[Nouveau] DRM changes

[Alexey Dobriyan]

On Wed, Mar 11, 2009 at 05:15:08PM +0000, Stuart Bennett wrote:
> Stephane Marchesin wrote:
> > Hi,
> > 
> > As part of aiming at upstreaming our code, I suppose we have to
> > discuss the DRM situation a little. In order to aim for merging, I
> > think we'd better be working on a linux kernel tree layout. And
> > considering we're technically the only ones still working in drm.git,
> > it doesn't really make sense to keep doing that for the sake of
> > sharing code with other drivers.
> > 
> > As we discussed on irc, there would be multiple changes related to this:
> > - we move to a linux kernel-like tree, that should make it easier when
> > upstreaming the code.
> > - this new tree is hosted in freedekstop.org in the nouveau/ git so we
> > don't need additional accounts for everyone all around and people can
> > keep pushing things (even better, all nouveau people can push to the
> > drm, which used to require mesa rights before)
> > - we keep a(some) branch(es) in the tree for backwards compat with
> > older kernels. Either in the form of separate kernel versions
> > including nouveau, or in the form of an out-of-tree-compilable
> > drm/nouveau module.
> > 
> > So, does that plan sound sane? Do you have better plans?
> > 
> > Stephane
> 
> (apologies for the crappy mailman archive->email forgery)
> 
> I have reservations about a full Linux kernel tree, if that's the proposal.
> 
> Assuming it is a relatively important goal that people should test 
> Nouveau, then it makes sense to make it as easy as possible for them to 
> do so.  Certainly as long as Nouveau has not merged to the Linux kernel, 
> our repository is the only (non-packaged) source for those wishing to 
> test.  Post merge, some repository other than Linus' kernel is still 
> going to be the place to point people at for new development and fixes 
> which are not in a kernel.org stable release.
> 
> I'd suggest that a) requiring 0.5 - 1 hour to git clone the half-gig or 
> so of our new kernel-based tree (longer if the fd.o machinery is having 
> a bad day)

If user already has Linus's tree (or some tree based on it), then there is
no need to fetch most of it again.

> and b) needing people to then checkout some random branch in 
> order for it to work with their kernel ( c) would be rebuild their 
> kernel, if the out-of-tree compilable thing doesn't happen ), are all 
> barriers to testers that are not currently there.  Although my usage may 
> be atypical (or git outdated), the repository size issue also bites 
> developers; cold-cache git diff and git status on the linux kernel takes 
> a noticeable time,

You don't do just git-diff, you do git-diff drivers/gpu/drm/ .

> and gitk, even if regularly invoked, eats disk and 
> processor for ages on each execution.
> 
> If the goal of these changes is to have a more Linux kernel-like layout, 
> could we not just change drm/linux-core, or make a new repo, so that it 
> mirrored everything necessary under drivers/drm?  I believe airlied 
> suggested this ages ago, and it would make moving code from Linux to 
> Nouveau or the other way round simpler.  Admittedly this doesn't work if 
> for some reason your development demands changes elsewhere in the Linux 
> tree, but in that case you may well have already failed the back-compat 
> aspect.
> 
> As for branching and back-compat, I'd have thought it more useful to 
> keep compat on the main branch (again, helping testers), and split 
> specific kernel-merge-aimed branches off from that, as automating ifdef 
> removal on a branch ought to be easier than manually adding compat to a 
> bunch of branches, but I guess in some way the solutions here are all 
> equivalent, and it's just which branch you bless as being called master.