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# Hermit Kernel
[](https://hermit-os.github.io/kernel/hermit/)

[](https://hermit.zulipchat.com/)
[](https://doi.org/10.5281/zenodo.14645534)
This is the kernel of the [Hermit](https://github.com/hermit-os) unikernel project.
## Requirements
* [`rustup`](https://www.rust-lang.org/tools/install)
## Building the kernel
Usually the kernel will be linked as static library to your applications.
- **Rust applications:** Instructions can be found in the [hermit-rs](https://github.com/hermit-os/hermit-rs) repository.
- **For C/C++ applications:** Instructions can be found in the [hermit-playground](https://github.com/hermit-os/hermit-playground) repository.
### Standalone static library build
```sh
cargo xtask build --arch x86_64
```
On completion, the script will print the path of `libhermit.a`.
If you want to build the kernel for aarch64, please replace `x86_64` by `aarch64`.
If you want to build the kernel for riscv64, please use `riscv64`.
### Control the kernel messages verbosity
This kernel uses the lightweight logging crate [log](https://github.com/rust-lang/log) to print kernel messages.
The environment variable `HERMIT_LOG_LEVEL_FILTER` controls the verbosity.
You can change it by setting it at compile time to a string matching the name of a [LevelFilter](https://docs.rs/log/0.4.8/log/enum.LevelFilter.html).
If the variable is not set, or the name doesn't match, then `LevelFilter::Info` is used by default.
```sh
$ HERMIT_LOG_LEVEL_FILTER=Debug cargo xtask build --arch x86_64
```
## Credits
This kernel is derived from following tutorials and software distributions:
1. Philipp Oppermann's [excellent series of blog posts][opp].
2. Erik Kidd's [toyos-rs][kidd], which is an extension of Philipp Opermann's kernel.
3. The Rust-based teaching operating system [eduOS-rs][eduos].
[opp]: http://blog.phil-opp.com/
[kidd]: http://www.randomhacks.net/bare-metal-rust/
[eduos]: http://rwth-os.github.io/eduOS-rs/
## License
Licensed under either of
* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
* MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
at your option.
## Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
The kernel is being developed on [hermit-os/kernel](https://github.com/hermit-os/kernel).
Create your own fork, send us a pull request, and chat with us on [Zulip](https://hermit.zulipchat.com/).