Arch Linux

AlexisBRENON

Member

Registered: 2018-09-06

Posts: 4

[SOLVED] LightDM do not display login prompt when session locked

Hi everyone,

I recently installed Arch on a desktop computer with an Intel video chipset (Xeon E3-1200) and a Nvidia graphics card (NVIDIA Corporation GF119 [GeForce GT 705]). I have two monitors connected to this graphics card.

After installation, I choose to use Gnome as a desktop environment (for its Wayland support) which comes with GDM, gnome-screensaver, and co. which worked as expected. But Gnome does not meet my preference and I switched to a good old XFCE session.
I disabled GDM service, replacing it with LightDM and installed light-locker.

Now, I can lock my session with:

dm-tool lock

or

light-locker-command -l

In both cases, the session is locked, but I never see the login prompt to unlock my session.
How can I solve this?

More detailed description:

After searching through the Internet I understood that when invoked, light-locker-command call dm-tool which send D-Bus message for session locking, handled by LightDM.
LightDM, lock the session (displaying an informative message) and launch another X server on VT8 to display its greeter, with login prompt allowing the user to unlock her session.

So, I tested different things:

• • Locking my session (dm-tool lock)

  • Going to VT7 (ctrl+alt+F7) to check that my session is locked

  • Going to VT8 (ctrl+alt+F8) which is blank (making my screens to go to sleep mode)

  • Going to tty6 (ctrl+alt+F6), log in as my normal user an unlock session with loginctl

  • Going back to VT7, my session is unlocked.

  • Looking for running processes (htop)

  • As root, killing the Xorg process launched on VT8 (display :1)

  • Locking (again) my session (dm-tool lock)

  • Now, the login prompt is displayed on VT8 and everything work!

• • Locking my session (dm-tool lock)

  • Going to VT7 (ctrl+alt+F7) to check that my session is locked

  • Going to VT8 (ctrl+alt+F8) which is blank and typing in my password (without any visual hint)

  • My session is unlocked and it seems OK.

IRC advised me to provide:

• Xorg configuration:
  Nothing custom:

  $ ls /usr/share/X11/xorg.conf.d/                   
  total 8,0K
  -rw-r--r-- 1 root root 1,4K  9 août  20:37 10-quirks.conf
  -rw-r--r-- 1 root root  945 11 juil. 19:06 40-libinput.conf
  
  $ ls /etc/X11/xorg.conf.d
  total 4,0K
  -rw-r--r-- 1 root root 346 17 août  08:25 00-keyboard.conf

  No xorg.conf file.

• Video setup:
  No Nvidia driver, nor nv or nouveau.

Then, some log files:

• For 1st test : blank screen Xorg.1.log after killing, working Xorg.1.log (terminating on session unlock)

• For 2nd test (blind password): lightdm, Xorg.1.log

Thanks,
Alexis.

Last edited by AlexisBRENON (2018-09-10 08:18:11)

AlexisBRENON

Member

Registered: 2018-09-06

Posts: 4

Re: [SOLVED] LightDM do not display login prompt when session locked

After further investigations, my graphics card uses the 'nouveau' driver. I installed 'xf86-video-nouveau'. I also installed 'libva-utils', 'mesa-vdpau', 'libva-intel-driver' but I do not think that it is related.
And now, everything works as expected.

Enjoy !