[Mesa-dev] [RFC] Concrete proposal to split classic
Hi list, We've talked about it a number of times, but I think it's time time to discuss splitting the classic drivers off of the main development branch again, although this time I have a concrete plan for how this would work. First, why? Basically, all of the classic drivers are in maintanence mode (even i965). Second, many of them rely on code that no one works on, and very few people still understand. There is no CI for most of them, and the Intel CI is not integrated with gitlab, so it's easy to unintentionally break them, and this breakage usually isn't noticed until just before or just after a release. 21.0 was held up (in small part, also me just getting behind) because of such breakages. I konw there is some interest in getting i915g in good enough shape that it could replace i915c, at least for the common case. I also am aware that Dave, Ilia, and Eric (with some pointers from Ken) have been working on a gallium driver to replace i965. Neither of those things are ready yet, but I've taken them into account. Here's the plan: 1) 21.1 release happens 2) we remove classic from master 3) 21.1 reaches EOL because of 21.2 4) we fork the 21.1 branch into a "classic-lts"¹ branch 5) we disable all vulkan and gallium drivers in said branch, at least at the Meson level 6) We change the name and precidence of the glvnd loader file 7) apply any build fixups (turn of intel generators for versions >= 7.5, for example 8) maintain that branch with build and critical bug fixes only This gives ditros and end users two options. 1) then can build *only* the legacy branch in the a normal Mesa provides libGL interfaces fashion 2) They can use glvnd and install current mesa and the legacy branch in parallel Because of glvnd, we can control which driver will get loaded first, and thus if we decide i915g or the i965 replacement is ready and turn it on by default it will be loaded by default. An end user who doesn't like this can add a new glvnd loader file that makes the classic drivers higher precident and continue to use them. Why fork from 21.1 instead of master? First, it allows us to delete classic immediately, which will allow refactoring to happen earlier in the cycle, and for any fallout to be caught and hopefully fixed before the release. Second, it means that when a user is switched from 21.1 to the new classic-lts branch, there will be no regressions, and no one has to spend time figuring out what broke and fixing the lts branch. When you say "build and critical bug fixes", what do you mean? I mean update Meson if we rely on something that in the future is deprecated and removed, and would prevent building the branch or an relying on some compiler behavior that changes, gaping exploitable security holes, that kind of thing. footnotes ¹Or whatever color you like your bikeshed signature.asc Description: signature ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
Re: [Mesa-dev] [RFC] Concrete proposal to split classic
On Mon, Mar 22, 2021 at 3:27 PM Dylan Baker wrote: > > Hi list, > > We've talked about it a number of times, but I think it's time time to > discuss splitting the classic drivers off of the main development branch > again, although this time I have a concrete plan for how this would > work. > > First, why? Basically, all of the classic drivers are in maintanence > mode (even i965). Second, many of them rely on code that no one works > on, and very few people still understand. There is no CI for most of > them, and the Intel CI is not integrated with gitlab, so it's easy to > unintentionally break them, and this breakage usually isn't noticed > until just before or just after a release. 21.0 was held up (in small > part, also me just getting behind) because of such breakages. > > I konw there is some interest in getting i915g in good enough shape that > it could replace i915c, at least for the common case. I also am aware > that Dave, Ilia, and Eric (with some pointers from Ken) have been > working on a gallium driver to replace i965. Neither of those things are > ready yet, but I've taken them into account. > > Here's the plan: > > 1) 21.1 release happens > 2) we remove classic from master > 3) 21.1 reaches EOL because of 21.2 > 4) we fork the 21.1 branch into a "classic-lts"¹ branch > 5) we disable all vulkan and gallium drivers in said branch, at least at >the Meson level > 6) We change the name and precidence of the glvnd loader file > 7) apply any build fixups (turn of intel generators for versions >= 7.5, >for example > 8) maintain that branch with build and critical bug fixes only I would like it if Intel could avoid garbage-collecting older-HW shared code for at least a release due aforementioned WIPs, but I think it's time to call the classic i965_dri.so and i915_dri.so done. +1 from me assuming that we validate that one can actually get a working X server with the mesa-legacy set installed. ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
Re: [Mesa-dev] [RFC] Concrete proposal to split classic
+1. I'd we think GLVND and X are ready for this, I think it's a good plan. On March 22, 2021 17:34:09 Eric Anholt wrote: On Mon, Mar 22, 2021 at 3:27 PM Dylan Baker wrote: Hi list, We've talked about it a number of times, but I think it's time time to discuss splitting the classic drivers off of the main development branch again, although this time I have a concrete plan for how this would work. First, why? Basically, all of the classic drivers are in maintanence mode (even i965). Second, many of them rely on code that no one works on, and very few people still understand. There is no CI for most of them, and the Intel CI is not integrated with gitlab, so it's easy to unintentionally break them, and this breakage usually isn't noticed until just before or just after a release. 