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

[Gerd Hoffmann <kraxel@redhat.com>]

   Hi,

>> Yes.  Backward compatibility.
>
> So at least deprecate it to be dropped later? I don't like that the code just gets
> bigger and bigger.

Deprecate them is fine.

> I was thinking of a different solution - one in which the same "READY" messages are
> written, but read from a different place. That would not have actually required any changes
> to the spice-server api. But if you say you prefer to add a completion callback, that's cool.
>
> Just to answer, I was thinking of this flow for the async commands:
>
> vcpu thread ->  pipe_to_red_worker : update_area_async
> red_worker thread ->  pipe_to_io_thread : update_area_async complete
>
> but that wouldn't have worked, would it? unless we made sure to prevent tries to do async/sync
> while async in progress.

The pipe is a libspice-server internal thing and it should stay that 
way.  libspice-server should be able to use something completely 
different for dispatcher <-> worker communication (say a linked job list 
with mutex locking and condition variable wakeup) and everything should 
continue to work.

cheers,
   Gerd