Re: [RFC PATCH v2 1/2] virtio-gpu: add resource create blob

[Gerd Hoffmann <kraxel@redhat.com>]

> > > > same goes for dma-buf imports (inside the guest).
> > >
> > > dma-buf import from another virtio driver is very interesting, but
> > > we'll probably need a some import UUID hypercall for that?
> >
> > No, just dma-buf import from somewhere, say a gpu passed to the guest
> > via pci pass-through does the rendering to a dma-buf and that dmabuf
> > gets imported into virtio-gpu for display in a host window.
> 
> I'm unfamiliar with that use case ... is there a chance the dma-buf is
> compressed/tiled?

Hmm, not fully sure but probably not.  I'd expect gpu drivers would
untile the BO when exporting to another driver because tiling modes
are typically hard-ware specific ...

> If so, we won't be able to query virglrenderer for the modifier and
> may need it in SCANOUT_BLOB unless there's another way to get it
> host-side.

No, there is no other magic way.  Userspace has to tell virtio-gpu what
format the dma-buf data has if it wants virtio-gpu do something with it,
the dma-buf itself is just a blob.

take care,
  Gerd