Problems with LightDM on linux-lts

bope · 2026-10-12 20:40:24

Hi. I'm very desperate. I have tried everything I could before asking here....
So, I have a Dell XPS laptop from 2019. It's integrated card is Intel i915 and it has a dedicated Nvidia card (1650). I also have an external monitor connected via hdmi port.
Currently I use XFCE4, an old 6.0.12 kernel and recently I've decided to install linux-lts kernel as well. Version 6.18.55.
Alas, when I installed that LTS kernel, re-generated the image and tried booting my system with that new Kernel it simply gets stuck before showing my LightDM.

Symptoms when booting LTS kernel (without "quiet" option):
1) Normal boot messages are being printed (I use systemd ofc)
2) My external monitor activates mirroring content of my laptop monitor
3) After what feels like almost end of the boot process I get a message "Started LightDm"
4) Laptop freezes up and CPU fans soon speeds up as if CPU is very active
5) I can't switch to tty2 and have to manually reboot my system.

I tried disabling LighDM and installing/using Slim and SDDM - same result.

Facts:
1) I don't have /etc/X11/xorg.conf file
2) I don't have any Nvidia drivers installed as I don't use my Nvidia card actively, I don't need them.
3) My Nouveau driver is blacklisted
4) I don't have any custom Intel config inside /etc/X11/xorg.d/
5) On 6.0.12 kernel everything runs perfectly
6) I have latest linux-firmware and linux-firmware-whence installed (but even with previous versions from 2024 the problem was the same).
7) My mkinitcpio has only module "i915" included and as for the HOOKS I have: base systemd autodetect microcode modconf kms keyboard keymap consolefont sd-vconsole block filesystems fsck
8) My LightDM config is (but this apparently is not related to LightDm itself):

[Seat:*]
A  greeter-wrapper=/etc/lightdm/Xgreeter
B  type=local
B  pam-service=lightdm
B  pam-autologin-service=lightdm-autologin
B  pam-greeter-service=lightdm-greeter
B  greeter-session=lightdm-slick-greeter
B  user-session=xfce
B  session-wrapper=/etc/lightdm/Xsession
B  autologin-user=boza

   [LightDM]
B  run-directory=/run/lightdm

Sources:
A  /etc/xdg/lightdm/lightdm.conf.d/90-greeter-wrapper.conf
B  /etc/lightdm/lightdm.conf

Interesting thing: when I disable LightDM and boot using LTS kernel I get a bash login prompt and after logging in when I type "startx" my desktop starts up normally! Also, when from that desktop I click on "Logout" or "Switch user" button, both screens go blank and laptop is frozen again. Also, same thing happens if I start LightDm from the console, before trying "startx".
I checked both X logs and LightDM logs and couldn't find any error report.

I'm simply out of ideas....

seth · Yesterday 06:44:06

LightDM is configured to autologin you into xfce, what happens if you disable that?
Does startx start xfce as well or just TWM/xterm/xclock?

I checked both X logs and LightDM logs and couldn't find any error report.

Make sure you were not looking at the Xorg log from the running server (in doubt archive it before running startx) and post both along the system journal for the failing boot, eg.

sudo journalctl -b -1 | nc termbin.com 9999

for the previous one

2) I don't have any Nvidia drivers installed as I don't use my Nvidia card actively, I don't need them.
3) My Nouveau driver is blacklisted

This is not a very good idea as it will result in nothing controlling the chip - disable it in the UEFI settings if you don't want to use it at all.

bope · Yesterday 22:24:22

Ok, so I tried disabling this LightDm option
autologin-user
but no luck.

When I disable LightDm altogether and login to bash, then startx my fully functional desktop appears. Ok, browser (Brave) password storage is locked but desktop works....

Regarding journal logs hmmmm not sure how to preserve them. That's the issue. Because when i try booting the 6.18 kernel with LightDM enabled, whole laptop together with screen just freezes.... When i reboot to 6.0.12 to disable and then again to 6.18 logs are gone :\

seth · Today 06:27:57

If you only boot the multi-user.target and instead of running startx start lightdm from there, does it work?

The journal logs multiple boots and you can also upload logs from the console by netcat'ing them into termbin like illustrated in #2
(Make sure this is immediately after a failed boot)

Arch Linux

#1 2026-10-12 20:40:24

Problems with LightDM on linux-lts

#2 Yesterday 06:44:06

Re: Problems with LightDM on linux-lts

#3 Yesterday 22:24:22

Re: Problems with LightDM on linux-lts

#4 Today 06:27:57

Re: Problems with LightDM on linux-lts

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