Setup xv6-riscv Development Environment

This article introduces how to set up the development environment of xv6-riscv.

Introduction

xv6 is a re-implementation of Dennis Ritchie’s and Ken Thompson’s Unix Version 6 (v6). The main purpose of xv6 is as a teaching operating system for MIT’s 6.1810^[1].

Environment

The system environment I use:

Ubuntu 24.04.1 LTS

Installation

We need to install related cross-compilation tools, as well as QEMU to simulate the RISC-V chip. The following commands are modified from mmikaitis/xv6-tools-container/xv6-tools-container.def^[2]。

1 2	`sudo apt update sudo apt install -y build-essential gcc-riscv64-linux-gnu qemu-system-riscv64 gdb-multiarch` BASH

Download xv6-riscv

1 2	`git clone git@github.com:mit-pdos/xv6-riscv.git cd xv6-riscv` BASH

Compile and Run

1 2	`make make qemu` BASH

Now you can see the following output, which means the compilation and running are successful:

xv6 kernel is booting

hart 2 starting
hart 1 starting
init: starting sh
$
TEXT

To exit QEMU, you can press Ctrl + A, then press X.

QEMU No Response After Startup

I encountered the problem of no response after starting make qemu when setting up the environment. Finally, I found this issue. The solution provided by the related PR works.

After my attempt, update the system and QEMU to the latest version can also solve the problem. I finally used Ubuntu 24.04.1 LTS and QEMU emulator version 8.2.2 (Debian 1:8.2.2+ds-0ubuntu1.2).

You may also download and compile the latest version of QEMU^[3].

wget https://download.qemu.org/qemu-8.2.2.tar.xz
tar -xf qemu-8.2.2.tar.xz
cd qemu-8.2.2
./configure --disable-kvm --disable-werror --prefix=/usr/local --target-list="riscv64-softmmu"
make
sudo make install
cd ..
BASH

When compiling QEMU, you may need to install Ninja^[4].

1	`sudo apt install ninja-build` BASH

IDE Remote Development

The project is located on a remote Linux server. If we want to develop using a powerful IDE locally instead of using vim and other text editors on the server, we can use Clion to connect to the server via SSH for development.

After the connection is established, you can develop as if you were working on a local project. Run make qemu in the terminal to run xv6-riscv.

Code Analysis

For some strange historical reason, Clion does not recognize the file structure of Makefile projects well. At first it says “This file does not belong to any project target”, and after marking the directory as “Project Sources and Headers”, it still fails to find the correct header file.

To solve this problem, we just need to create a CMakeLists.txt file to trick the IDE into recognizing the file structure of the project.

cmake_minimum_required(VERSION 3.24)
project(xv6 C)

set(CMAKE_C_STANDARD 99)

include_directories(.)

add_executable(xv6
        kernel
        mkfs
        user
        kernel/main.c
)
CMAKE