AMCFGR

Provides information on supported features, the number of counter groups implemented, the total number of activity monitor event counters implemented, and the size of the counters. AMCFGR is applicable to both the architected and the auxiliary counter groups.

Configuration

External register AMCFGR bits [31:0] are architecturally mapped to AArch64 System register AMCFGR_EL0[31:0] when FEAT_AMU_EXT32 is implemented.

External register AMCFGR bits [63:0] are architecturally mapped to AArch64 System register AMCFGR_EL0[63:0] when FEAT_AMU_EXT64 is implemented.

External register AMCFGR bits [31:0] are architecturally mapped to AArch32 System register AMCFGR[31:0].

It is IMPLEMENTATION DEFINED whether AMCFGR is implemented in the Core power domain or in the Debug power domain.

This register is present only when FEAT_AMUv1 is implemented. Otherwise, direct accesses to AMCFGR are RES0.

Attributes

Field descriptions

When FEAT_AMU_EXT64 is implemented:

Bits [63:32]

NCG, bits [31:28]

Defines the number of counter groups implemented, minus one.

The value of this field is an IMPLEMENTATION DEFINED choice of:

NCG	Meaning
0b0000	One counter group implemented.
0b0001	Two counter groups implemented.

All other values are reserved.

Access to this field is RO.

Bits [27:25]

HDBG, bit [24]

Halt-on-debug supported.

This feature must be supported, and so this bit is 0b1.

The value of this field is an IMPLEMENTATION DEFINED choice of:

HDBG	Meaning
0b0	AMCR.HDBG is RES0.
0b1	AMCR.HDBG is read/write.

Access to this field is RO.

Bits [23:14]

SIZE, bits [13:8]

Defines the size of the activity monitor event counters, minus one.

The counters are 64-bit, so the value of this field is 0b111111.

This field is used by software to determine the spacing of the counters in the memory-map. The counters are at doubleword-aligned addresses.

Reads as 0b111111.

Access to this field is RO.

N, bits [7:0]

Defines the number of activity monitor event counters implemented in all groups, minus one.

This field has an IMPLEMENTATION DEFINED value.

Access to this field is RO.

Otherwise:

NCG, bits [31:28]

Defines the number of counter groups implemented, minus one.

The value of this field is an IMPLEMENTATION DEFINED choice of:

NCG	Meaning
0b0000	One counter group implemented.
0b0001	Two counter groups implemented.

All other values are reserved.

Access to this field is RO.

Bits [27:25]

HDBG, bit [24]

Halt-on-debug supported.

This feature must be supported, and so this bit is 0b1.

The value of this field is an IMPLEMENTATION DEFINED choice of:

HDBG	Meaning
0b0	AMCR.HDBG is RES0.
0b1	AMCR.HDBG is read/write.

Access to this field is RO.

Bits [23:14]

SIZE, bits [13:8]

Defines the size of the activity monitor event counters, minus one.

The counters are 64-bit, so the value of this field is 0b111111.

This field is used by software to determine the spacing of the counters in the memory-map. The counters are at doubleword-aligned addresses.

Reads as 0b111111.

Access to this field is RO.

N, bits [7:0]

Defines the number of activity monitor event counters implemented in all groups, minus one.

This field has an IMPLEMENTATION DEFINED value.

Access to this field is RO.

Accessing AMCFGR

Accesses to this register use the following encodings:

When FEAT_AMU_EXT64 is implemented

Accessible at offset 0xE00 from AMU

Accesses on this interface are RO.

When FEAT_AMU_EXT32 is implemented

Accessible at offset 0xE00 from AMU

Accesses on this interface are RO.

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
RES0
NCG				RES0			HDBG	RAZ										SIZE						N

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
NCG				RES0			HDBG	RAZ										SIZE						N

AMCFGR, Activity Monitors Configuration Register

Purpose

Configuration

Attributes

Field descriptions

When FEAT_AMU_EXT64 is implemented:

Bits [63:32]

NCG, bits [31:28]

Bits [27:25]

HDBG, bit [24]

Bits [23:14]

SIZE, bits [13:8]

N, bits [7:0]

Otherwise:

NCG, bits [31:28]

Bits [27:25]

HDBG, bit [24]

Bits [23:14]

SIZE, bits [13:8]

N, bits [7:0]

Accessing AMCFGR

When FEAT_AMU_EXT64 is implemented

When FEAT_AMU_EXT32 is implemented