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AMCFGR, Activity Monitors Configuration Register

The AMCFGR characteristics are:

Purpose

Global configuration register for the activity monitors.

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] .

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

The power domain of AMCFGR is IMPLEMENTATION DEFINED.

This register is present only when AMUv1 is implemented. Otherwise, direct accesses to AMCFGR are RES0.

Attributes

AMCFGR is a 32-bit register.

Field descriptions

The AMCFGR bit assignments are:

313029282726252423222120191817161514131211109876543210
NCGRES0HDBGRAZSIZEN

NCG, bits [31:28]

Defines the number of counter groups.

The number of implemented counter groups is defined as [AMCFGR.NCG + 1].

If the number of implemented auxiliary activity monitor event counters is zero, this field has a value of 0b0000. Otherwise, this field has a value of 0b0001.

Bits [27:25]

Reserved, RES0.

HDBG, bit [24]

Halt-on-debug supported.

In Armv8, this feature must be supported, and so this bit is 0b1.

HDBGMeaning
0b0

AMCR.HDBG is RES0.

0b1

AMCR.HDBG is read/write.

Bits [23:14]

Reserved, RAZ.

SIZE, bits [13:8]

Defines the size of activity monitor event counters.

The size of the activity monitor event counters implemented by the Activity Monitors Extension is defined as [AMCFGR.SIZE + 1].

In Armv8, the counters are 64-bit, and so this field is 0b111111.

Note

Software also uses this field to determine the spacing of counters in the memory-map. In Armv8, the counters are at doubleword-aligned addresses.

N, bits [7:0]

Defines the number of activity monitor event counters.

The total number of counters implemented in all groups by the Activity Monitors Extension is defined as [AMCFGR.N + 1].

Accessing the AMCFGR

AMCFGR can be accessed through the memory-mapped interfaces:

ComponentOffsetInstance
AMU0xE00AMCFGR

Access on this interface is RO.



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