I wrote:

> I tested a kernel with options COM_REGMAP for com_dio on my hp425t
> (68040 25MHz) but it doesn't probe com properly (probed as 16450
> rather than 16550a) and doesn't work. (I haven't checked details yet)

Ah, sorry, it's my fault. I just added #define COM_REGMAP to
<dev/ic/comvar.h>, but com.c refers COM_REGMAP before including it.
(Is it better to move CSR_* definitions to comvar.h?)

> I mesured xfer rate via SLIP (9600bps, RTS/CTS flow control)
> on getting a 1.8MB file from i386 by ftp(1):
>  GENERIC on HEAD:		0.76KB/s (with 8 overflows)
>  GENERIC on gdamore-uart:	0.75KB/s (with 6 overflows)

GENERIC with COM_REGMAP on gadmore-uart also shows ~0.75KB/s.
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Izumi Tsutsui