Excerpts from netbsd: 8-Sep-97 Re: How about to config Hay.. enami
tsugutomo@but-b.or (2036)

> hayesesp0 at isa? port 0x280 irq 5	# Hayes ESP serial cards with ns16550
> com*	at hayesesp? port ?		# compatible mode.
> #com*	at hayesesp? port 0x3e8		# hardwiring port address.
> 
> Note that this patch doesn't include the patch to use the card over
> 115200 bps, since it is separate function.

Did you know that there is Linux driver source available
which uses enhanced features? (via www.hayes.com)
I don't know the ESP cards, and I don't know if this would
give us more performance, however.

Regarding your PR kern/4095: When I cleaned up the
serial console stuff some weeks ago, I came to the same
conclusion. I asked for testers at the mailing list too, but
there was nobody who could do it without too much effort.
Perhaps we should simply integrate it?

best regards
Matthias