Re: [git pull] drm request 3

From: Ed Tomlinson
Date: Thu Mar 04 2010 - 19:24:23 EST

On Thursday 04 March 2010 18:53:32 Linus Torvalds wrote:
> On Fri, 5 Mar 2010, Dave Airlie wrote:
> >
> > I'm not saying it doesn't happen in other drivers from time to time, but
> > when it does its treated as regression, for nouveau and STAGING that
> > isn't what the Nouveau project (which Stephane mostly speaks for) seems
> > to want at this stage.
> The problem with "at this stage" is that the stage has apparently been
> on-going for several years.
> Even if Stepane doesn't care, people inside RedHat/Fedora must care. Are
> you guys simply planning on never supporting F12 with 2.6.34? I'd expect
> it to be a _major_ pain to have that whole hardcoded "X and kernel must
> always change in lockstep".
> And the sad part is, it would be so nice if the X server would just dlopen
> the right thing automatically, so that the low-level driver wouldn't even
> need to care. It already does the whole "discover which driver to load"
> part, wouldn't it be nice if that code had automatic versioning too, and
> then a low-level driver really wouldn't have to care, everything would
> automatically do the right thing just when the version changes.
> Of course, the distro would still have to make all the different versions
> of libdrm available to users, but now updating one wouldn't screw over the
> others. So if you had a known-good setup with nouveau-0.0.15, you could
> install a nouveau-0.0.16 thing and _know_ that it won't affect that
> previous install at all.
> And yeah, I realize that those version numbers are "wrong". Normal library
> versioning rules about patchlevel not changing semantics are obviously
> broken here. But maybe the rules could even try to first start with the
> exact version, ie do a "" load, then a ""
> load, then a "" load and finally a "" load.
> But I guess that nothing even does that drmGetVersion() until the nouveau
> driver has already been loaded. Which kind of forces the low-level drivers
> to do any such versioning on their own.
> But wouldn't it be nice if something like this was done at a higher level,
> so that the drivers really wouldn't even need to care?

Why not support a _minimal_ ABI that will always let X start with nouveau?
Having X working does not mean that all forms of acceleration have to
work too. If X starts, even if is slow, users can easily check logs which
should have a message saying 'ABI change - upgrade your ...'.

Ed Tomlinson
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