Functional Description
ARM DDI 0388I
Copyright © 2008-2012 ARM. All rights reserved.
2-4
ID073015
Non-Confidential
2.2
Interfaces
The processor has the following external interfaces:
•
•
•
Program Flow Trace and Program Trace Macrocell
.
2.2.1
AXI interface
The Cortex-A9 processor implements AMBA 3 AXI interface. See the
AMBA AXI Protocol
Specification
for more information.
2.2.2
APB external debug interface
The Cortex-A9 processor implements the ARM Debug interface version 5. See the
CoreSight
Architecture Specification
for more information.
2.2.3
Program Flow Trace and Program Trace Macrocell
The Cortex-A9 processor implements the
Program Flow Trace
(PFT) architecture protocol. See
the
CoreSight Program Flow Trace Architecture Specification
.
PFT is an instruction-only trace protocol that uses waypoints to correlate the trace to the code
image. Waypoints are changes in the program flow or events such as branches or changes in
context ID that must be output to enable the trace. See the
CoreSight PTM-A9 Technical
Reference Manual
for more information about tracing with waypoints.
Program Trace Macrocell
(PTM) is a macrocell that implements the PFT architecture.
shows the PTM interface signals.
Figure 2-2 PTM interface signals
See
CoreSight PTM-A9 Technical Reference Manual
for more information.
Trace must be disabled in some regions. The prohibited regions are described in the
ARM
Architecture Reference Manual
. The Cortex-A9 processor must determine prohibited regions
for non-invasive debug in regions, including trace, performance monitoring, and PC sampling.
No waypoints are generated for instructions that are within a prohibited region.
Cortex-A9 processor
WPTCOMMIT[1:0]
WPTENABLE
WPTCONTEXTID[31:0]
WPTEXCEPTIONTYPE[3:0]
WPTFLUSH
WPTLINK
WPTPC[31:0]
WPTT32LINK
WPTTAKEN
WPTTARGETJBIT
WPTTARGETPC[31:0]
WPTTARGETTBIT
WPTTRACEPROHIBITED
WPTTYPE[2:0]
WPTVALID
WPTnSECURE
WPTFIFOEMPTY