Re: [Qemu-devel] [PATCHv3] qxl: move to UNDEFINED on DESTROY_ALL_SURFACES{, _ASYNC}

[Gerd Hoffmann]

On 06/29/11 16:29, Alon Levy wrote:
> On Wed, Jun 29, 2011 at 03:09:36PM +0200, Gerd Hoffmann wrote:
> > Hi,
> >
> > > +    case QXL_IO_DESTROY_ALL_SURFACES_ASYNC: +        d->mode =
> > > QXL_MODE_UNDEFINED;
> >
> > Should go to the async thread.
>
> doesn't it make more sense to do all state changes from the vcpu
> thread? async thread can run much later, if you have a
> QXL_IO_DESTROY_ALL_SURFACES_ASYNC followed by a
> QXL_IO_CREATE_PRIMARY_ASYNC where the driver did not wait for the
> completion of the ASYNC first, I would still like to support that,
> but it won't work if I move this to the async thread.

I think we should disallow doing any I/O ops while one is in progress 
(except maybe QXL_IO_LOG).  Most I/O commands are I/O commands because 
they either needed for device setup or must be synchronous anyway.

QXL_IO_CREATE_PRIMARY_ASYNC wasn't exactly clever designed I think. 
Would have been better to enter native mode with another I/O command, 
then send the create request for the primary through the rings like all 
other surface commands.  But given it is a rare event it isn't that a 
big issue either.

cheers,
  Gerd