# rCore-Tutorial-v3 rCore-Tutorial version 3.5. See the [Documentation in Chinese](https://rcore-os.github.io/rCore-Tutorial-Book-v3/). Official QQ group number: 735045051 ## news - 25/01/2022: Version 3.6.0 is on the way! Now we directly update the code on chX branches, please periodically check if there are any updates. ## Overview This project aims to show how to write an **Unix-like OS** running on **RISC-V** platforms **from scratch** in **[Rust](https://www.rust-lang.org/)** for **beginners** without any background knowledge about **computer architectures, assembly languages or operating systems**. ## Features * Platform supported: `qemu-system-riscv64` simulator or dev boards based on [Kendryte K210 SoC](https://canaan.io/product/kendryteai) such as [Maix Dock](https://www.seeedstudio.com/Sipeed-MAIX-Dock-p-4815.html) * OS * concurrency of multiple processes each of which contains mutiple native threads * preemptive scheduling(Round-Robin algorithm) * dynamic memory management in kernel * virtual memory * a simple file system with a block cache * an interactive shell in the userspace * **only 4K+ LoC** * [A detailed documentation in Chinese](https://rcore-os.github.io/rCore-Tutorial-Book-v3/) in spite of the lack of comments in the code(English version is not available at present) ## Prerequisites ### Install Rust See [official guide](https://www.rust-lang.org/tools/install). Install some tools: ```sh $ rustup target add riscv64gc-unknown-none-elf $ cargo install cargo-binutils --vers =0.3.3 $ rustup component add llvm-tools-preview $ rustup component add rust-src ``` ### Install Qemu Here we manually compile and install Qemu 5.0.0. For example, on Ubuntu 18.04: ```sh # install dependency packages $ sudo apt install autoconf automake autotools-dev curl libmpc-dev libmpfr-dev libgmp-dev \ gawk build-essential bison flex texinfo gperf libtool patchutils bc \ zlib1g-dev libexpat-dev pkg-config libglib2.0-dev libpixman-1-dev git tmux python3 python3-pip # download Qemu source code $ wget https://download.qemu.org/qemu-5.0.0.tar.xz # extract to qemu-5.0.0/ $ tar xvJf qemu-5.0.0.tar.xz $ cd qemu-5.0.0 # build $ ./configure --target-list=riscv64-softmmu,riscv64-linux-user $ make -j$(nproc) ``` Then, add following contents to `~/.bashrc`(please adjust these paths according to your environment): ``` export PATH=$PATH:/home/shinbokuow/Downloads/built/qemu-5.0.0 export PATH=$PATH:/home/shinbokuow/Downloads/built/qemu-5.0.0/riscv64-softmmu export PATH=$PATH:/home/shinbokuow/Downloads/built/qemu-5.0.0/riscv64-linux-user ``` Finally, update the current shell: ```sh $ source ~/.bashrc ``` Now we can check the version of Qemu: ```sh $ qemu-system-riscv64 --version QEMU emulator version 5.0.0 Copyright (c) 2003-2020 Fabrice Bellard and the QEMU Project developers ``` ### Install RISC-V GNU Embedded Toolchain(including GDB) Download the compressed file according to your platform From [Sifive website](https://www.sifive.com/software)(Ctrl+F 'toolchain'). Extract it and append the location of the 'bin' directory under its root directory to `$PATH`. For example, we can check the version of GDB: ```sh $ riscv64-unknown-elf-gdb --version GNU gdb (SiFive GDB-Metal 10.1.0-2020.12.7) 10.1 Copyright (C) 2020 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. ``` ### Install serial tools(Optional, if you want to run on K210) ```sh $ pip3 install pyserial $ sudo apt install python3-serial ``` ## Run our project ### Qemu ```sh $ git clone https://github.com/rcore-os/rCore-Tutorial-v3.git $ cd rCore-Tutorial-v3/os $ make run ``` After outputing some debug messages, the kernel lists all the applications available and enter the user shell: ``` /**** APPS **** mpsc_sem usertests pipetest forktest2 cat initproc race_adder_loop threads_arg race_adder_mutex_spin race_adder_mutex_blocking forktree user_shell huge_write race_adder race_adder_atomic threads stack_overflow filetest_simple forktest_simple cmdline_args run_pipe_test forktest matrix exit fantastic_text