Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wirel...

[safe/jmp/linux-2.6] / Documentation / sysrq.txt

diff --git a/Documentation/sysrq.txt b/Documentation/sysrq.txt
index cf42b82..5c17196 100644 (file)
--- a/Documentation/sysrq.txt
+++ b/Documentation/sysrq.txt
@@ -66,7 +66,8 @@ On all -  write a character to /proc/sysrq-trigger.  e.g.:
 'b'     - Will immediately reboot the system without syncing or unmounting
           your disks.
 
-'c'    - Will perform a kexec reboot in order to take a crashdump.
+'c'    - Will perform a system crash by a NULL pointer dereference.
+          A crashdump will be taken if configured.
 
 'd'    - Shows all locks that are held.
 
@@ -141,8 +142,8 @@ useful when you want to exit a program that will not let you switch consoles.
 re'B'oot is good when you're unable to shut down. But you should also 'S'ync
 and 'U'mount first.
 
-'C'rashdump can be used to manually trigger a crashdump when the system is hung.
-The kernel needs to have been built with CONFIG_KEXEC enabled.
+'C'rash can be used to manually trigger a crashdump when the system is hung.
+Note that this just triggers a crash if there is no dump mechanism available.
 
 'S'ync is great when your system is locked up, it allows you to sync your
 disks and will certainly lessen the chance of data loss and fscking. Note
@@ -176,13 +177,13 @@ virtual console (ALT+Fn) and then back again should also help.
 
 *  I hit SysRq, but nothing seems to happen, what's wrong?
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-There are some keyboards that send different scancodes for SysRq than the
-pre-defined 0x54. So if SysRq doesn't work out of the box for a certain
-keyboard, run 'showkey -s' to find out the proper scancode sequence. Then
-use 'setkeycodes <sequence> 84' to define this sequence to the usual SysRq
-code (84 is decimal for 0x54). It's probably best to put this command in a
-boot script. Oh, and by the way, you exit 'showkey' by not typing anything
-for ten seconds.
+There are some keyboards that produce a different keycode for SysRq than the
+pre-defined value of 99 (see KEY_SYSRQ in include/linux/input.h), or which
+don't have a SysRq key at all. In these cases, run 'showkey -s' to find an
+appropriate scancode sequence, and use 'setkeycodes <sequence> 99' to map
+this sequence to the usual SysRq code (e.g., 'setkeycodes e05b 99'). It's
+probably best to put this command in a boot script. Oh, and by the way, you
+exit 'showkey' by not typing anything for ten seconds.
 
 *  I want to add SysRQ key events to a module, how does it work?
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~