I installed Ubuntu 10.04 to my MacBook Pro (not the latest gen with i7, but one before that) on an external, USB harddrive (GRUB installed to the external as well).
When I hold down the option key to try to select the external, it doesn't show up.
After some looking around, my understanding is that it won't boot 'unsupported' operating system from an external drive. I have ran OSX from an external when I upgraded my harddrive.
What can I do (or is it even possible) to allow my MacBook Pro to boot the Ubuntu drive?