4.15.1. CoreSight or other ATB flush request

The PTM might output its trace data over an Advanced Trace Bus (ATB). This data is received by a trace sink, such as a CoreSight Trace Port Interface Unit (TPIU) in a CoreSight system.

A trace sink can send a flush request to the PTM. When the PTM receives such a request it must drain all trace currently in the FIFO, and output any trace it is constructing. It must output any atoms it has assembled in an atom packet.

The PTM acknowledges the trace flush only after it has output all of the flushed data.

If you have enabled timestamping, the PTM must output a timestamp when it has output all of the required data. Normally, it does this before acknowledging the trace flush. However, if conditions exist that prevent it outputting the timestamp then it does not delay the flush acknowledge excessively. This means that the PFT architecture does not guarantee that the timestamp is issued before the flush is acknowledged. However, after an ATB flush request the PTM must issue a timestamp, even if it does so after acknowledging the flush.

The PTM does not stop trace generation while servicing this flush request.

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