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

Geert Uytterhoeven
2004-10-06T15:38:50Z

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On Wed, 6 Oct 2004, [iso-8859-1] Jörn Engel wrote:
> On Wed, 6 October 2004 16:23:27 +0200, Geert Uytterhoeven wrote:
> > Ehrm, what do you mean with `default' console?
> >
> > If you mean `console as defined under nr.2',
> correct
> > yes, you want the console that
> > does do input.
>
> *I* don't always do. Remember how this thread got started? ;)

OK, so you want /dev/console to fall back to /dev/null, right?

> > > Taking the last one registered is basically random. If people care
> > > enough, they should explicitly state things on the command line.
> >
> > No, it's not. It's explicitly mentioned in the docs: if you use multiple
> > `console=', all of them get output, but input comes from the last one.
>
> Ah, true. I was barking up the "the was no 'console=' option, take
> the default" tree. Just started looking at the console code a few
> days ago.

Well, you're right that if the user specifies _no_ console= option at all, the
`first one in the linked list' will be used, which is the last one registered.
Usually (read: if enabled) tty0 registers automatically, and it's the only one.

Saying e.g. `console=ttyS0' causes the serial console to register itself (at
the head of the list).
Saying e.g. `console=tty0' afterwards causes the VT console to move back to the
head of the list.

So _if_ there are multiple struct consoles activated, order (read: policy) does
matter. But usually there's only one, and all others are explicitly to be
enabled with console=.

Anyway, I should cook up a patch so the /dev/console demux walks the list if
the one at the head of the list doesn't do input (read: it has no associated
tty struct).

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds