recalboxOS is compiled with buildroot.
Buildroot is a simple, efficient and easy-to-use tool to generate embedded Linux systems through cross-compilation. It compiles all recalboxOS system and software from source, and creates the archives that will be copied to your SD file at the installation.
It creates a minimal embedded linux system, corresponding exactly to what is needed on your system. This is why you have no package manager on recalboxOS, no compilator, no headers etc...
recalboxOS is the main project, that aggregates the sub-projects composing of the system :
recalbox-buildroot : https://github.com/digitalLumberjack/recalbox-buildroot (branch unified) The recalbox-buildroot project is the buildroot system. It create the whole linux os that will run on the recalbox. You can compile this project, then copy output files to a manually formatted SD card to run the system on a raspberryPi. But there is a better way, called recalbox-rescue.
recalbox-rescue : https://github.com/digitalLumberjack/recalbox-rescue (branch dual) Based on the awesome NOOBS distro from rpi team, the recalbox rescue allows you to easily install recalboxOS and have a rescue partition on your SD card. It's another minimal OS, that will download recalboxOS, format your SD card, and install the system for you. It will check if a new version is available from the net before installing SD card version.
recalbox-emulationstation : https://gitlab.com/recalbox/recalbox-emulationstation Based on the awesome Aloshi emulationstation 2, the frontend has been a little modified to have ogg bg music, language selection, update support and controller configuration.
recalbox-configgen : https://gitlab.com/recalbox/recalbox-configgen The automatic emulator configuration tool.
If you want to go deeper, and learn how to compile and modify recalboxOS, jump to [[Compilation & Modifications|Compilation-&-Modifications-(EN)]]
The recalboxOS is set up to run on 3 partitions :
The first partition of type FAT32, named BOOT, mounted on /boot on the system, contains all boot files
The second partition of type EXT4, named root, mounted on / on the system, contains all the system
The third partition of type FAT32, named SHARE, mounted on /recalbox/share on the system, contains all roms, bios, saves and screenshots.
User data is explained here : [[Customizing-System-directory-(EN)]]