reproduce (this is a W=1 build):
        git remote add trondmy-nfs git://git.linux-nfs.org/projects/trondmy/linux-nfs.git
        git fetch trondmy-nfs linux-next
        git checkout trondmy-nfs/linux-next
        b4 shazam https://lore.kernel.org/r/20260204010415.2149607-1-andriy.shevchenko@linux.intel.com

        # install powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc-linux-gnu
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # apt-get install sparse
        # sparse version: v0.6.4-73-gfbdde312

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/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=powerpc SHELL=/bin/bash fs/nfs/