No login prompt on serial if no monitor connected

[Alfonso Sanchez-Beato]

In a device that has both HDMI ouput *and* a serial console, no log-in prompt appears in the serial console if no monitor is connected, when "splash" is added to the kernel command line.

I see plymouthd taking 100% of the CPU. If I connect a monitor, then I get the serial console and plymouthd stops. That HDMI is connected or not should not influence the serial console prompt.

plymouthd backtrace shows it waiting for events:

#0 0x0000ffff9a948754 in __GI_epoll_pwait (epfd=3, events=events@entry=0xffff9aa3e2a0 <events>, maxevents=maxevents@entry=64, timeout=-1, set=set@entry=0x0)
    at ../sysdeps/unix/sysv/linux/epoll_pwait.c:42
#1 0x0000ffff9a9488e0 in epoll_wait (epfd=<optimized out>, events=events@entry=0xffff9aa3e2a0 <events>, maxevents=maxevents@entry=64, timeout=<optimized out>)
    at ../sysdeps/unix/sysv/linux/epoll_wait.c:32
#2 0x0000ffff9aa1b818 in ply_event_loop_process_pending_events (loop=0xaaaad24b53e0) at ply-event-loop.c:1230
#3 ply_event_loop_process_pending_events (loop=0xaaaad24b53e0) at ply-event-loop.c:1210
#4 0x0000ffff9aa1be98 in ply_event_loop_run (loop=0xaaaad24b53e0) at ply-event-loop.c:1310
#5 0x0000aaaace94c62c in main (argc=4, argv=0xffffefe2d748) at main.c:2294

[Sebastien Bacher (seb128)]

Thank you for your bug report, could you report it upstream on https://gitlab.freedesktop.org/plymouth/plymouth/-/issues ?
also which version of Ubuntu are you using and could you add a 'journalctl -b 0' log from the system after triggering the issue?

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. Please execute the following command only once, as it will automatically gather debugging information, in a terminal:

apport-collect 1931718

When reporting bugs in the future please use apport by using 'ubuntu-bug' and the name of the package affected. You can learn more about this functionality at https://wiki.ubuntu.com/ReportingBugs.

[Launchpad Janitor (janitor)]

[Expired for plymouth (Ubuntu) because there has been no activity for 60 days.]