JELOS is a fairly unique distribution as it is *built to order* and only enough of the operating system and applications are built for the purpose of booting and executing emulators and ports. Developers and others who would like to contribute to our project should read and agree to the [Contributor Covenant Code of Conduct](https://github.com/JustEnoughLinuxOS/distribution/blob/main/CODE_OF_CONDUCT.md) and [Contributing to JELOS](https://github.com/JustEnoughLinuxOS/distribution/blob/main/CONTRIBUTING.md) guides before submitting your first contribution.
## Filesystem Structure
We have a simple filesystem structure adopted from parent distributions CoreELEC, LibreELEC, etc.
Build roots for each device and that devices architecture(s). For ARM devices JELOS builds and uses a 32bit root for several of the cores used in the 64bit distribution.
Contains functions utilized during the build process including architecture specific build flags, optimizations, and functions used throughout the build workflow.
Used to build the Ubuntu container used to build JELOS. The container is hosted at [https://hub.docker.com/u/justenoughlinuxos](https://hub.docker.com/u/justenoughlinuxos)
All of the licenses used throughout the distribution packages are hosted here. If you're adding a package that contains a license, make sure it is available in this directory before submitting the PR.
All of the package set that is used to develop and build JELOS are hosted within the packages directory. The package structure documentation is available in [PACKAGE.md](PACKAGE.md)
Anything that is necessary to be run on a device after an upgrade should be added here. Be sure to apply a guard to test that the change needs to be executed before execution.
Hardware specific parameters are stored in the projects folder, anything that should not be included on every device during a world build should be isolated to the specific project or device here.
The tools directory contains utility scripts that can be used during the development process, including a simple tool to burn an image to a usb drive or sdcard.
Building JELOS requires an Ubuntu 22.04 host with approximately 200GB of free space for a single device, or 800GB of free space for a full world build. Other Linux distributions may be used when building using Docker, however this is untested and unsupported. We recommend building with no more than 8 cores.
Once you have cloned the repo, you will want to determine if you want to build the main branch which is more stable, or the development branch which is unstable but hosts our newest features.
|Branch|Purpose|
|----|----|
|main|Stable JELOS sources|
|dev|Unstable JELOS sources|
To check out our development branch, cd into the project directory and checkout `dev`.
Building JELOS is easy, the fastest and most recommended method is to instruct the build to use Docker, this is only known to work on a Linux system. To build JELOS with Docker use the table below.
> Devices that list a dependency require the dependency to be built first as that build will be used as the root of the device you are building. This will be done automatically by the build tooling when you start a build for your device.
> Note: Emulation Station package build requires additional steps because its source code located in a separate repository, see instructions inside, [link](https://github.com/JustEnoughLinuxOS/distribution/blob/main/packages/ui/emulationstation/package.mk).
### Special env variables
For development build, you can use the following env variables to customize the image. Some of them can be included in your `.bashrc` startup shell script.
To enable Screenscraper, GamesDB, and RetroAchievements, register at each site and apply the api keys in ~/developer_settings.conf or add them as environment variables. Unsetting one of the variables will disable it in EmulationStation. This configuration is picked up by EmulationStation during the build.
It is common to have imported package source code modifed to fit the use case. It's recommended to use a special shell script to built it in case you need to iterate over it. See below.
```
cd sources/wireguard-linux-compat
tar -xvJf wireguard-linux-compat-v1.0.20211208.tar.xz
After patch is generated, one can rebuild an individual package, see section above. The build system will automatically pick up patch files from `patches` directory. For testing, one can either copy the built binary to the console or burn the whole image on SD card.
If you already have a build for your device made using the above process, it's simple to shortcut the build process and create an image to test your changes quickly using the process below.
```
# Update the package version for a new package, or apply your patch as above.
