ID_ISAR5_EL1, AArch32 Instruction Set Attribute Register 5

The ID_ISAR5_EL1 characteristics are:

Purpose

Provides information about the instruction sets implemented by the PE in AArch32 state.

Must be interpreted with ID_ISAR0_EL1, ID_ISAR1_EL1, ID_ISAR2_EL1, ID_ISAR3_EL1, and ID_ISAR4_EL1.

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

Configuration

AArch64 System register ID_ISAR5_EL1 bits [31:0] are architecturally mapped to AArch32 System register ID_ISAR5[31:0] .

This register is present only when AArch32 is supported at any Exception level. Otherwise, direct accesses to ID_ISAR5_EL1 are UNKNOWN.

Attributes

ID_ISAR5_EL1 is a 64-bit register.

Field descriptions

The ID_ISAR5_EL1 bit assignments are:

Bits [63:32]

Reserved, RES0.

VCMA, bits [31:28]

Indicates AArch32 support for complex number addition and multiplication where numbers are stored in vectors. Defined values are:

All other values are reserved.

ARMv8.3-CompNum implements the functionality identified by 0b0001.

In Armv8.0, Armv8.1, and Armv8.2, the only permitted value is 0b0000.

From Armv8.3, the only permitted value is 0b0001.

RDM, bits [27:24]

Indicates whether the VQRDMLAH and VQRDMLSH instructions are implemented in AArch32 state. Defined values are:

All other values are reserved.

ARMv8.1-RDMA implements the functionality identified by the value 0b0001.

In Armv8.0, the only permitted value is 0b0000.

From Armv8.1, the only permitted value is 0b0001.

Bits [23:20]

Reserved, RES0.

CRC32, bits [19:16]

Indicates whether the CRC32 instructions are implemented in AArch32 state.

All other values are reserved.

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

From Armv8.1, the only permitted value is 0b0001.

SHA2, bits [15:12]

Indicates whether the SHA2 instructions are implemented in AArch32 state.

All other values are reserved.

In Armv8-A, the permitted values are 0b0000 and 0b0001.

SHA1, bits [11:8]

Indicates whether the SHA1 instructions are implemented in AArch32 state.

All other values are reserved.

In Armv8-A, the permitted values are 0b0000 and 0b0001.

AES, bits [7:4]

Indicates whether the AES instructions are implemented in AArch32 state.

All other values are reserved.

In Armv8-A, the permitted values are 0b0000 and 0b0010.

SEVL, bits [3:0]

Indicates whether the SEVL instruction is implemented in AArch32 state.

All other values are reserved.

In Armv8-A, the only permitted value is 0b0001.

if PSTATE.EL == EL0 then
    if IsFeatureImplemented("ARMv8.4-IDST") then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.SystemAccessTrap(EL2, 0x18);
        else
            AArch64.SystemAccessTrap(EL1, 0x18);
    else
        UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TID3 == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        return ID_ISAR5_EL1;
elsif PSTATE.EL == EL2 then
    return ID_ISAR5_EL1;
elsif PSTATE.EL == EL3 then
    return ID_ISAR5_EL1;