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The AMCFGR_EL0 provides information on the number of activity counters implemented and their size.
The AMCFGR_EL0 is a 32-bit register.
Size of counters, minus one.
This field defines the size of the largest counter
implemented by the activity monitors. In the Armv8-A architecture, the
largest counter has 64 bits, therefore the value of this field is
To access the AMCFGR_EL0:
MRS <Xt>, AMCFGR_EL0 ; Read AMCFGR_EL0 into Xt
Register access is encoded as follows:
Table D8-4 AMCFGR_EL0 encoding
The AMCFGR_EL0 can be accessed through the external debug interface, offset
0xE00. In this
case, it is read-only.
This register is accessible as follows:
If ACTLR_EL2.AMEN is 0, then Non-secure accesses to this register from EL0 and EL1 are trapped to EL2.
If ACTLR_EL3.AMEN is 0, then accesses to this register from EL0, EL1, and EL2 are trapped to EL3.
If AMUSERENR_EL0.EN is 0, then accesses to this register from EL0 are trapped to EL1.