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From: "Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>
To: xen-devel@lists.xenproject.org
Cc: "Stefano Stabellini" <sstabellini@kernel.org>,
	"Julien Grall" <julien@xen.org>, "Wei Liu" <wl@xen.org>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"George Dunlap" <George.Dunlap@eu.citrix.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Ian Jackson" <ian.jackson@eu.citrix.com>,
	"Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>,
	"Jan Beulich" <jbeulich@suse.com>
Subject: [Xen-devel] [PATCH v4 02/16] Document ioemu Linux stubdomain protocol
Date: Wed, 15 Jan 2020 03:39:41 +0100
Message-ID: <5f675457fe322c265b3337607bc78f07ffdb43bb.1579055705.git-series.marmarek@invisiblethingslab.com> (raw)
In-Reply-To: <cover.f819645cd9f5cf7a6f692f9661cfb4e670a2cd08.1579055705.git-series.marmarek@invisiblethingslab.com>

Add documentation for upcoming Linux stubdomain for qemu-upstream.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
---
 docs/misc/stubdom.txt | 50 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+)

diff --git a/docs/misc/stubdom.txt b/docs/misc/stubdom.txt
index 4c524f2..9c94c6b 100644
--- a/docs/misc/stubdom.txt
+++ b/docs/misc/stubdom.txt
@@ -75,6 +75,56 @@ Defined commands:
    - "running" - success
 
 
+Toolstack to Linux ioemu stubdomain protocol
+--------------------------------------------
+
+This section describe communication protocol between toolstack and
+qemu-upstream running in Linux stubdomain. The protocol include
+expectations of both stubdomain, and qemu.
+
+Setup (done by toolstack, expected by stubdomain):
+ - Block devices for target domain are connected as PV disks to stubdomain,
+   according to configuration order, starting with xvda
+ - Network devices for target domain are connected as PV nics to stubdomain,
+   according to configuration order, starting with 0
+ - [not implemented] if graphics output is expected, VFB and VKB devices are set for stubdomain
+   (its backend is responsible for exposing them using appropriate protocol
+   like VNC or Spice)
+ - other target domain's devices are not connected at this point to stubdomain
+   (may be hot-plugged later)
+ - QEMU command line is stored in
+   /vm/<target-uuid>/image/dmargs xenstore dir, each argument as separate key
+   in form /vm/<target-uuid>/image/dmargs/NNN, where NNN is 0-padded argument
+   number
+ - target domain id is stored in /local/domain/<stubdom-id>/target xenstore path
+?? - bios type is stored in /local/domain/<target-id>/hvmloader/bios
+ - stubdomain's console 0 is connected to qemu log file
+ - stubdomain's console 1 is connected to qemu save file (for saving state)
+ - stubdomain's console 2 is connected to qemu save file (for restoring state)
+ - next consoles are connected according to target guest's serial console configuration
+
+Environment exposed by stubdomain to qemu (needed to construct appropriate qemu command line and later interact with qmp):
+ - target domain's disks are available as /dev/xvd[a-z]
+ - console 2 (incoming domain state) is connected with FD 3
+ - console 1 (saving domain state) is added over QMP to qemu as "fdset-id 1" (done by stubdomain, toolstack doesn't need to care about it)
+ - nics are connected to relevant stubdomain PV vifs when available (qemu -netdev should specify ifname= explicitly)
+
+Startup:
+1. toolstack starts PV stubdomain with stubdom-linux-kernel kernel and stubdom-linux-initrd initrd
+2. stubdomain initialize relevant devices
+3. stubdomain starts qemu with requested command line, plus few stubdomain specific ones - including local qmp access options
+4. stubdomain starts vchan server on /local/domain/<stubdom-id>/device-model/<target-id>/qmp-vchan, exposing qmp socket to the toolstack
+5. qemu signal readiness by writing "running" to /local/domain/<stubdom-id>/device-model/<target-id>/state xenstore path
+6. now device model is considered running
+
+QEMU can be controlled using QMP over vchan at /local/domain/<stubdom-id>/device-model/<target-id>/qmp-vchan. Only one simultaneous connection is supported and toolstack needs to ensure that.
+
+Limitations:
+ - PCI passthrough require permissive mode
+ - only one nic is supported
+ - at most 26 emulated disks are supported (more are still available as PV disks)
+ - graphics output (VNC/SDL/Spice) not supported
+
 
