OSSL_KDF_PARAM_KBKDF_USE_L
p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_USE_L);
OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_USE_L, NULL),
*p++ = OSSL_PARAM_construct_int(OSSL_KDF_PARAM_KBKDF_USE_L, &use_l);
*p++ = OSSL_PARAM_construct_int(OSSL_KDF_PARAM_KBKDF_USE_L, &l);