plctlab/riscv-operating-system-mooc

《从头写一个RISC-V OS》课程配套的资源

Step by step, learn to develop an operating system on RISC-V

• 1. Introduction
• 2. Operating environment
• 3. Building and usage
• 4. References

1. Introduction

This course is used to teach and demonstrate how to write a simple operating system kernel for the RISC-V platform from scratch. Released under the BSD 2-Clause license (For details, please read the LICENSE file under the root directory of this repository).

If you have any questions or bug report, please use the issue tracking system on github.

Note: We also have a mirror repository on gitee (https://gitee.com/unicornx/riscv-operating-system-mooc), and we use the issue tracking system on gitee more actively than on github, all issue# filled in git commitment are from the issue tracking system of gitee.

2. Operating environment

Ubuntu 20.04 is recommended. Ubuntu 20.04 is currently the latest recommended long-term stable release of Ubuntu. It is also the easiest to install and run the environment in this environment.

Some students reported that they hope to still use Ubuntu 18.04. Because the official source of Ubunt 18.04 does not support the RISC-V development kit, so the environment is a little more complicated. I wrote a simple document, and you can refer here to have a try with Ubuntu 18.04.

All demo codes have been verified under the following environment. Please carefully check whether your Ubuntu version and kernel version are consistent with the following information.

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 20.04.3 LTS
Release:	20.04
Codename:	focal

$ uname -r
5.11.0-27-generic

At present, in the Ubuntu 20.04 environment, we can directly use the official GNU toolchain and QEMU emulator, and execute the following command to install online to start the test:

$ sudo apt update
$ sudo apt install build-essential gcc make perl dkms git gcc-riscv64-unknown-elf gdb-multiarch qemu-system-misc

3. Building and usage

• make：Compile and build
• make run：Start qemu and run
• make debug：Start debugging
• make code：Disassemble to view binary code
• make clean：cleanup

For specific use, please refer to the Makefile under the specific sub-project.

4. References

The design of this course refers to the following network resources, thank you :)

• The Adventures of OS：https://osblog.stephenmarz.com/index.html
• mini-riscv-os: https://github.com/cccriscv/mini-riscv-os
• Xv6, a simple Unix-like teaching operating system：https://pdos.csail.mit.edu/6.828/2020/xv6.html

riscv-operating-system-mooc's Issues

關於 External Interrupt

Hi there!

關於外部中斷，我有一些疑惑，還望各位指教，在介紹第 11 章的外部中斷時，提到了我們可以對 PLIC 設置外部中斷做到 UART 輸入的功能，針對這個地方，我有兩點疑問:

1. 我參考這一資訊，將外部中斷的處理方式移植到了 mini-riscv-os 上，但是我發現即使不在 OS 開機時也能使用 UART 輸入，想請問我是不是遺漏了什麼重要觀念
2. 呈上題，如果不開啟外部中斷也能使用 UART 輸入，那在什麼情況下才會產出 IRQ = 10 的情況呢?

謝謝。

在task_yield()调用r_mhartid()导致非法指令异常

Hi,
我正在尝试使用Rust实现RVOS。在实现第13章抢占式多任务的时候，在task_yield()中调用r_mhartid()导致 illegal instruction ，通过调试发现是csrr $0, mhartid这条指令导致的异常。 应该是与csrr这个指令有关，因为在测试csrw的时候也不行。
我的代码在这：https://github.com/RobotHuang/rvos-rust/blob/master/os/src/sched.rs#L145
Thanks

I got an error when I used make command in a certain folder in asm

System environment:

Distributor ID: Ubuntu
Description: Ubuntu 22.04.4 LTS
Release: 22.04
Codename: jammy

GNU Make

GNU Make 4.3
Built for x86_64-pc-linux-gnu
Copyright (C) 1988-2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Error

Makefile:1: *** missing separator. Stop.

Troubleshooting process

I found that the Makefile files in all folders under asm do not use standard universal syntax, like this:
../build.mk

There may be some versions that can support such writing, but there is no doubt that it is not supported on my system. I tried updating make, but it did not work. The general and correct writing should be as follows:
include ../build.mk

After making the changes it started working without a doubt

Ending

Correspondingly, I have sent a PR, I believe it will work well on any make version