sleep_simple yield hello_world pipe_large_test sleep phil_din_mutex **************/ Rust user shell >> ``` You can run any application except for `initproc` and `user_shell` itself. To run an application, just input its filename and hit enter. `usertests` can run a bunch of applications, thus it is recommended. Type `Ctrl+a` then `x` to exit Qemu. ### K210 Before chapter 6, you do not need a SD card: ```sh $ git clone https://github.com/rcore-os/rCore-Tutorial-v3.git $ cd rCore-Tutorial-v3/os $ make run BOARD=k210 ``` From chapter 6, before running the kernel, we should insert a SD card into PC and manually write the filesystem image to it: ```sh $ cd rCore-Tutorial-v3/os $ make sdcard ``` By default it will overwrite the device `/dev/sdb` which is the SD card, but you can provide another location. For example, `make sdcard SDCARD=/dev/sdc`. After that, remove the SD card from PC and insert it to the slot of K210. Connect the K210 to PC and then: ```sh $ git clone https://github.com/rcore-os/rCore-Tutorial-v3.git $ cd rCore-Tutorial-v3/os $ make run BOARD=k210 ``` Type `Ctrl+]` to disconnect from K210. ## Rustdoc Currently it can only help you view the code since only a tiny part of the code has been documented. You can open a doc html of `os` using `cargo doc --no-deps --open` under `os` directory. ## Working in progress Our first release 3.5.0 (chapter 1-7) has been published. There will be 9 chapters in our next release 3.6.0, where 2 new chapters will be added: * chapter 8: synchronization on a uniprocessor * chapter 9: I/O devices Current version is 3.6.0-alpha.1 and we are still working on it. Here are the updates since 3.5.0: ### Completed * [x] automatically clean up and rebuild before running our project on a different platform * [x] fix `power` series application in early chapters, now you can find modulus in the output * [x] use `UPSafeCell` instead of `RefCell` or `spin::Mutex` in order to access static data structures and adjust its API so that it cannot be borrowed twice at a time(mention `& .exclusive_access().task[0]` in `run_first_task`) * [x] move `TaskContext` into `TaskControlBlock` instead of restoring it in place on kernel stack(since ch3), eliminating annoying `task_cx_ptr2` * [x] replace `llvm_asm!` with `asm!` * [x] expand the fs image size generated by `rcore-fs-fuse` to 128MiB * [x] add a new test named `huge_write` which evaluates the fs performance(qemu\~500KiB/s k210\~50KiB/s) * [x] flush all block cache to disk after a fs transaction which involves write operation * [x] replace `spin::Mutex` with `UPSafeCell` before SMP chapter * [x] add codes for a new chapter about synchronization & mutual exclusion(uniprocessor only) * [x] bug fix: we should call `find_pte` rather than `find_pte_create` in `PageTable::unmap` * [x] clarify: "check validity of level-3 pte in `find_pte` instead of checking it outside this function" should not be a bug * [x] code of chapter 8: synchronization on a uniprocessor * [x] switch the code of chapter 6 and chapter 7 * [x] support signal mechanism in chapter 7/8(only works for apps with a single thread) * [x] Add boards/ directory and support rustdoc, for example you can use `cargo doc --no-deps --open` to view the documentation of a crate ### Todo(High priority) * [ ] review documentation, current progress: 5/9 * [ ] support user-level sync primitives in chapter 8 * [ ] code of chapter 9: device drivers based on interrupts, including UART and block devices * [ ] use old fs image optionally, do not always rebuild the image * [ ] add new system calls: getdents64/fstat * [ ] shell functionality improvement(to be continued...) * [ ] give every non-zero process exit code an unique and clear error type * [ ] effective error handling of mm module ### Todo(Low priority) * [ ] rewrite practice doc and remove some inproper questions * [ ] provide smooth debug experience at a Rust source code level * [ ] format the code using official tools * [ ] support other platforms ### Crates We will add them later.