After updating nvidia drivers from nvidia-glG04-375.39-21.1
nvidia-glG04-375.66-22.1 and rebooting, the login screen is black. This can be
mitigated by using another login manager (e.g. kdm), but still krunner for KDE
Plasma then crashes on login.

Both work again after switching to nuveau drivers by removing the nvidia
packages.

sddm output:

May 17 10:01:43 kakoehne-laptop.qt.io sddm[1912]: Initializing...
May 17 10:01:43 kakoehne-laptop.qt.io sddm[1912]: Starting...
May 17 10:01:43 kakoehne-laptop.qt.io sddm[1912]: Adding new display on vt 7
...
May 17 10:01:43 kakoehne-laptop.qt.io sddm[1912]: Display server starting...
May 17 10:01:43 kakoehne-laptop.qt.io sddm[1912]: Running: /usr/bin/X -nolisten
tcp -auth /run/sddm/{517ce033-4cd5-445f-8d4d-2daf65331da2} -background none
-noreset -displayfd 18 vt7
May 17 10:01:44 kakoehne-laptop.qt.io display-manager[1642]: Starting service
sddm..done
May 17 10:01:46 kakoehne-laptop.qt.io sddm[1912]: Running display setup script 
"/etc/X11/xdm/Xsetup"
May 17 10:01:46 kakoehne-laptop.qt.io sddm[1912]: Display server started.
May 17 10:01:46 kakoehne-laptop.qt.io sddm[1912]: Socket server starting...
May 17 10:01:46 kakoehne-laptop.qt.io sddm[1912]: Socket server started.
May 17 10:01:46 kakoehne-laptop.qt.io sddm[1912]: Greeter starting...
May 17 10:01:46 kakoehne-laptop.qt.io sddm[1912]: Adding cookie to
"/run/sddm/{517ce033-4cd5-445f-8d4d-2daf65331da2}"
May 17 10:01:46 kakoehne-laptop.qt.io sddm-helper[2101]: [PAM] Starting...
May 17 10:01:46 kakoehne-laptop.qt.io sddm-helper[2101]: [PAM]
Authenticating...
May 17 10:01:46 kakoehne-laptop.qt.io sddm-helper[2101]: [PAM] returning.
May 17 10:01:46 kakoehne-laptop.qt.io sddm-helper[2101]:
pam_unix(sddm-greeter:session): session opened for user sddm by (uid=0)
May 17 10:01:46 kakoehne-laptop.qt.io systemd[1]: Created slice User Slice of
sddm.
May 17 10:01:46 kakoehne-laptop.qt.io systemd-logind[1586]: New session 1 of
user sddm.
May 17 10:01:46 kakoehne-laptop.qt.io systemd[2103]:
pam_unix(systemd-user:session): session opened for user sddm by (uid=0)
May 17 10:01:46 kakoehne-laptop.qt.io systemd[1]: Started Session 1 of user
sddm.
May 17 10:01:46 kakoehne-laptop.qt.io sddm[1912]: Greeter session started
successfully
May 17 10:01:46 kakoehne-laptop.qt.io sddm-greeter[2111]: Reading from
"/usr/share/xsessions/gnome.desktop"
May 17 10:01:46 kakoehne-laptop.qt.io sddm-greeter[2111]: Reading from
"/usr/share/xsessions/icewm-session.desktop"
May 17 10:01:46 kakoehne-laptop.qt.io sddm-greeter[2111]: Reading from
"/usr/share/xsessions/icewm.desktop"
May 17 10:01:46 kakoehne-laptop.qt.io sddm-greeter[2111]: Reading from
"/usr/share/xsessions/kde-plasma.desktop"
May 17 10:01:46 kakoehne-laptop.qt.io sddm-greeter[2111]: Reading from
"/usr/share/xsessions/plasma5.desktop"
May 17 10:01:46 kakoehne-laptop.qt.io sddm-greeter[2111]: Reading from
"/usr/share/xsessions/xsession.desktop"
May 17 10:01:46 kakoehne-laptop.qt.io sddm-greeter[2111]: Connected to the
daemon.
May 17 10:01:46 kakoehne-laptop.qt.io sddm[1912]: Message received from
greeter: Connect
May 17 10:01:46 kakoehne-laptop.qt.io sddm-helper[2101]: [PAM] Ended.
May 17 10:01:46 kakoehne-laptop.qt.io sddm[1912]: Auth: sddm-helper exited with
11
May 17 10:01:46 kakoehne-laptop.qt.io sddm[1912]: Greeter stopped.
May 17 10:01:47 kakoehne-laptop.qt.io systemd[2106]:
pam_unix(systemd-user:session): session closed for user sddm
May 17 10:01:47 kakoehne-laptop.qt.io systemd[1]: Removed slice User Slice of
sddm.
May 17 10:01:48 kakoehne-laptop.qt.io systemd-coredump[2121]: Process 2111
(sddm-greeter) of user 483 dumped core.