OSLAR_EL1, OS Lock Access Register

The OSLAR_EL1 characteristics are:

Purpose

Used to lock or unlock the OS Lock.

Configuration

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

OSLAR_EL1 is in the Core power domain.

The OS Lock can also be locked or unlocked using DBGOSLAR.

If FEAT_Debugv8p2 is not implemented, it is IMPLEMENTATION DEFINED whether external debug accesses to OSLAR_EL1 are ignored and return an error when AllowExternalDebugAccess() returns FALSE for the access.

If FEAT_Debugv8p2 is implemented, external debug accesses to OSLAR_EL1 are ignored and return an error when AllowExternalDebugAccess() returns FALSE for the access.

Attributes

OSLAR_EL1 is a 32-bit register.

Field descriptions

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
RES0																															OSLK

Bits [31:1]

Reserved, RES0.

OSLK, bit [0]

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

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

Accessing OSLAR_EL1

Note

SoftwareLockStatus() depends on the type of access attempted and AllowExternalDebugAccess() has a new definition from Armv8.4. Refer to the Pseudocode definitions for more information.

OSLAR_EL1 can be accessed through the external debug interface:

Component	Offset	Instance
Debug	0x300	OSLAR_EL1

This interface is accessible as follows:

When IsCorePowered(), !DoubleLockStatus(), AllowExternalDebugAccess() and SoftwareLockStatus(), accesses to this register are WI.
When IsCorePowered(), !DoubleLockStatus(), AllowExternalDebugAccess() and !SoftwareLockStatus(), accesses to this register are WO.
When IsCorePowered(), !DoubleLockStatus(), !AllowExternalDebugAccess() and FEAT_Debugv8p2 is not implemented, accesses to this register are IMPDEF.
Otherwise, accesses to this register generate an error response.

04/07/2023 11:26; 1b994cb0b8c6d1ae5a9a15edbc8bd6ce3b5c7d68