systemd-getty-generator man page
systemd-getty-generator — Generator for enabling getty instances on the console
systemd-getty-generator is a generator that automatically instantiates serial-getty@.service on the kernel console /dev/console if that is not directed to the virtual console subsystem. It will also instantiate serial-getty@.service instances for virtualizer consoles, if execution in a virtualized environment is detected. Finally, it will instantiate container-getty@.service instances for additional container pseudo TTYs as requested by the container manager (see Container Interface). This should ensure that the user is shown a login prompt at the right place, regardless of which environment the system is started in. For example, it is sufficient to redirect the kernel console with a kernel command line argument such as console= to get both kernel messages and a getty prompt on a serial TTY. See kernel-parameters.txt for more information on the console= kernel parameter.
systemd-getty-generator implements systemd.generator(7).
Further information about configuration of gettys you may find in systemd for Administrators, Part XVI: Gettys on Serial Consoles (and Elsewhere).
systemd for Administrators, Part XVI: Gettys on Serial Consoles (and Elsewhere)
systemd.directives(7), systemd.generator(7), systemd.index(7).