Is there an up-to-date guide on setting up and using serial consoles
for first-time NetBSD/i386 serial console users?  For now, I'd like to
build a setup that uses a serial tty (COM0) for as much of the console
output as possible.

I UTSLed, and that suggested building building bootblocks in
sys/arch/i386/stand/biosboot_com0/. But with a slightly out-of-date
souces, that failed to find start_bootsect.o.
Am I missing something obvious?

Last, anyone got experience with mixing NetBSD serial consoles and
newer Intel "server" motherboard BIOS `serial consoles'?