Ah, it's documented in /usr/share/doc/systemd/README.Debian. Boot with holding left shift to get the grub boot menu, "e"dit the default entry, and append "systemd.debug" on the "linux" line. Then you have a root shell on Ctrl+Alt+F9.
Ah, it's documented in /usr/share/ doc/systemd/ README. Debian. Boot with holding left shift to get the grub boot menu, "e"dit the default entry, and append "systemd.debug" on the "linux" line. Then you have a root shell on Ctrl+Alt+F9.