Comment 2 for bug 469568

BTW, the reason I need this feature is so that I always have quick access to an emergency rescue system. I copied the contents of the Ubuntu installation DVD into /boot/rescue and then installed extlinux to boot this system. Extlinux is the preferable option as the installation DVD already uses isolinux which can trivially be converted to extlinux. In fact, I am surprised the installation disk doesn't come with instructions on how to do this.

I then tell Grub2 to add a menu entry to the boot entry which lets me start the rescue system instead of going through the normal boot process.

This comes in handy on a laptop as I am not normally in the habit of taking a rescue disk with me -- in fact, I don't even normally take the DVD drive with me. But always having access to a rescue disk is definitely very reassuring.