swd_flags
sdp->swd_flags &= ~SWF_ENABLE;
sdp->swd_flags |= SWF_ENABLE;
if ((sdp->swd_flags & SWF_BUSY) != 0)
sdp->swd_flags |= SWF_BUSY;
sdp->swd_flags &= ~SWF_BUSY;
if ((sdp->swd_flags & SWF_ENABLE) == 0)
sdp->swd_flags = SWF_FAKE;
if (swd == NULL || (swd->swd_flags & SWF_ENABLE) == 0)
sdp->swd_path, sdp->swd_flags);
sdp->swd_flags = SWF_FAKE; /* placeholder only */
if ((sdp->swd_flags & (SWF_INUSE|SWF_ENABLE)) == 0) {
sdp->swd_flags &= ~SWF_FAKE; /* going live */
sdp->swd_flags |= (SWF_INUSE|SWF_ENABLE);