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# XiangShan

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

中文说明[在此](readme.zh-cn.md)。

Copyright 2020-2022 by Institute of Computing Technology, Chinese Academy of Sciences.

Copyright 2020-2022 by Peng Cheng Laboratory.

## Docs and slides

[XiangShan-doc](https://github.com/OpenXiangShan/XiangShan-doc) is our official documentation repository. It contains design spec., technical slides, tutorial and more.

* Micro-architecture documentation of XiangShan has been published. Please check out https://xiangshan-doc.readthedocs.io

## 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](https://github.com/OpenXiangShan/XiangShan-doc/raw/main/publications/images/artifacts_available_dl.jpg)
![Artifacts Evaluated — Functional](https://github.com/OpenXiangShan/XiangShan-doc/raw/main/publications/images/artifacts_evaluated_functional_dl.jpg)
![Results Reproduced](https://github.com/OpenXiangShan/XiangShan-doc/raw/main/publications/images/results_reproduced_dl.jpg)

[Paper PDF](https://github.com/OpenXiangShan/XiangShan-doc/blob/main/publications/micro2022-xiangshan.pdf) | [IEEE Xplore](https://ieeexplore.ieee.org/abstract/document/9923860) | [BibTeX](https://github.com/OpenXiangShan/XiangShan-doc/blob/main/publications/micro2022-xiangshan.bib) | [Presentation Slides](https://github.com/OpenXiangShan/XiangShan-doc/blob/main/publications/micro2022-xiangshan-slides.pdf) | [Presentation Video](https://www.bilibili.com/video/BV1FB4y1j7Jy)

## Follow us

Wechat/微信：香山开源处理器

<div align=left><img width="340" height="117" src="images/wechat.png"/></div>

Zhihu/知乎：[香山开源处理器](https://www.zhihu.com/people/openxiangshan)

Weibo/微博：[香山开源处理器](https://weibo.com/u/7706264932)

You can contact us through [our mail list](mailto:[email protected]). All mails from this list will be archived to [here](https://www.mail-archive.com/[email protected]/).

## Architecture

The first stable micro-architecture of XiangShan is called Yanqihu (雁栖湖) [on the yanqihu branch](https://github.com/OpenXiangShan/XiangShan/tree/yanqihu), which has been developed since June 2020.

The second stable micro-architecture of XiangShan is called Nanhu (南湖) [on the nanhu branch](https://github.com/OpenXiangShan/XiangShan/tree/nanhu).

The current version of XiangShan, also known as Kunminghu (昆明湖), is still under development on the master branch.

The micro-architecture overview of Nanhu (南湖) is shown below.

![xs-arch-nanhu](images/xs-arch-nanhu.svg)



## 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
├── fudian                 # floating unit submodule of XiangShan
├── huancun                # L2/L3 cache submodule of XiangShan
├── difftest               # difftest co-simulation framework
└── ready-to-run           # pre-built simulation images
```

## IDE Support

### bsp
```
make bsp
```

### IDEA
```
make idea
```


## Generate Verilog

* Run `make verilog` to generate verilog code. The output file is `build/XSTop.v`.
* 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](https://github.com/OpenXiangShan/NEMU).
* 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](https://github.com/OpenXiangShan/nexus-am).
* Install `mill`. Refer to [the Manual section in this guide](https://com-lihaoyi.github.io/mill/mill/Intro_to_Mill.html#_installation).
* Clone this project and run `make init` to initialize submodules.

### Run with simulator

* Install [Verilator](https://verilator.org/guide/latest/), 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:

```bash
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
```

## Troubleshooting Guide

[Troubleshooting Guide](https://github.com/OpenXiangShan/XiangShan/wiki/Troubleshooting-Guide)

## Acknowledgement

In the development of XiangShan, some sub-modules from the open-source community are employed. All relevant usage is listed below.

| Sub-module         | Source                                                       | Detail                                                       |
| ------------------ | ------------------------------------------------------------ | ------------------------------------------------------------ |
| L2 Cache/LLC       | [Sifive block-inclusivecache](https://github.com/ucb-bar/block-inclusivecache-sifive) | Our new L2/L3 design are inspired by Sifive's `block-inclusivecache`. |
| Diplomacy/TileLink | [Rocket-chip](https://github.com/chipsalliance/rocket-chip)  | We reused the Diplomacy framework and TileLink utility that exist in rocket-chip to negotiate bus. |

We are grateful for the support of the open-source community and encourage other open-source projects to reuse our code within the scope of the [license](LICENSE).