3.3
Application Processor (AP) firmware
The AP firmware comprises ARM Trusted Firmware and a choice of either UEFI or U-Boot.
Note
The ARM deliverables only contain partial support for security and virtualization, and third-party
software vendors must work with the supplied software to integrate commercial trusted operating
systems and hypervisors, if required.
3.3.1
ARM Trusted Firmware
ARM Trusted Firmware provides a reference implementation of Secure World software for ARMv8-A,
including Exception Level 3 (EL3) software. It provides implementations of various ARM interface
standards, such as the
Power State Coordination Interface
(PSCI),
Trusted Board Boot Requirements
(TBBR) and Secure monitor code.
For more information on ARM Trusted Firmware, see
https://github.com/ARM-software/arm-trusted-
. You can obtain a validated source SHA by following the release code syncing instructions at
http://community.arm.com/groups/arm-development-platforms
.
The ARM Trusted Firmware code is designed for reuse or porting to other ARMv8-A model and
hardware platforms.
3.3.2
Unified extensible Interface Firmware (UEFI)
The
Unified Extensible Firmware Interface
(UEFI) is a boot firmware specification that the UEFI forum
maintains and develops. ARM is a member of the UEFI forum and contributes to the UEFI ARM
bindings.
Linaro provides an AArch64 implementation of this specification for ADPs, based on the EFI
Development Kit 2 (EDK2), available from Tianocore at
.
UEFI supports:
• Booting an Operating System from NOR Flash or USB mass storage.
• Ethernet and PXE boot.
• ACPI 5.1.
3.3.3
U-boot firmware
An alternative loader provided with certain pre-built Linaro image bundles that is used instead of UEFI.
The implementation is based on U-Boot from DENX, available from
http://www.denx.de/wiki/U-Boot
3 Firmware
3.3 Application Processor (AP) firmware
ARM DEN0928F
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3-28
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