System Control
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
4-39
ID021414
Non-Confidential
4.3.19
AArch64 Debug Feature Register 0, EL1
The ID_AA64DFR0_EL1 characteristics are:
Purpose
Provides top level information of the debug system in the AArch64
Execution state.
Usage constraints
This register is accessible as follows:
Configurations
ID_AA64DFR0_EL1 is architecturally mapped to external register
ID_AA64DFR0.
Attributes
ID_AA64DFR0_EL1 is a 64-bit register.
Figure 4-18
shows the ID_AA64DFR0_EL1 bit assignments.
Figure 4-18 ID_AA64DFR0_EL1 bit assignments
Table 4-47
shows the ID_AA64DFR0_EL1 bit assignments.
To access the ID_AA64DFR0_EL1:
EL0
EL1
(NS)
EL1
(S)
EL2
EL3
(SCR.NS = 1)
EL3
(SCR.NS = 0)
-
RO
RO
RO
RO
RO
4 3
8 7
12 11
16 15
20 19
24 23
28 27
0
63
RES
0
RES
0
Debugger
Tracever
PMUver
BRPs
WRPs
CTX_CMPs
RES
0
32 31
Table 4-47 ID_AA64DFR0_EL1 bit assignments
Bits
Name
Function
[63:32]
-
Reserved,
RES
0.
[31:28]
CTX_CMPs
Number of breakpoints that are context-aware, minus 1. These are the highest numbered
breakpoints:
0b0001
Two breakpoints are context-aware.
[27:24]
-
Reserved,
RES
0.
[23:20]
WRPs
The number of watchpoints minus 1:
0b0003
Four watchpoints.
[19:16]
-
Reserved,
RES
0.
[15:12]
BRPs
The number of breakpoints minus 1:
0b0005
Six breakpoints.
[11:8]
PMUver
Performance Monitors extension version.
0b0001
Performance monitor system registers implemented, PMUv3.
[7:4]
Tracever
Trace extension:
0b0000
Trace system registers not implemented.
[3:0]
Debugger
Debug architecture version:
0b0110
ARMv8-A debug architecture implemented.