reproduce (this is a W=1 build):
        mkdir -p ~/bin
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/commit/?id=b8af77951941e943434a76ef40fdc372bf95030e
        git remote add pdx86-platform-drivers-x86 https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git
        git fetch --no-tags pdx86-platform-drivers-x86 platform-drivers-x86-simatic-ipc
        git checkout b8af77951941e943434a76ef40fdc372bf95030e
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang ~/bin/make.cross W=1 O=build_dir ARCH=i386 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang ~/bin/make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/platform/x86/siemens/