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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:

6362616059585756555453525150494847464544434241403938373635343332
00000000000000000000000000000000
00000000LD00000000LR
313029282726252423222120191817161514131211109876543210

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

CRnop0op1op2CRm
0b10100b110b0000b1110b0100
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;
              


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