[Intel-gfx] [iGVT-g] Ask for comments of getting guest framebuffer in igvt-g

[Tian, Kevin]

> From: Gerd Hoffmann [mailto:kraxel at redhat.com]
> Sent: Tuesday, March 08, 2016 4:37 PM
> 
>   Hi,
> 
> > btw I don't think this vblank issue would be very significant. The main
> > targeted usage of GVT-g is for server virtualization/cloud, where
> > a remoting protocol is required for customer to see the content through
> > network.
> 
> The plan for that is to let the gpu video encoder process the guest
> framebuffer.  So the video encoder still being busy processing the
> buffer while the guest already started updating it can certainly lead to
> visible tearing.
> 
> I think using vblank to signal the guest when the host is done
> processing the framebuffer makes sense.  It'll simply throttle the guest
> in case the host is too busy to keep up.

Thanks Gerd for elaborating this part. We can have this requirement
considered once this new interface is agreed here. There may need
more consideration how to align "host is done processing" with virtual
vblank delivery. 

Thanks
Kevin