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AMCNTENCLR1_EL0, Activity Monitors Count Enable Clear Register 1

The AMCNTENCLR1_EL0 characteristics are:

Purpose

Disable control bits for the auxiliary activity monitors event counters, AMEVCNTR1<n>_EL0.

Configuration

AArch64 System register AMCNTENCLR1_EL0 bits [31:0] are architecturally mapped to AArch32 System register AMCNTENCLR1[31:0] .

AArch64 System register AMCNTENCLR1_EL0 bits [31:0] are architecturally mapped to External register AMCNTENCLR1[31:0] .

This register is present only when AMUv1 is implemented. Otherwise, direct accesses to AMCNTENCLR1_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

AMCNTENCLR1_EL0 is a 64-bit register.

Field descriptions

The AMCNTENCLR1_EL0 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
RES0
RES0P<n>, bit [n]
313029282726252423222120191817161514131211109876543210

Bits [63:16]

Reserved, RES0.

P<n>, bit [n], for n = 0 to 15

Activity monitor event counter disable bit for AMEVCNTR1<n>_EL0.

Bits [31:16] are RES0. Bits [15:N] are RAZ/WI. N is the value in AMCGCR_EL0.CG1NC.

Possible values of each bit are:

P<n>Meaning
0b0

When read, means that AMEVCNTR1<n>_EL0 is disabled. When written, has no effect.

0b1

When read, means that AMEVCNTR1<n>_EL0 is enabled. When written, disables AMEVCNTR1<n>_EL0.

On a Cold reset, this field resets to 0.

Accessing the AMCNTENCLR1_EL0

If the number of auxiliary activity monitor event counters implemented is zero, reads and writes of AMCNTENCLR1_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

The number of auxiliary activity monitor event counters implemented is zero exactly when AMCFGR_EL0.NCG == 0b0000.

Accesses to this register use the following encodings:

MRS <Xt>, AMCNTENCLR1_EL0

op0op1CRnCRmop2
0b110b0110b11010b00110b000
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 AMCNTENCLR1_EL0;
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 AMCNTENCLR1_EL0;
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TAM == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return AMCNTENCLR1_EL0;
elsif PSTATE.EL == EL3 then
    return AMCNTENCLR1_EL0;
              

MSR AMCNTENCLR1_EL0, <Xt>

op0op1CRnCRmop2
0b110b0110b11010b00110b000
if IsHighestEL(PSTATE.EL) then
    AMCNTENCLR1_EL0 = X[t];
else
    UNDEFINED;
              


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