Arch Linux

https://bbs.archlinux.org/viewtopic.php?pid=1887597

All Display Managers crashing, not only LightDM.

Confirmed.

There is an Illegal Instruction -error in Xorg.log. (log attached - attachment previously failed because of permission errors on my end :-F).

Same problem with startx/fvwm. Xorg Error message reads "Illegal instruction at address $ADR" with
$ADR being within /bin/lib/dri/radeonsi_dri.so (owned by mesa package). Crash seems to happen before
fvwm gets run.

Downgrade to v19.3.3 solves problem.

Additionally, mpv started from X session started *prior* to mesa upgrade crashes as well.

Occurring here with GDM and Nouveau drivers

same here with amdgpu driver

ok ignore this comment, I made mistake:) it's still due to AVX but not because of the existence of those files

<s>
Seems like, if you have these it should illegal instruction on you:

$ ls -la /usr/lib/libswrAVX*
lrwxrwxrwx 1 root root 15 Feb 14 17:55 /usr/lib/libswrAVX2.so -> libswrAVX2.so.0
lrwxrwxrwx 1 root root 19 Feb 14 17:55 /usr/lib/libswrAVX2.so.0 -> libswrAVX2.so.0.0.0
-rwxr-xr-x 1 root root 147008360 Feb 14 17:55 /usr/lib/libswrAVX2.so.0.0.0
lrwxrwxrwx 1 root root 14 Feb 14 17:55 /usr/lib/libswrAVX.so -> libswrAVX.so.0
lrwxrwxrwx 1 root root 18 Feb 14 17:55 /usr/lib/libswrAVX.so.0 -> libswrAVX.so.0.0.0
-rwxr-xr-x 1 root root 170765368 Feb 14 17:55 /usr/lib/libswrAVX.so.0.0.0

</s>

EDIT: of course only if you don't have avx/avx2 ( $ grep avx /proc/cpuinfo )
EDIT2: with the exception of current mesa git master 20.1.0_devel.120156.946eacbafb4-1 which has those AVX files but doesn't crash
EDIT3: I guess I was wrong, you may have those files and still work for you, because mesa-19.3.3-1-x86_64.pkg.tar.zst also has them and it works. Now I don't remember what was the context when I didn't see those files and it worked, but it must've been some git version I've compiled using the non-git mesa. PKGBUILD...
Oh craap I remembered, it was a git version of 19.3.4 which didn't have the "swr" in -D gallium-drivers=

Maybe we can update this issue upstream: https://gitlab.freedesktop.org/mesa/mesa/issues/2520

fyi, the upstream commit 689817c9dfde9a0852f2b2489cb0fa93ffbcb215 cherry-picked on 19.3.4 fixes this.

https://gitlab.freedesktop.org/mesa/mesa/issues/2520#note_411359

Should be fixed in mesa 19.3.4-2.
Anybody wants to verify?

Mesa 19.3.4-2 fixes the issue for me.

I can confirm mesa 19.3.4-2 fixes the issue for me also. Please note the issue was also affecting GDM on Wayland, not only Xorg.

19.3.4-2 Fixes for me as well(Xorg)

19.3.4-2 Fixes the issue for me as well, (with lxdm)