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ID_AFR0

ID_AFR0, Auxiliary Feature Register 0

The ID_AFR0 characteristics are:

Purpose

Provides information about the IMPLEMENTATION DEFINED features of the PE in AArch32 state.

Must be interpreted with the Main ID Register, MIDR.

For general information about the interpretation of the ID registers see 'Principles of the ID scheme for fields in ID registers'.

Configuration

AArch32 System register ID_AFR0 bits [31:0] are architecturally mapped to AArch64 System register ID_AFR0_EL1[31:0].

This register is present only when FEAT_AA32EL1 is implemented. Otherwise, direct accesses to ID_AFR0 are UNDEFINED.

Attributes

ID_AFR0 is a 32-bit register.

Field descriptions

313029282726252423222120191817161514131211109876543210
RES0IMPLEMENTATION DEFINEDIMPLEMENTATION DEFINEDIMPLEMENTATION DEFINEDIMPLEMENTATION DEFINED

Bits [31:16]

Reserved, RES0.

IMPLEMENTATION DEFINED, bits [15:12]

IMPLEMENTATION DEFINED.

IMPLEMENTATION DEFINED, bits [11:8]

IMPLEMENTATION DEFINED.

IMPLEMENTATION DEFINED, bits [7:4]

IMPLEMENTATION DEFINED.

IMPLEMENTATION DEFINED, bits [3:0]

IMPLEMENTATION DEFINED.

Accessing ID_AFR0

Accesses to this register use the following encodings in the System register encoding space:

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

coprocopc1CRnCRmopc2
0b11110b0000b00000b00010b011

if !IsFeatureImplemented(FEAT_AA32EL1) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HSTR_EL2().T0 == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HSTR().T0 == '1' then AArch32_TakeHypTrapException(0x03); elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HCR_EL2().TID3 == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HCR().TID3 == '1' then AArch32_TakeHypTrapException(0x03); else R(t) = ID_AFR0(); end; elsif PSTATE.EL == EL2 then R(t) = ID_AFR0(); elsif PSTATE.EL == EL3 then R(t) = ID_AFR0(); end;


2026-03-26 20:27:25, 2026-03_rel

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