The original motivation for EFI came during early development of the first Intel–HP Itanium systems in the mid-1990s. BIOS limitations (such as 16-bit real mode, 1 MB addressable memory space, assembly language programming, … 詳細

The interface defined by the EFI specification includes data tables that contain platform information, and boot and runtime services that are available to the OS loader and OS. UEFI … 詳細

Services
EFI defines two types of services: boot services and runtime services. Boot services are available … 詳細

SEC – Security Phase
This is the first stage of the UEFI boot but may have platform specific binary code that precedes it. (e.g., 詳細

Processor compatibility
As of version 2.5, processor bindings exist for Itanium, x86, x86-64, ARM (AArch32) and ARM64 (AArch64). Only little-endian processors can be … 詳細

UEFI machines can have one of the following classes, which were used to help ease the transition to UEFI:
• Class 0: Legacy BIOS
• Class 1: UEFI with a CSM interface and no external UEFI interface. The only UEFI interfaces are internal to … 詳細

Implementations
Intel's implementation of EFI is the Intel Platform Innovation Framework, codenamed Tiano. Tiano … 詳細