B2.57 ID_AA64DFR0_EL1, AArch64 Debug Feature Register 0, EL1

Provides top-level information about the debug system in AArch64.

Bit field descriptions

ID_AA64DFR0_EL1 is a 64-bit register, and is part of the Identification registers functional group.

This register is Read Only.

Figure B2-43 ID_AA64DFR0_EL1 bit assignments
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RES0, [63:32]
CTX_CMPs, [31:28]

Number of breakpoints that are context-aware, minus 1. These are the highest numbered breakpoints:

0x1Two breakpoints are context-aware.
RES0, [27:24]
WRPs, [23:20]

The number of watchpoints minus 1:

0x3Four watchpoints.
RES0, [19:16]
BRPs, [15:12]

The number of breakpoints minus 1:

0x5Six breakpoints.
PMUVer, [11:8]

Performance Monitors Extension version.

0x4Performance monitor system registers implemented, PMUv3.
TraceVer, [7:4]

Trace extension:

0x0Trace system registers not implemented.
DebugVer, [3:0]

Debug architecture version:

0x8Arm®v8‑A debug architecture implemented.

ID_AA64DFR0_EL1 is architecturally mapped to external register EDDFR.

Bit fields and details that are not provided in this description are architecturally defined. See the Arm® Architecture Reference Manual Armv8, for Armv8-A architecture profile.

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