From: Scott Anderson <scott_anderson@mvista•com>
To: gopi@india•tejasnetworks.com
Cc: linuxppc-dev@lists•linuxppc.org
Subject: Re: why is tty->pgrp set to -1 for console?
Date: Thu, 31 Jan 2002 13:34:34 -0800 [thread overview]
Message-ID: <3C59B86A.E24F89A1@mvista.com> (raw)
In-Reply-To: Pine.LNX.4.21.0201312050570.1490-100000@tn100build.india.tejasnetworks.com
gopi@india•tejasnetworks.com wrote:
> What is the correct procedure to follow to get around this problem
> and get ctrl-c working on console?
It looks like everyone is taking a swing at this one, so I think I'll
join in. First off, the easiest way I've found to track down why
ctrl-c doesn't work is to just run "ps -j". For ctrl-c to work, you
need a controlling terminal (the TTY column) and a process group. If
you have a '?' in the TTY column, ctrl-c won't work. In the past I
have seen this happen because of this code in drivers/char/tty_io.c:
if (device == SYSCONS_DEV) {
struct console *c = console_drivers;
while(c && !c->device)
c = c->next;
if (!c)
return -ENODEV;
device = c->device(c);
filp->f_flags |= O_NONBLOCK; /* Don't let /dev/console block */
noctty = 1;
}
Note that O_NOCTTY (no controlling terminal) is forced on whenever
/dev/console is opened (noctty = 1). Possible workarounds:
1) Run getty on something other than /dev/console. For example,
if you console is on the first serial port, run getty on /dev/ttyS0.
I believe this is the "correct" answer.
2) You could also change getty to do a TIOCSCTTY ioctl explicitly after
it has opened the terminal.
3) You could remove the forcing of noctty on from tty_io.c
Scott Anderson
scott_anderson@mvista•com MontaVista Software Inc.
(408)328-9214 1237 East Arques Ave.
http://www.mvista.com Sunnyvale, CA 94085
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2002-01-31 21:34 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-30 12:14 kernel hang when machine_restart called from isr gopi
2002-01-31 20:58 ` why is tty->pgrp set to -1 for console? gopi
2002-01-31 17:09 ` Daniel Jacobowitz
2002-01-31 21:34 ` Scott Anderson [this message]
2002-02-01 19:12 ` gopi
2002-02-21 0:53 ` Unable to write to SIMASK gopi
2002-02-20 21:27 ` Ricardo Scop
2002-02-21 17:34 ` gopi
-- strict thread matches above, loose matches on Subject: below --
2002-01-31 19:14 why is tty->pgrp set to -1 for console? David Boutcher
2002-01-31 20:49 ` mod+linuxppc-dev
2002-01-31 20:53 ` Dan Malek
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