[Mesa-dev] [Bug 108165] Assembler is incompatible with musl

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=108165

            Bug ID: 108165
           Summary: Assembler is incompatible with musl
           Product: Mesa
           Version: 18.1
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Other
          Assignee: mesa-dev at lists.freedesktop.org
          Reporter: ross at burtonini.com
        QA Contact: mesa-dev at lists.freedesktop.org
                CC: raj.khem at gmail.com

Quoting from a patch to disable assembler in the OpenEmbedded recipe:

Musl started blocking dlopen of libs with initial-exec references into
dynamic TLS area, via

https://github.com/kraj/musl/commit/5c2f46a214fceeee3c3e41700c51415e0a4f1acd

prior to that commit, musl was loading it and silently letting
subsequent TLS accesses via the miscompiled code clobber memory that
didn't belong to them

This was wrong behavior and it relied on additional space reserved by
libc in TLS space to adjust fo such broken libs, but it also fails
with glibc if the reserved space was already used up

Right fix is that  mesa should be patched to remove all the
initial-exec hacks and use real TLS, and -mtls-dialect=gnu2 (TLSDESC)
should be used on archs it's supported on (i386, x86_64, and aarch64)
to make up for the lost performance, but mesa hardcodes the initial-exec,
so there must be a reason that probably is better known to mesa devs.

Cause is some unknown part of mesa's x86 assembly code is broken by
readonly text segments

(CCing Khem who created the patch)

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20181003/6041831c/attachment.html>