A data processing apparatus controls cross-triggering of diagnostic
processes on a plurality of processing devices. The data processing
apparatus comprises a routing module having a plurality of broadcast
channels, one or more of the broadcast channels being operable to
indicate the occurrence of a diagnostic event on one or more of the
plurality of processing devices. The data processing apparatus also
comprises an mapping module associated with a corresponding processing
device. The interface module programmably asserts diagnostic event
signals from the associated processing device to one or more of the
plurality of broadcast channels and programmably retrieves diagnostic
events signals from processing devices other than the associated
processing device from one or more of the plurality of broadcast
channels. The retrieved diagnostic event data is used to facilitate
triggering of a diagnostic process on the associated processing device in
dependence upon said retrieved diagnostic event data.