4 Programming the TPIU for trace capture
The following points must be considered when programming the TPIU registers for trace capture.
- TPAs that are only capable of operation
with tracectl must only use the formatter in either bypass
or normal mode, not in continuous mode.
- Arm recommends that, following a trigger event within a multi-trace source configuration, a flush is performed to ensure that all historical information that is related to the trigger is output.
- If Flush on Trigger Event and Stop on Trigger Event options are chosen, then the
TPA does not capture any data after the trigger. When the TPIU is instructed to stop, it
discards any subsequent trace data, including data returned by the flush. Select Stop on
Flush completion instead.
- Multiple flushes can be scheduled using Flush on Trigger Event, Flush on flushin, and manual flush. When one of
these requests is made, it masks more requests of the same type. This masking means that
repeated writing to the manual flush bit does not schedule multiple manual requests unless
each is permitted to complete first.
- Unless multiple triggers are required, it is not
advisable to set both Trigger on Trigger Event and Trigger on Flush
Completion, if Flush on Trigger Event is also enabled. In addition,
if Trigger on trigin is enabled with this configuration,
it can also cause multiple trigger markers from one trigger request.