                                    PV-GRUB
                                    =======
-- 
git-series 0.9.1

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  parent reply index

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-15  2:39 [Xen-devel] [PATCH v4 00/16] Add support for qemu-xen runnning in a Linux-based stubdomain Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 01/16] Document ioemu MiniOS stubdomain protocol Marek Marczykowski-Górecki
2020-01-20 18:30   ` Jason Andryuk
2020-01-15  2:39 ` Marek Marczykowski-Górecki [this message]
2020-01-20 18:54   ` [Xen-devel] [PATCH v4 02/16] Document ioemu Linux " Jason Andryuk
2020-01-21 21:08     ` Marek Marczykowski-Górecki
2020-01-22 14:04       ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 03/16] libxl: fix qemu-trad cmdline for no sdl/vnc case Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 04/16] libxl: Allow running qemu-xen in stubdomain Marek Marczykowski-Górecki
2020-01-20 18:56   ` Jason Andryuk
2020-01-21 21:12     ` Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 05/16] libxl: Handle Linux stubdomain specific QEMU options Marek Marczykowski-Górecki
2020-01-20 19:24   ` Jason Andryuk
2020-01-21 21:18     ` Marek Marczykowski-Górecki
2020-01-22 14:25       ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 06/16] libxl: write qemu arguments into separate xenstore keys Marek Marczykowski-Górecki
2020-01-20 19:36   ` Jason Andryuk
2020-01-21 21:19     ` Marek Marczykowski-Górecki
2020-01-22 14:39       ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 07/16] xl: add stubdomain related options to xl config parser Marek Marczykowski-Górecki
2020-01-20 19:41   ` Jason Andryuk
2020-01-21 21:22     ` Marek Marczykowski-Górecki
2020-01-22 14:39       ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 08/16] tools/libvchan: notify server when client is connected Marek Marczykowski-Górecki
2020-01-20 19:44   ` Jason Andryuk
2020-01-21 21:28     ` Marek Marczykowski-Górecki
2020-01-22 14:43       ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 09/16] libxl: add save/restore support for qemu-xen in stubdomain Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 10/16] tools: add missing libxenvchan cflags Marek Marczykowski-Górecki
2020-01-20 19:58   ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 11/16] tools: add simple vchan-socket-proxy Marek Marczykowski-Górecki
2020-01-15 11:02   ` Jan Beulich
2020-01-16 17:11     ` Marek Marczykowski-Górecki
2020-01-17  8:13       ` Jan Beulich
2020-01-17 18:44   ` Rich Persaud
2020-01-17 18:56     ` Marek Marczykowski-Górecki
2020-01-21 19:43   ` Jason Andryuk
2020-01-21 23:09     ` Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 12/16] libxl: use vchan for QMP access with Linux stubdomain Marek Marczykowski-Górecki
2020-01-21 20:17   ` Jason Andryuk
2020-01-21 23:46     ` Marek Marczykowski-Górecki
2020-01-24 14:05       ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 13/16] Regenerate autotools files Marek Marczykowski-Górecki
2020-01-15 21:57   ` Rich Persaud
2020-01-21 20:56     ` Marek Marczykowski-Górecki
2020-01-21 21:28       ` Rich Persaud
2020-01-22  8:57         ` Lars Kurth
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 14/16] libxl: require qemu in dom0 even if stubdomain is in use Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 15/16] libxl: ignore emulated IDE disks beyond the first 4 Marek Marczykowski-Górecki
2020-01-21 20:24   ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 16/16] libxl: consider also qemu in stubdomain in libxl__dm_active check Marek Marczykowski-Górecki
2020-01-21 20:25   ` Jason Andryuk
2020-01-22 16:50 ` [Xen-devel] [PATCH v4 00/16] Add support for qemu-xen runnning in a Linux-based stubdomain Jason Andryuk

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