Heads up: F21 LLVM rebase

Adam Jackson ajax at redhat.com
Fri Dec 12 15:30:30 UTC 2014


On Fri, 2014-12-12 at 13:01 +0100, Marcin Juszkiewicz wrote:
> W dniu 11.12.2014 o 18:16, Adam Jackson pisze:
> > I've started staging an LLVM 3.5 rebase in F21.  I hope to have 
> > everything built by this Friday and the update available in testing 
> > by Monday.  Test feedback would be particularly appreciated on 
> > secondary arches and radeonsi 3D hardware.
> 
> Can someone explain to me (like to total idiot would be best) why after
> release of stable version developers start to update components? IMHO
> time for it was during F21 development and now work should concentrate
> on F22 with just stable fixes for released versions.

We need to update Mesa in stable releases for hardware enablement,
otherwise people buy new hardware and can't use 3D and then Fedora
sucks.  Mesa and LLVM are sufficiently closely entwined these days that
eventually I can't build fully-featured Mesa without updating LLVM.
This isn't the first time the llvm soname has changed within a release,
in fact it's happened at least once per release since F18 afaict.

Yes, it's disruptive, it's a gigantic pain in the ass, I don't enjoy
doing it at all.  llvm upstream seem to have no concept of consumable
interface design, so at this point around half of the llvm-using
components in Fedora have to be built from the same srpm as llvm itself;
most of them are only build-tested with clang, so I also get the joy of
trying to port them to gcc.  All this without having much working
knowledge of C++, on account of how I want to be able to look myself in
the mirror in the morning without crying.  I'm not a toolchain hacker.
I want not to work on this crap.

But either someone does it, or Mesa goes stale, so it's gotta get done.

On the flip side, by synchronizing llvm (and Mesa and friends) across
releases, graphics devel has more time to spend on _everyone_'s issues,
because we don't have to waste time tracking which bug was fixed in
which branch.

In this particular case I had _wanted_ to get 3.5 into F21 gold in the
first place [1], since it's sort of mandatory to make ppc64le actually
work.  The timing didn't quite work out, so it happens in updates
instead.  Sorry about that, life doesn't always admit pretty solutions.

[1] - https://lists.fedoraproject.org/pipermail/devel/2014-October/203463.html

- ajax



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