System Control
ARM DDI 0500D Copyright © 2013-2014 ARM. All rights reserved. 4-270
ID021414 Non-Confidential
Table 4-244 shows the CPUACTLR bit assignments.
Table 4-244 CPUACTLR bit assignments
Bits Name Function
[63:31] - Reserved,
RES0.
[30] FPDIDIS Disable floating-point dual issue. The possible values are:
0
Enable dual issue of floating-point, Advanced SIMD and Cryptography instructions. This is
the reset value.
1
Disable dual issue of floating-point, Advanced SIMD and Cryptography instructions.
[29] DIDIS Disable Dual Issue. The possible values are:
0
Enable Dual Issue of instructions. This is the reset value.
1
Disable Dual Issue of all instructions.
[28:27] RADIS Write streaming no-allocate threshold. The possible values are:
0b00
16th consecutive streaming cache line does not allocate in the L1 or L2 cache.
0b01
128th consecutive streaming cache line does not allocate in the L1 or L2 cache. This is the
reset value.
0b10
512th consecutive streaming cache line does not allocate in the L1 or L2 cache.
0b11
Disables streaming. All write-allocate lines allocate in the L1 or L2 cache.
[26:25] L1RADIS Write streaming no-L1-allocate threshold. The possible values are:
0b00
4th consecutive streaming cache line does not allocate in the L1 cache. This is the reset value.
0b01
64th consecutive streaming cache line does not allocate in the L1 cache.
0b10
128th consecutive streaming cache line does not allocate in the L1 cache.
0b11
Disables streaming. All write-allocate lines allocate in the L1 cache.
[24] DTAH Disable Transient allocation hint. The possible values are:
0
Normal operation. This is the reset value.
1
The Transient allocation hint in the MAIR is ignored and treated the same as non-transient
allocation types. The
LDNP
and
STNP
instructions in AArch64 behave the same as the equivalent
LDP
and
STP
instructions.
[23] STBPFRS Disable ReadUnique request for prefetch streams initiated by STB accesses:
0
ReadUnique used for prefetch streams initiated from STB accesses. This is the reset value.
1
ReadShared used for prefetch streams initiated from STB accesses.
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