Re: [PATCH] Console: fall back to /dev/null when no console is availlable

Russell King
2004-10-05T21:15:01Z

On Tue, Oct 05, 2004 at 02:06:59PM -0700, Greg KH wrote:
> On Tue, Oct 05, 2004 at 09:27:12PM +0100, Russell King wrote:
> > On Tue, Oct 05, 2004 at 08:52:14PM +0200, J?rn Engel wrote:
> > > Looks pretty trivial, but opinions on this subject may vary.
> > > Comments?
> >
> > There's a related problem. /sbin/hotplug. I keep seeing odd failures
> > from /sbin/hotplug scripts which go away when I ensure that fd0,1,2 are
> > directed at something real.
>
> Which scripts cause this problem?

I have no idea. Somewhere in the depths of the Red Hat networking
scripts. There's multiple of them calling multiple other programs
and it's impossible to debug what's going on. All I know is that
IPv6 doesn't get configured if fd0,1,2 are closed, but does if they're
open.

It could be a script, or some other program. There's no way to tell.

> > It's rather annoying because it currently means that, when my PCMCIA net
> > interface on the firewall comes up, the IPv4 configuration works fine
> > but IPv6 configuration falls dead on its nose without any explaination
> > why.
> >
> > And, like I say, redirecting fd0,1,2 fixes it.
>
> Redirecting it in the script itself? Or in the kernel like this patch?

I'm redirecting them in the /sbin/hotplug script to something sane,
but I think the kernel itself should be directing these three fd's
to somewhere whenever it invokes any user program, even if it is
/dev/null.

I think Alan disagrees with me, but I think the history that these
types of problems _keep_ cropping up over and over is proof enough
that it's necessary for sane userspace.

(Another example which is happening _now_: having /sbin/init die over
a suspend/resume cycle because you have no system console on your
embedded device isn't nice.)

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core