reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/commit/?id=b6a7a78fec52559fb6a14b9b3696f96eec3a1458
        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-v5
        git checkout b6a7a78fec52559fb6a14b9b3696f96eec3a1458
        # 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