Custom RISC‑V implementations increasingly require tight coupling between hardware and software development to ensure correctness, performance, and rapid iteration. This paper presents the RISC‑V Unified DB Instruction Set Simulator (RVUDB‑ISS), an open-source simulation‑driven framework that enables early‑stage HW/SW co‑development, configuration validation, and full‑stack debug prior to RTL availability. The ISS is automatically generated from a formally specified configuration, producing an implementation‑accurate model for custom RISC‑V cores and extensions.

RVUDB‑ISS supports configuration‑optimized binaries, enforcement of architectural corner cases, and precise modeling of implementation‑defined behaviors.
A key functionality is the ISS’s integrated debug experience: developers can run custom workloads, halt execution at the first instruction, and attach standard tools such as GDB and VS Code to provide a familiar SW debug environment. This enables full symbolic debug of custom cores without hardware availability, significantly reducing time‑to‑bring up, and improving quality at bring up.

Overall, RVUDB‑ISS demonstrates that simulation‑based debug for custom RISC‑V configurations enables earlier validation, higher code quality, and more reliable HW/SW co‑development compared to traditional pre and post‑silicon workflows.

The RISC-V Unified Database (UDB) serves as a machine-readable “source of truth” for written RISC-V specifications. To improve the ease of creating these specifications, Qualcomm collaborated with a team of Harvey Mudd College students to develop an Integrated Development Environment (IDE) toolkit that can support architects for RISC-V specifications. The team has worked to develop many of the features one would consider standard for developing in a programming language in a modern IDE, including syntax highlighting, autocompletion, and cross-referencing. The groundwork for this IDE also lays the foundation for other tool developers for the RISC-V ecosystem to use information contained in the UDB more efficiently.

The RISC-V Unified Database (UDB) serves as a machine-readable “source of truth” for written RISC-V specifications. To improve the ease of creating these specifications, Qualcomm collaborated with a team of Harvey Mudd College students to develop an Integrated Development Environment (IDE) toolkit that can support architects for RISC-V specifications. The team has worked to develop many of the features one would consider standard for developing in a programming language in a modern IDE, including syntax highlighting, autocompletion, and cross-referencing. The groundwork for this IDE also lays the foundation for other tool developers for the RISC-V ecosystem to use information contained in the UDB more efficiently.