C4.3 Etm Trace Unit Functional Description - ARM Cortex-A76 Core Technical Reference Manual

C4.3 ETM trace unit functional description
This section describes the functionality of the ETM trace unit.
The following figure shows the main functional blocks of the ETM trace unit.
Core interface
Trace generation
Filtering and triggering resources
FIFO
Trace out
100798_0300_00_en
CORECLK
Debug APB
Core
interface
This block monitors the behavior of the core and generates P0 elements that are essentially
executed branches and exceptions traced in program order.
The trace generation block generates various trace packets based on P0 elements.
You can limit the amount of trace data generated by the ETM through the process of filtering.
For example, generating trace only in a certain address range. More complicated logic analyzer
style filtering options are also available.
The ETM trace unit can also generate a trigger that is a signal to the trace capture device to stop
capturing trace.
The trace generated by the ETM trace unit is in a highly-compressed form.
The FIFO enables trace bursts to be flattened out. When the FIFO becomes full, the FIFO
signals an overflow. The trace generation logic does not generate any new trace until the FIFO is
emptied. This causes a gap in the trace when viewed in the debugger.
Trace from FIFO is output on the AMBA ATB interface.
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Filtering and triggering
resources
Core interface
block
reserved.
Non-Confidential
C4 Embedded Trace Macrocell

C4.3 ETM trace unit functional description

ETM
Trace out ATB
FIFO
Trace generation
Figure C4-1 ETM functional blocks
C4-395