Arm Cortex: Starting trace while cores are running produces undesired trace messages

If you start tracing while a core is running, the sequential configuration of trace components might produce undesired artifacts in the trace stream (e.g. considerable amount of  ITM trace before ETM messages start).

Note that Cortex trace does not have a global trace switch that "turns on / off" ITM, ETM etc. 

Possible solution:

1. Stop CPU(s) via Stop button in the Debug Toolbar. 

2. Start trace via the Begin New Session button in the Analyzer Toolbar. 

3. Run CPU(s) via the Debug Toolbar. 

4. Stop trace via Stop  the Analyzer Toolbar or stop CPU(s) via Stop  in the Debug Toolbar.