Magic Sysreg key problems.

[Rick Stevens]

On 08/20/2012 02:27 PM, Aaron Konstam uttered this comment:
> On Mon, 2012-08-20 at 13:20 -0700, Rick Stevens wrote:
>> On 08/20/2012 01:05 PM, Joe Zeff uttered this comment:
>>> On 08/20/2012 12:55 PM, Aaron Konstam wrote:
>>>> It is hard to know where to start with the problems with the use of the
>>>> SysReg key.. Since acording to the Wikipedia notes in order to get these
>>>> Magic SysReg features to work you have tp add the Ctrl button. So to
>>>> reboot you would have to use the Ctrl+Alt+SysReg+ b button. On my
>>>> workstation Keyboard this is nearly impossible to do because of the
>>>> position of the SysReg key in the upper right corner of the keyboard.
>>>> On my laptop where I can hit the keys the function fails to work.
>>>> Without the Ctrl all you get is screen shots which I do get.
>>>>
>>>> With the alternate approach  of:
>>>> echo key > /proc/sysreq-trigger the reboot works but I can't detect
>>>> anything else working.
>>>>
>>>> So how does one use these magic keys ?
>>>>
>>>
>>> I can't speak for anybody else, but when I've experimented with it, I
>>> used both hands.
>>
>> It's supposed to be a simultaneous press of ALT, SYSRQ (or PRINTSCREEN)
>> and the command key (B in your case). Note it only works if
>> /proc/sys/kernel/sysrq contains a non-zero value. To enable ALL
>> functionality, first set /proc/sys/kernel/sysrq to the value "1":
>>
>> 	echo "1" >/proc/sys/kernel/sysrq
>>
>> Then hit your key combo. Some keyboards may have issues with so many
>> simultaneous keypresses. In those cases hold down ALT, then press and
>> release SYSRQ, then press and release your command key and finally
>> release ALT.
>>
>> It's been a while since I futzed with it. If you have the kernel-doc
>> RPM installed, it's explained in
>>
>> 	/usr/share/doc/kernel-doc-(version)/Documentation/sysrq.txt
> I appreciate all these tips but none make the sysrq suctions work. I'll
> just give up.

Worked for me on my Dell laptop.  Process:

	1. Did 'echo "1" >/proc/sys/kernel/sysrq'
	2. Held down left-ALT, held down PRNTSCR, pressed "h"
	3. Released all three keys
	4. Ran "dmesg" and saw this:

[111065.967134] SysRq : HELP : loglevel(0-9) reBoot Crash 
terminate-all-tasks(E) memory-full-oom-kill(F) kill-all-tasks(I) 
thaw-filesystems(J) saK show-backtrace-all-active-cpus(L) 
show-memory-usage(M) nice-all-RT-tasks(N) powerOff show-registers(P) 
show-all-timers(Q) unRaw Sync show-task-states(T) Unmount force-fb(V) 
show-blocked-tasks(W) dump-ftrace-buffer(Z)

	5. Did 'echo "0" >/proc/sys/kernel/sysrq' to disable SYSRQ.

Fully updated F17, 3.5.2-1.fc17.x86_64, XFCE and xfwm4 window manager.
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- Rick Stevens, Systems Engineer, AllDigital    ricks at alldigital.com -
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-   To err is human.  To forgive, a large sum of money is needed.    -
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