B1.43
CPU Extended Control Register
The CPUECTLR characteristics are:
Purpose
Provides additional
IMPLEMENTATION DEFINED
configuration and control options for the processor.
Usage constraints
This register is accessible as follows:
EL0
(NS)
EL0
(S)
EL1
(NS)
EL1
(S)
EL2 EL3
(SCR.NS = 1)
EL3
(SCR.NS = 0)
-
-
RW
RW RW RW
RW
The CPUECTLR can be written dynamically.
Configurations
The CPUECTLR is mapped to the AArch64 CPUECTLR_EL1 register. See
Extended Control Register, EL1
.
Attributes
CPUECTLR is a 64-bit register.
7 6 5
3 2
RES
0
0
63
SMPEN
FPRETCTL
CPURETCTL
Figure B1-7 CPUECTLR bit assignments
[63:7]
Reserved,
RES0
.
SMPEN, [6]
Enable hardware management of data coherency with other cores in the cluster. The possible
values are:
0
Disables data coherency with other cores in the cluster. This is the reset value.
1
Enables data coherency with other cores in the cluster.
Set the SMPEN bit before enabling the caches, even if there is only one core in the system.
FPRETCTL, [5:3]
Advanced SIMD and floating-point retention control. The possible values are:
0b000
Disable the retention circuit. This is the reset value.
0b001
2 Architectural Timer ticks are required before retention entry.
0b010
8 Architectural Timer ticks are required before retention entry.
0b011
32 Architectural Timer ticks are required before retention entry.
0b100
64 Architectural Timer ticks are required before retention entry.
0b101
128 Architectural Timer ticks are required before retention entry.
0b110
256 Architectural Timer ticks are required before retention entry.
B1 AArch32 system registers
B1.43 CPU Extended Control Register
100236_0100_00_en
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B1-212
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Summary of Contents for Cortex-A35
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