KDE Plasma X11 login hang

Host: Debian Bookworm on Raspberry Pi 4B (USB/SSD boot)

Reported at https://bugs.kde.org/show_bug.cgi?id=467812

Testing the KDE Plasma desktop on Debian Bookworm on a Pi 4B running the 64 bit Debian (not Raspberry Pi) OS. Bookworm is a pending Debian release which at present (2023-03-25) is in "hard freeze" and it is important to get all functionality working.

2023-03-25 Previous

During testing to confirm that the bug https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1019700 had been fixed, it was noted that the desktop hung when logging in. In order to test the bug, the system was upgraded to Debian Unstable. When the system was on Debian Testing, the same issue occurred. Since Testing is in hard freeze (and to be released as Bookworm) the hang warranted further investigation and on Bookworm. This Pi 4B is ordinarily run on a different SSD with Bullseye installed and has not had this problem.

2023-03-25 Process

  1. Image the SSD with downloaded from https://raspi.debian.net/tested-images/.
  2. Boot and allow to resize and reboot and login. (Rebooting as necessary to get a session that did not exhibit the emmc timeout issue.)
  3. Housekeeping: hostname (charm), time zone, install sudo and vim and add user hbarta.
  4. apt update, apt upgrade
  5. Install a kernel (from Unstable) linux-image-6.1.0-7-arm64_6.1.20-1_arm64.deb downloaded from https://packages.debian.org/sid/linux-image-6.1.0-7-arm64. No additional dependencies were required.
  6. Reboot.
  7. Install a minimal KDE Plasma desktop (apt install plasma-desktop)
  8. Reboot. No DM. No xinit. No startx. Went ahead and installed sddm.
  9. Start sddm which brings up DM.
  10. Login in. Works as expected. Logout.
  11. Login using Wayland. Works as expected.

After concluding that everything was good, I continued testing and found myself unable to log in again. Additional operations included:

  1. Install Chromium and Konsole.
  2. Overclocking to 2MHz
  3. Back out of the overclock.
  4. Can't login.
  5. Add another user arnold and try to login as the new user. Still hangs.

~~Conclusion~~ 2023-03-25

Seems like a non-problem. Will continue to test. ... Sadly after some usage, login once again hangs. Will repeat the test.

  1. Image the SSD with downloaded from https://raspi.debian.net/tested-images/.
  2. Boot and allow to resize and reboot and login. (Rebooting as necessary to get a session that did not exhibit the emmc timeout issue.)
  3. Housekeeping: hostname (charm), time zone and add user hbarta.
  4. apt update, apt upgrade
  5. Install a kernel (from Unstable) linux-image-6.1.0-7-arm64_6.1.20-1_arm64.deb downloaded from https://packages.debian.org/sid/linux-image-6.1.0-7-arm64. No additional dependencies were required.
  6. apt install plasma-desktop sddm konsole chromium vim -y
  7. Reboot.
  8. Login (defaults to Wayland) and looks OK.
  9. Logout and start monitors dmesg -follow, cd /var/log;tail -f Xorg.0.log
  10. Login (Wayland) and all looks good.
  11. Logout
  12. Login (Wayland) and all looks good.
  13. Start and exit Konsole
  14. Start and exit Chromium
  15. logout and login
  16. Open Chromium. and open google.com. OK. Try to open second page and browser is foobar. Doesn't echo typing, finally able to open a second page (local MkDocs notes) and display is incomplete.
  17. Open system monitor and Konsole and they work OK. Close all and logout.
  18. Login to X.org session. Login hangs.
  19. systemctl restart sddm
  20. Login to X.org session. Login hangs.
  21. systemctl restart sddm
  22. Login to Wayland session. Login OK.

2023-03-26 Filing a bug report

  1. Collect information
  2. Prepare pastebin content

2023-03-26 try XFCE

Test two things:

  1. X11 works with another DE
  2. XFCE installs lightdm, can test that with KDE

Result:

  • XFCE (on X11) starts w/out issue using lightdm or sddm.
  • Plasma/X11 hangs when started using lightdm.
  • Plasma/Wayland starts normally from lightdm.

Bug report at https://bugs.kde.org/show_bug.cgi?id=467812

2023-04-29 further patches to test.

Ref: https://lore.kernel.org/all/20230428223500.23337-5-jim2101024@gmail.com/ and https://lore.kernel.org/all/20230428223500.23337-1-jim2101024@gmail.com/
Suggested by kibi

fetch the patch series from the LKML, and apply it either on the base commit mentioned there, or to current mainline master
(b4 is super useful, b4 mbox $message_id and you got an mbox ready to git am)