1. Incremental build flow - The SDSoC environment does not support any incremental build flow using the trace feature. To ensure the correct build of your application and correct trace collection, be sure to do a project clean first, followed by a build after making any changes to your source code. Even if the source code you change does not relate to or impact any function marked for hardware, you will see incorrect results.
  2. Programming and bitstream - The trace functionality is a "one-shot" type of analysis. The timer used for timestamping events is not started until the first event occurs and runs forever afterwards. If you run your software application once after programming the bitstream, the timer will be in an unknown state after your program is finished running. Running your software for a second time will result in incorrect timestamps for events. Be sure to program the bitstream first, followed by downloading your software application, each and every time you run your application to take advantage of the trace feature. Your application will run correctly a second time, but the trace data will not be correct. For Linux, you will need to reboot because the bitstream is loaded during boot time by U-Boot.
  3. Buffering up traces - In the SDSoC environment, traces are buffered up and read out in real-time as the application executes (although at a slower speed than they are created on the device), but are displayed after the application finishes in a post-processing fashion. This relies on having enough buffer space to store traces until they can be read out by the host PC. By default, there is enough buffer space for 1024 traces. After the buffer fills up, subsequent traces that are produced are dropped and lost. An error condition is set when the buffer overflows. Any traces created after the buffer overflows are not collected, and traces just prior to the overflow might be displayed incorrectly.
  4. Errors - In the SDSoC environment, traces are buffered up in hardware before being read out over JTAG by the host PC. If traces are produced faster than they are consumed, a buffer overflow event might occur. The trace infrastructure is cognizant of this and will set an error flag that is detected during the collection on the host PC. After the error flag is parsed during trace data collection, collection is halted and the trace data that was read successfully is prepared for display. However, some data read successfully just prior to the buffer overflow might appear incorrectly in the visualization.

After an overflow occurs, an error file is created in the <build_config>/_sds/trace directory with the name in the following format: archive_DAY_MON_DD_HH_MM_SS_-GMT_YEAR_ERROR. You must reprogram the device (reboot Linux, etc.) prior to running the application and collecting trace data again. The only way to reset the trace hardware in the design is with reprogramming.