Update error: Failed to start Light Display Manager

[AlanSmithee]

I am running Manjaro with the 5.8 kernel. After running the most recent update and rebootIng I just get a single line that says “Failed to start Light Display Manager.”

I tried following the steps described in the post titled “ [Failed to start light display manager after update] “ but it did not solve my issue.

I am not even sure how to diagnose what the source of the problem is. I have also booted into other kernels (5.7 and 4.14) but I get the same error.

I have an nvidia quadro p2000 on a lenovo p52 laptop.

[pobrn]

Please try to recover the Xorg logs from ~/.local/share/xorg/ and upload it to somewhere. Press Ctrl+Alt+F4 to access a TTY, log in, and then you can access the files. Then you can run

curl --upload-file FILENAME_HERE https://aptget.xyz

and share with us the links you get back.

[AlanSmithee]

Thanks for the quick response!

The forum won’t let me put a direct link in my post. But here is the url minus the https part:
aptget.xyz/EceMB/Xorg.0.log

[pobrn]

[ 654.482] (EE) No devices detected.
[ 654.482] (EE)
Fatal server error:
[ 654.482] (EE) no screens found(EE)

Hmmm…

Please run inxi -Fazy > inxi.out and upload inxi.out; also run sudo mhwd -li > mhwd.out and upload mhwd.out. Please also upload any file you find in /etc/X11/xorg.conf.d/.

[AlanSmithee]

Okay here are the files (typing this out on a phone is an interesting challenge):

aptget.xyz/s0DOu/inxi.out

aptget.xyz/5weUO/mhwd.out

aptget.xyz/aAGXg/00-keyboard.conf

aptget.xyz/6nC1l/50-synaptics.conf

aptget.xyz/lrc34/90-mhwd.conf

aptget.xyz/Fyy4k/optimus.conf

[AlanSmithee]

Okay, I used TimeShift to load an image from before the update and tried again.

I followed the steps as listed here: [Stable Update] 2020-09-08 - Kernels, Mesa, Browsers, KDE Apps 20.08.1, Systemd, LibreOffice 7.0.1, Deepin

Specifically, I did the following:

pamac remove nvidia-440xx-utils linux414-nvidia-440xx  linux58-nvidia-440xx cuda
mhwd --install pci nvidia-450xx

Although the command says “successfully installed video-nvidia-450xx” it is preceded by the following warnings and errors:

> WARNING: Possibly missing firmware for module: xhci_pci
> rmmod: ERROR: could not remove 'nouveau': No such file or directory
> rmmod: ERROR: could not remove module nouveau: No such file or directory
> rmmod: ERROR: could not remove 'ttm': No such file or directory
> rmmod: ERROR: could not remove module ttm: No such file or directory 
> rmmod: ERROR: could not remove 'drm_kms_helper': Resource temporarily unavailable
> rmmod: ERROR: could not remove module drm_kms_helper: Resource temporarily unavailable
> rmmod: ERROR: could not remove 'drm': Resource temporarily unavailable
> rmmod: ERROR: could not remove module drm: Resource temporarily unavailable
> modprobe: ERROR: could not insert 'nvidia': Exec format error
> xorg configuration file: '/etc/X11/mhwd.d/nvidia.conf'
> modprobe: ERROR: could not insert 'nvidia_drm': Exec format error

I reboot and I get the light display manager error as before. I then removed the 450 driver and re-installed the 440 driver but I get the same error messages and the light display manager error persists.

[pobrn]

Please use mhwd to remove the 440.xx series driver: sudo mhwd -r pci video-nvidia-440xx. As far as I see you want to use the nvidia driver, and not some kind of hybrid configuration, so I think you could try the following configuration:

Section "ServerLayout"
    Identifier "layout"
    Screen 0 "nvidia"
    Inactive "intel"
EndSection

Section "Device"
    Identifier "nvidia"
    Driver "nvidia"
    BusID "PCI:1:0:0"
EndSection

Section "Screen"
    Identifier "nvidia"
    Device "nvidia"
    Option "AllowEmptyInitialConfiguration"
EndSection

Section "Device"
    Identifier "intel"
    Driver "modesetting"
    BusID "PCI:0:2:0"
EndSection

Section "Screen"
    Identifier "intel"
    Device "intel"
EndSection

(source)

Save it as /etc/X11/xorg.conf.d/10-nvidia.conf. Back up and delete 90-mhwd.conf and optimus.conf.

[AlanSmithee]

I changed the configuration before changing the drivers and everything is still working. So that is a good sign.

running

sudo mhwd -r pci video-nvidia-440xx

gives the errors:

Removing video-nvidia-440xx...
Using default
Has lib32 support: true
Sourcing /var/lib/mhwd/local/pci/video-nvidia-440xx/MHWDCONFIG
Processing classid: 0300
Sourcing /var/lib/mhwd/scripts/include/0300
Processing classid: 0302
checking dependencies...
error: failed to prepare transaction (could not satisfy dependencies)
:: removing nvidia-440xx-utils breaks dependency 'nvidia-utils' required by cuda
:: removing linux57-nvidia-440xx breaks dependency 'linux57-nvidia-440xx' required by linux-latest-nvidia-440xx
Error: pacman failed!
Error: script failed!

I did the removal the same as before, but after rebooting it flashed two lines of “failed to load kernel module”, then goes back to the same error as before “Failed to start Light Display Manager.”

I noticed that 90-mhwd.conf had re-appeared in the folder, so I removed it, but after rebooting again it generated the same LDM error message.

[pobrn]

Remove the cuda and linux-latest-nvidia-440xx packages before running sudo mhwd -r pci video-nvidia-440xx.

[AlanSmithee]

Great! It is working now!

In case anyone runs into the same problem here are the exact steps I took:

1. Add 10-nvidia.conf file to the xorg.conf.d directory
2. Remove 90-mhwd.conf and optimus.conf from the same directory
3. sudo pacman -R cuda linux-latest-nvidia-440xx
4. sudo mhwd -r pci video-nvidia-440xx
5. sudo pacman -Syuu
6. sudo mhwd -i pci video-nvidia-450xx
7. Reboot