Arch Linux Bug Fixes

After upgrading Arch Linux (well… actually it’s a complete reinstall), I found some new bugs appearing. Here is some of my memos.

Core Dump

(Haswell, Broadwell Microcode Updates)

If you have a core dump but could not find the cause, you might need to update your microcode of Intel’s CISC CPU.

Here are situations one might faces.

  1. When I use KDE Plasma 5, the screen lock can not unlock my screen. After trying to unlock my screen for about 5 times. It crushes and required me to execute “loginctl unlock-sessions” on another tty to unlock my screen.
  2. When I logout or close some applications, KDE shows an error message box with bug report button.
  3. When I use NVIDIA cuDNN with caffe, it has a core dump while executing caffe.
  4. When I use OpenCL library in python, i.e. “import cv;”. Whenever the python script ends, there is a core dump.

When above errors happened, there is a segmentation fault in libpthread.so!!!

dmesg:

[ 1037.049770] traps: exo-open[4639] general protection ip:7fcf8cde1150 sp:7ffdb47b3f68 error:0 in libpthread-2.21.so[7fcf8cdcf000+18000]
[ 1037.338044] traps: chromium[4643] general protection ip:7f6e9248f150 sp:7ffc2b329c48 error:0 in libpthread-2.21.so[7f6e9247d000+18000]
[ 1038.637627] traps: exo-helper-1[4641] general protection ip:7fc9bc586150 sp:7ffc590b11b8 error:0 in libpthread-2.21.so[7fc9bc574000+18000]
[ 1563.263410] traps: exo-open[5860] general protection ip:7fbcafcb1150 sp:7fffaf2b1b88 error:0 in libpthread-2.21.so[7fbcafc9f000+18000]
[ 1563.541248] traps: chromium[5865] general protection ip:7f6571529150 sp:7fff0e0d9898 error:0 in libpthread-2.21.so[7f6571517000+18000]
[ 1565.023467] traps: exo-helper-1[5863] general protection ip:7f7008a5b150 sp:7ffe8751b268 error:0 in libpthread-2.21.so[7f7008a49000+18000]
[ 1565.806110] traps: exo-open[5912] general protection ip:7f378156e150 sp:7ffff5e809a8 error:0 in libpthread-2.21.so[7f378155c000+18000]
[ 1566.082173] traps: chromium[5917] general protection ip:7f5178539150 sp:7ffc84f4f198 error:0 in libpthread-2.21.so[7f5178527000+18000]
[ 1572.868808] traps: exo-helper-1[5915] general protection ip:7f42957c9150 sp:7ffddf89f388 error:0 in libpthread-2.21.so[7f42957b7000+18000]
[ 1669.886865] traps: chromium[5969] general protection ip:7f5a4a39e150 sp:7ffc84639608 error:0 in libpthread-2.21.so[7f5a4a38c000+18000]
[ 2465.870363] traps: chromium[7316] general protection ip:7f5a4a39e150 sp:7ffc84639608 error:0 in libpthread-2.21.so[7f5a4a38c000+18000]
[ 2858.156512] traps: chromium[8279] general protection ip:7f5a4a39e150 sp:7ffc84639608 error:0 in libpthread-2.21.so[7f5a4a38c000+18000]
[ 3546.898166] traps: chromium[9480] general protection ip:7f5a4a39e150 sp:7ffc84639608 error:0 in libpthread-2.21.so[7f5a4a38c000+18000]

All the errors are because Microcode on Intel CPUs is no longer loaded automatically, as it needs to be loaded very early in the boot process. This requires adjustments in the bootloader. If you have an Intel CPU, please follow the instructions in the wiki.

Actually this is mentioned in Arch Wiki-Beginner’s Guide, it’s a well written wiki with different boot loader instructions. I suggest to follow up this wiki to enjoy the most advanced system and packages in the world!

Screen Tearing

The second error is screen tearing on NVIDIA’s GPU.  There are many solutions on this problem. The most easy way is to force a full composition pipeline, regardless of the compositor you are using. Please refer to Arch Wiki-NVIDIA for further instructions.

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