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TLBTR: TLB Type Register

Purpose

Provides information about the TLB implementation. The register must define whether the implementation provides separate instruction and data TLBs, or a unified TLB. Normally, the IMPLEMENTATION DEFINED information in this register includes the number of lockable entries in the TLB.

Configuration

This register is present only when EL1 is capable of using AArch32. Otherwise, direct accesses to TLBTR are UNDEFINED.

Attributes

TLBTR is a 32-bit register.

Field descriptions

313029282726252423222120191817161514131211109876543210
IMPLEMENTATION DEFINEDnU

IMPLEMENTATION DEFINED, bits [31:1]

IMPLEMENTATION DEFINED.

nU, bit [0]

Not Unified TLB. Indicates whether the implementation has a unified TLB.

The value of this field is an IMPLEMENTATION DEFINED choice of:

nUMeaning
0b0

Unified TLB.

0b1

Separate Instruction and Data TLBs.

Access to this field is RO.

Accessing TLBTR

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

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

coprocopc1CRnCRmopc2
0b11110b0000b00000b00000b011

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T0 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T0 == '1' then AArch32.TakeHypTrapException(0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TID1 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.TID1 == '1' then AArch32.TakeHypTrapException(0x03); else R[t] = TLBTR; elsif PSTATE.EL == EL2 then R[t] = TLBTR; elsif PSTATE.EL == EL3 then R[t] = TLBTR;