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HACTLR2, Hyp Auxiliary Control Register 2

The HACTLR2 characteristics are:

Purpose

Provides additional space to the HACTLR register to hold IMPLEMENTATION DEFINED trap functionality.

Configuration

AArch32 System register HACTLR2 bits [31:0] are architecturally mapped to AArch64 System register ACTLR_EL2[63:32] .

In Armv8.0 and Armv8.1, it is IMPLEMENTATION DEFINED whether this register is implemented, or whether it causes UNDEFINED exceptions when accessed. The implementation of this register can be detected by examining ID_MMFR4.AC2.

From Armv8.2 this register must be implemented.

RW fields in this register reset to architecturally UNKNOWN values.

Attributes

HACTLR2 is a 32-bit register.

Field descriptions

The HACTLR2 bit assignments are:

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
IMPLEMENTATION DEFINED

IMPLEMENTATION DEFINED, bits [31:0]

IMPLEMENTATION DEFINED.

This field resets to an architecturally UNKNOWN value.

Accessing the HACTLR2

Accesses to this register use the following encodings:

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

coproc	opc1	CRn	CRm	opc2
0b1111	0b100	0b0001	0b0000	0b011

if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T1 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T1 == '1' then
        AArch32.TakeHypTrapException(0x03);
    else
        UNDEFINED;
elsif PSTATE.EL == EL2 then
    return HACTLR2;
elsif PSTATE.EL == EL3 then
    if SCR.NS == '0' then
        UNDEFINED;
    else
        return HACTLR2;

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

coproc	opc1	CRn	CRm	opc2
0b1111	0b100	0b0001	0b0000	0b011

if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T1 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T1 == '1' then
        AArch32.TakeHypTrapException(0x03);
    else
        UNDEFINED;
elsif PSTATE.EL == EL2 then
    HACTLR2 = R[t];
elsif PSTATE.EL == EL3 then
    if SCR.NS == '0' then
        UNDEFINED;
    else
        HACTLR2 = R[t];

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