FXPF_EXT_TXCB
sc->sc_flags |= FXPF_FC|FXPF_EXT_TXCB;
cbp->ext_txcb_dis = (sc->sc_flags & FXPF_EXT_TXCB) ? 0 : 1;
if (sc->sc_flags & FXPF_EXT_TXCB)
sc->sc_flags |= FXPF_FC|FXPF_EXT_TXCB;
sc->sc_flags |= FXPF_FC|FXPF_EXT_TXCB;
sc->sc_flags |= FXPF_FC|FXPF_EXT_TXCB;