Real Time Trace Solution for LEON/GRLIB System-on-Chip

Abstract

Debugging real-time systems is often a time consuming process since they always behave differently on real hardware than in an emulator. Aeroflex Gaisler has developed a complete SoC IP-library together with a SPARC CPU. The existing trace solution for the CPU is only capable of storing a very limited amount of debug data on chip. In this project a trace system was developed that is capable of creating a trace stream, and then transmit it over the high bandwidth PCI bus to a computer. Two different trace streams were developed. The “Full” version contains all the execution information possible for every instruction. The “Slim” trace version is designed for minimal bandwidth requirements. In order to achieve it an efficient and complex encoding is used to log time information and execution path through the program. However, the decoder requires that the trace binary is available when decoding the trace. To further reduce the bandwidth efficiency the OP-code is not traced, since it can be looked op afterwards in the binary. Arithmetic results are neither, but it might be possible to recreate those with an advanced decoder/emulator solution.