Re: increased verbosity in dmesg

["Randy.Dunlap" <rddunlap@osdl.org>]

> Greetings;
>
> The recently increased verbosity in the dmesg file is causeing the  "ring
> buffer" to overflow, and I am not now seeing the first few
> pages of the reboot in the dmesg file.
>
> I understand this 'ring' buffer has been expanded to about 16k but  that was
> way back in 2.1 days when that occured according to the
> Documentation.
>
> Is there any quick and dirty way to increase this to at least 32k, or  maybe
> even to 64k?  With half a gig of memory, this shouldn't be a  problem should
> it?
>
> I've done some grepping, but it appears I'm not grepping for the right  var
> name, so I'm coming up blank and need some help.

It's a config option in 2.6 and recent 2.5 kernels if DEBUG_KERNEL
is enabled:

config LOG_BUF_SHIFT
  int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL

In 2.4, edit kernel/printk.c and change the appropriate line:

#if defined(CONFIG_MULTIQUAD) || defined(CONFIG_IA64)
#define LOG_BUF_LEN     (65536)
#elif defined(CONFIG_ARCH_S390)
#define LOG_BUF_LEN     (131072)
#elif defined(CONFIG_SMP)
#define LOG_BUF_LEN     (32768)
#else
#define LOG_BUF_LEN     (16384)                 /* This must be a power of two */
#endif

~Randy