From mboxrd@z Thu Jan  1 00:00:00 1970
From: jnc@mercury.lcs.mit.edu (Noel Chiappa)
Date: Sun, 19 Mar 2017 02:37:12 -0400 (EDT)
Subject: [TUHS] 4.3BSD help: getty ignoring modem status
Message-ID: <20170319063712.3E54C18C09F@mercury.lcs.mit.edu>

    > From: Warren Toomey

    > So, DCD and CTS are being dropped, but getty (or something) isn't
    > responding and (presumably) sending a HUP signal to the shell.
    > Is there anybody with some modem or getty knowledge that can help?

I know very little of 4.x, but I did write a V6 DZ driver, back in the
Cenozoic or some such time period... :-)

Looking at the 4.3Tahoe (which particular 4.3 version is in question here,
anyway?) DZ driver:

  http://minnie.tuhs.org/cgi-bin/utree.pl?file=4.3BSD-Tahoe/usr/src/sys/vaxuba/dz.c

I find it hard (without further digging) to figure out how it gets from where
it should discover carrier has gone away (in dzrint(), from dztimer()) to the
rest of the system; they have added some linesw[] thing I don't know about.

Looking at the 4.2 driver:

  http://minnie.tuhs.org/cgi-bin/utree.pl?file=4.2BSD/usr/src/sys/vaxuba/dz.c

it seems (in the same routine) to do the right thing:

               gsignal(tp->t_pgrp, SIGHUP);

so in that version, it's sending a SIGHUP to the whole pgroup when the
carrier goes away - which should be the right thing.

	Noel