I installed Fedora 23 Workstation on an Intel NUC. When I boot without a display connected and log in over SSH, I see some anomalies.
systemd shows the boot process has not finished. The problem seems to be plymouth.
Here's the mystery - I'm sure plymouth is also used on Fedora Server. If you disable plymouth, you don't get any messages about the boot process from systemd. I'm sure lots of people are running display-less systems successfully. What's the problem with my system?
# systemctl status alan-nuc State: starting Jobs: 4 queued Failed: 0 units
Taking a hint from the systemd debugging guide:
# systemctl list-jobs JOB UNIT TYPE STATE 241 plymouth-quit-wait.service start running 111 graphical.target start waiting 247 systemd-update-utmp-runlevel.service start waiting 112 multi-user.target start waiting 4 jobs listed.
systemctl gdm looks ok. If you plug in a display it stays completely black until you restart gdm. I suspected that just showed a lack of display hotplug in the kernel driver. However, as soon as I stop the
plymouth goes away and the boot process is declared finished. Stopping an unrelated service like
chronyd doesn't have the same effect.
A little earlier, I noticed the same symptoms if I switch VTs (Ctrl+Alt+F2) at a certain point during the boot process. In this case, switching back to the initial VT (Ctrl+Alt+F1) allows startup to complete.