Info tidbit on Kernel Panic

from the Mint forums:

You finally got your Linux environment to crash. Ctrl+Alt+Backspace does nothing, nor do the F-keys. You know you shouldn't have installed that bad driver, but you did it anyway.

So you reach for the power button.

Stop.

Mashing in the power button to reboot could cause a problem if your hard drive is still being written to, and usually causes more problems than it solves. The Linux kernel includes a secret method of restarting your PC should it ever stop doing its job.

1. Hold down the Alt and SysRq (Print Screen) keys.
2. While holding those down, type the following in order. Nothing will appear to happen until the last letter is pressed: REISUB
3. Watch your computer reboot magically.

What the individual keys do in that sequence are not as important as what it does as a whole: stops all programs, unmounts all drives, and reboots. A lot safer than just cutting the power.

 

Very nice info! I read somewhere about this a LONG time ago(or something like it), thanks for posting. +rep

 

Huh... Interesting and useful little easteregg, that...

Just for trivia's sake, don't suppose you know why it's "REISUB" specifically?

 

I wish I'd have know that when I got a kernel panic in Kubuntu..I reached for the ol' power buttom....I'm using Mint KDE 4.2 for the time being and haven't yet had that problem...cudda been a flaky disc, but this is pretty great so I might keep it

 

dunno...but when I see the letters REISxxx I think of our friend Hans Reiser in the Slam

 

I tried it, but all it did was bring up a whole bunch of "save screenshot" instances.
So I guess this is just for mint ? Mine was SLED 10

I usually try CTRL+ALT+Del or do CTRL+ALT+F2, login as root and do a reboot.

 

Here you go. REISUB is a good, safe combo. Just space them out around 5 seconds apart. H is the most useful one, provided it works.

 

It should be done through console, otherwise X steals the keypresses. Also, the Magic SysRq option has to be enabled in the kernel during compilation (why not?). Recall that this option was designed to help recover safely from a kernel failure, NOT TO REBOOT. The X server kill and virtual console change keys you mentioned assume a working system.

 

If I cannot get to a console through a CTRL_ALT_F2, how can I ensure X wont steal the keypresses ?

 

That's cool.. I'll try that next time. My kde's been really buggy. Whenever I want it to restart/shutdown, it'll just go to a black screen with nothing but my mouse. And it'll stay like that. That happens 9/10 times

I end up having to do Ctrl Alt BkSpc and rebooting from kdm

 

Well, if you're in kernel panic, odds are pretty much certain that your X is already dead. You should know it when you see it. All the kernel panics I've experience have always happened under X. The screen just freezes and nothing registers. Think of Windows BSOD, except without the BS.