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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.[1]

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.[2] 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 "Santa Rosa"-based models in either 32 or 64-bit mode before Intel was able to come up with its own official specification.[3]

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.[3] To protect against UEFI firmware attacks, Apple rearchitected the booting process of Intel-based Macs to place its root of trust in the Apple T2 security chip.[4]


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.[5][6] Mac boot volumes may still retain an EFI partition for backwards compatibility.[7]


  1. Extensible Firmware Interface at the Free On-Line Dictionary Of Computing. 2004-10-23.
  2. NetBSD/macppc Model Support, NetBSD. Accessed 2021-03-04.
  3. 3.0 3.1 A Brief History of Apple and EFI by Christoph Pfisterer, rEFIt. 2008-12-29.
  4. Mac models with the Apple T2 Security Chip, Apple Inc. 2021-02-13.
  5. Apple unleashes M1, Apple Inc. 2020-11-10.
  6. Apple Platform Security: Secure Enclave overview, Apple Support. Accessed 2020-11-10.
  7. Last Week on My Mac: There’s more to the M1 than speed by hoakley, The Eclectic Light Company. 2020-11-29.

External links[]

FOLDOC logo This page uses GFDL licensed content from the Free On-line Dictionary of Computing.