Model No: A1181 (EMC 2139) also referred to by Mid-2007 when it finds a GPT disk (intern or extern via usb) with a EFI-System partition code EF00 in Fat32 format. The boat loader (e.g. GRUB2 2.00) must be stored at the EFI-System partition at /EFI/BOOT/bootia32.efi It does not require any MAC-formated partition, nor rEFIt, nor rEFInd I had to prepare the disk partitions before the system installation and manually install the boot loader after the system installion. Both is possible with e.g. Trisquel LiveCD (via the optical drive or a prepared usb device) It seems that Apple made the box wait some seconds when it doesn't find any OSX boat loader. This anti-feature lasted about 30 seconds in the first place. at some point it went down to about 5 seconds. Anyway pressing "alt" makes the boot manager menu appear almost immidiately. There you can choose to load any available boot loader (e.g. from intern hard disk and possibly in addition from a usb device pluged in) Although the boot loader must be 32-bit, it can load either 32-bit or 64-bit kernel! since there is no free firmware availble for the kernel to load. I am not sure about whether it accepts a Trisquel LiveCD since the optical drive in my box is somewhat broken and i had to go via an usb drive/pen For the graphics to work best i added the most recent kernel from http://jxself.org/linux-libre/ and the most recent Intel graphics driver from https://01.org/linuxgraphics/