Abstract: Software debugging is one of the most challenging factors in embedded system development.When debugging high-complexity,high real-time systems,single-step-breakpoint debugging time overhead is high,and tends to corrupt program execution behavior;the JTAG interface with serial-connection mechanism is flawed in achieving parallel access to complex multicore processors in operation.The on-chip tracing and debugging technology solves the problems of traditional debugging methods such as single-step-breakpoint and JTAG in debugging highly complex and real-time systems by non-intrusively obtaining program execution status through dedicated hardware.The existing on-chip tracing and debugging technologies mainly trace complete information,and generate a large amount of meaningless data,which easily causes path blocking or data loss,especially during concurrent debugging.In addition,the transmission of compressed data on narrow buses is not considered.A non-intrusive trace debugging system based on RISC-V for multicore microprocessors,RVTDS,is designed and implemented,which solves the data loss problem during high-speed parallel debugging of multicore microprocessors by reusing the platform-level interrupt controller within RISC-V cores.A data-flow tracing scheme for an on-chip bus and a control-flow filtering mechanism based on instruction bit domain matching are proposed to realize signal filtering and provide bus bandwidth statistics.A data compression method based on differential coding is proposed with an average data compression rate of more than 82%.A data packing scheme is proposed to realize the data transmission problem on a narrow bus with an average of about 1.5 path information per effective data beat.The system verification results show that RVTDS has a small amount of trace data compared with traditional debugging methods,and accomplishes the acquisition,transmission,and storage of multiple on-chip operation information of complex multi-core microprocessors flexibly and efficiently.

Key words: On-chip tracing and debugging, Non-intrusive, Debug, RVTDS, Multi-core Microprocessor