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

[Alon Levy]

On Thu, Jun 30, 2011 at 02:12:52PM +0200, Gerd Hoffmann wrote:
>   Hi,
> 
> >My thoughts exactly. Any reason to support the old non async messages if we
> >do this?
> 
> Yes.  Backward compatibility.

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

> 
> >The only difference with this approach is that we will have to do the reads 
> >from the
> >io thread of qemu,
> 
> Hmm?  Which reads?

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.

> 
> I'd add a completion callback to QXLInterface.
> 
> cheers,
>   Gerd
> 
>