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TPIDRURO
AArch32 Registers
AArch64 Registers
AArch32 Instructions
AArch64 Instructions
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TPIDRURO, PL0 Read-Only Software Thread ID Register

The TPIDRURO characteristics are:

Purpose

Provides a location where software executing at EL1 or higher can store thread identifying information that is visible to software executing at EL0, for OS management purposes.

The PE makes no use of this register.

Configuration

This register is banked between TPIDRURO and TPIDRURO_S and TPIDRURO_NS.

AArch32 System register TPIDRURO bits [31:0] are architecturally mapped to AArch64 System register TPIDRRO_EL0[31:0].

This register is present only when FEAT_AA32 is implemented. Otherwise, direct accesses to TPIDRURO are UNDEFINED.

Note

The PE never updates this register.

Attributes

TPIDRURO is a 32-bit register.

This register has the following instances:

Field descriptions

313029282726252423222120191817161514131211109876543210
TID

TID, bits [31:0]

Thread ID. Thread identifying information stored by software running at this Exception level.

The reset behavior of this field is:

Accessing TPIDRURO

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

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

coprocopc1CRnCRmopc2
0b11110b0000b11010b00000b011

if !IsFeatureImplemented(FEAT_AA32) then Undefined(); elsif PSTATE.EL == EL0 then if EL2Enabled() && (IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2)) && !ELIsInHost(EL0) && HSTR_EL2().T13 == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && (IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2)) && HSTR().T13 == '1' then AArch32_TakeHypTrapException(0x03); elsif EL2Enabled() && (IsFeatureImplemented(FEAT_AA64EL1) && !ELUsingAArch32(EL1)) && !ELIsInHost(EL0) && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3().FGTEn == '1') && HFGRTR_EL2().TPIDRRO_EL0 == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); else R(t) = TPIDRURO(); end; elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HSTR_EL2().T13 == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HSTR().T13 == '1' then AArch32_TakeHypTrapException(0x03); elsif HaveEL(EL3) && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) then R(t) = TPIDRURO_NS(); else R(t) = TPIDRURO(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) then R(t) = TPIDRURO_NS(); else R(t) = TPIDRURO(); end; elsif PSTATE.EL == EL3 then if SCR().NS == '0' then R(t) = TPIDRURO_S(); else R(t) = TPIDRURO_NS(); end; end;

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

coprocopc1CRnCRmopc2
0b11110b0000b11010b00000b011

if !IsFeatureImplemented(FEAT_AA32) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HSTR_EL2().T13 == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HSTR().T13 == '1' then AArch32_TakeHypTrapException(0x03); elsif HaveEL(EL3) && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) then TPIDRURO_NS() = R(t); else TPIDRURO() = R(t); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) then TPIDRURO_NS() = R(t); else TPIDRURO() = R(t); end; elsif PSTATE.EL == EL3 then if SCR().NS == '0' then TPIDRURO_S() = R(t); else TPIDRURO_NS() = R(t); end; end;

AArch32 Registers
AArch64 Registers
AArch32 Instructions
AArch64 Instructions
Index by Encoding
External Registers
External Registers by Offset
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2026-03-26 20:27:25, 2026-03_rel

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