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# EDDEVID, External Debug Device ID register 0

The EDDEVID characteristics are:

## Purpose

Provides extra information for external debuggers about features of the debug implementation.

## Configuration

It is IMPLEMENTATION DEFINED whether EDDEVID 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.

## Attributes

EDDEVID is a 32-bit register.

## Field descriptions

The EDDEVID bit assignments are:

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 | AuxRegs | RES0 | DebugPower | PCSample

#### Bits [31:28]

Reserved, RES0.

#### AuxRegs, bits [27:24]

Indicates support for Auxiliary registers. Permitted values for this field are:

AuxRegs | Meaning
--- | ---
0b0000 | None supported.
0b0001 | Support for External Debug Auxiliary Control Register, EDACR.

All other values are reserved.

#### Bits [23:8]

Reserved, RES0.

#### DebugPower, bits [7:4]
When ARMv8.3-DoPD is implemented:

Indicates support for the ARMv8.3-DoPD feature. Defined values of this field are:

DebugPower | Meaning
--- | ---
0b0000 | ARMv8.3-DoPD not implemented. Registers in the external debug interface register map are implemented in a mix of the Debug and Core power domains.
0b0001 | ARMv8.3-DoPD implemented. All registers in the external debug interface register map are implemented in the Core power domain.

ARMv8.3-DoPD implements the functionality added by the value 0b0001.

All other values are reserved.

####
Otherwise:

Reserved, RES0.

#### PCSample, bits [3:0]

Indicates the level of PC Sample-based Profiling support using external debug registers. Permitted values of this field are:

PCSample | Meaning
--- | ---
0b0000 | PC Sample-based Profiling Extension is not implemented in the external debug registers space.
0b0010 | Only EDPCSR and EDCIDSR are implemented. This option is only permitted if EL3 and EL2 are not implemented.
0b0011 | EDPCSR, EDCIDSR, and EDVIDSR are implemented.

All other values are reserved.

When ARMv8.2-PCSample is implemented, the only permitted value is 0b0000.

Note

ARMv8.2-PCSample implements the PC Sample-based Profiling Extension in the Performance Monitors register space, as indicated by the value of PMDEVID.PCSample.

## Accessing the EDDEVID

#### EDDEVID can be accessed through the external debug interface:

Component | Offset | Instance
--- | --- | ---
Debug | 0xFC8 | EDDEVID

This interface is accessible as follows:

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

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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