On Tue, 28 Jul 2020 at 10:37:40 +0200, Helge Kreutzmann wrote: > X is running on VT 7, so this is not the cause (and it does so for > many years already). ... > In http://0pointer.de/blog/projects/serial-console.html I read that X should > start on VT1? Maybe systemd is no confused?
It depends what starts X on your system. Display managers are encouraged to behave as described in that article, but not all do. GNOME's GDM (gdm3 in Debian) is an example of a display manager that does behave in that way. Recent versions of GDM use tty1 for GDM's own Wayland or X11 "greeter" (login screen), and ask systemd-logind for one additional VT per Wayland/X11 login session. By default, systemd-logind will start allocating VTs from tty2..tty5 if they have not already been used for a text-mode (getty) login prompt, skip tty6 (which it reserves for a text-mode login prompt), and continue from tty7. If you switch to tty2..tty5 before they have been used for a graphical login session, they will get a text-mode login prompt instead; if you visit all of tty2..tty5 before the first graphical login, then the first graphical login will end up on tty7. See logind.conf(5) for more details. In practice this usually means that GNOME systems have the greeter on tty1, the first graphical login on tty2, and the second and subsequent graphical logins (if you use "fast user switching" to get multiple parallel graphical logins) on tty3..tty5. Other display managers like lightdm, sddm or xdm might either be using tty1 (as encouraged by systemd) or tty7 (more traditional on Debian systems), and they might either reuse the greeter's X11 display for the user's login session (as xdm traditionally did) or allocate a separate VT for each login session (like GDM does). GDM specifically conflicts with getty@tty1.service, so that it can take over tty1 when the system boots in graphical mode, while leaving a getty on tty1 when the system boots in text mode. Other display managers might do something similar, or not. I don't think anyone is going to be able to solve this bug, or even say whether it *is* a bug, without more information about your system - in particular, what display manager you are using. > see all boot messages [on tty1], just if I need them During a normal boot, by default the screen is cleared before showing the login prompt, so the boot messages will not be visible anyway. However, systemd's rescue.target (the equivalent of sysvinit single user mode, runlevel 1) and emergency.target (like runlevel 1, but more so) do not do this. By default, the grub bootloader generates options for "recovery mode", which is implemented by adding "single" to the kernel command line to select systemd rescue.target or sysvinit runlevel 1 as applicable. smcv