jelos.org/docs/contribute/build.md

:octicons-stack-16: Building JELOS

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 Code of Conduct and Contributing to JELOS guides before submitting your first contribution.

1. Prep

Building JELOS requires a host with 200GB of free space for a single device, or 1TB of free space for a full world build.

!!! note "Expect your first build to take on the order of ten hours. You will need a stable internet connection, since hundreds of packages will be downloaded from their source."

Download errors often produce build failures with misleading error messages. If this happens to you, see the Troubleshooting section below.

After a clean build, all subsequent builds will go much faster (minutes) since 99% of the build work is cached.

Docker (Recommended)

!!! tip "Docker is the easiest and most reliable way to build JELOS."

You need no previous experience with Docker; you merely need to install it on your build machine. Newcomers to the project are strongly recommended to use this approach.

We recommend using Ubuntu 22.04 for the host machine, as this is well-tested and known to work. Other distributions and operating systems might also work for Docker builds, but are untested and unsupported.

sudo apt update
sudo apt install ca-certificates curl gnupg

sudo install -m 0755 -d /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
sudo chmod a+r /etc/apt/keyrings/docker.gpg

echo \
  "deb [arch="$(dpkg --print-architecture)" signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
  "$(. /etc/os-release && echo "$VERSION_CODENAME")" stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

sudo groupadd docker
sudo usermod -aG docker $USER
newgrp docker

docker run hello-world

Docker installation reference (source): Install using the apt repository and Linux post-installation steps.

The final command should produce a message indicating that Docker is properly installed. If you encounter any errors, see the reference links above.

Manual Build

Manual builds (outside of Docker) are only recommended for developers with specific needs that cannot be met by the Docker approach. The host configuration should match the Docker container as closely as possible, running Ubuntu 22.04 with all packages listed in the Dockerfile.

Virtual Machines

If you prefer to use a virtual machine for your build platform; keep in mind that results vary. There have been some reports of success with VMware Workstation (Player and Pro) and WSL and some unsuccessful attempts with VirtualBox. These reports are not definitive, but something to keep in mind if you prefer to use a VM.

2. Clone

After preparing the build machine, clone the JELOS git repository onto it.

cd ~
git clone https://github.com/JustEnoughLinuxOS/distribution.git

Selecting the Desired Branch

Once you have cloned the repo, decide whether 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.

cd distribution
git checkout dev

Filesystem Structure

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 device's 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.

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 packages used to develop and build JELOS are hosted within the packages directory. The package structure documentation is available here.

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 files 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.

3. Build

Building Device Images

Building JELOS is easy. From the root of your local repository, issue one of the make commands listed below, depending on the desired device and whether you are using Docker.

Devices	Dependency	Docker Command	Manual Command
AMD64		make docker-AMD64	make AMD64
RK3588		make docker-RK3588	make RK3588
RK3326		make docker-RK3326	make RK3326
RK3566		make docker-RK3566	make RK3566
RK3566-X55	RK3566	make docker-RK3566-X55	make RK3566-X55
S922X		make docker-S922X	make S922X
ALL DEVICES		make docker-world	make world

Devices that list a dependency require you to build the dependency first, since that build will be used as the root of the device you are building.

For example, the following command uses Docker to build the AMD64 image.

make docker-AMD64

Rightsized Builds

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	Default	Function
EMULATION_DEVICE	yes	Builds EmulationStation and all emulators if yes. Builds EmulationStation and NO emulators if no.
ENABLE_32BIT	yes	Builds a 32bit root and includes it in the image. Needed for 32bit cores and applications.
BASE_ONLY	false1	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: ¹ this property will change to yes/no for consistency in a future release.

Env Variables

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 to 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.

SSH Keys

export LOCAL_SSH_KEYS_FILE=~/.ssh/jelos/authorized_keys

WiFi SSID and password

export LOCAL_WIFI_SSID=MYWIFI
export LOCAL_WIFI_KEY=secret

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
export SCREENSCRAPER_DEV_LOGIN="devid=DEVID&devpassword=DEVPASSWORD"
# Apply for a GamesDB API Key here: https://forums.thegamesdb.net/viewforum.php?f=10
export GAMESDB_APIKEY="APIKEY"
# Find your Cheevos Web API key here: https://retroachievements.org/controlpanel.php
export CHEEVOS_DEV_LOGIN="z=RETROACHIEVEMENTSUSERNAME&y=APIKEYID"

Cleaning Additional Packages

make docker-shell
CLEAN_PACKAGES="linux ppsspp-sa" make AMD64
exit

The first and last lines should be omitted if building outside of Docker.

Troubleshooting

The very first build after a fresh checkout is the hardest. Give yourself sufficient time to generate the first build and work through any failures before attempting to modify JELOS.

• Download errors produce misleading failure messages. Beware of chasing red herrings. A network failure is much more likely than a bug in the makefile, given how frequently it is tested by the CI system and other devs.
• Try cleaning the failed package (see above) and building again.
• If you suspect a download failure, manually delete the relevant package(s) from the sources and build.JELOS-... directories, to force a full package re-download and re-build.
• Exhaust all options before using make clean since this deletes the build cache and takes hours to regenerate.
• As a very last resort, delete the entire local repository and start over.