Debug messaging with selective timestamp control

A data processing system having debug message generation uses processor circuitry to perform a plurality of processor operations. Global control circuitry is coupled to the processor circuitry. Debug circuitry is coupled to the global control circuitry for generating debug messages corresponding to predetermined processor operations. Message generation logic provides debug messages which selectively include a timestamp field providing information as to when a debug message is generated. Debug control circuitry is coupled to the global control circuitry and the message generation logic and has a timestamp control register. For each of a plurality of debug message types, the timestamp control register selectively enables or disables appending a timestamp to the debug message for that type of debug message. Enable logic is coupled to the timestamp control register for enabling or disabling the timestamp control register based on detecting a selected event in the data processing system.