Comment 5 for bug 1940514

With "splash" in cmdline, on shutdown, desktop images start plymouth with graphical splash on a shutdown TTY such that one should be seeing animation (and any graphical or text messages should be hidden from the user). One should be able to use alt-ctrl-arrowkeys to switch back to tty1 to still see messsages if one desires. Plymouth should continue to run.

normally on shutdown systemd-shutdown binary is called from the regular rootfs. It tries to kill and unmount all the things, and after it stops making any progress, it reexecs systemd-shutdown brinamy from /run/initramfs/shutdown.

That, in turn, is systemd-shutdown binary, _again_. But this time it has been performed with pivot root. Meaning the regular rootfs is now mounted as /oldroot/ and things are held up there.

I wonder if it is plymouth that is hodling up /dev/pts and like udevd holding up /dev. And if killing those in shutdown hooks is appropriate. Or for example running plymouth from /run/initramfs, rather than from rootfs.