System Control
ARM DDI 0500D
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4-273
ID021414
Non-Confidential
Table 4-245
shows the CPUECTLR bit assignments.
To access the CPUECTLR:
MRRC p15, 1, <Rt>, <Rt2>, c15; Read CPU Extended Control Register
MCRR p15, 1, <Rt>, <Rt2>, c15; Write CPU Extended Control Register
4.5.78
CPU Memory Error Syndrome Register
The CPUMERRSR characteristics are:
Purpose
Holds ECC errors on the:
•
L1 data RAMs.
•
L1 tag RAMs.
•
TLB RAMs.
This register is used for recording ECC errors on all processor RAMs.
Table 4-245 CPUECTLR bit assignments
Bits
Name
Function
[63:7]
-
Reserved,
RES
0.
[6]
SMPEN
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.
Note
Set the SMPEN bit before enabling the caches, even if there is only one core in the system.
[5:3]
FPRETCTL
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.
0b111
512 Architectural Timer ticks are required before retention entry.
Note
This field is present only if the Advanced SIMD and Floating-point Extension is implemented. Otherwise,
it is
RES
0.
[2:0]
CPURETCTL
CPU 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.
0b111
512 Architectural Timer ticks are required before retention entry.