UEFI
UEFI
Unified Extensible Firmware Interface (UEFI) is a specification that defines the software interface between an operating system and the platform firmware. It was designed to replace the legacy Basic Input/Output System (BIOS) interface, providing a more flexible and modern environment for booting a computer and for pre‑operating system tasks. UEFI supports a graphical user interface, networking capabilities, and a modular driver architecture, and it can run on both 32‑bit and 64‑bit processor architectures.
UEFI is managed by the UEFI Forum, an industry consortium that includes companies such as AMD, American Megatrends, Apple, Dell, Hewlett‑Packard, IBM, Insyde Software, Intel, Lenovo, Microsoft, and Phoenix Technologies. The specification was originally known as the Intel Boot Initiative and later renamed EFI before being adopted as the UEFI standard.
History
The development of EFI began in the mid‑1990s by Intel for use in its Itanium‑based systems, as the traditional BIOS could not scale to the 64‑bit environment. The first EFI specification (version 1.0) was released in 1999, followed by version 1.10 in 2000. In 2005, the specification was transferred to the Unified EFI Forum, which published the first unified UEFI specification (version 2.0) in 2006. Subsequent revisions have added features such as Secure Boot, network boot (PXE), and support for larger disk partitions (GPT).
Features and benefits
- Graphical user interface: UEFI firmware can provide a rich graphical interface before the operating system loads, allowing mouse support and advanced configuration options.
- Secure Boot: A security mechanism that ensures only signed and trusted bootloaders, drivers, and operating systems can be executed during the boot process.
- Support for GPT: UEFI works with the GUID Partition Table, overcoming the 2.2 TB limit of the legacy Master Boot Record (MBR) and allowing up to 128 partitions on a disk.
- Modular architecture: UEFI drivers can be loaded from separate device firmware, enabling support for new hardware without requiring changes to the main system firmware.
- Network capabilities: Provides built‑in network boot (Preboot Execution Environment) and the ability to access remote storage over a network.
- Fast boot: UEFI can initialize hardware in parallel and bypass certain legacy compatibility steps, reducing the time to load the operating system.
- Compatibility Support Module ( 0 ): Many UEFI implementations include a CSM that emulates a legacy BIOS, allowing older operating systems to boot on UEFI systems.
Adoption and compatibility
Since around 2012, most consumer computers have shipped with UEFI firmware instead of a traditional BIOS. Microsoft required UEFI and Secure Boot for systems running Windows 8 and later. Many Linux distributions also support UEFI booting, often using a small EFI system partition (ESP) formatted with a FAT32 file system. Despite the widespread adoption, some legacy operating systems and boot tools require the CSM for compatibility.