docs/design/firmware-design.rst

55 -  Boot Loader stage 3-2 (BL32) *Secure-EL1 Payload* (optional)
227        SYS_LED[2:1] - Exception Level (EL3=0x3, EL2=0x2, EL1=0x1, EL0=0x0)
314 #. BL1 passes control to the BL2 image at Secure EL1 (for AArch64) or at
320 BL1 loads and passes control to BL2 at Secure-EL1 (for AArch64) or at Secure
329 for subsequent stages of TF-A and normal world software. EL1 and EL0 are given
386 AArch64 BL32 (Secure-EL1 Payload) image load
395 Secure-EL1 Payload Dispatcher (see later) within BL31, which is responsible for
431 as its only purpose is to ensure TF-A BL2 is entered at S-EL1. To avoid
550 AArch64 BL32 (Secure-EL1 Payload) image initialization
553 If a BL32 image is present then there must be a matching Secure-EL1 Payload
566 EL3 Runtime Software initializes the EL2 or EL1 processor context for normal-
570 at the highest available Exception Level (EL2 if available, otherwise EL1).
847 #. Secure-EL1 Payload Dispatcher service
849    If a system runs a Trusted OS or other Secure-EL1 Payload (SP) then
850    it also requires a *Secure Monitor* at EL3 to switch the EL1 processor
851    context between the normal world (EL1/EL2) and trusted world (Secure-EL1).
856    The interface between the EL3 Runtime Software and the Secure-EL1 Payload is
858    Secure-EL1 Payload requires a specific Secure Monitor that runs as a runtime
859    service - within TF-A this service is referred to as the Secure-EL1 Payload
862    TF-A provides a Test Secure-EL1 Payload (TSP) and its associated Dispatcher
1064 and power feature settings, enabling access to PMU registers at EL1
1073 Secure-EL1 Payloads and Dispatchers
1076 On a production system that includes a Trusted OS running in Secure-EL1/EL0,
1083 TF-A uses a more general term for the BL32 software that runs at Secure-EL1 -
1084 the *Secure-EL1 Payload* - as it is not always a Trusted OS.
1086 TF-A provides a Test Secure-EL1 Payload (TSP) and a Test Secure-EL1 Payload
1095 The TSP runs in Secure-EL1. It is designed to demonstrate synchronous
1096 communication with the normal-world software running in EL1/EL2. Communication
1115 The Secure-EL1 Payload Dispatcher (SPD) service is responsible for initializing
1146    Secure-EL1. BL31 will exit to BL32 using the asynchronous method by
1149    When the BL32 has completed initialization at Secure-EL1, it returns to
1159    invoke a 'world-switch synchronous call' to Secure-EL1 to run the BL32
1237 reports the general purpose, EL3, Secure EL1 and some EL2 state registers.
2836    EL2/EL1 (MTE2) does require EL3 enablement and we need to set this option