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

[Alon Levy]

On Mon, Jun 20, 2011 at 05:50:32PM +0200, Gerd Hoffmann wrote:
> On 06/20/11 17:11, Alon Levy wrote:
> >On Mon, Jun 20, 2011 at 04:07:59PM +0200, Gerd Hoffmann wrote:
> >>>>What is the difference to one worker->stop() + worker->start() cycle?
> >>>>
> >>>
> >>>ok, stop+start won't disconnect any clients either. But does stop render 
> >>>all waiting commands?
> >>>I'll have to look, I don't know if it does.
> >>
> >>It does.  This is what qemu uses to flush all spice server state to
> >>device memory on migration.
> >>
> >>What is the reason for deleting all surfaces?
> >
> >Making sure all references are dropped to pci memory in devram.
> 
> Ah, because the spice server keeps a reference to the create command
> until the surface is destroyed, right?

Actually right, so my correction stands corrected.

> 
> There is is QXL_IO_DESTROY_ALL_SURFACES + worker->destroy_surfaces() ...
> 

Regarding QXL_IO_DESTROY_ALL_SURFACES, it destroys the primary surface too,
which is a little special, that's another difference - update_mem destroys
everything except the primary. I know I tried to destroy the primary but it
didn't work right, don't recall why right now, so I guess I'll have to retry.

> The QXL_IO_UPDATE_MEM command does too much special stuff IMHO.
> I also think we don't need to extend the libspice-server API.
> 
> We can add a I/O command which renders everything to device memory
> via stop+start.  We can zap all surfaces with the existing command +
Yes, start+stop work nicely, didn't realize (saw it before, assumed
it wouldn't be good enough), just need to destroy the surfaces too.

> worker call.  We can add a I/O command to ask qxl to push the
> release queue head to the release ring.

So you suggest to replace QXL_IO_UPDATE_MEM with what, two io commands instead
of using the val parameter?
 QXL_IO_UPDATE_MEM
 QXL_IO_FLUSH_RELEASE
?

> 
> Comments?
> 
> cheers,
>   Gerd
>