Cannot start SDDM after system upgrade

Maples31 · 2025-08-28 15:05:01

I cannot start SDDM after system upgrade, stuck at black screen with cursor in the top-left cornor and movable mouse cursor.

After a recent issue I can no longer boot my system properly. Here is the situation:

- Last night I ran `pacman -Syu` to upgrade my system.
- After reboot, SDDM appeared, but after entering my password it froze (occasionally I could log in successfully). I was still able to switch to a TTY.
- From TTY I reinstalled nvidia-open and nvidia-settings with `pacman -S nvidia-open nvidia-settings`
- After that change, I can no longer reach SDDM at all. Now the system boots to a black screen showing a non-blinking underscore in the top-left corner and a movable mouse cursor. SysRq works to reboot, but I cannot switch to a TTY anymore.

Here is my boot log: https://0x0.st/Ko5P.txt

Any advice on how to troubleshoot or fix this would be greatly appreciated.

Thanks!

seth · 2025-08-28 15:46:17

Aug 28 22:01:20 arch systemd-journald[575]: Time spent on flushing to /var/log/journal/c5449f777d8d431e8f20b82958e54fb5 is 2.889ms for 917 entries.

Journal ends w/ the initramfs, don't reboot w/ the power button

I was still able to switch to a TTY.

You should be able to post the journal from there?

There doesn't seem to be any GPU driver in the initramfs (neither i915 nor nvidia) so there's a high likelihood of a race condition (SDDM starts tooearly™)

SysRq works to reboot, but I cannot switch to a TTY anymore.

In that case and if hammering ctrl+alt+del doesn't reboot please go for the entire sysrq+REISUB dance (notably S and U will sync the filesystem and preserve the journal)

Maples31 · 2025-08-28 15:52:19

Thanks!

When I added `nvidia, nvidia_modeset, nvidia_drm, and nvidia_uvm` modules to the blacklist in /etc/modprobe.d/blacklist-nvidia.conf, and also removed the nvidia_drm.modeset=1 kernel parameter from grub.conf, I was able to successfully start SDDM and boot into the system.

Does this mean the issue is caused by the NVIDIA driver? How should I properly fix it?

seth · 2025-08-28 16:08:59

https://bbs.archlinux.org/viewtopic.php … 8#p2256488

Maples31 · 2025-08-28 16:35:41

After modifying sddm.service and adding ExecStartPre=/usr/bin/sleep 1, I still occasionally get a black screen (with mouse cursor and underscore), and occasionally I can enter SDDM. However, after entering my password in SDDM, the system freezes. At that point I can still switch to a TTY.

Here is the log from when the system froze after entering the password in SDDM: https://0x0.st/KoRG.txt

seth · 2025-08-28 19:46:24

Aug 29 00:26:12 arch sddm-helper[1550]: Starting X11 session: "" "/usr/share/sddm/scripts/Xsession \"/usr/bin/startplasma-x11\""

But then there're no signs of plasma ever starting.
Can you log into an icewm session or w/ a fresh user account?
Do you have a $HOME dir (the fat DEs do not like if there's no writable $HOME)

Fwwi, nvidia-open isn't suggested for Ada chips for now (but the binary nvidia module), "nvidia_drm.modeset=1" btw. meanwhile doesn't do anything anymore (simpledrm device still loads, fbdev=1 is default and required)

Arch Linux

#1 2025-08-28 15:05:01

Cannot start SDDM after system upgrade

#2 2025-08-28 15:46:17

Re: Cannot start SDDM after system upgrade

#3 2025-08-28 15:52:19

Re: Cannot start SDDM after system upgrade

#4 2025-08-28 16:08:59

Re: Cannot start SDDM after system upgrade

#5 2025-08-28 16:35:41

Re: Cannot start SDDM after system upgrade

#6 2025-08-28 19:46:24

Re: Cannot start SDDM after system upgrade

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