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/mcgrof/linux.git/commit/?id=7bb45e107b4d1f4d101b2124f0c2d3371249de11
        git remote add mcgrof https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux.git
        git fetch --no-tags mcgrof 20250722-iommu-hacks
        git checkout 7bb45e107b4d1f4d101b2124f0c2d3371249de11
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-15.1.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=m68k olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-15.1.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash drivers/iommu/iommufd/