From bfe8df3d314bddf30758bd738e0087e80964760c Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Tue, 16 Oct 2007 01:23:46 -0700 Subject: 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 Signed-off-by: Dave Jones Signed-off-by: Adrian Bunk Signed-off-by: Heiko Carstens Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/kernel-parameters.txt | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 085e4a095ea..760ed577617 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -349,6 +349,11 @@ and is between 256 and 4096 characters. It is defined in the file blkmtd_bs= blkmtd_count= + boot_delay= Milliseconds to delay each printk during boot. + Values larger than 10 seconds (10000) are changed to + no delay (0). + Format: integer + bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) bttv.radio= Most important insmod options are available as kernel args too. -- cgit v1.2.3