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EDDEVARCH: External Debug Device Architecture Register

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

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ARCHITECTPRESENTREVISIONARCHVERARCHPART

ARCHITECT, bits [31:21]

Defines the architecture of the component. For debug, this is Arm Limited.

Bits [31:28] are the JEP106 continuation code, 0x4.

Bits [27:21] are the JEP106 ID code, 0x3B.

Reads as 0b01000111011.

Access to this field is RO.

PRESENT, bit [20]

Indicates that the DEVARCH 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:

ARCHVERMeaning
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.

ARCHPARTMeaning
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:

ComponentOffsetInstance
Debug0xFBCEDDEVARCH

This interface is accessible as follows: