Re: [virtio-dev] [PATCH] Add virtio gpu specification.

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Oct 07, 2014 at 10:21:10AM +0200, Gerd Hoffmann wrote:
> On Mo, 2014-10-06 at 21:28 +0300, Michael S. Tsirkin wrote:
> > On Mon, Sep 22, 2014 at 04:25:46PM +0200, Gerd Hoffmann wrote:
> > > Signed-off-by: Dave Airlie <airlied@redhat.com>
> > > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> > 
> > Hi Herd, Dave,
> > 
> > I have created
> > https://issues.oasis-open.org/browse/VIRTIO-114
> > to track adding virtio-gpu.
> > 
> > Would you like to discuss this device on our next meeting tomorrow?
> 
> I think it is still to early for that.  There will be a new revision of
> the patch (after kvm forum probably), it doesn't match the current code
> any more.
> 
> > Overall I think it's a nice spec.
> 
> Thanks.
> 
> If you (or anybody else) spots any protocol design issues please speak
> up, it isn't merged upstream yet so we can fixup things without too much
> pain.  This is #1 on my virtio-gpu todo list.

OK, so maybe it's addressed, but one thing to look out for,
is documenting limits on host resource usage.
If you want the most flexibility, make them discoverable
and dynamic so we can shrink host resources if necessary,
but I think it's important not to have cases where guest
can basically request arbitrary resource allocations.
Similarly, introducing error recovery mechanism is
a good idea, so that host can report an error if
it sees an unexpected input, and guest recovers
more or less gracefully rather than crashes.

> > I think the main issue with the below is the lack of
> > conformance clauses, instead there are only general descriptions.
> > I noted this in some places but really, it's everywhere.
> 
> Yea, I suspect the virtio-gpu text basically needs to to a transition
> simliar to the informal virtio 0.9.x to oasis virtio 1.0.  I'll go over
> your comments when I prepare the next patch revision.
> 
> thanks,
>   Gerd
>