On Sat, 16 Jun 2018 21:40:10 -0700
Matt Turner <matts...@gentoo.org> wrote:

> Hello,
> 
> VIDEO_CARDS is an annoying mess. We used to have radeon, intel, and
> some others in media-libs/mesa's VIDEO_CARDS. radeon and intel
> corresponded to disparate sets of drivers -- VIDEO_CARDS=radeon has
> meant classic r100, r200, r300, and r600 drivers and gallium r600 and
> radeonsi drivers. VIDEO_CARDS=intel has meant classic i915 and i965
> drivers as well as gallium i915.
> 
> I added more-specific VIDEO_CARDS for those separate drivers a few
> years ago, so that users could set VIDEO_CARDS="radeon radeonsi" and
> only get the one radeonsi driver they actually wanted while still
> enabling support for x11-libs/libdrm's radeon support code which is
> used by most of those radeon drivers. Of course some users want this
> control and others don't care at all.
> 
> The confusion comes in with "classic" DRI drivers vs Gallium drivers.
> The Gallium abstraction layer allows a hardware driver to handle
> multiple APIs -- OpenGL, D3D9, OpenCL, video decode APIs, etc. For
> instance, users try to build the classic i965 driver (there is no
> Gallium driver for this hardware) with USE=opencl or USE=vaapi and
> don't understand why they didn't get what they wanted (or REQUIRED_USE
> prevents them from doing so).
> 
> Should of Mesa's USE flags, d3d9, llvm, lm_sensors, opencl, openmax,
> unwind, vaapi, vdpau, xa, and xvmc are Gallium-only. Should I make a
> USE_EXPAND for Gallium-only options to attempt to avoid confusion?
> Another point of confusion: not all Gallium drivers support all of
> these features. For instance only the r600 and radeonsi drivers
> support OpenCL. How to best handle this?
> 
> It seems like at one extreme you build an extensive set of
> REQUIRED_USE conditions that force users to micromanage their USE
> flags, or you let them enable all sorts of impossible combinations and
> deal with the confused bug reports.
> 
> I would like to somehow get rid of the 'classic' and 'gallium' USE
> flags entirely, but I'm not totally sure how. Maybe I can enable them
> dependent on VIDEO_CARDS...
> 
> Suggestions welcome.
> 

What about creating a tiny pkg that has all the combinations in a
dictionary and can set the USE and VIDEO_CARDS flags according to the
video card(s) you have.

This would be along the same lines as the
app-portage/cpuid2cpuflags pkg.  Then the pkg is updated as new drivers
and combinations are changed.  Perhaps have it run in pkg_postisnt to
print any irregularities it finds and ewarn they need fixing.

-- 
Brian Dolbec <dolsen>


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