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EDLAR, External Debug Lock Access Register

The EDLAR characteristics are:

Purpose

Allows or disallows access to the external debug registers through a memory-mapped interface.

Configuration

It is IMPLEMENTATION DEFINED whether EDLAR is implemented in the Core power domain or in the Debug power domain.

If ARMv8.3-DoPD is implemented, this register is in the Core power domain. If ARMv8.3-DoPD is not implemented, this register is in the Debug power domain.

EDLAR ignores writes if the Software Lock is not implemented and ignores writes for other accesses to the external debug interface.

The Software Lock provides a lock to prevent memory-mapped writes to the debug registers. Use of this lock mechanism reduces the risk of accidental damage to the contents of the debug registers. It does not, and cannot, prevent all accidental or malicious damage.

Software uses EDLAR to set or clear the lock, and EDLSR to check the current status of the lock.

Attributes

EDLAR is a 32-bit register.

Field descriptions

The EDLAR bit assignments are:

313029282726252423222120191817161514131211109876543210
KEY

KEY, bits [31:0]

Lock Access control. Writing the key value 0xC5ACCE55 to this field unlocks the lock, enabling write accesses to this component's registers through a memory-mapped interface.

Writing any other value to this register locks the lock, disabling write accesses to this component's registers through a memory mapped interface.

Accessing the EDLAR

EDLAR can be accessed through the memory-mapped interfaces:

ComponentOffsetInstance
Debug0xFB0EDLAR

This interface is accessible as follows:

  • When ARMv8.3-DoPD is not implemented or IsCorePowered() access to this register is WO.
  • Otherwise access to this register returns an Error.


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