Magic SysRq REISUB reacts but does not work

Questions about other topics - please check if your question fits better in another category before posting here
Forum rules
Before you post please read how to get help
slafochmed
Level 1
Level 1
Posts: 1
Joined: Wed Sep 18, 2013 11:07 am

Magic SysRq REISUB reacts but does not work

Postby slafochmed » Wed Sep 18, 2013 11:23 am

Hi all.
I am testing on the Magic SysRq REISUB key sequence to recover from problematic situations.
It is really paradox:
I am using Version 15 KDE and everything is working fine. On the desktop, I can go to Leave > restart and it works fine.
But, when using the Magic SysRq REISUB, the system reacts and seems to restart, but after 3 seconds, my screen does not get any signals and gets into "no signal" mode. After that, nothing happens. Trying REISUB again does not work. I have to switch off and on the hardware.
I am using a macmini on Intel, it makes that sound when restarting, it does so when doing REISUB.
I have a wireless keyboard that works out of the box, but cannot activate screen or do second REISUB after first REISUB.
I tried reconnecting the video cable but nothing helps.

When I do the normal desktop reboot, it works. I get a black screen, then white, then black again, but HERE is when REISUB behaves differently: I get the no signal screen, otherwise, with normal reboot, I see a cursor on the top left, then the KDE logo and the desktop loads.

I have looked and search for this problem but did not find anything like this. This is strange.
Anyone who can suggest what this could be? :?

deminted
Level 1
Level 1
Posts: 20
Joined: Thu Jan 12, 2012 4:34 pm

Re: Magic SysRq REISUB reacts but does not work

Postby deminted » Sun Sep 29, 2013 9:25 pm

It seems that someone (and their committee) thought is was a good idea to disable many of the useful things that one might use to recover from difficult situations.
It's the same crass mindset that had someone else remove the ability to switch off JavaScript easily in current Firefox (24.0).

So, first thing I do is go to System Settings, Regional settings, [Layouts], hit the button [Options...] (tucked away lower right), and tick the box for "Key Sequence to Kill the X-server". Go figure.

{Key sequence to kill the twerp who removed this as a default, I'm thinking. :roll: }

Then, back on topic,

Code: Select all

echo 1 | sudo tee /proc/sys/kernel/sysrq


That isn't quite enough, now you need to go to file /etc (in File System)
open sysctl.d using 'open as root'
edit 10-magic-sysrq.conf
comment out the ridiculous default, replace it with the code to allow all sensible 'magic' keys
("1 - enable all functions of sysrq". You might like to give it extra thought. I don't.)

Code: Select all

#kernel.sysrq = 127
kernel.sysrq = 1

save it, and remember to come out of elevated priviledges.

There, that was easy & intuitive, wasn't it? :evil:

Now you have a chance to rescue matters that go awry.

I wonder who thought it was a good idea to remove the safety net? And who the hell agreed with them.
At least they left us with ctrl+F2, r {probably an oversight?}

wayne128
Level 10
Level 10
Posts: 3418
Joined: Tue Jul 13, 2010 12:15 am

Re: Magic SysRq REISUB reacts but does not work

Postby wayne128 » Sun Sep 29, 2013 9:36 pm

deminted wrote:
There, that was easy & intuitive, wasn't it? :evil:


Now you have a chance to rescue matters that go awry.

I wonder who thought it was a good idea to remove the safety net? And who the hell agreed with them.
At least they left us with ctrl+F2, r {probably an oversight?}


:lol: :mrgreen: I like that highlighted sentence. :mrgreen:
I have never had success on using the magic key sequence.
so i live with whatever Linux distros 'offered'
all I do is use external means to boot the computer (RIPLinux, various Linux on Live DVD or Live USB, or even portable USB flash with Linux) and repair, or at time, sick of repair, replace. :lol:


Return to “Other topics”

Who is online

Users browsing this forum: AscLinux, Kardosh and 3 guests