Slackware64 14.2, OpenGL issue: i965_dri.so segmentation fault

dflavio · 03-04-2017, 02:31 AM

Dear all,

I am running Slackware64 14.2 (multilib) on a Thinkpad T460p with hybrid-graphics but using only the integrated intel GPU.

The outputs of lspci and uname -a are:

Code:

00:02.0 VGA compatible controller: Intel Corporation Device 191b (rev 06)

Linux darkstar 4.4.38 #2 SMP Sun Dec 11 16:18:36 CST 2016 x86_64 Intel(R)
Core(TM) i7-6700HQ CPU @ 2.60GHz GenuineIntel GNU/Linux

I have installed octave (4.2.0) from SlackBuilds (using Intel MKL) and encountered some OpenGL issue. After interaction with a plotting window
octave crashes. A backtrace gives:

Code:

Thread 1 "octave-gui" received signal SIGSEGV, Segmentation fault.
0x00007f4ee2a644fb in ?? () from /usr/lib64/xorg/modules/dri/i965_dri.so

First, I thouht it might be an octave issue, but the same version under openSUSE live did not crash. Further, also glthreads -p crashes with a similar backtrace:

Code:

Thread 3 "glthreads" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffef47c700 (LWP 6001)]
0x00007ffff2ecf8d7 in ?? () from /usr/lib64/xorg/modules/dri/i965_dri.so

I suspect it's a mesa (intel driver, kernel...?) issue. Under slackware64-live-current, plthreads -p just works fine. But since I never used current before, I hesitate to switch due to the (I assume) additional maintenance effort. Thus, any help to get the issue resolved under 14.2 would be greatly appreciated.

Thanks in advance,
Flavio

bassmadrigal · 03-04-2017, 03:31 PM

The intel mesa driver has been extremely hit or miss depending on your hardware. During the development of 14.2 many versions were tried and it seemed like there was always someone with an issue when it fixed other peoples' issues. It might be worth grabbing the source for the intel driver from -current and build it on your system and upgrade the package to see if it fixes the problem. If it does, you can simply blacklist that package to ensure you don't accidentally "upgrade" it using slackpkg to the stock version.

dflavio · 03-06-2017, 04:02 AM

Thanks for the input.

I have upgraded mesa to the version from -current (which also required upgrade of libedit, llvm and libclc). The good thing is that the octave issue seems to be resolved, but glthreads -p still crashes as before. Which other packages may I need to upgrade too?

bassmadrigal · 03-06-2017, 07:14 AM

I actually intended for you to upgrade the xf86-video-intel driver, not mesa itself (since that can include a lot of extra dependencies that need to be upgraded as well... as you saw). Forum member atelszewski created a few scripts to help minimize the effort in upgrading that driver.

orbea · 03-06-2017, 12:18 PM

Here are a few things you can try:

1. Try the modesetting ddx instead of xf86-video-intel and / or DRI3 instead of DRI2.
2. Try compiling libdrm and mesa from the git master.
3. Try compiling them with debugging symbols and get a backtrace with gdb. Report this to mesa devs @ #dri-devel and / or #intel-gfx @ freenode. The more willing you are to debug your issue the more likely someone will help there.
4. Also install apitrace from SBo and follow the documentation at their github wiki to make a GL trace of the issue and include this with the backtrace for when reporting upstream.

Alternately just accept that concurrent GL threads is not a very smart idea currently and try to not use anything that blows up your GL. Fwiw glthreads -p brought nouveau to its knees on my system when I tried it, enough that I opted to ssh in from another device and reboot.

dflavio · 03-08-2017, 09:58 AM

OK, as already mentioned upgrading mesa to version 13.0.4 seems to prevent octave from crashing, which was my main concern.

However, upgrading the xf86-video-intel driver to the latest version (xf86-video-intel-git_20170228_78d7a09-x86_64-1) did not prevent plthreads -p from crashing. Hence, I also upgraded libdrm to -current which did not help either. Only also enabling option DRI 3 kept glthreads from crashing.

Although I don't understand why updating xf86-video-intel, mesa, libdrm to -current is not enough to prevent plthread from crashing, given that it runs under slackware64-current-live without problems, I consider the issue as resolved.

Thanks again for your help!

Best,
Flavio

orbea · 03-08-2017, 12:41 PM

My understanding is that intel devs prefer the modesetting ddx now included with xorg-server and DRI3, so less developers are working on xf86-video-intel and DRI2 despite that most distros still default to them, I've seen this lead to some hard to diagnose bugs when using certain combinations of xf86-video-* and DRI2/3.