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# OSLAR_EL1, OS Lock Access Register

The OSLAR_EL1 characteristics are:

## Purpose

Used to lock or unlock the OS Lock.

## Configuration

AArch64 System register OSLAR_EL1 bits [31:0] are architecturally mapped to AArch32 System register DBGOSLAR[31:0] .

AArch64 System register OSLAR_EL1 bits [31:0] are architecturally mapped to External register OSLAR_EL1[31:0] .

## Attributes

OSLAR_EL1 is a 64-bit register.

## Field descriptions

The OSLAR_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 | OSLK
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 [63:1]

Reserved, RES0.

#### OSLK, bit [0]

On writes to OSLAR_EL1, bit[0] is copied to the OS Lock.

Use OSLSR_EL1.OSLK to check the current status of the lock.

## Accessing the OSLAR_EL1

Accesses to this register use the following encodings:

#### MSR OSLAR_EL1, <Xt>

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b10 | 0b000 | 0b0001 | 0b0000 | 0b100

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDOSA> != '00' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else OSLAR_EL1 = X[t]; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else OSLAR_EL1 = X[t]; elsif PSTATE.EL == EL3 then OSLAR_EL1 = X[t];

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

27/03/2019 21:59; e5e4db499bf9867a4b93324c4dbac985d3da9376

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