I have a 13" MacBook Pro early 2011 model. It will not boot from any Linux USB boot disks I have created. I know these disks are working on later models as I have tried with 2012 Retina 15" booting and working fine.
I have tried using rEFInd and various Linux distros but none will be detected on the 2011 model. I found this post:
Can I boot Linux (any distro?) from USB on a MacBook Air that has no hard drive?
However I am not sure where I can get the EFI drivers as the ones on the apple site are .pkg format and doesnt seem to be anything I can extract to copy to /efi/boot?