Heads up: Mesa/LLVM rebase and OpenGTL retirement in F20

[Adam Jackson]

On Fri, 2014-03-28 at 16:45 +0100, Kalev Lember wrote:
> On 03/28/2014 04:37 PM, Adam Jackson wrote:
> > RHEL's Mesa at this point links against a private build of llvm that
> > is explicitly _not_ part of The Platform, for exactly this reason:
> > it's not something we can commit to supporting for any use beyond
> > Mesa itself, even in the extreme short term.
> 
> This might be a good way forward for Fedora as well to avoid changing
> the system-wide llvm ABI mid release.

Eh.  We've done an llvm rebase before:

dmt:~% koji -q latest-pkg f18 llvm        
llvm-3.1-11.fc18                          f18                   salimma
dmt:~% koji -q latest-pkg f18-updates llvm
llvm-3.3-0.4.rc2.fc18                     f18-updates           ajax

People were pretty eager for it then, too, and we even did it _because_
we wanted a Mesa rebase to go with it.  llvm upstream doesn't do stable
branches, so there's really not a good solution here.  And tbf llvm
really is a research project more than a compiler in a lot of ways,
anyone building against it is going to discover they're building on sand
eventually, regardless of when Fedora updates it.

That said I'm not intrinsically opposed to doing, say, compat-llvm (in
fact I suggested it in F18).  Though if I had to choose between that and
mesa-private-llvm in Fedora... I dunno, they're both kind of terrible.
compat-llvm would let us stick to the rule about not shipping the same
source in two packages, but m-p-l might have marginally better
performance.  Neither one seems as sane to me as just accepting llvm as
not actually ABI.

- ajax