isdtor writes: > Hi all, > > I have a laptop in UEFI mode running CentOS 8.2. All works fine but when I enable Secure Boot, login via gdm is no longer possible. Console login is ok. > > I found some related discussions over on Ubuntu forums, suggesting that this could be related to 3rd-party kernel modules, such as nvidia. This laptop has only Intel builtin graphics, and every single module installed is part of the CentOS distribution. > > This is from a file /tmp/xses-.XXXXXX (random 6-char string) > > xrdb: Can't open display '' > xmodmap: unable to open display '' > Failed to import environment: Process org.freedesktop.systemd1 exited with status 1 > /usr/bin/xmbind: Can't open display > Unable to init server: Could not connect: Connection refused > > Something is different in the way Xorg is started. In this situation, the first part of the Xorg log file (under ~/.local) is a dump of X command line options. > > use: X [:<display>] [options] > -a # ... > -ac ... > ... I haven't been able to make any progress on this setup, except that after disabling Secure Boot again, it still keeps happening, probably 90% of the time. It could be some kind of race, but even waiting for a while after gdm is up and the text consoles have a prompt did not help. Rebooting and retrying until it works is the only option right now. What does seem to work, however, is switching back to Wayland, from Xorg. I had changed to Xorg in gdm custom.conf to look at some remote connectivity problems (can't get x2go to work).