[Mesa-dev] GL4.5 or bust...

Mon May 16 17:54:28 UTC 2016

On Mon, May 16, 2016 at 1:43 AM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> Hi all,
>
> On 16 May 2016 at 01:32, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>> On Sun, May 15, 2016 at 8:25 PM, Martin Peres <martin.peres at free.fr> wrote:
>>> On 16/05/16 02:55, Jason Ekstrand wrote:
>>>> On May 15, 2016 2:01 PM, "Martin Peres" <martin.peres at free.fr
>>>> <mailto:martin.peres at free.fr>> wrote:
>>>> >
>>>> > On 15/05/16 23:54, Ilia Mirkin wrote:
>>>> >>
>>>> >> On Sun, May 15, 2016 at 4:32 PM, Dave Airlie <airlied at gmail.com
>>>> >> <mailto:airlied at gmail.com>> wrote:
>>>> >>>
>>>> >>> So I said this on irc over the weekend and it seemed like we had some
>>>> >>> consensus on holding off 12.0 until we could announce 4.5 on some
>>>> >>> hardware. This assumes the FP64 stuff is going in at least.
>>>> >>>
>>>> >>> So I decided to roll out the proposal here, which is that we finish
>>>> >>> GL4.5 features off for at least Skylake I think.
>>>> >>>
>>>> >>> So what is needed/missing: please add as you see fit.
>>>> >>>
>>>> >>> a) robustness - radeonsi has some bits of this. We need to get
>>>> >>> KHR_robustness bits, that I think Kayden has patches started for, and
>>>> >>> i965 needs to ensure it uses robust buffer stuff. I don't think this
>>>> >>> one in unobtainable.
>>>> >>>
>>>> >>> b) cull_distance - I merged something, it broke, I'll fix it today,
>>>> >>> job done.
>>>> >>>
>>>> >>> c) enhanced_layouts - So tarceri has posted patches, we know that to
>>>> >>> do it properly we probably need to rip up attribute packing and
>>>> >>> rewrite it, however if Kayden thinks what tarceri has done is
>>>> >>> functional enough for now, we could merge the final pieces and work on
>>>> >>> perfection later.
>>>> >>>
>>>> >>> d) SIMD32 for i965 compute shaders - this is probably the most unknown
>>>> >>> to me, curro says he's got some patches, that need to rebase onto FP64
>>>> >>> when it lands, assuming he can do that, and reviewers can get on top
>>>> >>> of things, and we possibly only enable SIMD32 in the corner cases
>>>> >>> initially, it might be possible to get this landed.
>>>> >>>
>>>> >>> Have I missed anything? Should we go for it?
>>>> >>
>>>> >> The bugs that get triggered when you expose GL 4.3+ to UE4 games. Some
>>>> >> are ours, some are theirs. Someone needs to sign up for this work.
>>>> >>
>>>> >> Also, I'd like to mention that ES 3.2 is pretty close as well. But
>>>> >> probably not close enough to squeeze in here. Ian has started working
>>>> >> on the OES_shader_io_blocks bits of it (which IMO shouldn't be too bad
>>>> >> for someone who knows what all GLSL allows and what it doesn't), which
>>>> >> was the last remaining big chunk. I have preliminary patches for core
>>>> >> support of advanced blending, the rest should all be easy.
>>>> >>
>>>> >>> For radeonsi, I think the only other missing bit is qbo and
>>>> >>> clear_texture, which may or may not make it in time.
>>>> >>
>>>> >> I'm in favor of this plan. Nouveau should be ready for Fermi and
>>>> >> Kepler once Samuel's images patches for Fermi land (mostly reviewed,
>>>> >> had a couple of nits). Maxwell will be missing tess and images, and
>>>> >> it's unlikely that either of those will get done in a reasonable
>>>> >> period of time. I think we can just flip robustness on... probably not
>>>> >> meeting all the provisions of that spec, but ... meh.
>>>> >>
>>>> >> That said, we should put a cap on this timewise - if e.g. it becomes
>>>> >> clear that SIMD32 will take a long time (I think the biggest potential
>>>> >> issue of the batch), we should just cut a release. Maybe a 1 month
>>>> >> cap?
>>>> >
>>>> >
>>>> > Yeah, a cap of 1 month delay compared to the initial plan or 1
>>>> > week after the driver reaching 4.5 in master, whatever happens
>>>> > first.
>>>>
>>>> I agree with a time limit if we're going to do this. Another suggestion
>>>> that had been made is to go ahead with the release and then plan to release
>>>> mesa 13 as soon as we get 4.5. I'm personally OK with either.
>>>> --Jason
>>>>
>>> Let's see if it would prevent some superstitious people from updating :p
>>>
>>> In any case, I agree with Jason. Mesa is released often-enough and things
>>> will get a little buggy as games suddenly start exercising mesa is funny
>>> ways. So, let's not rush it out if it cannot reach the quality needed and
>>> just release another major version when it is ready.
>>
>> Of course the way to discover that games/applications suddenly start
>> exercising mesa in funny ways is to do a release... a bit of a catch
>> 22, wouldn't you say? I don't think developers and the users of
>> mesa-git are really going to be enough to get all the kinks out. And
>> the RC period should be sufficient time to fix any major issues that
>> pop up.
>>
>
> Let's see if I can summarise:
>  - People want to have a release with GL 4.5 capable driver(s)
>  - Mesa releasing is on a time based model, not a feature one.

This isn't set in stone. It's something we all decided on a while
back. It's worked well and continues to work well, but we can all
decide to make an exception or change it, if we get community
consensus.

>  - Saying "we must get these X things, no release until then, period"
> (GL 4.5 or bust) is just plain silly

This is not "summarising", this is your opinion. I like time based
release schedules as much as the next guy/girl, but there are case or
circumstances where exceptions make sense.

>  - If we amend ^^ to honour some timeline, than we may not reach the
> stated goad even with the imposed delay.
>  - Parties interested in the original timeline, may miss, are too shy,
> etc. to say anything against this last minute change.
>
> How about we do the following:
>  - Keep the plan as originally
>  - As people are happy that we have 1-2 drivers covering GL version X,
> branch off/feature freeze and release a few weeks later.
>  - Last but not least - let's try and bring up such discussions
> earlier, please ?
> If people have missed the earlier emails let me know we can improve on
> that. Don't just ignore them and shout at the last minute, please ?

I think we have to priorities here: making the 12.0 release and
getting 4.5 out as soon as possible. They don't actually conflict, we
just have to agree on the mechanism we use: 1) push out 12.0 a bit
(we'll need a deadline), 2) keep the 12.0 schedule but re-merge master
and push out the release if we get to 4.5 before the release or 3) cut
a release (12.1 or 13.0, whatever) as soon as we get to 4.5.

Kristian

> Thank you
> Emil
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