From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "Richard W.M. Jones" <rjones@redhat.com>,
jejb@linux.vnet.ibm.com, martin.petersen@oracle.com,
jasowang@redhat.com, linux-scsi@vger.kernel.org,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, hch@lst.de
Subject: Re: [PATCH 1/2] virtio: Reduce BUG if total_sg > virtqueue size to WARN.
Date: Fri, 11 Aug 2017 20:36:59 +0200 [thread overview]
Message-ID: <a7220de9-0a51-0548-03c0-236e37aa2ef4@redhat.com> (raw)
In-Reply-To: <20170811201843-mutt-send-email-mst@kernel.org>
On 11/08/2017 19:23, Michael S. Tsirkin wrote:
> On Fri, Aug 11, 2017 at 04:09:26PM +0200, Paolo Bonzini wrote:
>> On 10/08/2017 23:41, Michael S. Tsirkin wrote:
>>>>> Then we probably should fail probe if vq size is too small.
>>>> What does this mean?
>>>
>>> We must prevent driver from submitting s/g lists > vq size to device.
>>
>> What is the rationale for the limit?
>
> So the host knows what it needs to support.
>
>> both virtio-blk and virtio-scsi transmit their own value for the
>> maximum sg list size (max_seg in virtio-scsi, seg_max in virtio-blk).
>
> No other device has it, and it seemed like a good idea to
> limit it generally at the time.
>
> we can fix the spec to relax the requirement for blk and scsi -
> want to submit a proposal? Alternatively, add a generic field
> for that.
Yes, I can submit a proposal. blk and scsi are the ones that are most
likely to have very long sg lists.
When I was designing scsi I just copied that field from blk. :)
Paolo
next prev parent reply other threads:[~2017-08-11 18:37 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-10 16:40 [PATCH 0/2] virtio_scsi: Set can_queue based on size of virtqueue Richard W.M. Jones
2017-08-10 16:40 ` [PATCH 1/2] virtio: Reduce BUG if total_sg > virtqueue size to WARN Richard W.M. Jones
2017-08-10 16:47 ` Paolo Bonzini
2017-08-10 21:21 ` Michael S. Tsirkin
2017-08-10 21:30 ` Richard W.M. Jones
2017-08-10 21:31 ` Michael S. Tsirkin
2017-08-10 21:35 ` Richard W.M. Jones
2017-08-10 21:41 ` Michael S. Tsirkin
2017-08-10 21:50 ` Richard W.M. Jones
2017-08-11 14:09 ` Paolo Bonzini
2017-08-11 17:23 ` Michael S. Tsirkin
2017-08-11 18:36 ` Paolo Bonzini [this message]
2017-08-10 16:40 ` [PATCH 2/2] virtio: virtio_scsi: Set can_queue to the length of the virtqueue Richard W.M. Jones
2017-08-10 16:46 ` Paolo Bonzini
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=a7220de9-0a51-0548-03c0-236e37aa2ef4@redhat.com \
--to=pbonzini@redhat.com \
--cc=hch@lst.de \
--cc=jasowang@redhat.com \
--cc=jejb@linux.vnet.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=martin.petersen@oracle.com \
--cc=mst@redhat.com \
--cc=rjones@redhat.com \
--cc=virtualization@lists.linux-foundation.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®