GitHub - OpenXiangShan/XiangShan: Open-source high-performance RISC-V processor

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XiangShan (香山) is an open-source high-performance RISC-V processor project.

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Documentation

XiangShan's documentation is available at docs.xiangshan.cc.

XiangShan Design Document for Kunminghu V2R2 has been published separately. You can find it at docs.xiangshan.cc/projects/design.

XiangShan User Guide has been published separately. You can find it at docs.xiangshan.cc/projects/user-guide or XiangShan-User-Guide/releases.

We are using Weblate to translate documentation into English and other languages. Your contributions are welcome—come and help us improve it!

All XiangShan documents are licensed under the CC-BY-4.0.

Publications

MICRO 2022: Towards Developing High Performance RISC-V Processors Using Agile Methodology

Our paper introduces XiangShan and the practice of agile development methodology on high performance RISC-V processors. It covers some representative tools we have developed and used to accelerate the chip development process, including design, functional verification, debugging, performance validation, etc. This paper is awarded all three available badges for artifact evaluation (Available, Functional, and Reproduced).

Artifacts Available Artifacts Evaluated — Functional Results Reproduced

Paper PDF | IEEE Xplore | BibTeX | Presentation Slides | Presentation Video

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Architecture

The first stable micro-architecture of XiangShan is called Yanqihu (雁栖湖) and is on the yanqihu branch, which has been developed since June 2020.

The second stable micro-architecture of XiangShan is called Nanhu (南湖) and is on the nanhu branch.

The third-generation XiangShan microarchitecture, Kunminghu (昆明湖), is under active development on the kunminghu-v2 and kunminghu-v3 branches.

The micro-architecture overview of Kunminghu-V2 is shown below.

xs-arch-kunminghu

Branch Maintenance Status

Generation-Version Branch Maintained? Active Development?
Yanqihu yanqihu ✅ (minimum)
Nanhu-V2 nanhu ✅ (minimum)
Nanhu-V3 Siudya/Nanhu
Nanhu-V5 OpenXiangShan-Nanhu/OpenNanhu-V5 ✅ ✅
Kunminghu-V2 kunminghu-v2 ✅
Kunminghu-V3 kunminghu-v3 ✅ ✅

At the moment, kunminghu-v3 is still evolving rapidly and its functionality may not yet be stable. If you plan to use XiangShan for research, verification, or downstream applications, we recommend prioritizing kunminghu-v2.

This section is time-sensitive. If you believe any information here is outdated, please let us know in an issue and we will update it as soon as possible.

Last updated: 2026/06/30

Sub-directories Overview

Some of the key directories are shown below.

.
├── src
│   └── main/scala         # design files
│       ├── device         # virtual device for simulation
│       ├── system         # SoC wrapper
│       ├── top            # top module
│       ├── utils          # utilization code
│       └── xiangshan      # main design code
│           └── transforms # some useful firrtl transforms
├── scripts                # scripts for agile development
├── yunsuan                # yunsuan submodule of XiangShan
├── XSCache                # cache subsystem of XiangShan
├── difftest               # difftest co-simulation framework
└── ready-to-run           # pre-built simulation images

IDE Support

bsp

IDEA

Generate Verilog

  • Run make verilog to generate verilog code. This generates multiple .sv files in the build/rtl/ folder (e.g., build/rtl/XSTop.sv).
  • Refer to Makefile for more information.

Run Programs by Simulation

Prepare environment

  • Set environment variable NEMU_HOME to the absolute path of the NEMU project.
  • Set environment variable NOOP_HOME to the absolute path of the XiangShan project.
  • Set environment variable AM_HOME to the absolute path of the AM project.
  • Install mill. Refer to the Manual section in this guide.
  • Clone this project and run make init to initialize submodules.

Run with simulator

  • Install Verilator, the open-source Verilog simulator.
  • Run make emu to build the C++ simulator ./build/emu with Verilator.
  • Refer to ./build/emu --help for run-time arguments of the simulator.
  • Refer to Makefile and verilator.mk for more information.

Example:

make emu CONFIG=MinimalConfig EMU_THREADS=2 -j10
./build/emu -b 0 -e 0 -i ./ready-to-run/coremark-2-iteration.bin --diff ./ready-to-run/riscv64-nemu-interpreter-so

Run with xspdb

There are two ways to use xspdb:

  1. Quick Start with Prebuilt Binaries

    • Why choose this? It is lightweight and requires no compilation. A standard Python environment is enough to run the full XiangShan experience with low memory usage.
    • Step 1: Download Get the latest XSPdb from the run summary of the repository's Actions workflow.
    • Step 2: Extract & Run

  2. Build from source code

    • Install picker, a verification tool that supports high-level languages.
    • Run make pdb to build XiangShan Python binaries.
    • Run make pdb-run to run XiangShan binaries.

Example output and interaction:

$ make pdb-run
[Info] Set PMEM_BASE to 0x80000000 (Current: 0x80000000)
[Info] Set FIRST_INST_ADDRESS to 0x80000000 (Current: 0x80000000)
Using simulated 32768B flash
[Info] reset dut complete
> XiangShan/scripts/pdb-run.py(13)run()
-> while True:
(XiangShan) xload ready-to-run/microbench.bin   # Load binary (Tab-compatible)
(XiangShan) xwatch_commit_pc 0x80000004         # Set watchpoint
(XiangShan) xistep 3                            # Step until the next three instructions commit; stops at the watchpoint if hit
[Info] Find break point (Inst commit), break (step 2107 cycles) at cycle: 2207 (0x89f)
[Info] Find break point (Inst commit, Target commit), break (step 2108 cycles) at cycle: 2208 (0x8a0)
(XiangShan) xpc                                 # Print PC info
PC[0]: 0x80000000    Instr: 0x00000093
PC[1]: 0x80000004    Instr: 0x00000113
PC[2]: 0x0    Instr: 0x0
...
PC[7]: 0x0    Instr: 0x0
(XiangShan) xistep 1000000                      # Execute until the end of the binary
[Info] Find break point (Inst commit), break (step 2037 cycles) at cycle: 2207 (0x89f)
[Info] Find break point (Inst commit), break (step 2180 cycles) at cycle: 2207 (0x89f)
...
HIT GOOD LOOP at pc = 0xf0001cb0

Troubleshooting Guide

Troubleshooting Guide

Acknowledgement

The implementation of XiangShan is inspired by several key papers. We list these papers in XiangShan document, see: Acknowledgements. We very much encourage and expect that more academic innovations can be realised based on XiangShan in the future.

LICENSE

Copyright © 2020-2026 Institute of Computing Technology, Chinese Academy of Sciences.

Copyright © 2021-2026 Beijing Institute of Open Source Chip

Copyright © 2020-2022 by Peng Cheng Laboratory.

XiangShan is licensed under Mulan PSL v2.