DD_NEXT_INITBUF
nd_bsw4(DD_NEXT_INITBUF, dd_next);
if ((nd_bsr4(DD_NEXT_INITBUF) != dd_next)
dd_next_initbuf = nd_bsr4(DD_NEXT_INITBUF);
#define DD_SIZE (DD_NEXT_INITBUF + sizeof(char *))