Arch Linux

RanXom

Member

Registered: 2026-01-01

Posts: 7

SDDM shows black screen & _ cursor on cold boot (NVIDIA hybrid laptop)

Hello,

I encountered an issue where SDDM would fail to display the greeter on cold boot, leaving only an unblinking _ cursor in the top-left corner. The system itself was fully operational, but no graphical login appeared.

System details:
• Arch Linux (fully updated)
• KDE Plasma
• SDDM
• UEFI
• Hybrid GPU laptop: AMD iGPU & NVIDIA RTX 3060
• NVIDIA proprietary driver
• Wayland-capable setup

Symptoms:
• After reboot: black screen with _ cursor in top-left
• No visible greeter, no GUI input
• Ctrl+Alt+F2/F3 works (TTY3 accessible)
• systemctl status sddm reports active (running)
• No kernel panic or system freeze

Restarting SDDM from a TTY: sudo systemctl restart sddm, immediately shows the login screen, but only until the next reboot.

Key observation:
Systemd only tracks the daemon. (sddm daemon)
In this case, the greeter (sddm greeter) was starting successfully but never becoming visible.

The issue occurred only on cold boot, not after restarting SDDM.

What did not solve the issue:
• Reinstalling SDDM
• Reinstalling NVIDIA drivers
• Switching display servers without VT changes
• Disabling Wayland alone
• Checking logs for crashes (none present)

Logs showed the greeter session starting without errors.

Root cause:
This turned out to be a virtual terminal (VT) handoff failure during cold boot on a UEFI + NVIDIA hybrid system.

What was happening:
• On cold boot, the kernel firmware console remained active
• NVIDIA DRM initialized late
• SDDM started normally
• The greeter rendered off-screen
• No VT switch occurred
• Result: permanent _ cursor

Restarting SDDM works because it forces a VT switch. Cold boot does not.

Solution:
Force SDDM to explicitly own a VT and clear the framebuffer, and prevent a getty from racing on the same VT. With the following SDDM configuration:

Create: /etc/sddm.conf.d/00-force-x11.conf

```
[General]
DisplayServer=x11

[X11]
ServerArguments=-nolisten tcp -background none -seat seat0 vt1

[Wayland]
Enable=false
```

And disable getty on VT1:
sudo systemctl disable getty@tty1

After reboot:
• SDDM greeter appears reliably
• No _ cursor
• No manual restarts required
• Plasma works normally after login
• Issue resolved permanently

Notes:
• This is not an SDDM crash
• systemctl status sddm can be misleading (daemon ≠ greeter)
• The failure only manifests on cold boot
• Common on NVIDIA + UEFI + hybrid GPU setups

Marking as [SOLVED].

seth

Member

From: Don't DM me only for attention

Registered: 2012-09-03

Posts: 73,541

Re: SDDM shows black screen & _ cursor on cold boot (NVIDIA hybrid laptop)

Marking as [SOLVED].

Apparently not and also please don't post AI generated PSAs

[General]
DisplayServer=x11

[X11]
ServerArguments=-nolisten tcp -background none -seat seat0 vt1

[Wayland]
Enable=false

doesn't make much sense, sddm still defaults to X11 and you'd have to specify a wayland compositor anyway

Also

Restarting SDDM from a TTY: sudo systemctl restart sddm, immediately shows the login screen, but only until the next reboot.

this isn't only SDDM nor wayland related, see eg https://bbs.archlinux.org/viewtopic.php?id=311358

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