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SubjectRe: [PATCH] clean up kernel messages
Matt Mackall <mpm@selenic.com> wrote:
>
> This patch tidies up those annoying kernel messages. A typical kernel
> boot now looks like this:
>
> Loading Linux... Uncompressing kernel...
> #
>
> See? Much nicer. This patch saves about 375k on my laptop config and
> nearly 100k on minimal configs.
>

heh. Please take a look at
http://www.uwsg.iu.edu/hypermail/linux/kernel/0004.2/0709.html, see if
Graham did anything which you missed.

One problem was that

printk("foo");

will still cause the string "foo\0" to appear in the kernel image. That
was fixed in later gcc's, but it would be interesting to know which
compilers get it right.

>
> Index: af/include/linux/kernel.h
> ===================================================================
> --- af.orig/include/linux/kernel.h 2005-04-01 00:32:18.000000000 -0800
> +++ af/include/linux/kernel.h 2005-04-01 10:38:43.000000000 -0800
> @@ -115,10 +115,19 @@ extern int __kernel_text_address(unsigne
> extern int kernel_text_address(unsigned long addr);
> extern int session_of_pgrp(int pgrp);
>
> +#ifdef CONFIG_PRINTK
> asmlinkage int vprintk(const char *fmt, va_list args)
> __attribute__ ((format (printf, 1, 0)));
> asmlinkage int printk(const char * fmt, ...)
> __attribute__ ((format (printf, 1, 2)));
> +#else
> +static inline int vprintk(const char *s, va_list args)
> + __attribute__ ((format (printf, 1, 0)));
> +static inline int vprintk(const char *s, va_list args) { return 0; }
> +static inline int printk(const char *s, ...)
> + __attribute__ ((format (printf, 1, 2)));
> +static inline int printk(const char *s, ...) { return 0; }
> +#endif

Actually printk() is supposed to return the number of chars which it
printed. So if someone is doing:

while (len < 40)
len += printk("something");

you've gone and made them lock up.

But I think the number of places where we examine the printk return value
is near zero.

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