ARM ARM1176JZF-S User Manual

System Control Coprocessor
ARM DDI 0301H Copyright © 2004-2009 ARM Limited. All rights reserved. 3-47
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Attempts to read or write the Control Register from Secure or Non-secure User modes results
in an Undefined exception.
Attempts to write to this register in Secure Privileged mode when CP15SDISABLE is HIGH
result in an Undefined exception, see TrustZone write access disable on page 2-9.
Attempts to write Secure modify only bit in Non-secure privileged modes are ignored.
Attempts to read Secure modify only bits return the Secure bit value. Table 3-40 lists the actions
that result from attempted access for each mode.
Use of the Control Register
To use the Control Register it is recommended that you use a read modify write technique. To
use the Control Register read or write CP15 with:
• Opcode_1 set to 0
• CRn set to c1
• CRm set to c0
• Opcode_2 set to 0.
For example:
MRC p15, 0, <Rd>, c1, c0, 0 ; Read Control Register configuration data
MCR p15, 0, <Rd>, c1, c0, 0 ; Write Control Register configuration data
Normally, to set the V bit and the B, EE, and U bits you configure signals at reset.
The V bit depends on VINITHI at reset:
• VINITHI LOW sets V to 0
• VINITHI HIGH sets V to 1.
[2] C bit Banked Enables level one data cache.
0 = Data cache disabled, reset value.
1 = Data cache enabled.
[1] A bit Banked Enables strict alignment of data to detect alignment faults in data accesses. The A bit
setting takes priority over the U bit.
0 = Strict alignment fault checking disabled, reset value.
1 = Strict alignment fault checking enabled.
[0] M bit Banked Enables the MMU.
0 = MMU disabled, reset value.
1 = MMU enabled.
Table 3-39 Control Register bit functions (continued)
Bits
Field
name
Access Function
Table 3-40 Results of access to the Control Register
Access type Secure Privileged
Non-secure Privileged
User
Read Write
Secure modify only Secure bit Secure bit Ignored Undefined exception
Banked Secure bit Non-secure bit Non-secure bit Undefined exception

ARM ARM1176JZF-S Specifications

General

Brand	ARM
Model	ARM1176JZF-S
Category	Computer Hardware
Language	English