I have noticed that some hardware do not have a serial port. e.g. Thinkpad X40 and mac mini.
However, you can access a serial console through uplcom(8). As of OpenBSD 3.5, /etc/ttys ttyU0 "/usr/libexec/getty std.9600" vt100 on secure If you can show boot messages through a serial console, is it feasible to do so through a USB-serial interface? i.e. boot> set tty uplcom0 switching console to uplcom0 Ed.
