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ID_MMFR5, Memory Model Feature Register 5

The ID_MMFR5 characteristics are:

Purpose

Provides information about the implemented memory model and memory management support in AArch32 state.

For general information about the interpretation of the ID registers see 'Principles of the ID scheme for fields in ID registers' in the Arm® Architecture Reference Manual, Armv8, for Armv8-A architecture profile, section G7.1.3.

Configuration

AArch32 System register ID_MMFR5 bits [31:0] are architecturally mapped to AArch64 System register ID_MMFR5_EL1[31:0] .

Attributes

ID_MMFR5 is a 32-bit register.

Field descriptions

The ID_MMFR5 bit assignments are:

313029282726252423222120191817161514131211109876543210
RES0ETS

Bits [31:4]

Reserved, RES0.

ETS, bits [3:0]

From Armv8.0:

Support for Enhanced Translation Synchronization. Defined values are:

ETSMeaning
0b0000

Enhanced Translation Synchronization is not supported.

0b0001

Enhanced Translation Synchronization is supported.

All other values are reserved.

ARMv8.0-ETS implements the functionality identified by the value 0b0001.

From Armv8.0, the permitted values are 0b0000 and 0b0001.


Otherwise:

Reserved, RES0.

Accessing the ID_MMFR5

Accesses to this register use the following encodings:

MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coprocopc1CRnCRmopc2
0b11110b0000b00000b00110b110
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T0 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T0 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && (!IsZero(ID_MMFR5) || boolean IMPLEMENTATION_DEFINED "ID_MMFR5 trapped by HCR_EL2.TID3") && HCR_EL2.TID3 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && (!IsZero(ID_MMFR5) || boolean IMPLEMENTATION_DEFINED "ID_MMFR5 trapped by HCR.TID3") && HCR.TID3 == '1' then
        AArch32.TakeHypTrapException(0x03);
    else
        return ID_MMFR5;
elsif PSTATE.EL == EL2 then
    return ID_MMFR5;
elsif PSTATE.EL == EL3 then
    return ID_MMFR5;
              


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