Abstract: Current chip design projects require considerable manpower and time to carry out, and have certain risks. These conditions have limited the development of open-sourced chip design to some extent. To further reduce the threshold for chip development, research teams at University of California, Berkeley have designed the open ISA RISC-V. They also open-sourced the Rocket Chip project, the SoC implementation of RISC-V, and put forward Chisel, a new hardware construction language, for agile development. How do RISC-V, Rocket Chip and Chisel enable open-source chip agile development? With some case studies during the development of the Labeled RISC-V project led by the Institute of Computing Technology, Chinese Academy of Sciences, this article shows: 1) An open and active ISA ecosystem (such as RISC-V) is a necessary condition to promote chip innovation; 2) Chisel’s features such as bulk connection, metaprogramming, object-oriented programming, and functional programming, can greatly reduce the amount of code and improve code maintainability; 3) Agile development can achieve an order of magnitude improvement in coding efficiency, while achieving comparable or even better performance, power consumption and area overhead than traditional hardware development models.

Key words: RISC-V, Chisel, open-source, chip design, agile development