AMCFGR, Activity Monitors Configuration Register
The AMCFGR characteristics are:
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.
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 FEAT_AMUv1 is implemented. Otherwise, direct accesses to AMCFGR are RES0.
AMCFGR is a 32-bit register.
The AMCFGR bit assignments are:
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.
HDBG, bit 
From Armv8, this feature must be supported, and so this bit is 0b1.
AMCR.HDBG is RES0.
AMCR.HDBG is read/write.
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].
From Armv8, the counters are 64-bit, and so this field is 0b111111.
Software also uses this field to determine the spacing of counters in the memory-map. From 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:
Accesses on this interface are RO.