ARM Trusted Firmware

Terminology

Source: [1]

TEE

Trusted Execution Environment

OP-TEE

Open Portable Trusted Execution Environment [2]

EL0

Exception Level 0. Unprivileged (i.e. user space) runtime mode.

EL1

Exception Level 1. Standard OS (e.g. Linux) runtime mode.

EL3

Exception Level 3. "Secure world", trusted execution mode.

BL31

EL3 Runtime Firmware: AP_BL31

Also known as “SoC AP firmware” or “EL3 monitor firmware”. Its primary purpose is to handle transitions between the normal and secure world.

BL32

Secure-EL1 Payload (SP): AP_BL32

Typically this is a TEE or Trusted OS, providing runtime secure services to the normal world. However, it may refer to a more abstract Secure-EL1 Payload (SP).

External Links

• Official website [3]
• Official documentation [4]
  • Terminology [5]
• Official source code repository [6]
• Question on EL0/1/2/3 on ARMv8 [7]