SysRQ-P is not always useful on SMP systems, since it usually ends up showing
the backtrace of a CPU that is doing just fine, instead of the backtrace of
the CPU that is having problems.

This patch adds SysRQ show-all-cpus(L), which shows the backtrace of every
active CPU in the system.  It skips idle CPUs because some SMP systems are
just too large and we already know what the backtrace of the idle task looks
like.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Rik van Riel <riel@redhat.com>
Randy Dunlap <randy.dunlap@oracle.com>
Cc: <lwoodman@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Document sequence of keypresses that actually works. Yes, this changed
year-or-so ago.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In Documentation/sysrq.txt, the description of 'h' says that any key not
listed *above* will generate help.  That's obviously not true since all the
keys listed below 'h' will do what they are described to do, not display help.
 So change the text so that it says that any key not listed in the table will
generate help, which is what really happens.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sh uses the same sysrq trigger as ppc, update the documentation to
reflect that.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

I added the 'Q' to list. A short description in the `Ok, so what can I
use them for'-section, on when or why to use it would be nice!

Signed-off-by: Johannes Weiner <hannes-kernel@saeurebad.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Alphabetize the sysrq command keys list.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Change SysRq showBlockedTasks from sysrq-X to sysrq-W and show that in the
Help message.

It was previously done via X, but X is already used for Xmon on ppc & powerpc
platforms and this collision needs to be avoided.

All callers of register_sysrq_key() are now marked in the sysrq op/key table.
I didn't mark 'h' as Help because Help is just printed for any unknown key,
such as '?'.

Added some omitted sysrq key entries in the sysrq.txt file.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sysrq SAK is described as being something you should mistake for SAK from
c2 compliant systems - whoops.  What's meant is that it should *not* be
mistaken as such.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

This patch for 2.4.x updates the dead email address for 'Mydraal'
and since he no longer wishes to field questions concerning
SysRq or this document removes the statement stating otherwise.

Signed-off-by: Adrian Bunk <bunk@stusta.de>

This patch contains the most trivial from Rusty's trivial patches:
- spelling fixes
- remove duplicate includes

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>