TRBPTR_EL1 | Jon's Arm Reference

External register TRBPTR_EL1 bits [63:0] are architecturally mapped to AArch64 System register TRBPTR_EL1[63:0].

This register is present only when FEAT_TRBE_EXT is implemented. Otherwise, direct accesses to TRBPTR_EL1 are RES0.

Attributes

Field descriptions

PTR, bits [63:0]

Trace Buffer current write pointer address.

Defines the virtual address of the next entry to be written to the trace buffer.

If PMBIDR_EL1.Align is not zero, then it is IMPLEMENTATION DEFINED whether bits [M-1:0] are RES0 or read/write, where M is an integer between 1 and PMBIDR_EL1.Align inclusive.

The architecture places restrictions on the values that software can write to the pointer. For more information see 'Restrictions on Programming the Trace Buffer Unit'.

The reset behavior of this field is:

On a Cold reset, this field resets to an architecturally UNKNOWN value.

Accessing TRBPTR_EL1

The PE might ignore a write to TRBPTR_EL1 if any of the following apply:

TRBLIMITR_EL1.E == 0b1 and the Trace Buffer Unit is using Self-hosted mode.

TRBLIMITR_EL1.XE == 0b1 and the Trace Buffer Unit is using External mode.

TRBPTR_EL1 can be accessed through the external debug interface:

Component	Offset	Instance
TRBE	0x008	TRBPTR_EL1

Component

Offset

Instance

TRBE

0x008

TRBPTR_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.

63	62	61	60	59	58	57	56	55	54	53	52	51	50	49	48	47	46	45	44	43	42	41	40	39	38	37	36	35	34	33	32
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
PTR
PTR

TRBPTR_EL1: Trace Buffer Write Pointer Register

Purpose

Configuration

Attributes

Field descriptions

PTR, bits [63:0]

Accessing TRBPTR_EL1

TRBPTR_EL1 can be accessed through the external debug interface:

63	62	61	60	59	58	57	56	55	54	53	52	51	50	49	48	47	46	45	44	43	42	41	40	39	38	37	36	35	34	33	32
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
PTR
PTR

63	62	61	60	59	58	57	56	55	54	53	52	51	50	49	48	47	46	45	44	43	42	41	40	39	38	37	36	35	34	33	32
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
PTR
PTR

63	62	61	60	59	58	57	56	55	54	53	52	51	50	49	48	47	46	45	44	43	42	41	40	39	38	37	36	35	34	33	32
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
PTR
PTR