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# EDDEVARCH, External Debug Device Architecture Register

The EDDEVARCH characteristics are:

## Purpose

Identifies the programmers' model architecture of the external debug component.

## Configuration

When FEAT_DoPD is implemented, EDDEVARCH is in the Core power domain. Otherwise, EDDEVARCH is in the Debug power domain.

Implementation of this register is OPTIONAL.

## Attributes

EDDEVARCH 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
ARCHITECT | PRESENT | REVISION | ARCHVER | ARCHPART

#### ARCHITECT, bits [31:21]

Defines the architect of the component. For External Debug, this is Arm Limited.

Bits [31:28] are the JEP106 continuation code, 0b0100.

Bits [27:21] are the JEP106 identification code, 0b0111011.

Reads as 0b01000111011.

Access to this field is RO.

#### PRESENT, bit [20]

DEVARCH present. Indicates that the EDDEVARCH register is present.

Reads as 0b1.

Access to this field is RO.

#### REVISION, bits [19:16]

Defines the architecture revision. For architectures defined by Arm this is the minor revision.

For debug, the revision defined by Armv8 is 0x0.

All other values are reserved.

Reads as 0b0000.

Access to this field is RO.

#### ARCHVER, bits [15:12]

Architecture Version. Defines the architecture version of the component. Defined values are:

ARCHVER | Meaning
--- | ---
0b0110 | Armv8 debug architecture.
0b0111 | Armv8 debug architecture with Virtualization Host Extensions.
0b1000 | Armv8.2 debug architecture, FEAT_Debugv8p2.
0b1001 | Armv8.4 debug architecture, FEAT_Debugv8p4.
0b1010 | Armv8.8 debug architecture, FEAT_Debugv8p8.
0b1011 | Armv8.9 debug architecture, FEAT_Debugv8p9.

EDDEVARCH.ARCHVER and EDDEVARCH.ARCHPART are also defined as a single field, EDDEVARCH.ARCHID, so that EDDEVARCH.ARCHVER is EDDEVARCH.ARCHID[15:12].

FEAT_VHE implements the functionality identified by the value 0b0111.

FEAT_Debugv8p2 implements the functionality identified by the value 0b1000.

FEAT_Debugv8p4 implements the functionality identified by the value 0b1001.

FEAT_Debugv8p8 implements the functionality identified by the value 0b1010.

FEAT_Debugv8p9 implements the functionality identified by the value 0b1011.

From Armv8.1, when FEAT_VHE is implemented the value 0b0110 is not permitted.

From Armv8.2, the values 0b0110 and 0b0111 are not permitted.

From Armv8.4, the value 0b1000 is not permitted.

From Armv8.8, the value 0b1001 is not permitted.

From Armv8.9, the value 0b1010 is not permitted.

#### ARCHPART, bits [11:0]

Architecture Part. Defines the architecture of the component.

ARCHPART | Meaning
--- | ---
0xA15 | Armv8-A debug architecture.

EDDEVARCH.ARCHVER and EDDEVARCH.ARCHPART are also defined as a single field, EDDEVARCH.ARCHID, so that EDDEVARCH.ARCHPART is EDDEVARCH.ARCHID[11:0].

Armv8-A debug architecture.

Access to this field is RO.

## Accessing EDDEVARCH

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

Component | Offset | Instance
--- | --- | ---
Debug | 0xFBC | EDDEVARCH

This interface is accessible as follows:

- When FEAT_DoPD is implemented and !IsCorePowered(), accesses to this register generate an error response.
- Otherwise, accesses to this register are RO.

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

26/03/2024 09:49; 67c0ae5282a7629ba0ea0ba7267b43cd4f7939f6

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