System Control
ARM DDI 0388I
Copyright © 2008-2012 ARM. All rights reserved.
4-20
ID073015
Non-Confidential
•
Cortex-A9 processor accesses within a Cortex-A9 MPCore
processor
•
the target Cortex-A9 processor in a multi-processor cluster system.
Usage constraints
The MPIDR is:
•
only accessible in privileged mode
•
common to the Secure and Non-secure states.
Configurations
Available in all configurations. The value of the U bit, bit [30], indicates
if the configuration is a multiprocessor configuration or a uniprocessor
configuration.
Attributes
See the register summary in
.
shows the MPIDR bit assignments.
Figure 4-3 MPIDR bit assignments
shows the MPIDR bit assignments.
To access the MPIDR, read the CP15 register with:
MRC p15,0,<Rd>,c0,c0,5; read Multiprocessor ID register
31
8 7
0
U
SBZ
SBZ
12 11
Cluster ID
1
2
CPU
ID
1
30 29
Table 4-30 MPIDR bit assignments
Bits
Name
Function
[31]
-
Indicates the register uses the new multiprocessor format. This is always 1.
[30]
U bit
Multiprocessing Extensions:
0
Processor is part of an MPCore cluster
1
Processor is a uniprocessor.
[29:12]
-
SBZ.
[11:8]
Cluster ID
Value read in
CLUSTERID
configuration pins
a
. It identifies a Cortex-A9 MPCore processor in a system with
more than one Cortex-A9 MPCore processor present. SBZ for a uniprocessor configuration.
[7:2]
-
SBZ.
[1:0]
CPU ID
Indicates the CPU number in the Cortex-A9 MPCore configuration:
0x0
Processor is CPU0
0x1
Processor is CPU1
0x2
Processor is CPU2
0x3
Processor is CPU3.
In the uniprocessor version this value is fixed at
0x0
.
a. A uniprocessor implementation does not include any
CLUSTERID
pins.