reproduce (this is a W=1 build):
        # https://github.com/Freescale/linux-fslc/commit/156e54bbc99018164252576ccb464eaf23a84266
        git remote add freescale-fslc https://github.com/Freescale/linux-fslc
        git fetch --no-tags freescale-fslc 6.6-1.0.x-imx
        git checkout 156e54bbc99018164252576ccb464eaf23a84266
        # 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/vfio/