Bug#776911: gnome-shell: fails to start on i386 when [Mesa was] built with llvm-3.5

[intrigeri]

Hi,

Simon McVittie wrote (26 Feb 2015 08:54:10 GMT) :
> Context for Mesa maintainers: #775235 is that gnome-shell crashes in
> an i386 VM with its default choice of emulated CPU, with
> "LLVM ERROR: Do not know how to split the result of this operator!".
> See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=775235#10 for full
> backtrace.

Tails is affected by that bug
(https://labs.riseup.net/code/issues/8778); in case it may help
asserting the severity, comment #16 there (and some further ones,
particularly #19 and #22) have additional data about what exact vcpu
model and features are affected.

I've rebuilt the mesa package with the patch from
https://freedesktop.org/patch/34445/, and it fixes things for me, at
least with `-cpu qemu32'. I've asked the other Tails developer (Cc'd),
who is also experiencing this bug, to try and reproduce my results.

=> I believe at least one of these bugs should be reassigned to the
mesa package. I'll let the maintainers decide about that and about the
potential RC-ness.

If it helps, I can also do a more complete series of comparative tests
with various vcpus.

> Would use of llvm-3.4 for jessie be acceptable to the Mesa maintainers?
> According to https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=775235#15
> that fixes at least one of these merged bugs, perhaps all three.

I suspect that the release team will find that rebuilding mesa with
a different compiler is more invasive and risky, at this stage of the
release cycle, than applying a relatively simple patch. (The good news
is that we might get a release team member's opinion for free while
asking to the mesa maintainers :)

> Alternatively, would it be useful information for the Mesa maintainers
> if people tried Mesa 10.4.2 on affected systems?

I can do that if it helps, although I suspect it's too way late to let
that one migrate to testing.

Cheers,
--
intrigeri