* Thomas Renninger <trenn@xxxxxxx> wrote:
> Looking at WARN() again:
> #ifndef __WARN
> #ifndef __ASSEMBLY__
> extern void warn_slowpath(const char *file, const int line,
> const char *fmt, ...) __attribute__((format(printf, 3, 4)));
> #define WANT_WARN_ON_SLOWPATH
> #endif
> #define __WARN() warn_slowpath(__FILE__, __LINE__, NULL)
> #define __WARN_printf(arg...) warn_slowpath(__FILE__, __LINE__, arg)
> #else
> #define __WARN_printf(arg...) do { printk(arg); __WARN(); } while (0)
> #endif
>
> WARN_ONCE does throw a backtrace (warn_slowpath does) or I missed
> something...
> Thus WARN_ONCE makes a big difference to printk_once() (which does not
> exist? but would be neat...) and prints out the backtrace, right?
yes, correct. We use WARN()/WARN_ONCE() in places where an error is
surprising and where we want to print a backtrace too.
In this case you are right to point out that it's not a kernel bug but a
BIOS environment bug, and that the text itself uniquely identifies the place
it comes from. So using a printk is perfectly fine.
There's a few cleanups necessary with the printk solution too though, see my
previous mail for the details.
printk_once() would be nice indeed - it's a frequent construct.
Ingo
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