ttyS0
http://0pointer.de/blog/projects/serial-console.html
serial-getty@ttyS2.service
/sbin/agetty --keep-baud 115200 ttyS0 vt100 -n -l /bin/bash
http://0pointer.de/blog/projects/serial-console.html
serial-getty@ttyS2.service
/sbin/agetty --keep-baud 115200 ttyS0 vt100 -n -l /bin/bash