Recovering from a hard X lock up

[David L]

On Mon, Aug 10, 2009 at 4:39 AM, Tim wrote:
> On Mon, 2009-08-10 at 10:39 +0100, James Allsopp wrote:
>> My Fedora 10 machine locks up X completely, but I can still login via
>> SSH. The monitor still shows the X window, but nothing changes, no
>> clock, mouse nothing. X processes are still running, but not sure how to
>> go about shutting them down. Last night, I tried to get the system to
>> shut down sanely by running shutdown -h now and although the command ran
>> and I couldn't login via ssh anymore, the machine did not shut down.
>>
>> Can anyone tell me how to shutdown and restart X properly. Tried things
>> like startx( had a x lock file exists error) and init 3, but nothing worked.
>
> If X hadn't completely locked up, CTRL+ALT+BACKSPACE would have
> restarted X (that is BACKSPACE, the delete key that deletes to the left,
> not the DEL key that deletes to the right).
>
> If the keyboard was still being listened to, then CTRL+ALT+DEL should
> have rebooted (perhaps after hammering away at the keys a lot), as a
> second option instead of CTRL+ALT+BACKSPACE.

<snip>
I've seen similar symptoms ... for me, the keyboard is usually
dead I think, so any recovery procedure would have to be done
remotely through an ssh session.  I'm not sure if it's a valid way
to tell for sure, but I usually try the caps lock/num lock to see if
the little lights toggle to see if the keyboard is dead.  Whenever
they don't toggle, control-alt-* hasn't worked for me.  Even the
sys rq REISUB trick did nothing.  I've never tried unplugging
the USB keyboard and plugging it back in... I wonder if that could
help recover the keyboard.

Even if control-alt-backspace did work, my understanding was
that it was disabled by default in f11, but the poster was running
f10, so that's not his problem.

Regards,

            David