reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        git remote add joro-iommu https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git
        git fetch joro-iommu next
        git checkout joro-iommu/next
        b4 shazam https://lore.kernel.org/r/42722975eb1309a3e43f58099ff5b6c7bfb23d3d.1718994350.git.robin.murphy@arm.com
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-13.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arm olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-13.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash drivers/iommu/