why is tty->pgrp set to -1 for console?

gopi at india.tejasnetworks.com gopi at india.tejasnetworks.com
Sat Feb 2 06:12:51 EST 2002

Thanx, both the options 1 and 3 are working (I didnt try 2).

With option 1, wouldn't we have the problem of some important kernel
messages(say oops) not coming on the terminal as they are put on
'console'.  Even though kmsg will have it, it is good if we can see
it on the console in case something goes wrong.

ps: ours is an embedded system

On Thu, 31 Jan 2002, Scott Anderson wrote:

> gopi at 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 at mvista.com   MontaVista Software Inc.
>     (408)328-9214               1237 East Arques Ave.
>     http://www.mvista.com       Sunnyvale, CA  94085

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