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EDDFR1, External Debug Feature Register 1

The EDDFR1 characteristics are:

Purpose

Provides top level information about the debug system in AArch64.

Configuration

If FEAT_DoPD is not implemented then it is IMPLEMENTATION DEFINED whether EDDFR1 is in the Core power domain or Debug power domain. If FEAT_DoPD is implemented then EDDFR1 is in the Core power domain.

Note

If FEAT_DoPD is implemented, FEAT_DoubleLock is not implemented.

Attributes

EDDFR1 is a 64-bit register.

Field descriptions

6362616059585756555453525150494847464544434241403938373635343332
313029282726252423222120191817161514131211109876543210
RES0EBEPITEABLEPMICNTRSPMU
CTX_CMPsWRPsBRPsSYSPMUID

Bits [63:52]

Reserved, RES0.

EBEP, bits [51:48]

This field either has the same value as ID_AA64DFR1_EL1.EBEP or reads as zero.

ITE, bits [47:44]

This field either has the same value as ID_AA64DFR1_EL1.ITE or reads as zero.

ABLE, bits [43:40]

Address Breakpoint Linking Extension. Defined values are:

ABLEMeaning
0b0000

Address Breakpoint Linking Extension not implemented.

0b0001

Address Breakpoint Linking Extension implemented.

All other values are reserved.

FEAT_ABLE implements the functionality identified by the value 0b0001.

If FEAT_ABLE is not implemented, then the only permitted value is 0b0000.

From Armv9.4, when FEAT_ABLE is implemented, the value 0b0000 is not permitted.

PMICNTR, bits [39:36]

This field either has the same value as ID_AA64DFR1_EL1.PMICNTR or reads as zero.

SPMU, bits [35:32]

This field either has the same value as ID_AA64DFR1_EL1.SPMU or reads as zero.

CTX_CMPs, bits [31:24]
When FEAT_Debugv8p9 is implemented and EDDFR.CTX_CMPs == 0b1111:

Number of breakpoints that are context-aware, minus 1.

The value 0x00 means 16 breakpoints that are context-aware are implemented. Otherwise, this field is the number of breakpoints that are context-aware, minus 1.

The values 0x01 to 0x0F and 0x40 to 0xFF are reserved.

The value of this field is never greater than ID_AA64DFR1_EL1.BRPs.


Otherwise:

Reserved, RES0.

WRPs, bits [23:16]
When FEAT_Debugv8p9 is implemented and EDDFR.WRPs == 0b1111:

Number of watchpoints, minus 1.

The value 0x00 means 16 watchpoints are implemented. Otherwise, this field is the number of watchpoints, minus 1.

The values 0x01 to 0x0F and 0x40 to 0xFF are reserved.


Otherwise:

Reserved, RES0.

BRPs, bits [15:8]
When FEAT_Debugv8p9 is implemented and EDDFR.BRPs == 0b1111:

Number of breakpoints, minus 1.

The value 0x00 means 16 breakpoints are implemented. Otherwise, this field is the number of breakpoints, minus 1.

The values 0x01 to 0x0F and 0x40 to 0xFF are reserved.


Otherwise:

Reserved, RES0.

SYSPMUID, bits [7:0]

This field either has the same value as ID_AA64DFR1_EL1.SYSPMUID or reads as zero.

Accessing EDDFR1

EDDFR1 can be accessed through the external debug interface:

ComponentOffsetInstance
Debug0xD48EDDFR1

Accesses to this interface are RO.


30/09/2022 15:58; 21c5a6dd0fdaf10a712e2f2d6fffbdbd66d4d96f

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