System Control
ARM DDI 0388I
Copyright © 2008-2012 ARM. All rights reserved.
4-42
ID073015
Non-Confidential
4.3.23
NEON Busy Register
The NEON Busy Register characteristics are:
Purpose
Enables software to determine if a NEON instruction is executing.
Usage constraints
•
a read-only register in Secure state
•
a read-only register in Non-secure state.
Configurations
Available in all configurations.
Attributes
See the register summary in
shows the NEON Busy Register bit assignments
Figure 4-22 NEON Busy Register bit assignments
shows the NEON Busy Register bit assignments.
To access the NEON Busy Register, read the CP15 register with:
MRC p15,0,<Rd>,c15,c1,0; Read NEON Busy Register
4.3.24
Configuration Base Address Register
The Configuration Base Address Register characteristics are:
Purpose
Takes the physical base address value at reset.
Usage constraints
The Configuration Base Address Register is:
•
read/write in secure privileged modes
•
read-only in non-secure state
•
read-only in User mode.
Configurations
In Cortex-A9 uniprocessor implementations the base address is set to zero.
In Cortex-A9 MPCore implementations, the base address is reset to
PERIPHBASE[31:13]
so that software can determine the location of the
private memory region.
Attributes
See the register summary in
shows the Configuration Base Address Register bit assignments.
31
1
NEON busy
0
Reserved
Table 4-49 NEON Busy Register bit assignments
Bits
Name
Function
[31:1]
-
Reserved.
[0]
NEON busy
Software can use this to determine if a NEON instruction is executing. This bit is set to 1 if there is a NEON
instruction in the NEON pipeline, or in the processor pipeline.