38.13.4. Buildroot build variants
Allows you to have multiple versions of the GCC toolchain or root filesystem.
Analogous to the Linux kernel build variants but with the --build-id option instead:
./build-buildroot git -C "$(./getvar buildroot_source_dir)" checkout 2018.05 ./build-buildroot --buildroot-build-id 2018.05 git -C "$(./getvar buildroot_source_dir)" checkout - ./run ./run --buildroot-build-id 2018.05