Hermit Kernel

This is the kernel of the Hermit unikernel project.

For details, see the docs.

Requirements

• rustup

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 repository.
• For C/C++ applications: Instructions can be found in the hermit-c repository.

Standalone static library build

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 to print kernel messages. The environment variable HERMIT_LOG_LEVEL_FILTER controls the verbosity and follows the env_logger format but without the regex support. You can change it per module (including its submodules) by setting it to a string in the format [target][=level][,...], where the level is a string matching the name of a LevelFilter. If the target is omitted, the level is set as the global level. If the level is omitted, logs of all levels are printed for the target. A substring search pattern that will filter all modules can be provided after the target-level pairs with /<pattern>. If the variable is not set, cannot be parsed, or it does not provide a global level, then a global level LevelFilter::Info is used by default.

[!NOTE] Although the logger only prints name of the lowest level for the kernel modules, the match filter requires paths to start from the root, i.e. in the format hermit::MODULE_NAME::SUBMODULE_NAME.

$ HERMIT_LOG_LEVEL_FILTER="hermit::drivers::net=debug,smoltcp,error" 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.
2. Erik Kidd's toyos-rs, which is an extension of Philipp Opermann's kernel.
3. The Rust-based teaching operating system eduOS-rs.

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (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. Create your own fork, send us a pull request, and chat with us on Zulip.