reproduce (this is a W=1 build):
        # https://github.com/isilence/linux/commit/db28eb2f9cdc35a6dbf288322fc0da445a78b421
        git remote add isilence https://github.com/isilence/linux
        git fetch --no-tags isilence zcrx/next
        git checkout db28eb2f9cdc35a6dbf288322fc0da445a78b421
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=um olddefconfig
        make W=1 O=build_dir ARCH=um SHELL=/bin/bash