[arch-general] Debugging kernel panics (ATI Catalyst related?)

[Robbie Smith]

After the last updates, I was getting a kernel panic at reboot; 
hard-resetting and then powering on again and it seems to boot fine.

I suspect the problem has to do with the ATI Catalyst driver, as the 
panics occurred when rebooting after upgrading or downgrading the 
driver. I originally upgraded to 12.9, but rolled back to 12.8 after 
discovering that 12.9 broke my screen brightness keys. I also had to 
roll back Xorg to 1.12 because Catalyst doesn't support the new Xorg yet.

Both times I rebuilt the module and (just to be sure) the kernel image 
before rebooting. I rebuilt them again once the system was back up, 
rebooted, and it worked.

Any ideas how to debug, seeing as this just sort of popped up 
out-of-the-blue? If the kernel even logs a panic, where do I find it so 
I can figure out what caused it?