Re: [Qemu-devel] [PATCH 2/2] qxl: add QXL_IO_UPDATE_MEM for guest S3&S4 support

[Alon Levy <alevy@redhat.com>]

On Wed, Jun 29, 2011 at 11:01:11AM +0200, Gerd Hoffmann wrote:
>   Hi,
> 
> >>I think it will receive them after migration, since the command ring
> >>was stored.
> >Our confusion here is because you think there is still seemless migration. Unfortunately
> >it doesn't work right now, unless you plan to fix it the only form of migration right
> >now is switch-host, and for that those commands will be lost, the new connection will receive
> >images for each surface. If you treat the client as seemless you are completely right.
> 
> The spice server needs this too so it can render the surfaces
> correctly before sending the surface images to the client (or send
> the old surfaces and the commands on top of that).
> 
> That is one difference between qemu migration and S3 state: For qemu
> migration it is no problem to have unprocessed commands in the
> rings, they will simply be processed once the spice server state is
> restored. When the guest driver restores the state when it comes
> back from S3 it needs the command rings to do so, thats why they
> must be flushed before entering S3 ...

You mean it needs the command rings to be empty before, since they are lost
during the reset, right?

> 
> cheers,
>   Gerd
>