Subject: comsoftCAR wired high in com.c
To: None <>
From: Henning G. Schulzrinne <>
List: netbsd-bugs
Date: 01/23/1994 11:25:11
In trying to interface an APC UPS to my NetBSD-0.9 machine, I discovered
that the isa/com.c driver (both 0.9 and current) always sets
comsoftCAR to one. Thus, the !CLOCAL behavior differs from that in
the termios man page; in particular, open on /dev/tty?? succeeds even if
carrier is off. Neither the driver source nor the man page document
this bug.

According to Bernhard Schneck, BSDI 1.0 has fixed that bug, in case
you need inspiration...

Also, it appears as if TIOCM_CD and TIOCM_RI are interchanged, that is,
changes on line 8 of the (25-pin) RS-232 port appear as TIOCM_RI rather than
carrier detect.

Henning Schulzrinne (
AT&T Bell Laboratories  (MH 2A-244)
600 Mountain Ave; Murray Hill, NJ 07974
phone: +1 908 582-2262; fax: +1 908 582-5809