Kernel Crash? Get the dying moans...

So you had a kernel crash, when you were not around, and could not see on the console what the issue was. Or it happened on a server, which has a hardware watchdog which reboots the machine if it has crashed. So here is a way to get the messages which the kernel spit out before dying...

First of all you need to have enabled kernel crashdumps... there is no reason not to. So you are all set and the next time a crash happens the core is saved in a file called vmcore. Now fire up GDB and run the following commands

(gdb) set logging file ~/gdb.out                                                      
(gdb) set logging on
Copying output to ~/gdb.out.
(gdb) set print elements 41216
(gdb) set height 0            
(gdb) p (char*)__log_buf

The file gdb.out will now contain the messages, open it in and replace all instances of '\n' with a real newline (using something like ":%s/\\n/\r/gc" in vim), and you will see something like this

<4>ide-floppy driver 0.99.newide
<6>usbcore: registered new driver hiddev
<6>usbcore: registered new driver usbhid
<6>drivers/usb/input/hid-core.c: v2.6:USB HID core driver
<6>PNP: PS/2 Controller [PNP0303:KBC0,PNP0f13:MSE0] at 0x60,0x64 irq 1,12

Happy Debugging! (I KNOW it wont be HAPPY :P)