- 2021.11.20: Now we are updating our labs. Please checkout chX-dev Branches for our current new labs. (Notice: please see the [Dependency] section in the end of this doc)
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**.
* 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
* 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)
Now we are still updating our project, you can find latest changes on branches `chX-dev` such as `ch1-dev`. We are intended to publish first release 3.5.0 after completing most of the tasks mentioned below.
Overall progress: ch7
### 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)
### Todo(High priority)
* [ ] support Allwinner's RISC-V D1 chip
* [ ] bug fix: we should call `find_pte` rather than `find_pte_create` in `PageTable::unmap`
* [ ] bug fix: check validity of level-3 pte in `find_pte` instead of checking it outside this function
* [ ] 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
