./MinUI/makefile: 1. clones toolchains into ./MinUI/toolchains 2. builds toolchains via toolchain/PLATFORM/makefile(.build)
./MinUI/makefile.toolchain: 1. build PLATFORM via makefile.toolchain(build) 2. which invokes workspace/PLATFORM/makefile(all) 3. which invokes workspace/PLATFORM/show/makefile(all)