Methods and apparatus for output of high-bandwidth debug data/traces in electronic devices using embedded high-speed debug port(s). Debug data is received from multiple blocks and buffered in a buffer. The buffer's output is operatively coupled to one or more high-speed serial I/O interfaces via muxing logic during debug test operations. The buffered data is encoded as serialized data and sent over the one or more high-speed serial I/O interfaces to a logic device that receives serialized data and de-serializes it to generate parallel debug data that is provided to a debugger. The buffer may be configured as a bandwidth-adapting buffer that facilitates transfer of debug data that is received at a variable combined data rate outbound via the one or more high-speed serial I/O interfaces at a data rate corresponding to the bandwidth of the serial I/O interfaces.