reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git/commit/?id=0d485bc4c7200bf8f115c4283fd7b48997f5813d
        git remote add wsa https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git
        git fetch --no-tags wsa renesas/hwspinlock/refactor-alloc-buildtest
        git checkout 0d485bc4c7200bf8f115c4283fd7b48997f5813d

        # 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 SHELL=/bin/bash drivers/hwspinlock/