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AMAIR_EL2, Auxiliary Memory Attribute Indirection Register (EL2)

The AMAIR_EL2 characteristics are:

Purpose

Provides IMPLEMENTATION DEFINED memory attributes for the memory regions specified by MAIR_EL2.

Configuration

AArch64 System register AMAIR_EL2 bits [31:0] are architecturally mapped to AArch32 System register HAMAIR0[31:0] .

AArch64 System register AMAIR_EL2 bits [63:32] are architecturally mapped to AArch32 System register HAMAIR1[31:0] .

If EL2 is not implemented, this register is RES0 from EL3.

This register has no effect if EL2 is not enabled in the current Security state.

RW fields in this register reset to architecturally UNKNOWN values.

Attributes

AMAIR_EL2 is a 64-bit register.

Field descriptions

The AMAIR_EL2 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
IMPLEMENTATION DEFINED
IMPLEMENTATION DEFINED
313029282726252423222120191817161514131211109876543210

AMAIR_EL2 is permitted to be cached in a TLB.

IMPLEMENTATION DEFINED, bits [63:0]

IMPLEMENTATION DEFINED.

This field resets to an architecturally UNKNOWN value.

Accessing the AMAIR_EL2

AMAIR_EL2 is permitted to be cached in a TLB.

When HCR_EL2.E2H is 1, without explicit synchronization, access from EL2 using the mnemonic AMAIR_EL2 or AMAIR_EL1 are not guaranteed to be ordered with respect to accesses using the other mnemonic.

Accesses to this register use the following encodings:

MRS <Xt>, AMAIR_EL2

op0op1CRnCRmop2
0b110b1000b10100b00110b000
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && HCR_EL2.NV == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        UNDEFINED;
elsif PSTATE.EL == EL2 then
    return AMAIR_EL2;
elsif PSTATE.EL == EL3 then
    return AMAIR_EL2;
              

MSR AMAIR_EL2, <Xt>

op0op1CRnCRmop2
0b110b1000b10100b00110b000
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && HCR_EL2.NV == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        UNDEFINED;
elsif PSTATE.EL == EL2 then
    AMAIR_EL2 = X[t];
elsif PSTATE.EL == EL3 then
    AMAIR_EL2 = X[t];
              

MRS <Xt>, AMAIR_EL1

op0op1CRnCRmop2
0b110b0000b10100b00110b000
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TRVM == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<NV2,NV1,NV> == '111' then
        return NVMem[0x148];
    else
        return AMAIR_EL1;
elsif PSTATE.EL == EL2 then
    if HCR_EL2.E2H == '1' then
        return AMAIR_EL2;
    else
        return AMAIR_EL1;
elsif PSTATE.EL == EL3 then
    return AMAIR_EL1;
              

MSR AMAIR_EL1, <Xt>

op0op1CRnCRmop2
0b110b0000b10100b00110b000
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TVM == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<NV2,NV1,NV> == '111' then
        NVMem[0x148] = X[t];
    else
        AMAIR_EL1 = X[t];
elsif PSTATE.EL == EL2 then
    if HCR_EL2.E2H == '1' then
        AMAIR_EL2 = X[t];
    else
        AMAIR_EL1 = X[t];
elsif PSTATE.EL == EL3 then
    AMAIR_EL1 = X[t];
              


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