Comment 23 for bug 338083

it needs to go at the end of the kernel command line (in /boot/grub/menu.lst)

rather than editing the menu file each time, you can press e on the grub screen that offers you boot choices, then select the line with the kernel and press e again, and add the reboot parameter.

I've tried many variations of the reboot parameter on my macbook pro 5,1 - none work for me.