>> I tried defining -DSUPPORT_SERIAL and -DDIRECT_SERIAL,
>> along with the rest of the stuff on that line, including setting the baud
>> rate to 9600.  (see src/sys/arch/i386/stand/biosboot/Makefile for details),
>
>That looks well so far... If you always want a serial console,
>you probably don't want COMCONS_KEYPRESS - this switches
>to the serial console if you press a key in the right moment.
>Did you change the initio() argument in main() to CONSDEV_COM0?

Is there a reason the initio() argument isn't CONSDEV_AUTO?  It would
seem to me that this wouldn't affect the standard case (booting from
a "normal" console), and it would make building serial bootblocks easier.

--Ken