From 89e71703e166b3c91c39f0c1e8ba5cf628e26e1d Mon Sep 17 00:00:00 2001 From: Carsten Emde Date: Tue, 19 Jul 2011 13:51:17 +0100 Subject: net: sysrq via icmp There are (probably rare) situations when a system crashed and the system console becomes unresponsive but the network icmp layer still is alive. Wouldn't it be wonderful, if we then could submit a sysreq command via ping? This patch provides this facility. Please consult the updated documentation Documentation/sysrq.txt for details. Signed-off-by: Carsten Emde --- Documentation/sysrq.txt | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/sysrq.txt b/Documentation/sysrq.txt index 8cb4d7842a5f..d458683453ab 100644 --- a/Documentation/sysrq.txt +++ b/Documentation/sysrq.txt @@ -57,10 +57,17 @@ On PowerPC - Press 'ALT - Print Screen (or F13) - , On other - If you know of the key combos for other architectures, please let me know so I can add them to this section. -On all - write a character to /proc/sysrq-trigger. e.g.: - +On all - write a character to /proc/sysrq-trigger, e.g.: echo t > /proc/sysrq-trigger +On all - Enable network SysRq by writing a cookie to icmp_echo_sysrq, e.g. + echo 0x01020304 >/proc/sys/net/ipv4/icmp_echo_sysrq + Send an ICMP echo request with this pattern plus the particular + SysRq command key. Example: + # ping -c1 -s57 -p0102030468 + will trigger the SysRq-H (help) command. + + * What are the 'command' keys? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 'b' - Will immediately reboot the system without syncing or unmounting -- cgit v1.2.3