libdrm_amdgpu being forked and merged into Mesa

[Bas Nieuwenhuizen]

On Fri, Oct 25, 2024 at 4:36 PM Michel Dänzer <michel.daenzer at mailbox.org>
wrote:

> On 2024-10-25 12:18, Bas Nieuwenhuizen wrote:
> > On Fri, Oct 25, 2024 at 11:21 AM Michel Dänzer <
> michel.daenzer at mailbox.org <mailto:michel.daenzer at mailbox.org>> wrote:
> >
> >     On 2024-10-24 17:08, Marek Olšák wrote:
> >     > We don't need to share the same VMID between ROCm and Mesa. We
> don't
> >     > need to share the same driver FD between ROCm and Mesa either. It
> will
> >     > be like having 2 different processes, and that should always work.
> >
> >     Per
> https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31756#note_2626236
> <
> https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31756#note_2626236>,
> does anything prevent the application from passing the same DRM file
> description (doesn't need to be the same *descriptor*) to separate drivers?
> (Not sure it can even pass a DRM fd to ROCm, surely can e.g. to radeonsi &
> AMDVLK though)
> >
> >
> > In RADV the app has no way to pass in a drm fd, there is only a way to
> query the major/minor from the fd (
> https://registry.khronos.org/vulkan/specs/1.3-extensions/html/chap55.html#VK_EXT_physical_device_drm
> <
> https://registry.khronos.org/vulkan/specs/1.3-extensions/html/chap55.html#VK_EXT_physical_device_drm
> >).
>
> Hmm. So Wayland compositors which use Vulkan have to share BOs from Vulkan
> into their DRM file description for KMS via dma-buf?
>
>
> How about ROCm, no way to pass in / retrieve a DRM file descriptor there
> either?
>
>
> > (not to mention that it would mean that any users would need to use
> libdrm_amdgpu. Given that the most likely combination of GBM with shared
> fd/handle stuff is kernel modesetting and nobody uses libdrm_amdgpu with
> that, having a shared libdrm_amdgpu would not help there)
>
> Not sure what you mean here, Wayland compositors use radeonsi with KMS.
>
> That is what I mean, since they use KMS directly, anything that radeonsi
does wrt using or not using libdrm_amdgpu doesn't impact them.

(note that some compositors, like gamescope do the actual dmabuf dance)

>
> --
> Earthling Michel Dänzer       \        GNOME / Xwayland / Mesa developer
> https://redhat.com             \               Libre software enthusiast
>
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