linux-kernel - [PATCH 1/2] sysrq: Document hexadecimal values for kernel.sysrq bitmask

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Date:	Mon, 07 Oct 2013 00:48:46 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>
Cc:	Dave Jones <davej@...hat.com>, Bastian Blank <waldi@...ian.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/2] sysrq: Document hexadecimal values for kernel.sysrq
 bitmask

It makes more sense to enter a bitmask in hexadecimal rather than
decimal.  Sadly we can't make it read back as hexadecimal.

Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 Documentation/sysrq.txt | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/Documentation/sysrq.txt b/Documentation/sysrq.txt
index 8cb4d78..1c0471d 100644
--- a/Documentation/sysrq.txt
+++ b/Documentation/sysrq.txt
@@ -20,18 +20,21 @@ in /proc/sys/kernel/sysrq:
    1 - enable all functions of sysrq
   >1 - bitmask of allowed sysrq functions (see below for detailed function
        description):
-          2 - enable control of console logging level
-          4 - enable control of keyboard (SAK, unraw)
-          8 - enable debugging dumps of processes etc.
-         16 - enable sync command
-         32 - enable remount read-only
-         64 - enable signalling of processes (term, kill, oom-kill)
-        128 - allow reboot/poweroff
-        256 - allow nicing of all RT tasks
+          2 =   0x2 - enable control of console logging level
+          4 =   0x4 - enable control of keyboard (SAK, unraw)
+          8 =   0x8 - enable debugging dumps of processes etc.
+         16 =  0x10 - enable sync command
+         32 =  0x20 - enable remount read-only
+         64 =  0x40 - enable signalling of processes (term, kill, oom-kill)
+        128 =  0x80 - allow reboot/poweroff
+        256 = 0x100 - allow nicing of all RT tasks
 
 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.
+
 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
 allowed (by a user with admin privileges).


-- 
Ben Hutchings
If at first you don't succeed, you're doing about average.
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