systemd-getty-generator — Generator for enabling getty instances on the console
/usr/lib/systemd/system-generators/systemd-getty-generator
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. This should
                ensure that the user is shown a login prompt at the
                right place, regardless in which environment the
                system is started. 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 the generator
                specification.
Further information about configuration of gettys you may find in systemd for Administrators, Part XVI: Gettys on Serial Consoles (and Elsewhere).