System Control
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
4-197
ID021414
Non-Confidential
Table 4-194
shows the ACTLR bit assignments.
To access the ACTLR:
MRC p15, 0, <Rt>, c1, c0, 1 ; Read ACTLR into Rt
MCR p15, 0, <Rt>, c1, c0, 1 ; Write Rt to ACTLR
4.5.29
Architectural Feature Access Control Register
The CPACR characteristics are:
Purpose
Controls access to CP0 to CP13, and indicates which of CP0 to CP13 are
implemented.
Usage constraints
This register is accessible as follows:
The CPACR has no effect on instructions executed at EL2.
Configurations
CPACR is architecturally mapped to AArch64 register CPACR_EL1. See
Architectural Feature Access Control Register
on page 4-57
.
Table 4-194 ACTLR bit assignments
Bits
Name
Function
[31:7]
-
Reserved,
RES
0.
[6]
L2ACTLR access control
L2ACTLR write access control. The possible values are:
0
The register is not write accessible from a lower exception level. This
is the reset value.
1
The register is write accessible from EL2.
[5]
L2ECTLR access control
L2ECTLR write access control. The possible values are:
0
The register is not write accessible from a lower exception level. This
is the reset value.
1
The register is write accessible from EL2.
[4]
L2CTLR access control
L2CTLR write access control. The possible values are:
0
The register is not write accessible from a lower exception level. This
is the reset value.
1
The register is write accessible from EL2.
[3:2]
-
Reserved,
RES
0.
[1]
CPUECTLR access control
CPUECTLR write access control. The possible values are:
0
The register is not write accessible from a lower exception level. This
is the reset value.
1
The register is write accessible from EL2.
[0]
CPUACTLR access control
CPUACTLR write access control. The possible values are:
0
The register is not write accessible from a lower exception level. This
is the reset value.
1
The register is write accessible from EL2.
EL0
(NS)
EL0
(S)
EL1
(NS)
EL1
(S)
EL2
EL3
(SCR.NS = 1)
EL3
(SCR.NS = 0)
-
-
RW
RW
RW
RW
RW