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Commit e8b5cbb0 authored by Ben Hutchings's avatar Ben Hutchings Committed by Greg Kroah-Hartman
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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: default avatarBen Hutchings <ben@decadent.org.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 190c6cc3

Documentation/sysrq.txt

+11 −8
Original line number Diff line number Diff line
@@ -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).