PRRR, Primary Region Remap Register

The PRRR characteristics are:

Purpose

Controls the top level mapping of the TEX[0], C, and B memory region attributes.

Configuration

AArch32 System register PRRR bits [31:0] are architecturally mapped to AArch64 System register MAIR_EL1[31:0] when EL3 is not implemented or EL3 is using AArch64.

AArch32 System register PRRR bits [31:0] are architecturally mapped to AArch32 System register MAIR0[31:0] when EL3 is not implemented or EL3 is using AArch64.

AArch32 System register PRRR bits [31:0] (PRRR_S) are architecturally mapped to AArch32 System register MAIR0[31:0] (MAIR0_S) when EL3 is using AArch32.

AArch32 System register PRRR bits [31:0] (PRRR_NS) are architecturally mapped to AArch32 System register MAIR0[31:0] (MAIR0_NS) when EL3 is using AArch32.

This register is present only when AArch32 is supported. Otherwise, direct accesses to PRRR are UNDEFINED.

MAIR0 and PRRR are the same register, with a different view depending on the value of TTBCR.EAE:

Attributes

PRRR is a 32-bit register.

Field descriptions

When TTBCR.EAE == 0:

313029282726252423222120191817161514131211109876543210
NOS7NOS6NOS5NOS4NOS3NOS2NOS1NOS0RES0NS1NS0DS1DS0TR7TR6TR5TR4TR3TR2TR1TR0

NOS<n>, bit [n+24], for n = 7 to 0

Not Outer Shareable. NOS<n> is the Outer Shareable property for memory attributes n, if the region is mapped as Normal memory that is not Inner Non-cacheable, Outer Non-cacheable, and the appropriate PRRR.{NS0, NS1} field identifies the region as shareable. n is the value of the concatenation of the {TEX[0], C, B} bits from the translation table descriptor. The possible values of each NOS<n> field other than NOS6 are:

NOS<n>Meaning
0b0

Memory region is Outer Shareable.

0b1

Memory region is Inner Shareable.

The value of this bit is ignored if the region is:

The meaning of the NOS6 field is IMPLEMENTATION DEFINED.

The reset behavior of this field is:

Bits [23:20]

Reserved, RES0.

NS1, bit [19]

Mapping of S = 1 attribute for Normal memory regions. This field is used in determining the Shareability of a memory region that is mapped to Normal memory and both:

The possible values of this bit are:

NS1Meaning
0b0

Region is Non-shareable.

0b1

Region is shareable. The value of the appropriate PRRR.NOS<n> field determines whether the region is Inner Shareable or Outer Shareable.

The reset behavior of this field is:

NS0, bit [18]

Mapping of S = 0 attribute for Normal memory regions. This field is used in determining the Shareability of a memory region that is mapped to Normal memory and both:

The possible values of this bit are:

NS0Meaning
0b0

Region is Non-shareable.

0b1

Region is shareable. The value of the appropriate PRRR.NOS<n> field determines whether the region is Inner Shareable or Outer Shareable.

The reset behavior of this field is:

DS1, bit [17]

Mapping of S = 1 attribute for Device memory. From Armv8, all types of Device memory are Outer Shareable, and therefore this bit is RES1.

The reset behavior of this field is:

DS0, bit [16]

Mapping of S = 0 attribute for Device memory. From Armv8, all types of Device memory are Outer Shareable, and therefore this bit is RES1.

The reset behavior of this field is:

TR<n>, bits [2n+1:2n], for n = 7 to 0

TR<n> is the primary TEX mapping for memory attributes n, and defines the mapped memory type for a region with attributes n. n is the value of the concatenation of the {TEX[0], C, B} bits from the translation table descriptor. The possible values for each field other than TR6 are:

TR<n>Meaning
0b00

Device-nGnRnE memory

0b01

Device-nGnRE memory

0b10

Normal memory

The value 0b11 is reserved. The effect of programming a field to 0b11 is CONSTRAINED UNPREDICTABLE.

The meaning of the TR6 field is IMPLEMENTATION DEFINED.

When FEAT_XS is implemented, stage 1 Inner Write-Back Cacheable, Outer Write-Back Cacheable memory types have the XS attribute set to 0.

The reset behavior of this field is:

Accessing PRRR

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

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

coprocopc1CRnCRmopc2
0b11110b0000b10100b00100b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T10 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T10 == '1' then AArch32.TakeHypTrapException(0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TRVM == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.TRVM == '1' then AArch32.TakeHypTrapException(0x03); elsif HaveEL(EL3) && ELUsingAArch32(EL3) then if TTBCR.EAE == '1' then return MAIR0_NS; else return PRRR_NS; else if TTBCR.EAE == '1' then return MAIR0; else return PRRR; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && ELUsingAArch32(EL3) then if TTBCR.EAE == '1' then return MAIR0_NS; else return PRRR_NS; else if TTBCR.EAE == '1' then return MAIR0; else return PRRR; elsif PSTATE.EL == EL3 then if TTBCR.EAE == '1' then if SCR.NS == '0' then return MAIR0_S; else return MAIR0_NS; else if SCR.NS == '0' then return PRRR_S; else return PRRR_NS;

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

coprocopc1CRnCRmopc2
0b11110b0000b10100b00100b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T10 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T10 == '1' then AArch32.TakeHypTrapException(0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TVM == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.TVM == '1' then AArch32.TakeHypTrapException(0x03); elsif HaveEL(EL3) && ELUsingAArch32(EL3) then if TTBCR.EAE == '1' then MAIR0_NS = R[t]; else PRRR_NS = R[t]; else if TTBCR.EAE == '1' then MAIR0 = R[t]; else PRRR = R[t]; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && ELUsingAArch32(EL3) then if TTBCR.EAE == '1' then MAIR0_NS = R[t]; else PRRR_NS = R[t]; else if TTBCR.EAE == '1' then MAIR0 = R[t]; else PRRR = R[t]; elsif PSTATE.EL == EL3 then if SCR.NS == '0' && CP15SDISABLE == HIGH then UNDEFINED; elsif SCR.NS == '0' && CP15SDISABLE2 == HIGH then UNDEFINED; else if TTBCR.EAE == '1' then if SCR.NS == '0' then MAIR0_S = R[t]; else MAIR0_NS = R[t]; else if SCR.NS == '0' then PRRR_S = R[t]; else PRRR_NS = R[t];


20/09/2021 11:02; d4a233ffbdfb36e47856c443a7ce9a85f5e501ca

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