For SysRq, we just can get hot key list from Documentation/sysrq.txt

, but in the most of cases, the user can't access it by hand on

using SysRq to debug, so it is better for SysRq to provide an online

help for the users.
SysRq has already provided a similiar help before this patch, but it

is not so definite that the user doesn't know what happened and how

to do on pressing an undefined hot key.
In addition, that funtion has a big loop with another big loop

embedded which is very inefficient, it is intended to skip some hot

key help info for such a function as "Changing Loglevel", just print

a help info for this, that is very unnecessary. In fact, the key '0'

 - '8' have different results the user should know.
This patch add this online help function, it'll print thw whole hot

key list and corresponding function descriptions, it can print the new

defined hot key without any changed needed.
The output is the below on pressing an undefined hot key:
SysRq : <6>this hot key isn't defined.
SysRq Help Information:
  Hot Key      Function Description

===========    ====================

ALT+SysRq+0    Changing Loglevel to this value

ALT+SysRq+1    Changing Loglevel to this value

ALT+SysRq+2    Changing Loglevel to this value

ALT+SysRq+3    Changing Loglevel to this value

ALT+SysRq+4    Changing Loglevel to this value

ALT+SysRq+5    Changing Loglevel to this value

ALT+SysRq+6    Changing Loglevel to this value

ALT+SysRq+7    Changing Loglevel to this value

ALT+SysRq+8    Changing Loglevel to this value

ALT+SysRq+9    Changing Loglevel to this value

ALT+SysRq+a    Not defined

ALT+SysRq+b    Resetting

ALT+SysRq+c    Trigger a crashdump

ALT+SysRq+d    Not defined

ALT+SysRq+e    Terminate All Tasks

ALT+SysRq+f    Manual OOM execution

ALT+SysRq+g    Not defined

ALT+SysRq+h    Not defined

ALT+SysRq+i    Kill All Tasks

ALT+SysRq+j    Not defined

ALT+SysRq+k    SAK

ALT+SysRq+l    Not defined

ALT+SysRq+m    Show Memory

ALT+SysRq+n    Nice All RT Tasks

ALT+SysRq+o    P...
[ message continues ]

This will scroll out of users view on small terminals.
Plus this is practically guaranteed to get out of sync with

reality. If you did this to make sysrq printing faster... then that is

very bad optimization.

									Pavel

--

(english) http://www.livejournal.com/~pavelmachek

(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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This char array is just for output, thees are jsut the keys sysrq has

defined, in the current

design of sysrq, to add a new key is not easy unless you use an existed

but unused key,

so this has no problem.
SysRq is just for debugging or emergent handling, so this array is

impossible to result in

any bad effects, it is just for convenience.
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^^^
It does not make any sense to put the printk level just before the

newline, since the newline resets it to the default level.
Andreas.
--

Andreas Schwab, SuSE Labs, schwab@suse.de

SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany

PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5

"And now for something completely different."

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