On 2023/10/19 8:25, Gurchetan Singh wrote:


On Tue, Oct 10, 2023 at 9:41 PM Huang Rui <ray.hu...@amd.com <mailto:ray.hu...@amd.com>> wrote:

    On Tue, Oct 10, 2023 at 11:52:14PM +0800, Dmitry Osipenko wrote:
     > On 10/10/23 18:40, Dmitry Osipenko wrote:
     > > On 10/10/23 16:57, Huang Rui wrote:
     > >> These definitions are used fro qemu, and qemu imports this
    marco in the
     > >> headers to enable gfxstream, venus, cross domain, and drm (native
     > >> context) for virtio gpu. So it should add them even kernel
    doesn't use
     > >> this.
     > >>
     > >> Signed-off-by: Huang Rui <ray.hu...@amd.com
    <mailto:ray.hu...@amd.com>>
     > >> Reviewed-by: Akihiko Odaki <akihiko.od...@daynix.com
    <mailto:akihiko.od...@daynix.com>>
     > >> ---
     > >>
     > >> Changes V1 -> V2:
     > >> - Add all capsets including gfxstream and venus in kernel
    header (Dmitry Osipenko)
     > >>
     > >> Changes V2 -> V3:
     > >> - Add missed capsets including cross domain and drm (native
    context)
     > >>   (Dmitry Osipenko)
     > >>
     > >> v1:
    https://lore.kernel.org/lkml/20230915105918.3763061-1-ray.hu...@amd.com/ 
<https://lore.kernel.org/lkml/20230915105918.3763061-1-ray.hu...@amd.com/>
     > >> v2:
    https://lore.kernel.org/lkml/20231010032553.1138036-1-ray.hu...@amd.com/ 
<https://lore.kernel.org/lkml/20231010032553.1138036-1-ray.hu...@amd.com/>
     > >>
     > >>  include/uapi/linux/virtio_gpu.h | 4 ++++
     > >>  1 file changed, 4 insertions(+)
     > >>
     > >> diff --git a/include/uapi/linux/virtio_gpu.h
    b/include/uapi/linux/virtio_gpu.h
     > >> index f556fde07b76..240911c8da31 100644
     > >> --- a/include/uapi/linux/virtio_gpu.h
     > >> +++ b/include/uapi/linux/virtio_gpu.h
     > >> @@ -309,6 +309,10 @@ struct virtio_gpu_cmd_submit {
     > >>
     > >>  #define VIRTIO_GPU_CAPSET_VIRGL 1
     > >>  #define VIRTIO_GPU_CAPSET_VIRGL2 2
     > >> +#define VIRTIO_GPU_CAPSET_GFXSTREAM 3
     > >
     > > The GFXSTREAM capset isn't correct, it should be
    GFXSTREAM_VULKAN in
     > > accordance to [1] and [2]. There are more capsets for GFXSTREAM.
     > >
     > > [1]
     > >
    
https://github.com/google/crosvm/blob/main/rutabaga_gfx/src/rutabaga_utils.rs#L172 
<https://github.com/google/crosvm/blob/main/rutabaga_gfx/src/rutabaga_utils.rs#L172>
     > >
     > > [2]
     > >
    
https://patchwork.kernel.org/project/qemu-devel/patch/20231006010835.444-7-gurchetansi...@chromium.org/
 
<https://patchwork.kernel.org/project/qemu-devel/patch/20231006010835.444-7-gurchetansi...@chromium.org/>
     >
     > Though, maybe those are "rutabaga" capsets that not related to
     > virtio-gpu because crosvm has another defs for virtio-gpu capsets
    [3].
     > The DRM capset is oddly missing in [3] and code uses "rutabaga"
    capset
     > for DRM and virtio-gpu.
     >
     > [3]
     >
    
https://github.com/google/crosvm/blob/main/devices/src/virtio/gpu/protocol.rs#L416 
<https://github.com/google/crosvm/blob/main/devices/src/virtio/gpu/protocol.rs#L416>

    Yes, [3] is the file that I referred to add these capsets
    definitions. And
    it's defined as gfxstream not gfxstream_vulkan.

     >
     > Gurchetan, could you please clarify which capsets definitions are
     > related to virtio-gpu and gfxstream. The
     > GFXSTREAM_VULKAN/GLES/MAGMA/COMPOSER or just the single GFXSTREAM?


It should be GFXSTREAM_VULKAN.  The rest are more experimental and easy to modify in terms of the enum value, should the need arise.

I imagine the virtio-spec update to reflect the GFXSTREAM to GFXSTREAM_VULKAN change will happen eventually.

I think this is a matter what the committee should determine, but in general I don't think it is OK to change the existing identifier.

I also think even experimental values should be added to virtio spec at an early stage unless such an "experiment" is done only on one laptop. We can obsolete a capset anytime so it's more important to avoid conflicts of capsets.

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