From c22ab332902333f83766017478c1ef6607ace681 Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Mon, 5 Mar 2012 14:59:10 -0800 Subject: kmsg_dump: don't run on non-error paths by default Since commit 04c6862c055f ("kmsg_dump: add kmsg_dump() calls to the reboot, halt, poweroff and emergency_restart paths"), kmsg_dump() gets run on normal paths including poweroff and reboot. This is less than ideal given pstore implementations that can only represent single backtraces, since a reboot may overwrite a stored oops before it's been picked up by userspace. In addition, some pstore backends may have low performance and provide a significant delay in reboot as a result. This patch adds a printk.always_kmsg_dump kernel parameter (which can also be changed from userspace). Without it, the code will only be run on failure paths rather than on normal paths. The option can be enabled in environments where there's a desire to attempt to audit whether or not a reboot was cleanly requested or not. Signed-off-by: Matthew Garrett Acked-by: Seiji Aguchi Cc: Seiji Aguchi Cc: David Woodhouse Cc: Marco Stornelli Cc: Artem Bityutskiy Cc: KOSAKI Motohiro Cc: Vivek Goyal Cc: Don Zickus Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/kernel-parameters.txt | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation/kernel-parameters.txt') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 033d4e69b43b..d99fd9c0ec0e 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2211,6 +2211,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. default: off. + printk.always_kmsg_dump= + Trigger kmsg_dump for cases other than kernel oops or + panics + Format: (1/Y/y=enable, 0/N/n=disable) + default: disabled + printk.time= Show timing data prefixed to each printk message line Format: (1/Y/y=enable, 0/N/n=disable) -- cgit v1.2.1