If you have a J-Trace debug probe for Cortex-M3, you can use ETM trace and SWO trace concurrently.

In this case, if you activate the ETM trace and the SWO trace, SWO trace data will also be collected in the ETM trace buffer, instead of being streamed via the SWO channel. This means that the SWO trace data will not be displayed until the execution has stopped, instead of being continuously updated live in the SWO Trace window.