System Control
ARM DDI 0388I
Copyright © 2008-2012 ARM. All rights reserved.
4-33
ID073015
Non-Confidential
shows the NSACR bit assignments.
To access the NSACR, read or write the CP15 register with:
MRC p15, 0,<Rd>, c1, c1, 2; Read NSACR data
MCR p15, 0,<Rd>, c1, c1, 2; Write NSACR data
See the
Cortex-A9 Floating-Point Unit Technical Reference Manual
and
Cortex-A9 NEON
Media Processing Engine Technical Reference Manual
for more information.
Table 4-39 NSACR bit assignments
Bits
Name
Function
[31:19]
-
UNK/SBZP.
[18]
NS_SMP
Determines if the SMP bit of the Auxiliary Control Register is writable in Non-secure state:
0
A write to Auxiliary Control Register in Non-secure state takes an Undefined Instruction
exception and the SMP bit is write ignored. This is the reset value.
1
A write to Auxiliary Control Register in Non-secure state can modify the value of the SMP
bit. Other bits are write ignored.
[17]
TL
Determines if lockable TLB entries can be allocated in Non-secure state:
0
Lockable TLB entries cannot be allocated. This is the reset value.
1
Lockable TLB entries can be allocated.
[16]
PLE
Controls NS accesses to the Preload Engine resources:
0
Only Secure accesses to CP15 c11 are permitted. All Non-secure accesses to CP15 c11 are
trapped to
UNDEFINED
. This is the default value.
1
Non-secure accesses to the CP15 c11 domain are permitted. That is, PLE resources are
available in the Non-secure state.
If the Preload Engine is not implemented, this bit is RAZ/WI. See
[15]
NSASEDIS
Disable Non-secure Advanced SIMD Extension functionality:
0
This bit has no effect on the ability to write CPACR.ASEDIS. This is the reset value.
1
The CPACR.ASEDIS bit, when executing in Non-secure state, has a fixed value of 1 and
writes to it are ignored.
See the
Cortex-A9 Floating-Point Unit Technical Reference Manual
and
Cortex-A9 NEON Media
Processing Engine Technical Reference Manual
for more information.
[14]
NSD32DIS
Disable the Non-secure use of D16-D31 of the VFP register file:
0
This bit has no effect on the ability to write CPACR. D32DIS. This is the reset value.
1
The CPACR.D32DIS bit, when executing in Non-secure state, has a fixed value of 1 and
writes to it are ignored.
See the
Cortex-A9 Floating-Point Unit Technical Reference Manual
and
Cortex-A9 NEON Media
Processing Engine Technical Reference Manual
for more information.
[13:12]
-
UNK/SBZP.
[11]
CP11
Determines permission to access coprocessor 11 in the Non-secure state:
0
Secure access only. This is the reset value.
1
Secure or Non-secure access.
[10]
CP10
Determines permission to access coprocessor 10 in the Non-secure state:
0
0 = Secure access only. This is the reset value.
1
1 = Secure or Non-secure access.
[9:0]
-
UNK/SBZP.