MODALIAS=acpi:PNP0A06: :lzd*j"T%߸ţ 8am_J*j"TpOF?--- title: Hacking on systemd category: Contributing layout: default SPDX-License-Identifier: LGPL-2.1-or-later --- # Hacking on systemd We welcome all contributions to systemd. If you notice a bug or a missing feature, please feel invited to fix it, and submit your work as a [GitHub Pull Request (PR)](https://github.com/systemd/systemd/pull/new). Please make sure to follow our [Coding Style](CODING_STYLE.md) when submitting patches. Also have a look at our [Contribution Guidelines](CONTRIBUTING.md). When adding new functionality, tests should be added. For shared functionality (in `src/basic/` and `src/shared/`) unit tests should be sufficient. The general policy is to keep tests in matching files underneath `src/test/`, e.g. `src/test/test-path-util.c` contains tests for any functions in `src/basic/path-util.c`. If adding a new source file, consider adding a matching test executable. For features at a higher level, tests in `src/test/` are very strongly recommended. If that is not possible, integration tests in `test/` are encouraged. Please also have a look at our list of [code quality tools](CODE_QUALITY.md) we have setup for systemd, to ensure our codebase stays in good shape. Please always test your work before submitting a PR. For many of the components of systemd testing is straightforward as you can simply compile systemd and run the relevant tool from the build directory. For some components (most importantly, systemd/PID 1 itself) this is not possible, however. In order to simplify testing for cases like this we provide a set of `mkosi` build files directly in the source tree. [mkosi](https://github.com/systemd/mkosi) is a tool for building clean OS images from an upstream distribution in combination with a fresh build of the project in the local working directory. To make use of this, please install the `mkosi` package (if not packaged for your distro, it can be downloaded from the [GitHub repository](https://github.com/systemd/mkosi). `mkosi` will build an image for the host distro by default. mkosi-13 or newer version is required. It is sufficient to type `mkosi` in the systemd project directory to generate a disk image `image.raw` you can boot either in `systemd-nspawn` or in an UEFI-capable VM: ```sh $ mkosi boot ``` or: ```sh $ mkosi qemu ``` Every time you rerun the `mkosi` command a fresh image is built, incorporating all current changes you made to the project tree. To save time when rebuilding, you can use mkosi's incremental mode (`-i`). This instructs mkosi to build a set of cache images that make future builds a lot faster. Note that the `-i` flag both instructs mkosi to build cached images if they don't exist yet and to use cached images if they already exist so make sure to always specify `-i` if you want mkosi to use the cached images. If you're going to build mkosi images that use the same distribution and release that you're currently using, you can speed up the initial mkosi run by having it reuse the host's package cache. To do this, create a mkosi override file in mkosi.default.d/ (e.g 20-local.conf) and add the following contents: ``` [Content] Cache= # (e.g. /var/cache/dnf) ``` If you want to do a local build without mkosi, most distributions also provide very simple and convenient ways to install all development packages necessary to build systemd: ```sh # Fedora $ sudo dnf builddep systemd # Debian/Ubuntu $ sudo apt-get build-dep systemd # Arch $ sudo pacman install asp $ asp checkout systemd $ cd systemd/trunk $ makepkg -seoc ``` Putting this all together, here's a series of commands for preparing a patch for systemd: ```sh # Install build dependencies (see above) # Install a recent version of mkosi (either via your distro's package manager if # available there or from the github repository otherwise) $ git clone https://github.com/systemd/systemd.git $ cd systemd $ git checkout -b # where BRANCH is the name of the bran