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# LORID_EL1, LORegionID (EL1)

The LORID_EL1 characteristics are:

## Purpose

Indicates the number of LORegions and LORegion descriptors supported by the PE.

## Configuration

This register is present only from Armv8.1. Otherwise, direct accesses to LORID_EL1 are UNDEFINED.

If no LORegion descriptors are implemented, then the registers LORC_EL1, LORN_EL1, LOREA_EL1, and LORSA_EL1 are RES0.

## Attributes

LORID_EL1 is a 64-bit register.

## Field descriptions

The LORID_EL1 bit assignments are:

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
RES0
RES0 | LD | RES0 | LR
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

#### Bits [63:24]

Reserved, RES0.

#### LD, bits [23:16]

Number of LORegion descriptors supported by the PE. This is an 8-bit binary number.

#### Bits [15:8]

Reserved, RES0.

#### LR, bits [7:0]

Number of LORegions supported by the PE. This is an 8-bit binary number.

Note

If LORID_EL1 indicates that no LORegions are implemented, then LoadLOAcquire and StoreLORelease will behave as LoadAcquire and StoreRelease.

## Accessing the LORID_EL1

Accesses to this register use the following encodings:

#### MRS <Xt>, LORID_EL1

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b11 | 0b000 | 0b1010 | 0b0100 | 0b111

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TLOR == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.TLOR == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else return LORID_EL1; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.TLOR == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else return LORID_EL1; elsif PSTATE.EL == EL3 then return LORID_EL1;

AArch32 Registers | AArch64 Registers | AArch32 Instructions | AArch64 Instructions | Index by Encoding | External Registers | External Registers by Offset | Registers by Functional Group | Proprietary Notice

15/04/2019 16:47; 8c23526ba8a13a72aada4137daf3e3977b49036e

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