Arch Linux

hmmSalat

Member

Registered: 2020-02-29

Posts: 5

[SOLVED] GDM shows black screen with non blinking kb and mouse cursor

Hey,

I am using Gnome 3.38.4-1 on X11 with GDM 3.38.2.1-1 and nvidia 460.75-5.

Problem:
On boot, gdm fails to start. It only shows a black screen with a keyboard cursor (not blinking) and a mouse cursor.
I can login using tty and start gnome using "startx" without any problems. When the gnome-session is locked (Win+L) it jumps to the graphical GDM lock screen. At this point, it is impossible to login to the existing gnome-session again because i get a "login failed" loop. The GDM lockscreen behaves like somebody keeps pressing the "enter"-key and i am not able to type in my password.

journalctl -u gdm.service -b shows:

[***@arch-desktop ~]$ journalctl -u gdm.service -b
-- Journal begins at Sun 2020-12-13 20:41:57 CET, ends at Fri 2021-04-02 17:09:44 CEST. --
Apr 02 17:08:16 arch-desktop systemd[1]: Starting GNOME Display Manager...
Apr 02 17:08:16 arch-desktop systemd[1]: Started GNOME Display Manager.

I tried:
https://wiki.archlinux.org/index.php/GD … ite_cursor
https://wiki.archlinux.org/index.php/GD … rg_backend
https://wiki.archlinux.org/index.php/GD … is_present

Can anybody help?

Last edited by hmmSalat (2021-04-02 17:15:17)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,885

Re: [SOLVED] GDM shows black screen with non blinking kb and mouse cursor

This can happen on SSDs when the graphical session tries to start before the graphics driver is fully initialized, see: https://wiki.archlinux.org/index.php/NV … de_setting for how to setup your mkinitcpio/initramfs to ensure the graphics modules are ready early.

hmmSalat

Member

Registered: 2020-02-29

Posts: 5

Re: [SOLVED] GDM shows black screen with non blinking kb and mouse cursor

It worked! Thank you.

linerman

Member

Registered: 2021-02-16

Posts: 80

Re: [SOLVED] GDM shows black screen with non blinking kb and mouse cursor

Hi,

I had similar problem lately. Strangely, it happened suddenly. Through the whole time lightdm started smoothly, but suddenly it did not and I had to add the modules to the mkinitcpio.
I did not changed anything in my desktop configuration, nor did not change any hardware.
That solved the issue, but I wonder how does that work?
I mean, why suddenly lightdm stopped loading? May somebody explains that?

Last edited by linerman (2021-04-03 06:31:47)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,885

Re: [SOLVED] GDM shows black screen with non blinking kb and mouse cursor

It's a race condition, because things are started in parallel with as many cores as are available. So depending on what started how and when you can have 100 boots with it working and one with it failing and vice versa.  The standard way systemd delays the graphics output/starting of graphical target is by checking whether drm is loaded but apparently the kernel says that is the case before the actual graphics driver has finished loading. So xorg/graphics try to start but attempting to use the graphics device throws an error.  Adding them to the initramfs isn't really the "technically" proper solution as you are just giving the graphics device a head-start so that it should always get ready in time, but you'd have the same issue if that wasn't the case for any reason.

This isn't limited to nvidia and can happen with all graphics cards and drivers.

linerman

Member

Registered: 2021-02-16

Posts: 80

Re: [SOLVED] GDM shows black screen with non blinking kb and mouse cursor

Hi,

Thank you very much for the explanation.
You have mentioned that adding modules to initramfs is not technically proper solution. So is there any other solution of that issue?