From http://www.cyberciti.biz/tips/reboot-linux-box-after-a-kernel-panic.html
To reboot automatically after a kernel panic, add kernel.panic = N
to /etc/sysctl.conf.
This specifies the kernel behaviour on a panic. By default, the kernel will not reboot after a panic, but this option will cause a kernel reboot after N seconds. For example following boot parameter will force to reboot Linux after 10 seconds:
kernel.panic = 10
You may want to enable and use magic system request keys (SysRq).