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TPIDR_EL1: EL1 Software Thread ID Register

Purpose

Provides a location where software executing at EL1 can store thread identifying information, for OS management purposes.

The PE makes no use of this register.

Configuration

AArch64 System register TPIDR_EL1 bits [31:0] are architecturally mapped to AArch32 System register TPIDRPRW[31:0].

Attributes

TPIDR_EL1 is a 64-bit register.

Field descriptions

6362616059585756555453525150494847464544434241403938373635343332
313029282726252423222120191817161514131211109876543210
Thread ID
Thread ID

Bits [63:0]

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

The reset behavior of this field is:

Accessing TPIDR_EL1

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

MRS <Xt>, TPIDR_EL1

op0op1CRnCRmop2
0b110b0000b11010b00000b100

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGRTR_EL2.TPIDR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else X[t, 64] = TPIDR_EL1; elsif PSTATE.EL == EL2 then X[t, 64] = TPIDR_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = TPIDR_EL1;

MSR TPIDR_EL1, <Xt>

op0op1CRnCRmop2
0b110b0000b11010b00000b100

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGWTR_EL2.TPIDR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else TPIDR_EL1 = X[t, 64]; elsif PSTATE.EL == EL2 then TPIDR_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then TPIDR_EL1 = X[t, 64];