Document custom graphics driver extensions

[orowith2os]

The current method of how Flatpak handles graphics libraries is incompatible with projects such as @asahiLinux, as those projects might need special or otherwise incompatible (uAPI breakage) versions of Mesa or other graphics libs that Flathub or other repos don't ship.

Having documentation on making custom graphics drivers is also useful for Linux gamers using Flatpak for apps like @bottlesdevs, as a custom version of Mesa could improve performance or game compatibility.

EDIT: Mentioned this issue to the mesa-git extension issue tracker: https://gitlab.com/freedesktop-sdk/mesa-git-extension/-/issues/12

[TingPing]

I don't have time to add this to the docs here atm but the broad ideas are here: https://blog.tingping.se/2018/08/26/flatpak-host-extensions.html

What's written there is actually exactly what AshaiLinux should be doing.

[bbhtt]

Is there anything left to document here?

Unmaintained extensions are already documented and an example on how the GL extension point works in fdsdk is here https://docs.flatpak.org/en/latest/extension.html#extension-point

I don't see something specific for Graphics driver to document here.

The plan for Asahi is to publish a GL.ashai extension at some point with the DRM_ASAHI_UNSTABLE_UABI_VERSION version as suffix. At most 2 such extensions is supposed to be published from fdsdk to Flathub.

Flatpak will have to gain support for detecting the UABI version similar to how Nvidia works using DRM_IOCTL_ASAHI_GET_PARAM call. Valentin David had started working on the Flatpak bit a few months ago.

[TingPing]

Asahi actually now ships their own extension as of a few weeks ago.

I think this is fine to close.