This buildroot can be used to build RetroFW cross-compilation toolchain and the OS image.
First, clone or download the repo and run:
make RetroFW_defconfig BR2_EXTERNAL=retrofw
You only need to run this once.
Then, to build the toolchain, run:
make toolchain
You can also build particular libraries and packages this way, for example to build SDL and SDL_Image:
make sdl sdl_image
To build the OS image, run:
make
NOTE: Set BR2_JLEVEL=0
to compile in parallel.