Hi, all:
I would appreciate if someone would explain me if the attached patch
does the right thing. The problem is that I do not use the framebuffer,
and use a serial console. Whenever a legacy /sbin/init tries to
open /dev/tty0, the system oopses dereferencing conswitchp in
visual_init().
-- Pete
diff -ur -X dontdiff linux-2.5.30-sp_pbk/drivers/char/console.c linux-2.5.30-sparc/drivers/char/console.c
--- linux-2.5.30-sp_pbk/drivers/char/console.c Thu Aug 1 14:16:34 2002
+++ linux-2.5.30-sparc/drivers/char/console.c Sun Aug 18 23:14:20 2002
@@ -652,7 +652,7 @@
int vc_allocate(unsigned int currcons) /* return 0 on success */
{
- if (currcons >= MAX_NR_CONSOLES)
+ if (currcons >= MAX_NR_CONSOLES || conswitchp == NULL)
return -ENXIO;
if (!vc_cons[currcons].d) {
long p, q;
On Mon, 19 Aug 2002, Pete Zaitcev wrote:
> I would appreciate if someone would explain me if the attached patch
> does the right thing. The problem is that I do not use the framebuffer,
> and use a serial console. Whenever a legacy /sbin/init tries to
> open /dev/tty0, the system oopses dereferencing conswitchp in
> visual_init().
And this worked before?
conswitchp must never be NULL, say `conswitchp = &dummy_con;' in your setup.c
if you have a serial console.
>From looking at arch/sparc/kernel/setup.c, perhaps you have
CONFIG_DUMMY_CONSOLE=n?
> -- Pete
>
> diff -ur -X dontdiff linux-2.5.30-sp_pbk/drivers/char/console.c linux-2.5.30-sparc/drivers/char/console.c
> --- linux-2.5.30-sp_pbk/drivers/char/console.c Thu Aug 1 14:16:34 2002
> +++ linux-2.5.30-sparc/drivers/char/console.c Sun Aug 18 23:14:20 2002
> @@ -652,7 +652,7 @@
>
> int vc_allocate(unsigned int currcons) /* return 0 on success */
> {
> - if (currcons >= MAX_NR_CONSOLES)
> + if (currcons >= MAX_NR_CONSOLES || conswitchp == NULL)
> return -ENXIO;
> if (!vc_cons[currcons].d) {
> long p, q;
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
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
On Mon, Aug 19, 2002 at 02:36:25PM +0200, Geert Uytterhoeven wrote:
> On Mon, 19 Aug 2002, Pete Zaitcev wrote:
> > I would appreciate if someone would explain me if the attached patch
> > does the right thing. The problem is that I do not use the framebuffer,
> > and use a serial console. Whenever a legacy /sbin/init tries to
> > open /dev/tty0, the system oopses dereferencing conswitchp in
> > visual_init().
>
> And this worked before?
I was simillary surprised when it happened (between 2.5.25 and 2.5.26 if
my memory serves correctly).
> conswitchp must never be NULL, say `conswitchp = &dummy_con;' in your setup.c
> if you have a serial console.
No, it does not work that way for very loooong... Just remove VGA device from
your box, VGA con_startup will fail and conswitchp will become NULL... And
in 2.5.26 more than 50% of archs (including i386) does not use dummy_con, it
leaves conswitchp uninitialized (== NULL).
> > diff -ur -X dontdiff linux-2.5.30-sp_pbk/drivers/char/console.c linux-2.5.30-sparc/drivers/char/console.c
> > --- linux-2.5.30-sp_pbk/drivers/char/console.c Thu Aug 1 14:16:34 2002
> > +++ linux-2.5.30-sparc/drivers/char/console.c Sun Aug 18 23:14:20 2002
> > @@ -652,7 +652,7 @@
> >
> > int vc_allocate(unsigned int currcons) /* return 0 on success */
> > {
> > - if (currcons >= MAX_NR_CONSOLES)
> > + if (currcons >= MAX_NR_CONSOLES || conswitchp == NULL)
> > return -ENXIO;
> > if (!vc_cons[currcons].d) {
> > long p, q;
In 2.5.25 con_init and vty_init was one function, which checked conswitchp == NULL
at beginning. In 2.5.26 it was spilt down, and vty_init does no conswitchp checking,
it blindly registers console tty driver. Proper fix is putting
if (!conswitchp) return;
at the beginning of vty_init(), unless we support hotplug tty. If we support hotplug tty,
then your fix is probably correct, but it needs deeper inspection, as no tty code
ever expected conswitchp == NULL.
Petr Vandrovec
[email protected]
> Date: Mon, 19 Aug 2002 14:36:25 +0200 (MEST)
> From: Geert Uytterhoeven <[email protected]>
> > I would appreciate if someone would explain me if the attached patch
> > does the right thing. The problem is that I do not use the framebuffer,
> > and use a serial console. Whenever a legacy /sbin/init tries to
> > open /dev/tty0, the system oopses dereferencing conswitchp in
> > visual_init().
> > int vc_allocate(unsigned int currcons) /* return 0 on success */
> > {
> > - if (currcons >= MAX_NR_CONSOLES)
> > + if (currcons >= MAX_NR_CONSOLES || conswitchp == NULL)
>
> And this worked before?
>
> conswitchp must never be NULL, say `conswitchp = &dummy_con;' in your setup.c
> if you have a serial console.
>
> >From looking at arch/sparc/kernel/setup.c, perhaps you have
> CONFIG_DUMMY_CONSOLE=n?
This only works if CONFIG_FB is present, and I do not want to add
one more useless chunk of code to the build. All my boxes have
serial consoles (like I said, I would throw CONFIG_VT away if
only it was not welded into the rest of the code so well).
-- Pete
From: Pete Zaitcev <[email protected]>
Date: Sat, 24 Aug 2002 00:57:56 -0400
> CONFIG_DUMMY_CONSOLE=n?
This only works if CONFIG_FB is present
Not true, only video/Config.in has this (false) dependency.
If you say define_bool CONFIG_DUMMY_CONSOLE=y in Sparc configuration
then dummycon.o will be built by itself and it will work.