Apparatus and method for combining trace data from a plurality of trace sources

A method of operating an apparatus having an input interface to receive trace data from a plurality of trace sources, an output interface from which to issue a trace stream incorporating the trace data from each of said plurality of trace sources, and a network of interconnected funnel elements to combine the trace data received at the input interface from said plurality of trace sources in order to produce said trace stream, each funnel element having a plurality of input ports and an output port, the method comprising:

• providing associated control circuitry for each funnel element to control connection of the input ports to the output port;
• arranging each input port to receive one of trace data from one of said trace sources and trace data output from an output port of another funnel element in said network;
• at each control circuitry:
• determining, from information provided by at least one setup transaction received by that control circuitry, control data indicative of a number of trace sources whose trace data is to be routed through each of the input ports of the associated funnel element;
• and
• controlling a timing allocation of the associated funnel element's output port to each input port in dependence on said control data, such that a proportion of the bandwidth of the output interface available to each trace source is independent of topology of the funnel elements within the network.

An apparatus, comprising:

• an input interface to receive trace data from a plurality of trace sources;
• an output interface from which to issue a trace stream incorporating the trace data from each of said plurality of trace sources;
• a network of interconnected funnel elements to combine the trace data received at the input interface from said plurality of trace sources in order to produce said trace stream;
• each funnel element having a plurality of input ports and an output port, and having associated control circuitry to control connection of the input ports to the output port, each input port arranged to receive one of trace data from one of said trace sources and trace data output from an output port of another funnel element in said network;
• the control circuitry being arranged to determine, from information provided by at least one setup transaction received by the control circuitry, control data indicative of a number of trace sources whose trace data is to be routed through each of the input ports of the associated funnel element, and to control a timing allocation of the associated funnel element's output port to each input port in dependence on said control data;
• wherein the control circuitry of each funnel element whose output port is connected to an input port of a further funnel element in said network is arranged, in response to at least one trigger condition, to issue the setup transaction to the control circuitry of said further funnel element.