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SubjectRe: console_loglevel is broken on ia64
On Wed, 17 Oct 2001, Keith Owens wrote:
> kernel/printk.c has this abomination.
>
> /* Keep together for sysctl support */
> int console_loglevel = DEFAULT_CONSOLE_LOGLEVEL;
> int default_message_loglevel = DEFAULT_MESSAGE_LOGLEVEL;
> int minimum_console_loglevel = MINIMUM_CONSOLE_LOGLEVEL;
> int default_console_loglevel = DEFAULT_CONSOLE_LOGLEVEL;
>
> sysctl assumes that the 4 variables occupy contiguous storage. They
> don't on ia64, console_loglevel is separate from the other variables.
>
> echo 6 4 1 7 > /proc/sys/kernel/printk
>
> on ia64 overwrites console_loglevel and the next 3 integers, whatever
> they happen to be. On 2.4.12 it corrupts console_sem, other ia64
> kernels will corrupt different data.
>
> Does anybody fancy a small project to clean up these variables? They
> need to become an integer array (say console_printk) containing 4
> elements, which is what sysctl assumes. All references to these fields
> have to be changed to refer to the corresponding array element. That
> should be as simple as

This is not the only problem related to sysctl. We still have

{KERN_REALROOTDEV, "real-root-dev", &real_root_dev, sizeof(int)

in kernel/sysctl.c, with

kdev_t real_root_dev;

in init/main.c,

extern kdev_t real_root_dev;

in drivers/block/rd.c, and

typedef unsigned short kdev_t;

in <linux/kdev_t.h>. Kaboom on big endian boxes, escpecially if the alignment
rules are 2-bytes, like on m68k.

In the m68k tree we have (since ages) a patch to change real_root_dev to int
and add some casts. Patch available upon request.

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

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