Embedded Trace Macrocell
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
13-76
ID021414
Non-Confidential
13.9
Interaction with debug and performance monitoring unit
This section describes:
•
Interaction with the performance monitoring unit
.
•
Effect of debug double lock on trace register access
.
13.9.1
Interaction with the performance monitoring unit
The Cortex-A53 processor includes a
Performance Monitoring Unit
(PMU) that enables events,
such as cache misses and instructions executed, to be counted over a period of time. See
Chapter 12
Performance Monitor Unit
for more information. This section describes how the
PMU and ETM trace unit function together.
Use of PMU events by the ETM trace unit
All PMU architectural events are available to the ETM trace unit through the extended input
facility. See the
ARM
®
Architecture Reference Manual ARMv8, for ARMv8-A architecture
profile
for more information on PMU events.
The ETM trace unit uses four extended external input selectors to access the PMU events. Each
selector can independently select one of the PMU events, that are then active for the cycles
where the relevant events occur. These selected events can then be accessed by any of the event
registers within the ETM trace unit.
Table 12-28 on page 12-36
describes the PMU events.
13.9.2
Effect of debug double lock on trace register access
All trace register accesses through the memory-mapped and external debug interfaces behave
as if the processor power domain is powered down when debug double lock is set. For more
information on debug double lock, see the
ARM
®
Architecture Reference Manual ARMv8, for
ARMv8-A architecture profile
.