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

Geert Uytterhoeven
2004-10-06T08:44:43Z

On Wed, 6 Oct 2004, Willy Tarreau wrote:
> On Wed, Oct 06, 2004 at 12:58:57AM +0300, Denis Vlasenko wrote:
> > > + if (open("/dev/null", O_RDWR, 0) == 0)
> > > + printk(" Falling back to /dev/null.\n");
> > > + }
> >
> > What will happen if /dev is totally empty?
>
> ... Which is the most probable reason causing this trouble.

Indeed, but there are other known cases.

Some debug methods use register_console() to get their print routines
registered. If people forget to say e.g. `console=tty0' afterwards, the debug
console without the real device cannot be opened through /dev/console, and they
get a mysterious error. Usually /dev/console _is_ present in the root fs.

Perhaps a better fix is to modify the /dev/console demux code to fall back to
`/dev/null' (quotes to indicate this has nothing to do with a present /dev/null
on your root fs or ramdisk, but that it's the virtual null device) if the
struct console corresponding to /dev/console is not an existing tty device.

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