reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/commit/?id=40825509eee50f129e051f3415ad2a5459ac05eb
        git remote add jarkko-tpmdd git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git
        git fetch --no-tags jarkko-tpmdd tpm2key-v2
        git checkout 40825509eee50f129e051f3415ad2a5459ac05eb
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/char/tpm/