TRBMPAM_EL1 Trace Buffer MPAM Configuration Register TRBMPAM_EL1 is in the Core power domain when FEAT_TRBE_EXT is implemented and FEAT_TRBE_MPAM is implemented TRBE 0x040 TRBMPAM_EL1 When DoubleLockStatus(), or !IsCorePowered(), or OSLockStatus(), or !AllowExternalTraceBufferAccess(addrdesc) ERROR RW TRBMPAM_EL1 Architectural AArch64 63 0 63 0 63 0 63 0 Defines the PARTID, PMG, and MPAM_SP values used by the trace buffer unit in external mode. TRBE TRBMPAM_EL1 is a 64-bit register. 63 27 63:27 Reserved, RES0. EN 26 26 26 Enable. Enables use of non-Default MPAM values. This field is ignored by the PE when SelfHostedTraceEnabled() == TRUE. 0b0 Use Default physical PARTID and Default physical PMG values, and the PARTID space corresponding to the trace physical address space defined by TRBMAR_EL1.PAS. 0b1 Use TRBMPAM_EL1.{PARTID, PMG, MPAM_SP}. '0' MPAM_SP 25 24 25:24 Partition Identifier space. Selects the PARTID space. If the Trace Buffer Unit is using external mode and either TRBMPAM_EL1.MPAM_SP is set to reserved value, or the IMPLEMENTATION DEFINED authentication interface prohibits invasive debug of the Security state corresponding to the Partition Identifier space selected by TRBMPAM_EL1.MPAM_SP, then when the Trace Buffer Unit receives trace data from the trace unit, it does not write the trace data to memory and generates a trace buffer management event. The interface prohibits invasive debug of the Security state if any of the following apply: ExternalInvasiveDebugEnabled() == FALSE. Secure state is implemented, ExternalSecureInvasiveDebugEnabled() == FALSE and TRBMPAM_EL1.MPAM_SP is 0b00. FEAT_RME is implemented, ExternalRootInvasiveDebugEnabled() == FALSE, and TRBMPAM_EL1.MPAM_SP is 0b10. FEAT_RME is implemented, ExternalRealmInvasiveDebugEnabled() == FALSE, and TRBMPAM_EL1.MPAM_SP is 0b11. This field is ignored by the PE when SelfHostedTraceEnabled() == TRUE. 0b00 PARTID is in the Secure PARTID space. When FEAT_Secure is implemented 0b01 PARTID is in the Non-secure PARTID space. 0b10 PARTID is in the Root PARTID space. When FEAT_RME is implemented 0b11 PARTID is in the Realm PARTID space. When FEAT_RME is implemented AU PMG 23 16 23:16 Performance Monitoring Group. Selects the PMG. Only sufficient low-order bits are required to represent the TRBDEVID1.PMG_MAX. Higher-order bits are RES0. This field is ignored by the PE when SelfHostedTraceEnabled() == TRUE. AU PARTID 15 0 15:0 Partition Identifier. Selects the PARTID. Only sufficient low-order bits are required to represent the TRBDEVID1.PARTID_MAX. Higher-order bits are RES0. This field is ignored by the PE when SelfHostedTraceEnabled() == TRUE. AU The PE might ignore a write to TRBMPAM_EL1 if any of the following apply: TRBLIMITR_EL1.E is 1 and the Trace Buffer Unit is using Self-hosted mode. TRBLIMITR_EL1.XE is 1 and the Trace Buffer Unit is using External mode. 2026-03-26 20:27:25 2026-03_rel