Patent ID: 8407529

Claim:
A data processing apparatus having one or more trace data sources, said trace data sources operating to generate respective streams of trace data, at least one of said trace data sources comprising: a trace data generator responsive to activity in monitored circuitry to generate trace data representing said activity; a synchronization marker generator coupled to said trace data generator, said synchronization marker generator operating to generate a synchronization marker and insert said synchronization marker into said trace data stream, said synchronization marker identifying a synchronization position in said trace data stream; and a controller coupled to said synchronization marker generator, said controller operating to initiate said synchronization marker generator to generate and insert said synchronization marker into said trace data stream; wherein said controller controls initiation in dependence on behavior of said data processing apparatus downstream of said trace data generator with respect to trace data flow, said apparatus comprising one or more trace handling circuits arranged to handle trace data generated by said trace data generator of said at least one trace data source; wherein said one or more trace handling circuits each have requesting circuitry for issuing a synchronization request and said controller of said at least one trace data source is responsive to receipt of said synchronization request to initiate said synchronization marker generator, wherein at least one of said one or more trace handling circuits handles trace data from a plurality of said trace data sources; said requesting circuitry of said at least one trace handling circuit is arranged to issue a global synchronization request to said plurality of trace data sources; and for each of said plurality of trace data sources, said controller initiates said synchronization marker generator in response to receipt of said global synchronization request, wherein said at least one trace handling circuit receives trace data from said plurality of trace data sources via respective trace data paths; and said requesting circuitry of said at least one trace handling circuit issues said global synchronization request to said plurality of trace data sources via said trace data paths.