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

[Gerd Hoffmann <kraxel@redhat.com>]

   Hi,

>> 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?

I'd like to (a) avoid updating the libspice-server API if possible and 
(b) have one I/O command for each logical step.  So going into S3 could 
look like this:

   (0) stop putting new commands into the rings
   (1) QXL_IO_NOTIFY_CMD
   (2) QXL_IO_NOTIFY_CURSOR
       qxl calls notify(), to make the worker thread empty the command
       rings before it processes the next dispatcher request.
   (3) QXl_IO_FLUSH_SURFACES (to be implemented)
       qxl calls stop()+start(), spice-server renders all surfaces,
       thereby flushing state to device memory.
   (4) QXL_IO_DESTROY_ALL_SURFACES
       zap surfaces
   (5) QXL_IO_FLUSH_RELEASE (to be implemented)
       push release queue head into the release ring, so the guest
       will see it and can release everything.

(1)+(2)+(4) exist already.
(3)+(5) can be done without libspice-server changes.

Looks workable?

cheers,
   Gerd