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.
Building JELOS requires an Ubuntu 22.04 host with 200GB of free space for a single device, or 1TB of free space for a full world build. Other Linux distributions may be used when building using Docker, however this is untested and unsupported.
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`.
We have a simple filesystem structure adopted from parent distributions CoreELEC, LibreELEC, etc.
```
.
├── build.JELOS-DEVICE.ARCHITECTURE
├── config
├── distributions
├── Dockerfile
├── licenses
├── Makefile
├── packages
├── post-update
├── projects
├── release
├── scripts
├── sources
└── tools
```
**build.JELOS-DEVICE.ARCHITECTURE**
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.
**config**
Contains functions utilized during the build process including architecture specific build flags, optimizations, and functions used throughout the build workflow.
**distributions**
Distributions contains distribution specific build flags and parameters and splash screens.
**Dockerfile**
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)
**licenses**
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.
**Makefile**
Used to build one or more JELOS images, or to build and deploy the Ubuntu container.
**packages**
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)
**post-update**
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.
**projects**
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.
**release**
The output directory for all of the build images.
**scripts**
This directory contains all of the scripts used to fetch, extract, build, and release the distribution. Review Makefile for more details.
**sources**
As the distribution is being built, package source are fetched and hosted in this directory. They will persist after a `make clean`.
**tools**
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 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 | Dependency | Docker Command |
| ---- | ---- | ---- |
|AMD64||```make docker-AMD64```|
|RK3588||```make docker-RK3588```|
|RK3326||```make docker-RK3326```|
|RK3566||```make docker-RK3566```|
|RK3566-X55||```make docker-RK3566-X55```|
|S922X||```make docker-S922X```|
|ALL DEVICES||```make docker-world```|
> 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.
Next, build the version of JELOS for your device. See the table above for dependencies.
JELOS supports various build variables which alter the behavior of the distribution for specific purposes including debugging, or hosting containers. The options are defined below and are passed on the make command line. Ex. `BASE_ONLY=true make docker-RK3566`.
|Build Option|Setting|Function|
|----|----|----|
|EMULATION_DEVICE|yes|Builds EmulationStation and all emulators, builds EmulationStation and NO emulators if false.|
|ENABLE_32BIT|yes|Builds a 32bit root and includes it in the image. Needed for 32bit cores and applications.|
|BASE_ONLY|false<sup>1</sup>|Builds only the bare minimum packages, includes Weston on supported devices. Does not build EmulationStation.|
|CONTAINER_SUPPORT|no|Builds support for running containers on JELOS|
> Note: <sup>1</sup> this property will change to yes/no for consistency in a future release.
For development builds, you can use the following env variables to customize the image or change build time functionality. To make them globally available to the builds, add them to ${HOME}/.JELOS/options.
|Variable|Function|
|----|----|
|LOCAL_SSH_KEYS_FILE|Enables using ssh public keys for access without the root password.|
|LOCAL_WIFI_SSID|The SSID of the network the device should connect too automatically.|
|LOCAL_WIFI_KEY|The WIFI authentication key for the connection."|
|SCREENSCRAPER_DEV_LOGIN|Login information for screenscraper.fr.|
|GAMESDB_APIKEY|Login information for thegamesdb.net.|
|CHEEVOS_DEV_LOGIN|Login information for retroachievements.org.|
|CLEAN_PACKAGES|Allows specifying packages to clean during a build.|
#### Screenscraper, GamesDB, and RetroAchievements
To enable Screenscraper, GamesDB, and RetroAchievements, register at each site and apply the api keys in ${HOME}/.JELOS/options. Unsetting one of the variables will disable it in EmulationStation. This configuration is picked up by EmulationStation during the build.
```
# Apply for a Screenscraper API Key here: https://www.screenscraper.fr/forumsujets.php?frub=12&numpage=0
> Note: An EmulationStation package standalone 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).
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.
vim/emacs/vscode/notepad.exe
# Export the variables needed to complete your build, we'll assume you are building AMD64, update the device to match your configuration.
