Bug 109259

Summary:	Mesa compiled with LLVM/clang-7.0 segfaults
Product:	Mesa	Reporter:	Tomasz Paweł Gajc <tpgxyz>
Component:	Mesa core	Assignee:	mesa-dev
Status:	RESOLVED MOVED	QA Contact:	mesa-dev
Severity:	normal
Priority:	medium
Version:	18.3
Hardware:	Other
OS:	All
Whiteboard:
i915 platform:		i915 features:

Description Tomasz Paweł Gajc 2019-01-09 12:47:31 UTC

Hi,

we have noticed that mesa-18.3.x segfault when it is compiled with LLVM/clang-7.0.x and run on older hardware.

After some deep digging we noticed this may be related to missing AVX instructions on these machines, even if we build for generic x86_64, i686 targets.

Fast workaround for eliminating segfaults was to build Mesa with gcc :(
https://github.com/OpenMandrivaAssociation/mesa/commit/4d330587a4d80012c5888e1a33a01a7a979b84e8

Rebuilding Mesa with LLVM/clang-7.0.1 still segfaults. 

Our users have reported this occurs on:
r600 driver
nvidia gfx card
AMD Athlon II X4 620
AMD Phenom II x4 N930
Intel Quad 9650
Intel i3 530

Links to bug reports:
https://issues.openmandriva.org/show_bug.cgi?id=2381
https://issues.openmandriva.org/show_bug.cgi?id=2393

Comment 1 Tomasz Paweł Gajc 2019-01-09 12:48:21 UTC

Build logs for mesa compiled with LLVM/clang-7.0.1 can be found here
https://abf.openmandriva.org/build_lists/351189

Comment 2 Tomasz Paweł Gajc 2019-01-09 12:54:29 UTC

When building mesa with clang these flags are used
-pthread -mavx2 -mfma -mbmi2 -mf16c -DKNOB_ARCH=KNOB_ARCH_AVX2 
 with gcc
[-pthread -mavx -DKNOB_ARCH=KNOB_ARCH_AVX

Comment 3 Dylan Baker 2019-01-09 18:12:15 UTC

I'm confused, you're targeting generic x86_64, but compiling with -mavx and -mavx2?

Additionally, there's a bug with SWR (I can't find it right now), due to global constructors that mean that if you build SWR you have to have the special instructions it relies on.

Comment 4 GitLab Migration User 2019-09-18 20:27:31 UTC

-- GitLab Migration Automatic Message --

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