Extensible Firmware Interface

Extensible Firmware Interface (EFI) is a set of specifications developed by Intel to define the interface between an operating system (OS) and platform firmware, aiming to reduce OS dependence on details of the firmware implementation.. 2004-10-23.
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==EFI in Intel-based Macs==
===EFI 1.x (32-bit)===
Apple phased out its previous use of Open Firmware in favor of EFI during its transition from PowerPC to Intel processors.NetBSD/macppc Model Support, NetBSD. Accessed 2021-03-04. The first Intel-based Mac was the MacBook Pro, introduced in January 2006 with a 32-bit implementation of the EFI 1.10 standard. In 2007, Apple unilaterally implemented a "fat" binary of EFI 1.10 to support booting on ""-based models in either 32 or 64-bit mode before Intel was able to come up with its own official specification.A Brief History of Apple and EFI by Christoph Pfisterer, rEFIt. 2008-12-29. 
===UEFI 2.x (64-bit)===
The Extensible Firmware Interface Development Kit (EDK) version 2 implemented Intel's updated Unified Extensible Firmware Interface (UEFI) specification, which formally adds 64-bit support. Apple began implementing UEFI 2.0 features along with EFI 1.10 in late 2008. To protect against UEFI firmware s, Apple rearchitected the booting process of Intel-based Macs to place its root of trust in the Apple T2 security chip.Mac models with the Apple T2 Security Chip, Apple Inc. 2021-02-13.
===Deprecation===
Starting in November 2020, Apple began phasing out its use of UEFI in favor of iBoot, which uses the Apple M1's built-in Secure Enclave.Apple unleashes M1, Apple Inc. 2020-11-10.Apple Platform Security: Secure Enclave overview, Apple Support. Accessed 2020-11-10. Mac boot volumes may still retain an EFI partition for backwards compatibility.Last Week on My Mac: There’s more to the M1 than speed by hoakley, The Eclectic Light Company. 2020-11-29.
==References==
==External links==
*UEFI firmware security in an Intel-based Mac at Apple Support (2021-02-18)
*EDK II UEFI at the ARM Community
* at Wikipedia
Category:Technical terminology