Provides the memory attribute encodings corresponding to the possible AttrIndx values in a Long-descriptor format translation table entry for stage 1 translations at EL2.
AArch64 System register MAIR_EL2 bits [31:0] are architecturally mapped to AArch32 System register HMAIR0[31:0].
AArch64 System register MAIR_EL2 bits [63:32] are architecturally mapped to AArch32 System register HMAIR1[31:0].
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.
MAIR_EL2 is a 64-bit register.
| 63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32 |
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Attr7 | Attr6 | Attr5 | Attr4 | ||||||||||||||||||||||||||||
| Attr3 | Attr2 | Attr1 | Attr0 | ||||||||||||||||||||||||||||
MAIR_EL2 is permitted to be cached in a TLB.
Memory Attribute encoding.
When FEAT_AIE is implemented and stage 1 Attributes Index Extension is enabled and AttrIndx[3] in a Long descriptor format translation table entry is 0, or when FEAT_AIE is not implemented, AttrIndx[2:0] gives the value of <n> in Attr<n>.
When FEAT_AIE is implemented and stage 1 Attributes Index Extension is enabled and AttrIndx[3] in a Long descriptor format translation table entry is 1, see MAIR2_ELx.Attr
Attr is encoded as follows:
| Attr | Meaning |
|---|---|
| 0b0000dd00 | Device memory. See encoding of 'dd' for the type of Device memory. |
| 0b0000dd01 | If FEAT_XS is implemented: Device memory with the XS attribute set to 0. See encoding of 'dd' for the type of Device memory. Otherwise, UNPREDICTABLE. |
| 0b0000dd1x | UNPREDICTABLE. |
| 0booooiiii, (oooo != 0000 and iiii != 0000) | Normal memory. See encoding of 'oooo' and 'iiii' for the type of Normal Memory. |
| 0b01000000 | If FEAT_XS is implemented: Normal Inner Non-cacheable, Outer Non-cacheable memory with the XS attribute set to 0. Otherwise, UNPREDICTABLE. |
| 0b10100000 | If FEAT_XS is implemented: Normal Inner Write-through Cacheable, Outer Write-through Cacheable, Read-Allocate, No-Write Allocate, Non-transient memory with the XS attribute set to 0. Otherwise, UNPREDICTABLE. |
| 0b11110000 | If FEAT_MTE2 is implemented: Tagged Normal Inner Write-Back, Outer Write-Back, Read-Allocate, Write-Allocate Non-transient memory. Otherwise, UNPREDICTABLE. |
| 0bxxxx0000, where xxxx != 0000 and xxxx != 0100 and xxxx != 1010 and xxxx != 1111 | UNPREDICTABLE. |
'dd' is encoded as follows:
| dd | Meaning |
|---|---|
| 0b00 | Device-nGnRnE memory |
| 0b01 | Device-nGnRE memory |
| 0b10 | Device-nGRE memory |
| 0b11 | Device-GRE memory |
'oooo' is encoded as follows:
| 'oooo' | Meaning |
|---|---|
| 0b0000 | See encoding of Attr |
| 0b00RW, RW not 0b00 | Normal memory, Outer Write-Through Transient |
| 0b0100 | Normal memory, Outer Non-cacheable |
| 0b01RW, RW not 0b00 | Normal memory, Outer Write-Back Transient |
| 0b10RW | Normal memory, Outer Write-Through Non-transient |
| 0b11RW | Normal memory, Outer Write-Back Non-transient |
R = Outer Read-Allocate policy, W = Outer Write-Allocate policy.
'iiii' is encoded as follows:
| 'iiii' | Meaning |
|---|---|
| 0b0000 | See encoding of Attr |
| 0b00RW, RW not 0b00 | Normal memory, Inner Write-Through Transient |
| 0b0100 | Normal memory, Inner Non-cacheable |
| 0b01RW, RW not 0b00 | Normal memory, Inner Write-Back Transient |
| 0b10RW | Normal memory, Inner Write-Through Non-transient |
| 0b11RW | Normal memory, Inner Write-Back Non-transient |
R = Inner Read-Allocate policy, W = Inner Write-Allocate policy.
The R and W bits in 'oooo' and 'iiii' fields have the following meanings:
| R or W | Meaning |
|---|---|
| 0b0 | No Allocate |
| 0b1 | Allocate |
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:
When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, access from EL2 using the mnemonic MAIR_EL2 or MAIR_EL1 is not guaranteed to be ordered with respect to accesses using the other mnemonic.
Accesses to this register use the following encodings in the System register encoding space:
MRS <Xt>, MAIR_EL2
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b100 | 0b1010 | 0b0010 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then X[t, 64] = MAIR_EL2; elsif PSTATE.EL == EL3 then X[t, 64] = MAIR_EL2;
MSR MAIR_EL2, <Xt>
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b100 | 0b1010 | 0b0010 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then MAIR_EL2 = X[t, 64]; elsif PSTATE.EL == EL3 then MAIR_EL2 = X[t, 64];
MRS <Xt>, MAIR_EL1
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b000 | 0b1010 | 0b0010 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2.TRVM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGRTR_EL2.MAIR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() == '111' then X[t, 64] = NVMem[0x140]; else X[t, 64] = MAIR_EL1; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then X[t, 64] = MAIR_EL2; else X[t, 64] = MAIR_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = MAIR_EL1;
MSR MAIR_EL1, <Xt>
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b000 | 0b1010 | 0b0010 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2.TVM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGWTR_EL2.MAIR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() == '111' then NVMem[0x140] = X[t, 64]; else MAIR_EL1 = X[t, 64]; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then MAIR_EL2 = X[t, 64]; else MAIR_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then MAIR_EL1 = X[t, 64];