reproduce (this is a W=1 build):
        # https://github.com/Xilinx/linux-xlnx/commit/f4aa5b97b5e1735f72676a44811c60268bde49bf
        git remote add xilinx-xlnx https://github.com/Xilinx/linux-xlnx
        git fetch --no-tags xilinx-xlnx master
        git checkout f4aa5b97b5e1735f72676a44811c60268bde49bf

        # 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 modules_install