Generator for enabling getty instances on the console
/lib/systemd/system-generators/systemd-getty-generator
systemd-getty-generator is a generator that automatically instantiates [email protected] on the kernel console /dev/console if that is not directed to the virtual console subsystem. It will also instantiate [email protected] instances for virtualizer consoles, if execution in a virtualized environment is detected. Finally, it will instantiate [email protected] instances for additional container pseudo TTYs as requested by the container manager (see \m[blue]Container Interface\m[]\s-2\u[1]\d\s+2). 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 \m[blue]kernel-parameters.txt\m[]\s-2\u[2]\d\s+2 for more information on the console= kernel parameter.
systemd-getty-generator implements the \m[blue]generator specification\m[]\s-2\u[3]\d\s+2.
Further information about configuration of gettys you may find in \m[blue]systemd for Administrators, Part XVI: Gettys on Serial Consoles (and Elsewhere)\m[]\s-2\u[4]\d\s+2.
Container Interface
http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface/
kernel-parameters.txt
https://www.kernel.org/doc/Documentation/kernel-parameters.txt
generator specification
http://www.freedesktop.org/wiki/Software/systemd/Generators
systemd for Administrators, Part XVI: Gettys on Serial Consoles (and Elsewhere)
http://0pointer.de/blog/projects/serial-console.html