Generation of trace signals within a data processing apparatus

A data processing apparatus comprising:

• a plurality of trace modules for receiving input signals from one or more components whose behaviours are to be traced, each trace module being arranged to generate from its respective input signals trace signals for outputting over a corresponding trace bus;
• and
• funnel logic coupled to the trace buses of the trace modules so as to receive as input trace signals the trace signals output on each trace bus, and being arranged to generate at an output port a trace stream derived from the input trace signals, the output port having a maximum bandwidth which is less than the collective maximum bandwidth of the trace buses coupled to the funnel logic;
• the funnel logic being arranged to control the issuance of trace signals by the trace modules to ensure that the input trace signals can be output from the output port without exceeding the maximum bandwidth of the output port, wherein the funnel logic comprises a request handler for receiving request signals from each trace module wishing to output trace signals onto its corresponding trace bus, and for applying predetermined criteria to determine from the received request signals which trace module should provide trace signals to the funnel logic.

A data processing apparatus, comprising:

• a plurality of trace modules for receiving input signals from one or more components whose behaviours are to be traced, each trace module being arranged to generate from its respective input signals trace signals for outputting over a corresponding trace bus;
• and
• funnel logic coupled to the trace buses of the trace modules so as to receive as input trace signals the trace signals output on each trace bus, and being arranged to generate at an output port a trace stream derived from the input trace signals, the output port having a maximum bandwidth which is less than the collective maximum bandwidth of the trace buses coupled to the funnel logic;
• the funnel logic being arranged to control the issuance of trace signals by the trace modules to ensure that the input trace signals can be output from the output port without exceeding the maximum bandwidth of the output port, wherein the issuance of trace signals by at least one of the trace modules is not controllable by the funnel logic, the data processing apparatus further comprising a stalling buffer for each such trace module coupled between that trace module and the funnel logic to buffer trace signals output by that trace module.

A method of generating trace signals within a data processing apparatus having a component whose behaviour is to be traced, the method comprising using a trace generation unit to perform the steps of:

• (i) receiving input signals from the component indicative of the behaviour;
• (ii) generating from said input signals high priority and low priority trace signals for outputting to a trace receiving device;
• and
• (iii) during said step (ii), being responsive to assertion of a suppression signal from the trace receiving device to suppress generation of the low priority trace signals.

A method of generating trace signals within a data processing apparatus having a plurality of trace modules for receiving input signals from one or more components whose behaviours are to be traced, each trace module being arranged to generate from its respective input signals trace signals for outputting over a corresponding trace bus, the method comprising the steps of:

• (a) receiving at funnel logic as input trace signals the trace signals output on each trace bus;
• (b) generating at an output port of the funnel logic a trace stream derived from the input trace signals, the output port having a maximum bandwidth which is less than the collective maximum bandwidth of the trace buses coupled to the funnel logic;
• and
• (c) controlling the issuance of trace signals by the trace modules to ensure that the input trace signals can be output from the output port without exceeding the maximum bandwidth of the output port, wherein said step (c) comprises the steps of:
• receiving request signals from each trace module wishing to output trace signals onto its corresponding trace bus;
• and
• applying predetermined criteria to determine from the received request signals which trace module should provide trace signals to the funnel logic.

A method of generating trace signals within a data processing apparatus having a plurality of trace modules for receiving input signals from one or more components whose behaviours are to be traced, each trace module being arranged to generate from its respective input signals trace signals for outputting over a corresponding trace bus, the method comprising the steps of:

• (a) receiving at funnel logic as input trace signals the trace signals output on each trace bus;
• (b) generating at an output port of the funnel logic a trace stream derived from the input trace signals, the output port having a maximum bandwidth which is less than the collective maximum bandwidth of the trace buses coupled to the funnel logic;
• and
• (c) controlling the issuance of trace signals by the trace modules to ensure that the input trace signals can be output from the output port without exceeding the maximum bandwidth of the output port, wherein the issuance of trace signals by at least one of the trace modules is not controllable by the funnel logic, the data processing apparatus further comprising a stalling buffer for each such trace module coupled between that trace module and the funnel logic to buffer trace signals output by that trace module.