reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux.git/commit/?id=29b6c55defd03d6cd9ea2b19545a3b67fd618fa3
        git remote add axboe https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux.git
        git fetch --no-tags axboe tty-nowait
        git checkout 29b6c55defd03d6cd9ea2b19545a3b67fd618fa3
        # apt-get install llvm-dev

        # save the config file
        make W=1 ARCH=i386 olddefconfig
        make W=1 ARCH=i386 
        make W=1 headers_install
        make W=1 -C tools/testing/selftests