Re: [tlug] troubleshooting lockup

["Josh Glover" <jmglov@example.com>]

On 08/09/06, stephen@example.com <stephen@example.com> wrote:

> Magic SYSREQ key to the rescue!

Yeah. I mentioned this to Mike at the last meeting, but the thing to
do when your Linux box locks up is to promptly press the Ctrl, Alt,
and SysRq (also known as Print Screen on most keyboards) keys, and,
holding them down, type the following key sequence:

e (pause for a few seconds)   # send SIGINT to all processes
i (pause for a few seconds)  # send SIGTERM to all processes
s (pause for a few seconds)  # sync the kernel's buffers to disk
u (pause for a few seconds)  # unmount filesystems
b  # reboot the computer

Of course, in order for this to work, you will need to make sure that
your kernel was compiled with the CONFIG_MAGIC_SYSRQ option. Simply:

grep CONFIG_MAGIC_SYSRQ /usr/src/linux/.config

If you don't see a line saying:

CONFIG_MAGIC_SYSRQ=y

You need to run "make menuconfig" (or "make xconfig" if you prefer),
then select "Kernel hacking" from the top-level menu. Select "Kernel
debugging" if it is not already, then "Magic SysRq key" (which will
appear when you turn on "Kernel debugging"). Save and exit, then
recompile your kernel.

-Josh