Software-driven Debug Framework for Embedded RISC-V, that Transparently Emulates the Industry Standard Debug Framework

Hardware support for external debug is essential for development and maintenance of embedded softwares. However, external debug module and debug interface are often removed in the production, for optimization. In this paper, we propose a software-driven debug framework for embedded RISC-V system. Our framework transparently emulates the debug hardware, by utilizing one external interrupt and 1.04 KB of memory on the target. The overhead is negligible, compared to the removable debug module and IO pads for the debug interface, which occupy as much as 12.7% and 60.6% area of CPU subsystem, respectively.