reproduce (this is a W=1 build):
        # https://github.com/yiliu1765/iommufd/commit/5d36234649d8f6673b0f658ed6591f35ba5c626d
        git remote add yiliu1765-iommufd https://github.com/yiliu1765/iommufd.git
        git fetch --no-tags yiliu1765-iommufd bak-0618
        git checkout 5d36234649d8f6673b0f658ed6591f35ba5c626d
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/iommu/intel/ sound/pci/hda/