reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b38aa697bcdc6529a912c18ddd093b1329b3d8b1
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout b38aa697bcdc6529a912c18ddd093b1329b3d8b1
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=mips olddefconfig
        ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash dtbs_check