[RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Deepak Rawat]

> > > Thanks for the review. Unfortunately only the first vmbus message
> > > take
> > > effect and subsequent calls are ignored. I originally implemented
> > > using
> > > vram helpers but I figured out calling this vmbus message again
> > > won't
> > > change the vram location.
> 
> /me notices there also is user_ctx.  What is this?

Not sure, I will try to get in touch with hyper-v folks internally to
see if page-flip can be used.

> 
> > I think that needs a very big comment. Maybe even enforce that with
> > a
> > "vram_gpa_set" boolean in the device structure, and complain if we
> > try to
> > do that twice.
> > 
> > Also I guess congrats to microsoft for defining things like that :-
> > /
> 
> I would be kind of surprised if the virtual device doesn't support
> pageflips.  Maybe setting vram_gpa just isn't the correct way to do
> it.  Is there a specification available?
> 
> There are a number of microsoft folks in Cc:  Anyone willing to
> comment?
> 
> thanks,
>   Gerd
> 
> PS: And, yes, in case pageflips really don't work going with shmem
>     helpers + blits is reasonable.
>