System Control
ARM DDI 0388I
Copyright © 2008-2012 ARM. All rights reserved.
4-25
ID073015
Non-Confidential
4.3.9
System Control Register
The SCTLR characteristics are:
Purpose
Provides control and configuration of:
•
memory alignment and endianness
•
memory protection and fault behavior
•
MMU and cache enables
•
interrupts and behavior of interrupt latency
•
location for exception vectors
•
program flow prediction.
Usage constraints
The SCTLR is:
•
Only accessible in privileged modes.
•
Partially banked.
shows banked and secure modify only
bits.
Configurations
Available in all configurations.
Attributes
See the register summary in
.
shows the SCTLR bit assignments.
Figure 4-8 SCTLR bit assignments
shows the SCTLR bit assignments.
31 30 29 28 27 26 25 24
14 13 12 11 10
3 2 1 0
M
I
NMFI
Reserved
Reserved
Reserved
V
Z
C A
23 22 21 20 19
9
SW bit
18 17 16 15
RR bit
TE
AFE
TRE
EE
HA
Table 4-35 SCTLR bit assignments
Bits
Name
Access
Function
[31]
-
-
SBZ.
[30]
TE
Banked
Thumb exception enable:
0
Exceptions, including reset, are handled in ARM state
1
Exceptions, including reset, are handled in Thumb state.
The
TEINIT
signal defines the reset value.
[29]
AFE
Banked
Access Flag enable bit:
0
Full access permissions behavior. This is the reset value.
The software maintains binary compatibility with ARMv6K behavior.
1
Simplified access permissions behavior.
The Cortex-A9 processor redefines the AP[0] bit as an access flag.
The TLB must be invalidated after changing the AFE bit.
[28]
TRE
Banked
This bit controls the TEX remap functionality in the MMU:
0
TEX remap disabled. This is the reset value.
1
TEX remap enabled.