EFI
The Extensible Firmware Interface (EFI) is a specification that defines a software interface between an operating system and platform firmware. EFI is intended as a significantly improved replacement of the old legacy BIOS firmware interface historically used by all IBM PC-compatible personal computers. The EFI specification was originally developed by Intel, and is now managed by the Unified EFI Forum and is officially known as Unified EFI (UEFI).
Services
EFI defines boot services, which include text and graphical console support on various devices, bus, block and file services, and runtime services, such as date, time and NVRAM services.
Device drivers
In addition to standard architecture-specific device drivers, the EFI specification provides for a processor-independent device driver environment, called EFI Byte Code or EBC. System firmware is required by the UEFI specification to carry an interpreter for any EBC images that reside in or are loaded into the environment. In that sense, EBC is similar to Open Firmware, the hardware-independent firmware used in PowerPC-based Apple Macintosh and Sun Microsystems SPARC computers, amongst others.
Some architecture-specific (non-EBC) EFI device driver types can have interfaces for use from the operating system. This allows the OS to rely on EFI for basic graphics and network support until OS specific drivers are loaded.
Boot manager
An EFI boot manager is also used to select and load the operating system, removing the need for a dedicated boot loader mechanism (the OS boot loader is an EFI application).
Tags: EFI
