The Extensible Firmware Interface(EFI) is a software interface between an operating system and the platform firmware. In contrast to the BIOS that takes 64kb space and uses a 16-bit processor mode, EFI takes 4MB, is written in 32-/64-bit and in theory positions itself as platform-independent. However, reality is different and achieving a full compatibility to all platforms is impossible.
Clover is an operating system boot loader for computers already equipped with an UEFI BIOS and for those not equipped. An operating systems(OS) may support EFI (OS X, Windows 7 64-bit, Linux) or not (Windows XP). Legacy boot is used for the last one, that is, the old BIOS system is used to handle boot sectors.
EFI is not only present during the booting of an OS, but it also creates tables and services that are accessible to the OS, and the operability of the OS depends on the correct functionality of EFI. It is not possible to boot OS X from the built-in UEFI. Neither is it possible to boot OS X with the original DUET. CloverEFI and CloverGUI take care of a great amount of tasks to correct the internal tables and provide a possibility to run OS X.
Last edited by Kuming Aoba, 2015-04-28 15:26:38