[Mesa-dev] Remove classic drivers or fork src/mesa for gallium?

[Kristian Høgsberg]

On Wed, Dec 4, 2019 at 10:31 AM Rob Clark <robdclark at gmail.com> wrote:
>
> On Wed, Dec 4, 2019 at 9:48 AM Eric Anholt <eric at anholt.net> wrote:
> >
> > On Tue, Dec 3, 2019 at 4:39 PM Marek Olšák <maraeo at gmail.com> wrote:
> > >
> > > Hi,
> > >
> > > Here are 2 proposals to simplify and better optimize the GL->Gallium translation.
> > >
> > > 1) Move classic drivers to a fork of Mesa, and remove them from master. Classic drivers won't share any code with master. glvnd will load them, but glvnd is not ready for this yet.
> > >
> > > 2) Keep classic drivers. Fork src/mesa for Gallium. I think only mesa/main, mesa/vbo, mesa/program, and drivers/dri/common need to be forked and mesa/state_tracker moved. src/gallium/state-trackers/gl/ can be the target location.
> > >
> > > Option 2 is more acceptable to people who want to keep classic drivers in the tree and it can be done right now.
> >
> > (resending reply-all)
> >
> > I object to both of these.  They increase work for Mesa folks like me
> > who do tree-wide work.
> >
> > I feel like we're finally (formats, util/ helpers, etc.) paying down
> > the technical debt that we built with gallium copying so much of
> > src/mesa/main, and saying "let's go duplicate more code so we can do
> > some unspecified optimization work" gets me really upset.
>
> tbf option #1 would be a copy of the code.. but a copy that we'd
> (hopefully) ignore from the perspective of tree-wide cleanup/refactor.
> If we started refactoring the legacy fork, that would strongly defeat
> the purpose of having it!
>
> Given that we don't have most of the classic drivers (other than i965)
> in CI, and presumably not many folks who are tracking master test the
> old classic drivers, moving them off to a fork seems to me to
> significantly reduce the risk of refactorings (whether it be for perf
> or for cleanup).

Another option would be to do a LTS-kind of release of mesa and then
drop the non-gallium drivers. It could even be limited in scope to the
non-gallium drivers, in the sense that we'd only do releases for fixes
to those drivers. It's basically option 1), but saying that we still
care about maintaining the drivers, but they wont receive new
features. With i965 being at GL 4.6, I don't think that's an
unreasonable stance (contrast with years ago when i965 feature level
was lagging the hw capability and spec).

At the end of the day, it will impact the Intel team the most and I
think it's largely their call.

Kristian

>
> BR,
> -R
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