All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Eric Farman <farman@linux.vnet.ibm.com>, qemu-devel@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	Cornelia Huck <cornelia.huck@de.ibm.com>,
	Alexander Graf <agraf@suse.de>
Subject: Re: [Qemu-devel] [RFC PATCH v1 0/5] Enable virtio-scsi boot from /dev/sgX
Date: Wed, 26 Apr 2017 17:48:06 +0200	[thread overview]
Message-ID: <76868ba7-610d-ef56-bbd4-ed26f55164dd@de.ibm.com> (raw)
In-Reply-To: <20170426144645.12476-1-farman@linux.vnet.ibm.com>

On 04/26/2017 04:46 PM, Eric Farman wrote:
> Today, trying to boot a guest from a SCSI LUN on s390x yields the following:
> 
>   virtio-blk               = OK
>   virtio-scsi and /dev/sdX = OK
>   virtio-scsi and /dev/sgX = FAIL
> 
> Example of the failing scenario:
> 
>   /usr/bin/qemu-system-s390x ...
>     -device virtio-scsi-ccw,id=scsi0,devno=fe.0.0001
>     -drive file=/dev/sg2,if=none,id=drive0,format=raw
>     -device scsi-generic,bus=scsi0.0,channel=0,scsi-id=0,drive=drive0,id=disk0
>   LOADPARM=[........]
>   Using virtio-scsi.
>   Using SCSI scheme.
>   ..
>   ! virtio-scsi:read_many: STATUS=02 RSPN=70 KEY=0b CODE=00 QLFR=06, sure !
> 
> Why do we care?  Well, libvirt converts a virtio-scsi device from the host
> SCSI address (host:bus:target:lun) into the associated /dev/sgX device,
> which means we can't boot from virtio-scsi and have to rely on virtio-blk
> for this action.
> 
> The short version of what happens is the host device driver rejects our
> requests because the transfer lengths are too long for it to satisfy.
> A virtio-scsi disk connected via scsi-generic is fine as a non-boot device
> because the guest kernel is able to break up the requests for us.  So we just
> need to handle this situation for the boot process.

Out of curiosity. Why is the guest kernel submitting "short enough" requests?
If it querying the device itself via scsi commands before issuing commands?

  parent reply	other threads:[~2017-04-26 15:48 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-26 14:46 [Qemu-devel] [RFC PATCH v1 0/5] Enable virtio-scsi boot from /dev/sgX Eric Farman
2017-04-26 14:46 ` [Qemu-devel] [RFC PATCH v1 1/5] hw/scsi: Override the max_sectors value for virtio-scsi Eric Farman
2017-05-05  7:39   ` Paolo Bonzini
2017-05-05  7:50   ` Christian Borntraeger
2017-04-26 14:46 ` [Qemu-devel] [RFC PATCH v1 2/5] pc-bios/s390-ccw: Remove duplicate blk_factor adjustment Eric Farman
2017-05-05  7:10   ` Christian Borntraeger
2017-04-26 14:46 ` [Qemu-devel] [RFC PATCH v1 3/5] pc-bios/s390-ccw: Move SCSI block factor to outer read Eric Farman
2017-04-26 14:46 ` [Qemu-devel] [RFC PATCH v1 4/5] pc-bios/s390-ccw: Break up virtio-scsi read into multiples Eric Farman
2017-04-26 15:17   ` Eric Blake
2017-04-26 15:24     ` Eric Farman
2017-04-26 16:00       ` Eric Farman
2017-04-26 15:47     ` Cornelia Huck
2017-04-26 14:46 ` [Qemu-devel] [RFC PATCH v1 5/5] pc-bios/s390-ccw.img: rebuild image Eric Farman
2017-04-26 15:48 ` Christian Borntraeger [this message]
2017-04-26 16:13   ` [Qemu-devel] [RFC PATCH v1 0/5] Enable virtio-scsi boot from /dev/sgX Eric Farman
2017-05-05  7:41 ` Fam Zheng
2017-05-05 15:03   ` Eric Farman
2017-05-05 15:13     ` Paolo Bonzini
2017-05-05 16:12       ` Eric Farman
2017-05-06  8:24         ` Paolo Bonzini
2017-05-08  7:00           ` Christian Borntraeger
2017-05-08 15:00             ` Eric Farman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=76868ba7-610d-ef56-bbd4-ed26f55164dd@de.ibm.com \
    --to=borntraeger@de.ibm.com \
    --cc=agraf@suse.de \
    --cc=cornelia.huck@de.ibm.com \
    --cc=farman@linux.vnet.ibm.com \
    --cc=mst@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=qemu-devel@nongnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.