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authorBen Hutchings <ben@decadent.org.uk>2013-10-07 01:05:46 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-10-16 13:01:44 -0700
commit8eaede49dfdc1ff1d727f9c913665b8009945191 (patch)
tree094c592c127142c4f01766fb82e3a7973c87ca1c /Documentation/sysrq.txt
parente8b5cbb041130ef297c90f8af2d3d45dfb9e6d15 (diff)
downloadlinux-8eaede49dfdc1ff1d727f9c913665b8009945191.tar.bz2
sysrq: Allow magic SysRq key functions to be disabled through Kconfig
Turn the initial value of sysctl kernel.sysrq (SYSRQ_DEFAULT_ENABLE) into a Kconfig variable. Original version by Bastian Blank <waldi@debian.org>. Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/sysrq.txt')
-rw-r--r--Documentation/sysrq.txt13
1 files changed, 6 insertions, 7 deletions
diff --git a/Documentation/sysrq.txt b/Documentation/sysrq.txt
index 1c0471dc70fe..0e307c94809a 100644
--- a/Documentation/sysrq.txt
+++ b/Documentation/sysrq.txt
@@ -11,11 +11,9 @@ regardless of whatever else it is doing, unless it is completely locked up.
You need to say "yes" to 'Magic SysRq key (CONFIG_MAGIC_SYSRQ)' when
configuring the kernel. When running a kernel with SysRq compiled in,
/proc/sys/kernel/sysrq controls the functions allowed to be invoked via
-the SysRq key. By default the file contains 1 which means that every
-possible SysRq request is allowed (in older versions SysRq was disabled
-by default, and you were required to specifically enable it at run-time
-but this is not the case any more). Here is the list of possible values
-in /proc/sys/kernel/sysrq:
+the SysRq key. The default value in this file is set by the
+CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE config symbol, which itself defaults
+to 1. Here is the list of possible values in /proc/sys/kernel/sysrq:
0 - disable sysrq completely
1 - enable all functions of sysrq
>1 - bitmask of allowed sysrq functions (see below for detailed function
@@ -32,8 +30,9 @@ in /proc/sys/kernel/sysrq:
You can set the value in the file by the following command:
echo "number" >/proc/sys/kernel/sysrq
-The number may be written either as decimal or as hexadecimal with the
-0x prefix.
+The number may be written here either as decimal or as hexadecimal
+with the 0x prefix. CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE must always be
+written in hexadecimal.
Note that the value of /proc/sys/kernel/sysrq influences only the invocation
via a keyboard. Invocation of any operation via /proc/sysrq-trigger is always