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TCR2MASK_EL2

TCR2MASK_EL2, Extended Translation Control Masking Register (EL2)

The TCR2MASK_EL2 characteristics are:

Purpose

Mask register to prevent updates of fields in TCR2_EL2 on writes.

Configuration

This register is present only when FEAT_SRMASK is implemented and FEAT_AA64 is implemented. Otherwise, direct accesses to TCR2MASK_EL2 are UNDEFINED.

If EL2 is not implemented, this register is RES0 from EL3.

This register has no effect if EL2 is not enabled in the current Security state.

Attributes

TCR2MASK_EL2 is a 64-bit register.

Field descriptions

6362616059585756555453525150494847464544434241403938373635343332
313029282726252423222120191817161514131211109876543210
RES0
RES0FNG1FNG0A2DisCH1DisCH0AMEC1AMEC0HAFTPTTWIRES0D128AIEPOEE0POEPIEPnCH

Bits [63:19]

Reserved, RES0.

FNG1, bit [18]
When FEAT_ASID2 is implemented:

Mask bit for FNG1.

FNG1Meaning
0b0

TCR2_EL2.FNG1 is writable.

0b1

TCR2_EL2.FNG1 is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

FNG0, bit [17]
When FEAT_ASID2 is implemented:

Mask bit for FNG0.

FNG0Meaning
0b0

TCR2_EL2.FNG0 is writable.

0b1

TCR2_EL2.FNG0 is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

A2, bit [16]
When FEAT_ASID2 is implemented:

Mask bit for A2.

A2Meaning
0b0

TCR2_EL2.A2 is writable.

0b1

TCR2_EL2.A2 is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

DisCH1, bit [15]
When FEAT_D128 is implemented:

Mask bit for DisCH1.

DisCH1Meaning
0b0

TCR2_EL2.DisCH1 is writable.

0b1

TCR2_EL2.DisCH1 is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

DisCH0, bit [14]
When FEAT_D128 is implemented:

Mask bit for DisCH0.

DisCH0Meaning
0b0

TCR2_EL2.DisCH0 is writable.

0b1

TCR2_EL2.DisCH0 is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

AMEC1, bit [13]
When FEAT_MEC is implemented:

Mask bit for AMEC1.

AMEC1Meaning
0b0

TCR2_EL2.AMEC1 is writable.

0b1

TCR2_EL2.AMEC1 is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

AMEC0, bit [12]
When FEAT_MEC is implemented:

Mask bit for AMEC0.

AMEC0Meaning
0b0

TCR2_EL2.AMEC0 is writable.

0b1

TCR2_EL2.AMEC0 is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

HAFT, bit [11]
When FEAT_HAFT is implemented:

Mask bit for HAFT.

HAFTMeaning
0b0

TCR2_EL2.HAFT is writable.

0b1

TCR2_EL2.HAFT is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

PTTWI, bit [10]
When FEAT_THE is implemented:

Mask bit for PTTWI.

PTTWIMeaning
0b0

TCR2_EL2.PTTWI is writable.

0b1

TCR2_EL2.PTTWI is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

Bits [9:6]

Reserved, RES0.

D128, bit [5]
When FEAT_D128 is implemented:

Mask bit for D128.

D128Meaning
0b0

TCR2_EL2.D128 is writable.

0b1

TCR2_EL2.D128 is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

AIE, bit [4]
When FEAT_AIE is implemented:

Mask bit for AIE.

AIEMeaning
0b0

TCR2_EL2.AIE is writable.

0b1

TCR2_EL2.AIE is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

POE, bit [3]
When FEAT_S1POE is implemented:

Mask bit for POE.

POEMeaning
0b0

TCR2_EL2.POE is writable.

0b1

TCR2_EL2.POE is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

E0POE, bit [2]
When FEAT_S1POE is implemented:

Mask bit for E0POE.

E0POEMeaning
0b0

TCR2_EL2.E0POE is writable.

0b1

TCR2_EL2.E0POE is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

PIE, bit [1]
When FEAT_S1PIE is implemented:

Mask bit for PIE.

PIEMeaning
0b0

TCR2_EL2.PIE is writable.

0b1

TCR2_EL2.PIE is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

PnCH, bit [0]
When FEAT_THE is implemented:

Mask bit for PnCH.

PnCHMeaning
0b0

TCR2_EL2.PnCH is writable.

0b1

TCR2_EL2.PnCH is not writable.

The reset behavior of this field is:


Otherwise:

Reserved, RES0.

Accessing TCR2MASK_EL2

When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, accesses from EL2 using the accessor name TCR2MASK_EL2 or TCR2MASK_EL1 are not guaranteed to be ordered with respect to accesses using the other accessor name.

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

MRS <Xt>, TCR2MASK_EL2

op0op1CRnCRmop2
0b110b1000b00100b01110b011

if !(IsFeatureImplemented(FEAT_SRMASK) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64_SystemAccessTrap(EL2, 0x18); else Undefined(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else X{64}(t) = TCR2MASK_EL2(); end; elsif PSTATE.EL == EL3 then X{64}(t) = TCR2MASK_EL2(); end;

MSR TCR2MASK_EL2, <Xt>

op0op1CRnCRmop2
0b110b1000b00100b01110b011

if !(IsFeatureImplemented(FEAT_SRMASK) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64_SystemAccessTrap(EL2, 0x18); else Undefined(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif !IsZero(TCR2MASK_EL2()) then Undefined(); else TCR2MASK_EL2() = X{64}(t); end; elsif PSTATE.EL == EL3 then TCR2MASK_EL2() = X{64}(t); end;

MRS <Xt>, TCR2MASK_EL1

op0op1CRnCRmop2
0b110b0000b00100b01110b011

if !(IsFeatureImplemented(FEAT_SRMASK) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT2) && ((HaveEL(EL3) && SCR_EL3().FGTEn2 == '0') || HFGRTR2_EL2().nTCR2MASK_EL1 == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && (!IsHCRXEL2Enabled() || HCRX_EL2().SRMASKEn == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif EffectiveHCR_EL2_NVx() IN {'111'} then X{64}(t) = NVMem(0x338); else X{64}(t) = TCR2MASK_EL1(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif ELIsInHost(EL2) then X{64}(t) = TCR2MASK_EL2(); else X{64}(t) = TCR2MASK_EL1(); end; elsif PSTATE.EL == EL3 then X{64}(t) = TCR2MASK_EL1(); end;

MSR TCR2MASK_EL1, <Xt>

op0op1CRnCRmop2
0b110b0000b00100b01110b011

if !(IsFeatureImplemented(FEAT_SRMASK) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT2) && ((HaveEL(EL3) && SCR_EL3().FGTEn2 == '0') || HFGWTR2_EL2().nTCR2MASK_EL1 == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && (!IsHCRXEL2Enabled() || HCRX_EL2().SRMASKEn == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif EffectiveHCR_EL2_NVx() IN {'111'} then NVMem(0x338) = X{64}(t); elsif !IsZero(TCR2MASK_EL1()) then Undefined(); else TCR2MASK_EL1() = X{64}(t); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif ELIsInHost(EL2) then if !IsZero(TCR2MASK_EL2()) then Undefined(); else TCR2MASK_EL2() = X{64}(t); end; else TCR2MASK_EL1() = X{64}(t); end; elsif PSTATE.EL == EL3 then TCR2MASK_EL1() = X{64}(t); end;


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

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