21.0 was held up (in small part, also me just getting behind) because of such breakages. I konw there is some interest in getting i915g in good enough shape that it could replace i915c, at least for the common case. I also am aware that Dave, Ilia, and Eric (with some pointers from Ken) have been working on a gallium driver to replace i965. Neither of those things are ready yet, but I've taken them into account. Here's the plan: 1) 21.1 release happens 2) we remove classic from master 3) 21.1 reaches EOL because of 21.2 4) we fork the 21.1 branch into a "classic-lts"¹ branch 5) we disable all vulkan and gallium drivers in said branch, at least at the Meson level 6) We change the name and precidence of the glvnd loader file 7) apply any build fixups (turn of intel generators for versions >= 7.5, for example 8) maintain that branch with build and critical bug fixes only I would like it if Intel could avoid garbage-collecting older-HW shared code for at least a release due aforementioned WIPs, but I think it's time to call the classic i965_dri.so and i915_dri.so done. I'm happy to leave older hardware support in the tree for now. We need to keep the vec4 compiler for HSW Vulkan support for now and there's no harm in keeping old hardware support in ISL. I'm a little tempted to let HSW Vulkan bitrot in the LTS branch too but it does still pick up features here and there so I'm unsure if that's a good idea or not. --Jason +1 from me assuming that we validate that one can actually get a working X server with the mesa-legacy set installed. ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
Re: [Mesa-dev] [RFC] Concrete proposal to split classic
On Monday, March 22, 2021 3:15:30 PM PDT Dylan Baker wrote: > Hi list, > > We've talked about it a number of times, but I think it's time time to > discuss splitting the classic drivers off of the main development branch > again, although this time I have a concrete plan for how this would > work. > > First, why? Basically, all of the classic drivers are in maintanence > mode (even i965). Second, many of them rely on code that no one works > on, and very few people still understand. There is no CI for most of > them, and the Intel CI is not integrated with gitlab, so it's easy to > unintentionally break them, and this breakage usually isn't noticed > until just before or just after a release. 21.0 was held up (in small > part, also me just getting behind) because of such breakages. > > I konw there is some interest in getting i915g in good enough shape that > it could replace i915c, at least for the common case. I also am aware > that Dave, Ilia, and Eric (with some pointers from Ken) have been > working on a gallium driver to replace i965. Neither of those things are > ready yet, but I've taken them into account. > > Here's the plan: > > 1) 21.1 release happens > 2) we remove classic from master > 3) 21.1 reaches EOL because of 21.2 > 4) we fork the 21.1 branch into a "classic-lts"¹ branch > 5) we disable all vulkan and gallium drivers in said branch, at least at >the Meson level > 6) We change the name and precidence of the glvnd loader file > 7) apply any build fixups (turn of intel generators for versions >= 7.5, >for example > 8) maintain that branch with build and critical bug fixes only > > This gives ditros and end users two options. > 1) then can build *only* the legacy branch in the a normal Mesa provides >libGL interfaces fashion > 2) They can use glvnd and install current mesa and the legacy branch in >parallel > > Because of glvnd, we can control which driver will get loaded first, and > thus if we decide i915g or the i965 replacement is ready and turn it on > by default it will be loaded by default. An end user who doesn't like > this can add a new glvnd loader file that makes the classic drivers > higher precident and continue to use them. > > Why fork from 21.1 instead of master? > > First, it allows us to delete classic immediately, which will allow > refactoring to happen earlier in the cycle, and for any fallout to be > caught and hopefully fixed before the release. Second, it means that > when a user is switched from 21.1 to the new classic-lts branch, there > will be no regressions, and no one has to spend time figuring out what > broke and fixing the lts branch. > > When you say "build and critical bug fixes", what do you mean? > > I mean update Meson if we rely on something that in the future is > deprecated and removed, and would prevent building the branch or an > relying on some compiler behavior that changes, gaping exploitable > security holes, that kind of thing. > > footnotes > ¹Or whatever color you like your bikeshed Hi Dylan, I largely like this plan. i915 and r200 and novueau_vieux definitely need to be forked off, to keep them working as we do core refactors. In the past, we weren't working on core much, and so they largely kept working with some pain, but not -too- much effort. But these days, we're seeing a lot of work from Marek and others to clean up and rework a lot of core drawing code, state upload code, and so on. I remember all the work Tim did to rework uniform handling and ancient classic was a pain point for him as well. I had to track down like 5 overlapping Piglit regressions on i915 this release cycle, just to get the driver working...no worse than it was before. And i915 is tested regularly in the Intel CI. r200 isn't tested regularly. Doubtful about vieux. I had thought about also forking other old drivers like i915g or r300g. But it sounds like there's still some interest in i915g, and those tend to get fixed up as the Gallium infrastructure is still actively being maintained (unlike things like swrast and tnl). So I guess we can leave those in mainline. I'm hesitant about i965. One thing I will say is that, if i965 is included in the plan, there would probably be more interest in working on that branch than mere "critical bug fixes" as you defined. We might discover new games that don't work; people might write bug fixes for i965, at which point we should merge and ship them. But we could still do on-demand releases when enough interesting bug fixes have piled up, rather than doing them on a schedule. That should hopefully not be too burdensome. While a part of me hates the idea of forking i965 off, I think it may actually be the best call. We haven't done any new interesting feature development on those platforms in ages, and they're complete in terms of OpenGL spec support. We aren't spending any time optimizing performance on those platforms. They're pretty much in bug-fix-only mode already. Whether th
