]> err.no Git - linux-2.6/commit
slow down printk during boot
authorRandy Dunlap <rdunlap@xenotime.net>
Tue, 16 Oct 2007 08:23:46 +0000 (01:23 -0700)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Tue, 16 Oct 2007 16:42:49 +0000 (09:42 -0700)
commitbfe8df3d314bddf30758bd738e0087e80964760c
treed04db4fb2592e2d416073681903f05f5b30f204b
parent1bcf548293aef19b0797348332cf1dfbf2116cef
slow down printk during boot

Optionally add a boot delay after each kernel printk() call, crudely
measured in milliseconds, with a maximum delay of 10 seconds per printk.

Enable CONFIG_BOOT_PRINTK_DELAY=y and then add (e.g.):
"lpj=loops_per_jiffy boot_delay=100"
to the kernel command line.

It has been useful in cases like "during boot, my machine just reboots or the
screen goes black" by slowing down printk, (and adding initcall_debug), we can
usually see the last thing that happened before the lights went out which is
usually a valuable clue.

[akpm@linux-foundation.org: not all architectures implement CONFIG_HZ]
[akpm@linux-foundation.org: fix lots of stuff]
[bunk@stusta.de: kernel/printk.c: make 2 variables static]
[heiko.carstens@de.ibm.com: fix slow down printk on boot compile error]
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Documentation/kernel-parameters.txt
include/linux/jiffies.h
init/calibrate.c
kernel/printk.c
lib/Kconfig.debug