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AMEVCNTR1<n>_EL0, Activity Monitors Event Counter Registers 1, n = 0 - 15

The AMEVCNTR1<n>_EL0 characteristics are:

Purpose

Provides access to the auxiliary activity monitor event counters.

Configuration

AArch64 System register AMEVCNTR1<n>_EL0 bits [63:0] are architecturally mapped to AArch32 System register AMEVCNTR1<n>[63:0] .

AArch64 System register AMEVCNTR1<n>_EL0 bits [63:0] are architecturally mapped to External register AMEVCNTR1<n>[63:0] .

This register is present only when AMUv1 is implemented. Otherwise, direct accesses to AMEVCNTR1<n>_EL0 are UNDEFINED.

Some or all RW fields of this register have defined reset values. These apply only if the PE resets into an Exception level that is using AArch64. Otherwise, RW fields in this register reset to architecturally UNKNOWN values.

Attributes

AMEVCNTR1<n>_EL0 is a 64-bit register.

Field descriptions

The AMEVCNTR1<n>_EL0 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
ACNT
ACNT
313029282726252423222120191817161514131211109876543210

ACNT, bits [63:0]

Auxiliary activity monitor event counter n.

Value of auxiliary activity monitor event counter n, where n is the number of this register and is a number from 0 to 15.

If the counter is enabled, writes to this register have UNPREDICTABLE results.

On a Cold reset, this field resets to 0.

Accessing the AMEVCNTR1<n>_EL0

If <n> is greater than or equal to the number of auxiliary activity monitor event counters, reads and writes of AMEVCNTR1<n>_EL0 are CONSTRAINED UNPREDICTABLE, and the following behaviors are permitted:

  • Accesses to the register are UNDEFINED.
  • Accesses to the register behave as RAZ/WI.
  • Accesses to the register execute as a NOP.
Note

AMCGCR_EL0.CG1NC identifies the number of auxiliary activity monitor event counters.

Accesses to this register use the following encodings:

MRS <Xt>, AMEVCNTR1<n>_EL0

op0CRnop1op2CRm
0b110b11010b0110b[n:2:0]0b110[n:3]
if PSTATE.EL == EL0 then
    if !ELUsingAArch32(EL1) && AMUSERENR_EL0.EN == '0' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.SystemAccessTrap(EL2, 0x18);
        else
            AArch64.SystemAccessTrap(EL1, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && CPTR_EL2.TAM == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TAM == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return AMEVCNTR1_EL0[UInt(op2<2:0>)];
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && CPTR_EL2.TAM == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TAM == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return AMEVCNTR1_EL0[UInt(op2<2:0>)];
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TAM == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return AMEVCNTR1_EL0[UInt(op2<2:0>)];
elsif PSTATE.EL == EL3 then
    return AMEVCNTR1_EL0[UInt(op2<2:0>)];
              

MSR AMEVCNTR1<n>_EL0, <Xt>

op0CRnop1op2CRm
0b110b11010b0110b[n:2:0]0b110[n:3]
if IsHighestEL(PSTATE.EL) then
    AMEVCNTR1_EL0[UInt(op2<2:0>)] = X[t];
else
    UNDEFINED;
              


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