TRBIDR_EL1, Trace Buffer ID Register
The TRBIDR_EL1 characteristics are:
Describes constraints on using the Trace Buffer Unit to software, including whether the Trace Buffer Unit can be programmed at the current Exception level.
This register is present only when FEAT_TRBE is implemented. Otherwise, direct accesses to TRBIDR_EL1 are UNDEFINED.
TRBIDR_EL1 is a 64-bit register.
The TRBIDR_EL1 bit assignments are:
F, bit 
Flag Updates. Defines whether the address translation performed by the Trace Buffer Unit manages the Access Flag and dirty state. Defined values are:
Trace buffer address translation does not manage the Access flag and dirty state in translation tables.
Trace buffer address translation manages the Access Flag and dirty state in the same way as the MMU on this PE.
P, bit 
Programming not allowed. The trace buffer is owned by a higher Exception level or by the other Security state. Defined values are:
The owning Exception level is the current Exception level or a lower Exception level, and the owning Security state is the current Security state.
The owning Exception level is a higher Exception level, or the owning Security state is not the current Security state.
- If EL3 is implemented and either MDCR_EL3.NSTB == 0b00 or MDCR_EL3.NSTB == 0b01, meaning the owning Security state is Secure state, this bit reads as one from:
- Non-secure EL2.
- Non-secure EL1.
- If Secure EL2 is implemented and enabled, and MDCR_EL2.E2TB == 0b00, Secure EL1.
- If EL3 is implemented and either MDCR_EL3.NSTB == 0b10 or MDCR_EL3.NSTB == 0b11, meaning the owning Security state is Non-secure state, this bit reads as one from:
- Secure EL1.
- If Secure EL2 is implemented, Secure EL2.
- If EL2 is implemented and MDCR_EL2.E2TB == 0b00, Non-secure EL1.
- If EL3 is not implemented, EL2 is implemented, and MDCR_EL2.E2TB == 0b00, this bit reads as one from EL1.
- Otherwise, this bit reads as zero.
Align, bits [3:0]
All other values are reserved.
Accessing the TRBIDR_EL1
Accesses to this register use the following encodings:
MRS <Xt>, TRBIDR_EL1
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HDFGRTR_EL2.TRBIDR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else return TRBIDR_EL1; elsif PSTATE.EL == EL2 then return TRBIDR_EL1; elsif PSTATE.EL == EL3 then return TRBIDR_EL1;