SBT_ENABLED
if (sc->sc_flags & SBT_ENABLED)
sc->sc_flags |= SBT_ENABLED;
if (!(sc->sc_flags & SBT_ENABLED))
sc->sc_flags &= ~SBT_ENABLED;
KASSERT(sc->sc_flags & SBT_ENABLED);
KASSERT(sc->sc_flags & SBT_ENABLED);
KASSERT(sc->sc_flags & SBT_ENABLED);