TRBTRG_EL1: Trace Buffer Trigger Counter Register

Purpose

Specifies the number of bytes of trace to capture following a Detected Trigger before a Trigger Event.

External register TRBTRG_EL1 bits [63:0] are architecturally mapped to AArch64 System register TRBTRG_EL1[63:0].

TRBTRG_EL1 is in the Core power domain.

This register is present only when FEAT_TRBE_EXT is implemented. Otherwise, direct accesses to TRBTRG_EL1 are RES0.

TRBTRG_EL1 is a 64-bit register.

Reserved, RES0.

Trigger count.

Specifies the number of bytes of trace to capture following a Detected Trigger before a Trigger Event.

TRBTRG_EL1 decrements by 1 for every byte of trace written to the trace buffer when all of the following are true:

The architecture places restrictions on the values that software can write to the counter.

Note

As a result of the restrictions an implementation might treat some of TRG[M:0] as RES0, where M is defined by TRBIDR_EL1.Align.

The reset behavior of this field is:

The PE might ignore a write to TRBTRG_EL1 if any of the following apply:

Component	Offset	Instance
TRBE	0x020	TRBTRG_EL1

This interface is accessible as follows:

When DoubleLockStatus(), or !IsCorePowered(), or OSLockStatus() or !AllowExternalTraceBufferAccess(), accesses to this register generate an error response.
Otherwise, accesses to this register are RW.