The ETM contains a First-In-First-Out (FIFO) buffer that holds the traced data for transmission through the trace port. When this FIFO buffer becomes full, trace information is lost unless you have programmed the ETM to stall (temporarily stop) the processor.

The system can include a facility to stall the processor until the FIFO buffer is empty. To enable this, select the option Stall processor to prevent overflow. When the number of bytes left in the FIFO buffer is reduced to the number of bytes you set in FIFO highwater, the processor stalls as soon as possible. It restarts when the FIFO buffer is empty.

 This capability is not supported by all systems. See the documentation that accompanies your system to find out whether FIFOFULL is implemented.