[Mesa-dev] [RFC] Compatibility between old dri modules and new loaders, and vice verse

[Dave Airlie]

>
> As kindly hinted by Marek, currently we do have a wide selection of
> supported dri <> loader combinations.
>
> Although we like to think that things never break, we have to admit
> that not many of us test every possible combinations of dri modules
> and loaders. With the chances getting smaller as the time gap (age)
> between the two increases. As such I would like to ask if we're
> interested in gradually depreciating as the gap grows beyond X years.
>
> The rough idea that I have in my mind is:
> - Check for obsolete extensions (requirements for such) - both in the
> dri modules and the loaders (including the xserver).
> - Add some WARN messages ("You're using an old loader/DRI module.
> Update to XXX or later") when such code path is hit.
> - After X mesa releases, we remove the dri extension from the
> module(s) and bump the requirement(s) in the loader(s).
>
> And now the more important question why ?
>  - Very rarely tested and not actively supported - if it works it
> works, we only cover one stable branch.
>  - Having a quick look at the the "if extension && extension.version
>>= y" maze does leave most of us speechless.
>  - Will allow us to start removing a few of the nasty quirks/hacks
> that we currently have laying around.
>
> Worth mentioning:
>  - Depreciation period will be based on the longest time frame set by
> LTS versions of distros. For example if Debian A ships X and mesa 3
> years apart, while Ubuntu does is ~2.5 and RedHat ~2.8, we'll stick
> with 3 years.
>  - libGL dri1 support... it's been almost four years since the removal
> of the dri1 modules. Since then the only activity that I've noticed by
> Connor Behan on the r128 front. Although it seems that he has covered
> the ddx and is just looking at the kernel side of things. Should we
> consider mesa X (10.6 ?) as the last one that supports such old
> modules in it's libGL and give it a much needed cleanup ?
>
>
> How would people feel about this - do we have any strong ack/nack
> about the idea ? Are there many people/companies that support distros
> where the xserver <> mesa gap is over, say 2 years ?

We still ship 7.11 based dri1 drivers in RHEL6, and there is still a
chance of us rebasing to newer Mesa in that depending on schedules.

ajax might have a different opinion, on how likely that is, but
that would be at least another year from now where we'd want DRI1
to work.

Dave.