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[Qemu-devel] Re: Live migration protocol, device features, ABIs and othe
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts |
Date: |
Tue, 24 Nov 2009 18:05:00 +0200 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
On Tue, Nov 24, 2009 at 03:21:34PM +0100, Juan Quintela wrote:
> "Michael S. Tsirkin" <address@hidden> wrote:
> > On Tue, Nov 24, 2009 at 12:39:50PM +0200, Dor Laor wrote:
> >> On 11/23/2009 02:15 PM, Juan Quintela wrote:
> >>> Dor Laor<address@hidden> wrote:
> >>>> > In the last couple of days we discovered some issues regarding stable
> >>>> > ABI and the robustness of the live migration protocol. Let's just jump
> >>>> > right into it, ordered by complexity:
> >>>> >
> >>>> > 1. Control*every* feature exposed to the guest by qemu cmdline:
> >>>> >
> >>>> > While thinking on cross version migration, and reviewing some
> >>>> > patches, I noticed that there are many times that we use feature
> >>>> > bits
> >>>> > in order to expose functionality for the guest driver - example:
> >>>> > VIRTIO_BLK_F_BARRIER, but we do not control it from qemu cmdline.
> >>> In my opinion this is madness, qemu command line is already too
> >>> complicated. I agree with anthony to put it in the command line.
> >>
> >> Qemu's cmdline is currently our config file.. Actually there is nothing
> >> wrong with it. Human users shouldn't be interested with these changes
> >> and management software should not have problem manipulating it.
> >> We do need flexibility of controlling our features like any other
> >> software component.
> >>
> >>> I will go further, and think that this kind of issues should be put into
> >>> the machine type.
> >>>
> >>> If you start qemu with -M pc-0.10, it should save the state in a 0.10
> >>> compatible way (that don't happens at the moment, but it should work
> >>> that way).
> >>
> >> That's the idea - to keep it part of qdev and by default use it with -M.
> >
> > I think we want to keep these things separate:
> > machine description should be for things that
> > are both guest visible and not changeable by guest,
> > so it absolutely must stay constant as long as guest
> > it alive.
>
> That is exactly what we need here, that version of the savevm protocol
> for each device is the same.
>
> Later, Juan.
A device already supports load for a range
of versions between X and Y. We want to support
saving to a range of versions.
Which versions to use is a separate decision
which should be taken on run time, not
at startup time.
--
MST
- Re: [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, (continued)
- Re: [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Gerd Hoffmann, 2009/11/25
- Re: [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Michael S. Tsirkin, 2009/11/25
- Re: [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Gerd Hoffmann, 2009/11/25
- Re: [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Michael S. Tsirkin, 2009/11/25
- [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Juan Quintela, 2009/11/25
- [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Michael S. Tsirkin, 2009/11/25
[Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Dor Laor, 2009/11/24
- [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Michael S. Tsirkin, 2009/11/24
- [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Juan Quintela, 2009/11/24
- [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Michael S. Tsirkin, 2009/11/24
- [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts,
Michael S. Tsirkin <=
- [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Juan Quintela, 2009/11/25
- [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Michael S. Tsirkin, 2009/11/25
- [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Juan Quintela, 2009/11/25
[Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts, Michael S. Tsirkin, 2009/11/24