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

[Gerd Hoffmann]

  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 ...

cheers,
  Gerd