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Re: [Qemu-devel] [PATCH 3/4] virtio: modify savevm to have a stable wire
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] [PATCH 3/4] virtio: modify savevm to have a stable wire format |
Date: |
Fri, 14 Dec 2012 07:59:29 -0600 |
User-agent: |
Notmuch/0.13.2+93~ged93d79 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) |
Paolo Bonzini <address@hidden> writes:
> Il 14/12/2012 01:57, Rusty Russell ha scritto:
>> With the new code we only need the head from that structure.
>
> We also need to do again all validation of the elements if we fetch it
> back from the data. Sometimes the parsed data is saved elsewhere (e.g.
> in a SCSIRequest struct that is serialized by the SCSI subsystem) and
> that data may be inconsistent with whatever you read from guest memory.
> It's a can of worms.
>
>>> I'm certainly in favor of cleaning up the savevm format and probably
>>> leaving the existing load/save functions as-is for legacy purposes.
>>> I'll leave that as an exercise for someone else though :-)
>>
>> What is the rule about new versions? Can we introduce a new save
>> version at any time, or only at major qemu version changes?
>
> Any time, but we provide a backwards-compatible loader for older
> versions.
Well.. if we can avoid bumping the version, we should. Bumping the
version breaks migration from new -> old so it's preferrable that we
don't do it unless it's absolutely required.
Regards,
Anthony Liguori
>
> Paolo
[Qemu-devel] [PATCH 2/4] virtio: add wrapper for saving/restoring virtqueue elements, Anthony Liguori, 2012/12/10
[Qemu-devel] [PATCH 1/4] savevm: introduce little endian variants of savevm routines, Anthony Liguori, 2012/12/10
[Qemu-devel] [PATCH 4/4] virtio: bump migration version number, Anthony Liguori, 2012/12/10
Re: [Qemu-devel] [RFC 0/4] virtio: stabilize migration format, Stefan Hajnoczi, 2012/12/11