When users wish to list and manually choose from all available boot volumes, holding the options key down will display locally bootable volumes. Some users have noticed that this boot menu has started displaying other boot options than the desired and expected ones.
Apple Discussions poster Richard Pini writes:
"I have two volumes on [my computer]; one large ('Macbook') with all my work, etc. on it, and one small ('Rescue')...When I hold down the option key to switch between boot volumes, my choices are now 'EFI Boot' (instead of 'Macbook') and 'Rescue', even though in the finder, 'Macbook' shows up normally."
This change seems to have occurred as a result of some modification to the volume structure on the drive. For the most part, this issue has occured upon restoring a clone of the hard drive after upgrading the drive to a larger one, specifically when users move their internal drives to an external drive enclosure, then clone the data to new hardware installed in the computer.
Despite the "EFI Boot" name showing in the boot menu options, volumes can boot normally, and the drive will appear with the proper name in the Finder. As such, users might safely opt to do nothing; however, users might try the following to prevent the name change.
Try a different cloning scheme While cloning should be a bit-for-bit transfer, it is possible that small differences in the drive structure can be overlooked by cloning software in certain situations. As such, users might try alternate cloning methods, such as the following:
- Clone to a temporary external disk, then replace the internal disk and clone back.
- Put the new disk in an external enclosure and clone to it, then replace the internal disk with the newly cloned one.
Use a disk utility to repair the drive Obtain a copy of "TechTool Pro", "Drive Genius", or "DiskWarrior" and perform a repair on the drive. Users can try running the verification routine available via "Disk Utility", but this has generally not been as in depth of a scan as third-party disk utility software.
Change the default startup disk in the System Preferences This may not do the trick, but users can try changing or reassigning the default startup volume in the "Startup Disk" system preferences. This might have an effect on firmware settings which could be displaying the volume name in the boot menu.
Reset the PRAM PRAM holds some boot information, and as such users might benefit from a PRAM reset. To do this, reboot the system and hold the options-command-P-R keys all at once until the system goes through a few reset cycles, and then release the keys and allow the computer to boot normally.Reformat Along with trying different cloning schemes as described in the first suggestion, users might try using Disk Utility to erase all partitions on the drive. This can be done by loading the disk into Disk Utility, and then selecting the disk device (not the volume itself), choose "0 partitions" from the drop down menu in the "Partitions" tab.