Creating a EFI partition

disk-utilityefihard drivepartition

I have been having trouble installing OS X Mavericks and I think I found the problem. It told me I couldn't boot up with Macintosh HD, so I verified my disk and I got this error: This disk doesn't contain an EFI system partition

So I figured out I can create one like this (tell me if I'm wrong): sudo gpt add -b 40 -i 1 -s 409600 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B disk0 from this question, but they also said the "index" must be 1, so I can't have anything at that index.

I ran diskutil list and this is the output:

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *250.1 GB   disk0
   1:                  Apple_HFS Macintosh HD            233.0 GB   disk0s1
   2:                 Linux Swap                         4.0 GB     disk0s2

So I need to figure out how to move the indexes of Macintosh HD and that Linux Swap thing to indexes 2 and 3 instead of 1 and 2.

I don't know if this can be done without wiping and formatting my hard drive which I don't want to do, but if it can I would love to know how. Thanks!

By the way I'm on OS X mountain lion

Best Answer

Usually EFI is on your Macintosh HD. It's likely still there, but not used due to messed up settings. This very easy to fix:

  • Boot into a Recovery partition, DVD, or USB drive. Using the installation media that came with your device will suffice.
  • Once loaded, you'll be presented an interface like:

Recovery Mode Utilities

  • Close this window, and you'll be prompted to choose between Startup disk, Cancel, and Restart.
  • Select Startup Disk. The mere act of opening this utility with run the appropriate bless command in the background, repairing your EFI setup.
  • Select Macintosh HD
  • Restart
  • Come back to Ask Different and up vote this successful answer :D
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