {
> +        LIBXL_SLIST_REMOVE(&ddomain->guests, dguest, libxl__ddomain_guest,
> +                           next);
> +        LOG(DEBUG, "removed domain %u from the list of active guests",
> +                   dguest->domid);
> +        free(dguest);
> +    }
>       return;
>   }
>   
> 

Thank you! After applying the patch I have not observed `xl devd` 
crashing and now I can run guests with multiple block devices from the 
same DomD.

Reinis

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [BUG] xl devd segmentation fault on xl block-detach
  2017-05-03 17:02       ` Wei Liu
  2017-05-04  9:23         ` Reinis Martinsons
@ 2017-05-04  9:51         ` Ian Jackson
  2017-05-10  9:03           ` Roger Pau Monné
  1 sibling, 1 reply; 8+ messages in thread
From: Ian Jackson @ 2017-05-04  9:51 UTC (permalink / raw)
  To: Wei Liu; +Cc: Reinis Martinsons, Roger Pau Monné, xen-devel

Wei Liu writes ("Re: [Xen-devel] [BUG] xl devd segmentation fault on xl block-detach"):
> Can you give the following patch a try? This applies to 4.8.
> 
> Not sure if there is a better way to fix it though. Ian and Roger?

I find the logic here rather awkward.  I do remember reviewing it and
becoming a bit confused at the time and it seems that even though I
eventually convinced myself it was OK, I was wrong.

> From: Wei Liu <wei.liu2@citrix.com>
> Date: Wed, 3 May 2017 17:55:42 +0100
> Subject: [PATCH] libxl: fix backend_watch_callback
> 
> That function needs to cope with spurious events. The original "skip"
> path blindly freed dguest even when it needed to stay in ddomain list.
> 
> Free dguest iff it is newly added to the list. That way we don't free
> the one that should stay on the list and we don't unnecessarily add a
> stale dguest entry to ddomain list.

AFAICT right now you are right.  But I see another possible way of
fixing it:

How about moving the num_devs == 0 check, and associated cleanup, to
the exit path ?  That way a if new guest struct is spuriously
allocated, it will automatically be freed.  It would mean that the
freeing of dguest would depend only on other invariants already in the
code, rather than on explicit tracking.

The invariants are, I think:

 * Any libxl__ddomain_device is either
     * on some list libxl__ddomain_guest->devices
     * being processed for removal, and referenced by a device
       remove async call initiated by remove_device and which will
       call device_complete() when done
   but not both!

 * Any libxl__domain_guest is on the list libxl__ddomain->guests.

 The above apply even within any function, except very briefly when
 transitioning from one state to another (eg creation, destruction).

 * SUM(libxl__domain_guest->num_*) != 0, when we return from the
   outermost callback.  (Ie, there are no leftover empty guest
   structs.)


Thinking about this like this, and observing the control flow, leads
me to think I have found another bug.

Consider what happens if a device is removed while it is still being
added.  That is, an event comes in which causes us to call add_device.
add_device sets up the callback and starts doing work (eg hotplug
scripts).  Before that finishes, the device is removed again.
backend_watch_callback will tear the device down and free dev.

But dev is still referenced by the add_device operation, and when it
completes, device_complete will call
  libxl__device_backend_path(gc, aodev->dev)

There ought to be a (perhaps implicit) invariant that
 * Any dev referenced by an aodev call is legit

But this invariant is violated by backend_watch_callback, which frees
it despite it not knowing whether there is a callback in flight.


Perhaps we should do explicit reference counting.

Ian.

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [BUG] xl devd segmentation fault on xl block-detach
  2017-05-04  9:51         ` Ian Jackson
@ 2017-05-10  9:03           ` Roger Pau Monné
  0 siblings, 0 replies; 8+ messages in thread
From: Roger Pau Monné @ 2017-05-10  9:03 UTC (permalink / raw)
  To: Ian Jackson; +Cc: Reinis Martinsons, Wei Liu, xen-devel

On Thu, May 04, 2017 at 10:51:01AM +0100, Ian Jackson wrote:
> Wei Liu writes ("Re: [Xen-devel] [BUG] xl devd segmentation fault on xl block-detach"):
> > Can you give the following patch a try? This applies to 4.8.
> > 
> > Not sure if there is a better way to fix it though. Ian and Roger?
> 
> I find the logic here rather awkward.  I do remember reviewing it and
> becoming a bit confused at the time and it seems that even though I
> eventually convinced myself it was OK, I was wrong.
> 
> > From: Wei Liu <wei.liu2@citrix.com>
> > Date: Wed, 3 May 2017 17:55:42 +0100
> > Subject: [PATCH] libxl: fix backend_watch_callback
> > 
> > That function needs to cope with spurious events. The original "skip"
> > path blindly freed dguest even when it needed to stay in ddomain list.
> > 
> > Free dguest iff it is newly added to the list. That way we don't free
> > the one that should stay on the list and we don't unnecessarily add a
> > stale dguest entry to ddomain list.
> 
> AFAICT right now you are right.  But I see another possible way of
> fixing it:
> 
> How about moving the num_devs == 0 check, and associated cleanup, to
> the exit path ?  That way a if new guest struct is spuriously
> allocated, it will automatically be freed.  It would mean that the
> freeing of dguest would depend only on other invariants already in the
> code, rather than on explicit tracking.
> 
> The invariants are, I think:
> 
>  * Any libxl__ddomain_device is either
>      * on some list libxl__ddomain_guest->devices
>      * being processed for removal, and referenced by a device
>        remove async call initiated by remove_device and which will
>        call device_complete() when done
>    but not both!
> 
>  * Any libxl__domain_guest is on the list libxl__ddomain->guests.
> 
>  The above apply even within any function, except very briefly when
>  transitioning from one state to another (eg creation, destruction).
> 
>  * SUM(libxl__domain_guest->num_*) != 0, when we return from the
>    outermost callback.  (Ie, there are no leftover empty guest
>    structs.)

Yes, that seems better so that there's no code duplication. Will send a patch
shortly.

> 
> Thinking about this like this, and observing the control flow, leads
> me to think I have found another bug.
> 
> Consider what happens if a device is removed while it is still being
> added.  That is, an event comes in which causes us to call add_device.
> add_device sets up the callback and starts doing work (eg hotplug
> scripts).  Before that finishes, the device is removed again.
> backend_watch_callback will tear the device down and free dev.
> 
> But dev is still referenced by the add_device operation, and when it
> completes, device_complete will call
>   libxl__device_backend_path(gc, aodev->dev)
> 
> There ought to be a (perhaps implicit) invariant that
>  * Any dev referenced by an aodev call is legit

Right, maybe an easier solution would be to not pass the stored libxl__device
to the async functions, and instead copy it to a temporary one that's GC'ed
afterwards. AFAICT the async operations only rely on the libxl__device, so
passing a device tracked by the GC should solve this without refcounting, will
send a patch for this also.

Roger.

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^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2017-05-10  9:03 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-05-03  0:04 [BUG] xl devd segmentation fault on xl block-detach Reinis Martinsons
2017-05-03 10:27 ` Wei Liu
2017-05-03 13:27   ` Reinis Martinsons
2017-05-03 14:31     ` Wei Liu
2017-05-03 17:02       ` Wei Liu
2017-05-04  9:23         ` Reinis Martinsons
2017-05-04  9:51         ` Ian Jackson
2017-05-10  9:03           ` Roger Pau Monné

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