"Jailbreaking" a Mac

/EFI/boot/refind_ia32.efi ?> /EFI/boot/bootia32.efi

Steps

• Boot into a live CD
• Install rEFInd
• Setup system like normal

Requirements

• ISO2USB EFI Booter for Mac
• A Live CD with loopback support
  • xubuntu works well

Installation

• Ensure the ISO file will fit on your USB flash drive. Backup important content from your drive — it will be erased.
• Make one large partition on your USB flash drive, using e.g. (g)parted, (c)gdisk, or (c)fdisk. You can use either a GUID partition table (GPT — unless you’re using (c)fdisk) or an MSDOS/MBR partition table, both will work. Use “Microsoft basic data” (code 0700) as the partition type.
• Format the partition with FAT32. (g)parted can do this. Alternatively, you can type mkfs.vfat -F 32 /dev/sdX1 from the command line (after replacing the “X” with the correct letter for your USB drive). Formatting with HFS+, as some sources indicate, didn’t work for me.
• Mount your drive and cd into it (as root: # mkdir /mnt/usb && mount /dev/sdX1 /mnt/usb && cd /mnt/usb).
• Create the directory efi/boot/ in the current directory (# mkdir -p efi/boot/) — (i.e., the full path of this directory is /mnt/usb/efi/boot/ if your USB drive is mounted in /mnt/usb/).
• Copy either bootIA32.efi or bootX64.efi to the new directory (depending on whether you have a 32 or 64-bit system), and rename the file to boot.efi.
  • Old White Macbook needs bootIA32.efi
• Copy the downloaded LiveCD image to the new directory, and rename it to boot.iso.

That’s all. The USB drive now contains two directories and two files, and should boot. Make sure you used the file and directory names as provided here. For clarity, all that is now on your USB drive is (relative to the root directory of that drive): /efi/boot/boot.iso /efi/boot/boot.efi

In order to install Linux, I booted Kubuntu using the method described above, installed rEFInd from there, which then allowed me to boot from a normal Live USB flash drive. I ended up installing Arch Linux. The details and non-trivialities of the Linux installation will be described in a future post. I didn’t manage to install Linux without installing rEFInd though, so in retrospect I might as well have installed rEFInd on my new disc, mounted as an external disc to my other Linux computer.