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AIDR_EL1

AIDR_EL1, Auxiliary ID Register

The AIDR_EL1 characteristics are:

Purpose

Provides IMPLEMENTATION DEFINED identification information.

The value of this register must be interpreted in conjunction with the value of MIDR_EL1.

Configuration

AArch64 System register AIDR_EL1 bits [31:0] are architecturally mapped to AArch32 System register AIDR[31:0].

This register is present only when FEAT_AA64 is implemented. Otherwise, direct accesses to AIDR_EL1 are UNDEFINED.

Attributes

AIDR_EL1 is a 64-bit register.

Field descriptions

6362616059585756555453525150494847464544434241403938373635343332
313029282726252423222120191817161514131211109876543210
IMPLEMENTATION DEFINED
IMPLEMENTATION DEFINED

IMPLEMENTATION DEFINED, bits [63:0]

IMPLEMENTATION DEFINED.

Accessing AIDR_EL1

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

MRS <Xt>, AIDR_EL1

op0op1CRnCRmop2
0b110b0010b00000b00000b111

if !IsFeatureImplemented(FEAT_AA64) then UnimplementedIDRegister(); elsif PSTATE.EL == EL0 then if IsFeatureImplemented(FEAT_IDST) then if EL2Enabled() && HCR_EL2().TGE == '1' then AArch64_SystemAccessTrap(EL2, 0x18); else AArch64_SystemAccessTrap(EL1, 0x18); end; else Undefined(); end; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2().TID1 == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3().FGTEn == '1') && HFGRTR_EL2().AIDR_EL1 == '1' then AArch64_SystemAccessTrap(EL2, 0x18); else X{64}(t) = AIDR_EL1(); end; elsif PSTATE.EL == EL2 then X{64}(t) = AIDR_EL1(); elsif PSTATE.EL == EL3 then X{64}(t) = AIDR_EL1(); end;


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

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