reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k.git/commit/?id=b971c823ecb945e93fbe49e98884e4ef9ee5e859
        git remote add geert-m68k https://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k.git
        git fetch --no-tags geert-m68k master
        git checkout b971c823ecb945e93fbe49e98884e4ef9ee5e859

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # apt-get install sparse
        # sparse: v0.6.5-rc1

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.5.0 ~/lkp-tests/kbuild/make.cross W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=m68k olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.5.0 ~/lkp-tests/kbuild/make.cross W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=m68k SHELL=/bin/bash drivers/usb/