Tag Archive for 'gptsync'

Fedora, Macs and EFI

When installing Linux beside OS X, Fedora toggles the boot flag on for its partition. This causes GPT to see it as an “EFI boot partition,” rather than “Basic Data”. This appears to cause a problem if you want to triple boot with Windows and under OS X the disk utility will see it as one whole partition, with the Linux half missing.

To fix this, toggle the boot flag to off using parted and then sync the GPT partition table to the master boot record partition table. It’s easiest to do this while the installer’s running (switch to TTY2) else you’ll have to install anaconda under your install to get gptsync (or run it from the rEFIt menu).

Simply run the following:
parted /dev/sda
toggle 3 boot
gptsync /dev/sda

The gptsync command should spit out the “Current GPT partition table” which should show something like:
EFI System (FAT)
Basic Data
Basic Data (if you have a fourth partition for Windows)

The “Proposed new MBR partition table” should show something like:
EFI Protective
FAT32 (LBA) (or NTFS, depending if it's already been formated)

Now Windows should install cleanly on the fourth partition (if you’re doing that) and the partition structure under OS X should be correct.