reproduce (this is a W=1 build):
        git checkout 8e929cb546ee42c9a61d24fae60605e9e3192354
        b4 shazam https://lore.kernel.org/r/3-v2-fd55d00a60b2+c69-arm_no_split_jgg@nvidia.com
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/iommu/