SM_PRIV_SIZE
p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
#define SM_priv_sz (XDR_QUADLEN(SM_PRIV_SIZE))
p = xdr_inline_decode(xdr, SM_PRIV_SIZE);
p = xdr_inline_decode(xdr, SM_PRIV_SIZE);
unsigned char data[SM_PRIV_SIZE];