Subject: DRM development process wiki page..
Date: Wednesday 27th August 2008 00:15:12 UTC (over 8 years ago)
Okay I've put some thoughts up at: http://dri.freedesktop.org/wiki/DRMProcess and I've pasted it in below this for discussion. some other points: a) People are pushing for a process change, we will have something change, however this isn't a who shouts loudest competition, so more than likely you'll end up compromising, deal with the fact that nirvana for you may be hell for others. b) BSD developers do exist now, giving out that they didn't exist in the past or aren't adding features is pointless. Would you seriously start developing features before getting the code caught up?. So live with the fact that we should help the BSD guys *if* its practical. So we shouldn't do anything major that alienates their further development. (personally I care little for BSD, the license or the OSes, however I'm attempting to be some way fair). c) We get testers from drm master, we get better testers using drm master for features than a separate kernel tree. We get better regression tests from getting stuff upstream. However upstreaming stuff to Linus is not how to find regressions, it helps but its suboptimal in that he will eventually ignore us if the regression rate gets too high. So upstreaming is great for features like GEM, however it would suck for something like vblank-rework. This appears to point at, upstream is great if you touch one driver and exist in your own world, however if you want interfaces that all drivers can use like vbl-rework you need to work somewhere else or carry two interfaces until everyone is ported. So lets see if we can improve this for everyone... Dave. DRM Development Process (Proposed) 1. Master branch in Linux tree style with links for BSD etc. 2. Always compatible with current release Linux kernel + with backwards compat *where* practical for older kernels. We should probably limit the back compat to like 6 kernel revisions or something. 3. Macros for BSD compat to wrap Linux APIs. So we minimise the nightmare of macros in driver code. no more DRM_ if they can be avoided. Patches 1. All patches to be sent to the mailing list with S-O-B, no patches to be committed to master branch. Nothing goes upstream or into master without Signed-off-by and maintainers Signed-off-by. 2. Do not mix cleanup and developement ever. If you move a bunch of registers or code into a separate file, do just that in one patch. 3. Backwards compat patches in separate patches. So first patch should be upstreamable, backwards compat patches should be in sequence. Upstream first policy This policy places a restriction on users of the drm, i.e. Mesa, DDX, X server. No upstream release should include code that hasn't been included in a Linux kernel release cycle. Upstream can use a --enable-experimental-kernel-api type flag but default build should never require any unreleased kernel/drm API to build or run. Distros should not enable experimental APIs in releases, unless they are willing to version their kernel and other components against each other and deal with the fallout of API changes. All userspace APIs need to be submitted to dri-devel and to the Linux kernel list, also all patches which need exports or use new non-drm kernel functionality should be reviewed by both lists. Note: Do not expect because your code works that you won't have to re-write it all for upstream. So upstream ideas early esp when you interface to other kernel components. Development 1. For large features or new drivers create a new branch in drm tree. Stay in the branch, these branches will never ever get merged ever. ever. When the developers feel the branch is suitable for upstream, they need to create a clean set of patches following the rules above. All API additions need to be reviewed and feedback taken on board. If this involves another round of development, nuke the old branch and/or start a new one from the patchset. Repeat cycle. When patches are approved by anyone who cares they will get merged into the drm master and into the upstream drm-next queue. Backwards compat patches will be merged into drm master. 2. For minor cleanups and fixes, patches should be sent to dri-devel. 3. If a patch gets reverted from upstream kernel for a regression it will also be reverted from the drm master branch. 4. If someone gets in the queue and you conflict you get to keep the mess. DRM tree layout (plans) 1. Create drivers/gpu/drm/ exactly a mirror of current upstream. 2. Add backwards compat cleanly on top of this tree with some patches. 3. Add BSD compat in places that need it. 4. Migrate BSD to using the upstream src files instead of the shared-core ones. 5. Evict all non-upstream patches to branches, currently * - GEM - TTM - vblank-rework - i915 various bits, mmio oq interface. Suggestions + help needed In the future we may find we need a transitory drm-testing branch that merges all the currently in development branches. This might help in resolving conflicts before they happen. It would be nice to tinderbox build the drm mainline and drm-testing against the last 6 released kernels. ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ --