diff --git a/sys/arch/arm/omap/if_cpsw.c b/sys/arch/arm/omap/if_cpsw.c
index e377dd0..4930ac3 100644
--- a/sys/arch/arm/omap/if_cpsw.c
+++ b/sys/arch/arm/omap/if_cpsw.c
@@ -572,6 +572,7 @@ cpsw_attach(device_t parent, device_t self, void *aux)
 	}
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->sc_enaddr);
 
 	/* The attach is successful. */
@@ -1303,7 +1304,7 @@ next:
 		ifp->if_timer = 0;
 
 	if (handled)
-		cpsw_start(ifp);
+		if_schedule_deferred_start(ifp);
 
 	return handled;
 }
diff --git a/sys/arch/emips/ebus/if_le_ebus.c b/sys/arch/emips/ebus/if_le_ebus.c
index 85ede58..3314b03 100644
--- a/sys/arch/emips/ebus/if_le_ebus.c
+++ b/sys/arch/emips/ebus/if_le_ebus.c
@@ -216,6 +216,7 @@ enic_attach(device_t parent, device_t self, void *aux)
 
 	/* Attach the interface. */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->sc_enaddr);
 
 	sc->sc_sh = shutdownhook_establish(enic_shutdown, ifp);
@@ -540,7 +541,7 @@ enic_init(struct ifnet *ifp)
 	printf("enic_init <- %x\n",ctl);
 #endif
 
-	enic_start(ifp);
+	if_schedule_deferred_start(ifp);
 
 	return 0;
 }
@@ -819,7 +820,7 @@ void enic_tint(struct enic_softc *sc, uint32_t saf, paddr_t phys)
 		ifp->if_timer = 0;
 
 	ifp->if_flags &= ~IFF_OACTIVE;
-	enic_start(ifp);
+	if_schedule_deferred_start(ifp);
 #if DEBUG
 	sc->it = 1;
 #endif
diff --git a/sys/arch/macppc/dev/if_bm.c b/sys/arch/macppc/dev/if_bm.c
index 1c845a1..cffa51e4 100644
--- a/sys/arch/macppc/dev/if_bm.c
+++ b/sys/arch/macppc/dev/if_bm.c
@@ -260,6 +260,7 @@ bmac_attach(device_t parent, device_t self, void *aux)
 	bmac_reset_chip(sc);
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->sc_enaddr);
 }
 
@@ -441,7 +442,7 @@ bmac_intr(void *v)
 		sc->sc_if.if_flags &= ~IFF_OACTIVE;
 		sc->sc_if.if_timer = 0;
 		sc->sc_if.if_opackets++;
-		bmac_start(&sc->sc_if);
+		if_schedule_deferred_start(&sc->sc_if);
 	}
 
 	/* XXX should do more! */
diff --git a/sys/arch/macppc/dev/if_gm.c b/sys/arch/macppc/dev/if_gm.c
index 95518cc..8ceafd4 100644
--- a/sys/arch/macppc/dev/if_gm.c
+++ b/sys/arch/macppc/dev/if_gm.c
@@ -247,6 +247,7 @@ gmac_attach(device_t parent, device_t self, void *aux)
 		ifmedia_set(&mii->mii_media, IFM_ETHER|IFM_AUTO);
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, laddr);
 	rnd_attach_source(&sc->sc_rnd_source, xname, RND_TYPE_NET,
 			  RND_FLAG_DEFAULT); 
@@ -343,7 +344,7 @@ gmac_tint(struct gmac_softc *sc)
 
 	ifp->if_flags &= ~IFF_OACTIVE;
 	ifp->if_timer = 0;
-	gmac_start(ifp);
+	if_schedule_deferred_start(ifp);
 }
 
 void
diff --git a/sys/arch/mips/adm5120/dev/if_admsw.c b/sys/arch/mips/adm5120/dev/if_admsw.c
index 0fac2e6..f7b9bf3 100644
--- a/sys/arch/mips/adm5120/dev/if_admsw.c
+++ b/sys/arch/mips/adm5120/dev/if_admsw.c
@@ -480,6 +480,7 @@ admsw_attach(device_t parent, device_t self, void *aux)
 
 		/* Attach the interface. */
 		if_attach(ifp);
+		if_deferred_start_init(ifp, NULL);
 		ether_ifattach(ifp, enaddr);
 		enaddr[5]++;
 	}
@@ -886,7 +887,7 @@ admsw_txintr(struct admsw_softc *sc, int prio)
 		ifp = &sc->sc_ethercom[0].ec_if;
 
 		/* Try to queue more packets. */
-		admsw_start(ifp);
+		if_schedule_deferred_start(ifp);
 
 		/*
 		 * If there are no more pending transmissions,
diff --git a/sys/arch/mips/alchemy/dev/if_aumac.c b/sys/arch/mips/alchemy/dev/if_aumac.c
index 8be6234..1d9543d 100644
--- a/sys/arch/mips/alchemy/dev/if_aumac.c
+++ b/sys/arch/mips/alchemy/dev/if_aumac.c
@@ -338,6 +338,7 @@ aumac_attach(device_t parent, device_t self, void *aux)
 
 	/* Attach the interface. */
 	if_attach(ifp); 
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, enaddr);
 
 	rnd_attach_source(&sc->rnd_source, device_xname(self),
@@ -578,7 +579,7 @@ aumac_txintr(struct aumac_softc *sc)
 		ifp->if_flags &= ~IFF_OACTIVE;
 
 		/* Try to queue more packets. */
-		aumac_start(ifp);
+		if_schedule_deferred_start(ifp);
 	}
 
 	if (pkts)
diff --git a/sys/arch/mips/atheros/dev/if_ae.c b/sys/arch/mips/atheros/dev/if_ae.c
index c55b13b..f3fd53e 100644
--- a/sys/arch/mips/atheros/dev/if_ae.c
+++ b/sys/arch/mips/atheros/dev/if_ae.c
@@ -383,6 +383,7 @@ ae_attach(device_t parent, device_t self, void *aux)
 	 * Attach the interface.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, enaddr);
 	ether_set_ifflags_cb(&sc->sc_ethercom, ae_ifflags_cb);
 
@@ -993,7 +994,7 @@ ae_intr(void *arg)
 	}
 
 	/* Try to get more packets going. */
-	ae_start(ifp);
+	if_schedule_deferred_start(ifp);
 
 	if (handled)
 		rnd_add_uint32(&sc->sc_rnd_source, status);
diff --git a/sys/arch/playstation2/dev/if_smap.c b/sys/arch/playstation2/dev/if_smap.c
index f708454..41b9296 100644
--- a/sys/arch/playstation2/dev/if_smap.c
+++ b/sys/arch/playstation2/dev/if_smap.c
@@ -246,6 +246,7 @@ smap_attach(struct device *parent, struct device *self, void *aux)
 	}
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, emac3->eaddr);
 	
 	spd_intr_establish(SPD_NIC, smap_intr, sc);
@@ -321,8 +322,7 @@ smap_intr(void *arg)
 	
 	/* if transmission is pending, start here */
 	ifp = &sc->ethercom.ec_if;
-	if (IFQ_IS_EMPTY(&ifp->if_snd) == 0)
-		smap_start(ifp);
+	if_schedule_deferred_start(ifp);
 	rnd_add_uint32(&sc->rnd_source, cause | sc->tx_fifo_ptr << 16);
 
 	return (1);
diff --git a/sys/arch/powerpc/ibm4xx/dev/if_emac.c b/sys/arch/powerpc/ibm4xx/dev/if_emac.c
index d33a1d3..2fda655 100644
--- a/sys/arch/powerpc/ibm4xx/dev/if_emac.c
+++ b/sys/arch/powerpc/ibm4xx/dev/if_emac.c
@@ -550,6 +550,7 @@ emac_attach(device_t parent, device_t self, void *aux)
 	 * Attach the interface.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, enaddr);
 
 #ifdef EMAC_EVENT_COUNTERS
@@ -1559,7 +1560,7 @@ emac_txeob_intr(void *arg)
 	handled |= emac_txreap(sc);
 
 	/* try to get more packets going */
-	emac_start(&sc->sc_ethercom.ec_if);
+	if_schedule_deferred_start(&sc->sc_ethercom.ec_if);
 
 	return handled;
 }
diff --git a/sys/arch/sgimips/hpc/if_sq.c b/sys/arch/sgimips/hpc/if_sq.c
index 14afb1b..e2786ec 100644
--- a/sys/arch/sgimips/hpc/if_sq.c
+++ b/sys/arch/sgimips/hpc/if_sq.c
@@ -324,6 +324,7 @@ sq_attach(device_t parent, device_t self, void *aux)
 	IFQ_SET_READY(&ifp->if_snd);
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->sc_enaddr);
 
 	memset(&sc->sq_trace, 0, sizeof(sc->sq_trace));
@@ -1110,7 +1111,7 @@ sq_txintr(struct sq_softc *sc)
 		ifp->if_timer = 0;
 
 	SQ_TRACE(SQ_TXINTR_EXIT, sc, sc->sc_prevtx, status);
-	sq_start(ifp);
+	if_schedule_deferred_start(ifp);
 
 	return 1;
 }
diff --git a/sys/arch/sgimips/mace/if_mec.c b/sys/arch/sgimips/mace/if_mec.c
index d35cb72..3cee66e 100644
--- a/sys/arch/sgimips/mace/if_mec.c
+++ b/sys/arch/sgimips/mace/if_mec.c
@@ -614,6 +614,7 @@ mec_attach(device_t parent, device_t self, void *aux)
 
 	/* attach the interface */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->sc_enaddr);
 
 	/* establish interrupt */
@@ -1607,9 +1608,9 @@ mec_intr(void *arg)
 		}
 	}
 
-	if (sent && !IFQ_IS_EMPTY(&ifp->if_snd)) {
+	if (sent) {
 		/* try to get more packets going */
-		mec_start(ifp);
+		if_schedule_deferred_start(ifp);
 	}
 
 	if (handled)
diff --git a/sys/arch/sun2/dev/if_ec.c b/sys/arch/sun2/dev/if_ec.c
index 9b6b6c2..1ff2dee 100644
--- a/sys/arch/sun2/dev/if_ec.c
+++ b/sys/arch/sun2/dev/if_ec.c
@@ -232,6 +232,7 @@ ec_attach(device_t parent, device_t self, void *aux)
 
 	/* Now we can attach the interface. */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	idprom_etheraddr(myaddr);
 	ether_ifattach(ifp, myaddr);
 	aprint_normal_dev(self, "address %s\n", ether_sprintf(myaddr));
@@ -434,9 +435,7 @@ ec_intr(void *arg)
 			sc->sc_ethercom.ec_if.if_opackets++;
 			sc->sc_jammed = 0;
 			ifp->if_flags &= ~IFF_OACTIVE;
-			IFQ_POLL(&ifp->if_snd, m0);
-			if (m0 != NULL)
-				ec_start(ifp);
+			if_schedule_deferred_start(ifp);
 		}
 	} else {
 
@@ -656,9 +655,7 @@ ec_coll(struct ec_softc *sc)
 		sc->sc_jammed = 1;
 		sc->sc_colliding = 0;
 		ifp->if_flags &= ~IFF_OACTIVE;
-		IFQ_POLL(&ifp->if_snd, m0);
-		if (m0 != NULL)
-			ec_start(ifp);
+		if_schedule_deferred_start(ifp);
 	} else {
 		jams = MAX(sc->sc_colliding, EC_BACKOFF_PRNG_COLL_MAX);
 		sc->sc_backoff_seed =
diff --git a/sys/arch/x86/pci/if_vmx.c b/sys/arch/x86/pci/if_vmx.c
index b89f9ca..e9f9b42 100644
--- a/sys/arch/x86/pci/if_vmx.c
+++ b/sys/arch/x86/pci/if_vmx.c
@@ -1717,6 +1717,7 @@ vmxnet3_setup_interface(struct vmxnet3_softc *sc)
 	ifmedia_set(&sc->vmx_media, IFM_ETHER|IFM_AUTO);
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->vmx_lladdr);
 	ether_set_ifflags_cb(&sc->vmx_ethercom, vmxnet3_ifflags_cb);
 	vmxnet3_link_status(sc);
@@ -1747,7 +1748,7 @@ vmxnet3_evintr(struct vmxnet3_softc *sc)
 	if (event & VMXNET3_EVENT_LINK) {
 		vmxnet3_link_status(sc);
 		if (sc->vmx_link_active != 0)
-			vmxnet3_start(&sc->vmx_ethercom.ec_if);
+			if_schedule_deferred_start(&sc->vmx_ethercom.ec_if);
 	}
 
 	if (event & (VMXNET3_EVENT_TQERROR | VMXNET3_EVENT_RQERROR)) {
diff --git a/sys/dev/marvell/if_mvgbe.c b/sys/dev/marvell/if_mvgbe.c
index 77b45f0..a411b3a 100644
--- a/sys/dev/marvell/if_mvgbe.c
+++ b/sys/dev/marvell/if_mvgbe.c
@@ -909,6 +909,7 @@ mvgbe_attach(device_t parent, device_t self, void *aux)
 	 * Call MI attach routines.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 
 	ether_ifattach(ifp, sc->sc_enaddr);
 	ether_set_ifflags_cb(&sc->sc_ethercom, mvgbe_ifflags_cb);
@@ -1050,8 +1051,7 @@ mvgbe_intr(void *arg)
 			mvgbe_txeof(sc);
 	}
 
-	if (!IFQ_IS_EMPTY(&ifp->if_snd))
-		mvgbe_start(ifp);
+	if_schedule_deferred_start(ifp);
 
 	rnd_add_uint32(&sc->sc_rnd_source, datum);
 
diff --git a/sys/dev/marvell/if_mvxpe.c b/sys/dev/marvell/if_mvxpe.c
index 5ce019d..a38515d 100644
--- a/sys/dev/marvell/if_mvxpe.c
+++ b/sys/dev/marvell/if_mvxpe.c
@@ -503,6 +503,7 @@ mvxpe_attach(device_t parent, device_t self, void *aux)
 	 * Call MI attach routines.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 
 	ether_ifattach(ifp, sc->sc_enaddr);
 	ether_set_ifflags_cb(&sc->sc_ethercom, mvxpe_ifflags_cb);
@@ -1479,8 +1480,7 @@ mvxpe_rxtxth_intr(void *arg)
 	}
 	mvxpe_sc_unlock(sc);
 
-	if (!IFQ_IS_EMPTY(&ifp->if_snd))
-		mvxpe_start(ifp);
+	if_schedule_deferred_start(ifp);
 
 	rnd_add_uint32(&sc->sc_rnd_source, datum);
 
diff --git a/sys/dev/pci/if_age.c b/sys/dev/pci/if_age.c
index 5a24574..67a29f2 100644
--- a/sys/dev/pci/if_age.c
+++ b/sys/dev/pci/if_age.c
@@ -285,6 +285,7 @@ age_attach(device_t parent, device_t self, void *aux)
 		ifmedia_set(&sc->sc_miibus.mii_media, IFM_ETHER | IFM_AUTO);
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->sc_enaddr);
 
 	if (pmf_device_register1(self, NULL, age_resume, age_shutdown))
@@ -535,7 +536,7 @@ age_intr(void *arg)
 				age_init(ifp);
 			}
 
-			age_start(ifp);
+			if_schedule_deferred_start(ifp);
 
 			if (status & INTR_SMB)
 				age_stats_update(sc);
diff --git a/sys/dev/pci/if_alc.c b/sys/dev/pci/if_alc.c
index d0be34b..a82f0ac 100644
--- a/sys/dev/pci/if_alc.c
+++ b/sys/dev/pci/if_alc.c
@@ -1466,6 +1466,7 @@ alc_attach(device_t parent, device_t self, void *aux)
 		ifmedia_set(&sc->sc_miibus.mii_media, IFM_ETHER | IFM_AUTO);
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->alc_eaddr);
 
 	if (!pmf_device_register(self, NULL, NULL))
@@ -2300,8 +2301,7 @@ alc_intr(void *arg)
 		}
 
 		alc_txeof(sc);
-		if (!IFQ_IS_EMPTY(&ifp->if_snd))
-			alc_start(ifp);
+		if_schedule_deferred_start(ifp);
 	}
 
 	/* Re-enable interrupts. */
diff --git a/sys/dev/pci/if_bce.c b/sys/dev/pci/if_bce.c
index 252d768..11cb818 100644
--- a/sys/dev/pci/if_bce.c
+++ b/sys/dev/pci/if_bce.c
@@ -445,6 +445,7 @@ bce_attach(device_t parent, device_t self, void *aux)
 
 	/* Attach the interface */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	sc->enaddr[0] = bus_space_read_1(sc->bce_btag, sc->bce_bhandle,
 	    BCE_MAGIC_ENET0);
 	sc->enaddr[1] = bus_space_read_1(sc->bce_btag, sc->bce_bhandle,
@@ -713,7 +714,7 @@ bce_intr(void *xsc)
 			bce_init(ifp);
 		rnd_add_uint32(&sc->rnd_source, intstatus);
 		/* Try to get more packets going. */
-		bce_start(ifp);
+		if_schedule_deferred_start(ifp);
 	}
 	return (handled);
 }
diff --git a/sys/dev/pci/if_bge.c b/sys/dev/pci/if_bge.c
index d07a5fd..d855975 100644
--- a/sys/dev/pci/if_bge.c
+++ b/sys/dev/pci/if_bge.c
@@ -4061,6 +4061,7 @@ alloc_retry:
 	 */
 	DPRINTFN(5, ("if_attach\n"));
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	DPRINTFN(5, ("ether_ifattach\n"));
 	ether_ifattach(ifp, eaddr);
 	ether_set_ifflags_cb(&sc->ethercom, bge_ifflags_cb);
@@ -4788,8 +4789,8 @@ bge_intr(void *xsc)
 	/* Re-enable interrupts. */
 	bge_writembx_flush(sc, BGE_MBX_IRQ0_LO, statustag);
 
-	if (ifp->if_flags & IFF_RUNNING && !IFQ_IS_EMPTY(&ifp->if_snd))
-		bge_start(ifp);
+	if (ifp->if_flags & IFF_RUNNING)
+		if_schedule_deferred_start(ifp);
 
 	return 1;
 }
diff --git a/sys/dev/pci/if_bnx.c b/sys/dev/pci/if_bnx.c
index a51490c..0f20423 100644
--- a/sys/dev/pci/if_bnx.c
+++ b/sys/dev/pci/if_bnx.c
@@ -846,6 +846,7 @@ bnx_attach(device_t parent, device_t self, void *aux)
 
 	/* Attach to the Ethernet interface list. */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp,sc->eaddr);
 
 	callout_init(&sc->bnx_timeout, 0);
@@ -5384,8 +5385,7 @@ bnx_intr(void *xsc)
 	    BNX_PCICFG_INT_ACK_CMD_INDEX_VALID | sc->last_status_idx);
 
 	/* Handle any frames that arrived while handling the interrupt. */
-	if (!IFQ_IS_EMPTY(&ifp->if_snd))
-		bnx_start(ifp);
+	if_schedule_deferred_start(ifp);
 
 	return 1;
 }
diff --git a/sys/dev/pci/if_cas.c b/sys/dev/pci/if_cas.c
index de3b20b..84f1213 100644
--- a/sys/dev/pci/if_cas.c
+++ b/sys/dev/pci/if_cas.c
@@ -609,6 +609,7 @@ cas_config(struct cas_softc *sc, const uint8_t *enaddr)
 
 	/* Attach the interface. */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, enaddr);
 
 	rnd_attach_source(&sc->rnd_source, device_xname(sc->sc_dev),
@@ -2016,7 +2017,7 @@ cas_tint(struct cas_softc *sc, u_int32_t status)
 	if (sc->sc_tx_cnt == 0)
 		ifp->if_timer = 0;
 
-	cas_start(ifp);
+	if_schedule_deferred_start(ifp);
 
 	return (1);
 }
diff --git a/sys/dev/pci/if_de.c b/sys/dev/pci/if_de.c
index eb8ef36..8faf1c2 100644
--- a/sys/dev/pci/if_de.c
+++ b/sys/dev/pci/if_de.c
@@ -4111,7 +4111,7 @@ tulip_intr_handler(
 	if (sc->tulip_flags & (TULIP_WANTTXSTART|TULIP_TXPROBE_ACTIVE|TULIP_DOINGSETUP|TULIP_PROMISC)) {
 	    tulip_tx_intr(sc);
 	    if ((sc->tulip_flags & TULIP_TXPROBE_ACTIVE) == 0)
-		tulip_ifstart(&sc->tulip_if);
+		if_schedule_deferred_start(&sc->tulip_if);
 	}
     }
     if (sc->tulip_flags & TULIP_NEEDRESET) {
@@ -5136,6 +5136,7 @@ tulip_attach(
     TULIP_ETHER_IFATTACH(sc);
 #else
     if_attach(ifp);
+    if_deferred_start_init(ifp, NULL);
 #if defined(__NetBSD__) || (defined(__FreeBSD__) && BSD >= 199506)
     TULIP_ETHER_IFATTACH(sc);
 #endif
diff --git a/sys/dev/pci/if_dge.c b/sys/dev/pci/if_dge.c
index b39a27b..5341eeb 100644
--- a/sys/dev/pci/if_dge.c
+++ b/sys/dev/pci/if_dge.c
@@ -943,6 +943,7 @@ dge_attach(device_t parent, device_t self, void *aux)
 	 * Attach the interface.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, enaddr);
 	rnd_attach_source(&sc->rnd_source, device_xname(sc->sc_dev),
 	    RND_TYPE_NET, RND_FLAG_DEFAULT);
@@ -1578,7 +1579,7 @@ dge_intr(void *arg)
 			dge_init(ifp);
 
 		/* Try to get more packets going. */
-		dge_start(ifp);
+		if_schedule_deferred_start(ifp);
 	}
 
 	return (handled);
diff --git a/sys/dev/pci/if_et.c b/sys/dev/pci/if_et.c
index a9ff3e8..021d85b 100644
--- a/sys/dev/pci/if_et.c
+++ b/sys/dev/pci/if_et.c
@@ -284,6 +284,7 @@ et_attach(device_t parent, device_t self, void *aux)
 		ifmedia_set(&sc->sc_miibus.mii_media, IFM_ETHER | IFM_AUTO);
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->sc_enaddr);
 
 	callout_init(&sc->sc_tick, 0);
@@ -1971,7 +1972,7 @@ et_txeof(struct et_softc *sc)
 	if (tbd->tbd_used + ET_NSEG_SPARE <= ET_TX_NDESC)
 		ifp->if_flags &= ~IFF_OACTIVE;
 
-	et_start(ifp);
+	if_schedule_deferred_start(ifp);
 }
 
 void
diff --git a/sys/dev/pci/if_ipw.c b/sys/dev/pci/if_ipw.c
index 72d526b..0c0a6e4 100644
--- a/sys/dev/pci/if_ipw.c
+++ b/sys/dev/pci/if_ipw.c
@@ -297,6 +297,7 @@ ipw_attach(device_t parent, device_t self, void *aux)
 	    ether_sprintf(ic->ic_myaddr));
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ieee80211_ifattach(ic);
 
 	/* override state transition machine */
@@ -1215,7 +1216,7 @@ ipw_tx_intr(struct ipw_softc *sc)
 
 	/* Call start() since some buffer descriptors have been released */
 	ifp->if_flags &= ~IFF_OACTIVE;
-	(*ifp->if_start)(ifp);
+	if_schedule_deferred_start(ifp);
 }
 
 static int
diff --git a/sys/dev/pci/if_iwi.c b/sys/dev/pci/if_iwi.c
index 7576f0a..c8a578f 100644
--- a/sys/dev/pci/if_iwi.c
+++ b/sys/dev/pci/if_iwi.c
@@ -355,6 +355,7 @@ iwi_attach(device_t parent, device_t self, void *aux)
 	memcpy(ifp->if_xname, device_xname(self), IFNAMSIZ);
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ieee80211_ifattach(ic);
 	/* override default methods */
 	ic->ic_node_alloc = iwi_node_alloc;
@@ -1444,7 +1445,7 @@ iwi_tx_intr(struct iwi_softc *sc, struct iwi_tx_ring *txq)
 	ifp->if_flags &= ~IFF_OACTIVE;
 
 	/* Call start() since some buffer descriptors have been released */
-	(*ifp->if_start)(ifp);
+	if_schedule_deferred_start(ifp);
 }
 
 static int
diff --git a/sys/dev/pci/if_iwm.c b/sys/dev/pci/if_iwm.c
index ac404f3..9b6d665 100644
--- a/sys/dev/pci/if_iwm.c
+++ b/sys/dev/pci/if_iwm.c
@@ -3330,7 +3330,7 @@ iwm_mvm_rx_tx_cmd(struct iwm_softc *sc,
 			 * I guess net80211 does all sorts of stunts in
 			 * interrupt context, so maybe this is no biggie.
 			 */
-			(*ifp->if_start)(ifp);
+			if_schedule_deferred_start(ifp);
 		}
 	}
 }
@@ -6831,9 +6831,10 @@ iwm_attach(device_t parent, device_t self, void *aux)
 #else
 	ether_ifattach(ifp, ic->ic_myaddr);	/* XXX */
 #endif
-	if_register(ifp);
 	/* Use common softint-based if_input */
 	ifp->if_percpuq = if_percpuq_create(ifp);
+	if_deferred_start_init(ifp, NULL);
+	if_register(ifp);
 
 	callout_init(&sc->sc_calib_to, 0);
 	callout_setfunc(&sc->sc_calib_to, iwm_calib_timeout, sc);
diff --git a/sys/dev/pci/if_iwn.c b/sys/dev/pci/if_iwn.c
index 3d20ba9..db65d3e 100644
--- a/sys/dev/pci/if_iwn.c
+++ b/sys/dev/pci/if_iwn.c
@@ -593,6 +593,7 @@ iwn_attach(device_t parent __unused, device_t self, void *aux)
 	memcpy(ifp->if_xname, device_xname(self), IFNAMSIZ);
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ieee80211_ifattach(ic);
 	ic->ic_node_alloc = iwn_node_alloc;
 	ic->ic_newassoc = iwn_newassoc;
@@ -2341,7 +2342,7 @@ iwn_tx_done(struct iwn_softc *sc, struct iwn_rx_desc *desc, int ackfailcnt,
 		sc->qfullmsk &= ~(1 << ring->qid);
 		if (sc->qfullmsk == 0 && (ifp->if_flags & IFF_OACTIVE)) {
 			ifp->if_flags &= ~IFF_OACTIVE;
-			(*ifp->if_start)(ifp);
+			if_schedule_deferred_start(ifp);
 		}
 	}
 }
diff --git a/sys/dev/pci/if_lii.c b/sys/dev/pci/if_lii.c
index b4e3f76..659dc25 100644
--- a/sys/dev/pci/if_lii.c
+++ b/sys/dev/pci/if_lii.c
@@ -336,6 +336,7 @@ lii_attach(device_t parent, device_t self, void *aux)
 	sc->sc_ec.ec_capabilities = ETHERCAP_VLAN_MTU;
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, eaddr);
 
 	if (pmf_device_register(self, NULL, NULL))
@@ -1048,7 +1049,7 @@ lii_txintr(struct lii_softc *sc)
 	}
 
 	if (sc->sc_free_tx_slots)
-		lii_start(ifp);
+		if_schedule_deferred_start(ifp);
 }
 
 static int
diff --git a/sys/dev/pci/if_msk.c b/sys/dev/pci/if_msk.c
index 309ecea..dc39e3b 100644
--- a/sys/dev/pci/if_msk.c
+++ b/sys/dev/pci/if_msk.c
@@ -1135,6 +1135,7 @@ msk_attach(device_t parent, device_t self, void *aux)
 	 * Call MI attach routines.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc_if->sk_enaddr);
 
 	if (pmf_device_register(self, NULL, msk_resume))
@@ -1972,10 +1973,10 @@ msk_intr(void *xsc)
 
 	CSR_WRITE_4(sc, SK_Y2_ICR, 2);
 
-	if (ifp0 != NULL && !IFQ_IS_EMPTY(&ifp0->if_snd))
-		msk_start(ifp0);
-	if (ifp1 != NULL && !IFQ_IS_EMPTY(&ifp1->if_snd))
-		msk_start(ifp1);
+	if (ifp0 != NULL)
+		if_schedule_deferred_start(ifp0);
+	if (ifp1 != NULL)
+		if_schedule_deferred_start(ifp1);
 
 	rnd_add_uint32(&sc->rnd_source, status);
 
diff --git a/sys/dev/pci/if_nfe.c b/sys/dev/pci/if_nfe.c
index d7c1ca6..6b43729 100644
--- a/sys/dev/pci/if_nfe.c
+++ b/sys/dev/pci/if_nfe.c
@@ -409,6 +409,7 @@ nfe_attach(device_t parent, device_t self, void *aux)
 		ifmedia_set(&sc->sc_mii.mii_media, IFM_ETHER | IFM_AUTO);
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->sc_enaddr);
 	ether_set_ifflags_cb(&sc->sc_ethercom, nfe_ifflags_cb);
 
@@ -631,8 +632,8 @@ nfe_intr(void *arg)
 		}
 	}
 
-	if (handled && !IF_IS_EMPTY(&ifp->if_snd))
-		nfe_start(ifp);
+	if (handled)
+		if_schedule_deferred_start(ifp);
 
 	return handled;
 }
diff --git a/sys/dev/pci/if_pcn.c b/sys/dev/pci/if_pcn.c
index 7a8499f..c662efd 100644
--- a/sys/dev/pci/if_pcn.c
+++ b/sys/dev/pci/if_pcn.c
@@ -812,6 +812,7 @@ pcn_attach(device_t parent, device_t self, void *aux)
 
 	/* Attach the interface. */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, enaddr);
 	rnd_attach_source(&sc->rnd_source, device_xname(self),
 	    RND_TYPE_NET, RND_FLAG_DEFAULT);
@@ -1288,7 +1289,7 @@ pcn_intr(void *arg)
 			pcn_init(ifp);
 
 		/* Try to get more packets going. */
-		pcn_start(ifp);
+		if_schedule_deferred_start(ifp);
 	}
 
 	return (handled);
diff --git a/sys/dev/pci/if_rtwn.c b/sys/dev/pci/if_rtwn.c
index f6d00d7..148977d 100644
--- a/sys/dev/pci/if_rtwn.c
+++ b/sys/dev/pci/if_rtwn.c
@@ -357,9 +357,10 @@ rtwn_attach(device_t parent, device_t self, void *aux)
 
 	if_initialize(ifp);
 	ieee80211_ifattach(ic);
-	if_register(ifp);
 	/* Use common softint-based if_input */
 	ifp->if_percpuq = if_percpuq_create(ifp);
+	ifp->if_deferred_start = if_deferred_start_create(ifp, NULL);
+	if_register(ifp);
 
 	/* override default methods */
 	ic->ic_newassoc = rtwn_newassoc;
@@ -3519,7 +3520,7 @@ rtwn_intr(void *xsc)
 	if ((status & RTWN_INT_ENABLE_TX) && sc->qfullmsk == 0) {
 		struct ifnet *ifp = GET_IFP(sc);
 		ifp->if_flags &= ~IFF_OACTIVE;
-		rtwn_start(ifp);
+		if_schedule_deferred_start(ifp);
 	}
 
 	/* Enable interrupts. */
diff --git a/sys/dev/pci/if_sip.c b/sys/dev/pci/if_sip.c
index d587ad7..ad2734e 100644
--- a/sys/dev/pci/if_sip.c
+++ b/sys/dev/pci/if_sip.c
@@ -1283,6 +1283,7 @@ sipcom_attach(device_t parent, device_t self, void *aux)
 	 * Attach the interface.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, enaddr);
 	ether_set_ifflags_cb(&sc->sc_ethercom, sip_ifflags_cb);
 	sc->sc_prev.ec_capenable = sc->sc_ethercom.ec_capenable;
@@ -1952,7 +1953,7 @@ sipcom_intr(void *arg)
 	bus_space_write_4(sc->sc_st, sc->sc_sh, SIP_IER, IER_IE);
 
 	/* Try to get more packets going. */
-	sipcom_start(ifp);
+	if_schedule_deferred_start(ifp);
 
 	return (handled);
 }
diff --git a/sys/dev/pci/if_sk.c b/sys/dev/pci/if_sk.c
index cc43889..291533a 100644
--- a/sys/dev/pci/if_sk.c
+++ b/sys/dev/pci/if_sk.c
@@ -1458,6 +1458,7 @@ sk_attach(device_t parent, device_t self, void *aux)
 	 * Call MI attach routines.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 
 	ether_ifattach(ifp, sc_if->sk_enaddr);
 
@@ -2397,10 +2398,10 @@ sk_intr(void *xsc)
 
 	CSR_WRITE_4(sc, SK_IMR, sc->sk_intrmask);
 
-	if (ifp0 != NULL && !IFQ_IS_EMPTY(&ifp0->if_snd))
-		sk_start(ifp0);
-	if (ifp1 != NULL && !IFQ_IS_EMPTY(&ifp1->if_snd))
-		sk_start(ifp1);
+	if (ifp0 != NULL)
+		if_schedule_deferred_start(ifp0);
+	if (ifp1 != NULL)
+		if_schedule_deferred_start(ifp1);
 
 	rnd_add_uint32(&sc->rnd_source, status);
 
diff --git a/sys/dev/pci/if_ste.c b/sys/dev/pci/if_ste.c
index 1159fe6..f2fd198 100644
--- a/sys/dev/pci/if_ste.c
+++ b/sys/dev/pci/if_ste.c
@@ -505,6 +505,7 @@ ste_attach(device_t parent, device_t self, void *aux)
 	 * Attach the interface.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, enaddr);
 
 	/*
@@ -912,7 +913,7 @@ ste_intr(void *arg)
 	    sc->sc_IntEnable);
 
 	/* Try to get more packets going. */
-	ste_start(ifp);
+	if_schedule_deferred_start(ifp);
 
 	return (1);
 }
diff --git a/sys/dev/pci/if_stge.c b/sys/dev/pci/if_stge.c
index 4f5d189..b5c6b58 100644
--- a/sys/dev/pci/if_stge.c
+++ b/sys/dev/pci/if_stge.c
@@ -658,6 +658,7 @@ stge_attach(device_t parent, device_t self, void *aux)
 	 * Attach the interface.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, enaddr);
 
 #ifdef STGE_EVENT_COUNTERS
@@ -1141,7 +1142,7 @@ stge_intr(void *arg)
 	    sc->sc_IntEnable);
 
 	/* Try to get more packets going. */
-	stge_start(ifp);
+	if_schedule_deferred_start(ifp);
 
 	return (1);
 }
diff --git a/sys/dev/pci/if_ti.c b/sys/dev/pci/if_ti.c
index 317ed3c..b2d8df7 100644
--- a/sys/dev/pci/if_ti.c
+++ b/sys/dev/pci/if_ti.c
@@ -1866,6 +1866,7 @@ ti_attach(device_t parent, device_t self, void *aux)
 	 * Call MI attach routines.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, eaddr);
 
 	/*
@@ -2180,9 +2181,8 @@ ti_intr(void *xsc)
 	/* Re-enable interrupts. */
 	CSR_WRITE_4(sc, TI_MB_HOSTINTR, 0);
 
-	if ((ifp->if_flags & IFF_RUNNING) != 0 &&
-	    IFQ_IS_EMPTY(&ifp->if_snd) == 0)
-		ti_start(ifp);
+	if ((ifp->if_flags & IFF_RUNNING) != 0)
+		if_schedule_deferred_start(ifp);
 
 	return (1);
 }
diff --git a/sys/dev/pci/if_txp.c b/sys/dev/pci/if_txp.c
index b74c108..14ef3a8 100644
--- a/sys/dev/pci/if_txp.c
+++ b/sys/dev/pci/if_txp.c
@@ -343,6 +343,7 @@ txp_attach(device_t parent, device_t self, void *aux)
 	 * Attach us everywhere
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, enaddr);
 
 	if (pmf_device_register1(self, NULL, NULL, txp_shutdown))
@@ -652,7 +653,7 @@ txp_intr(void *vsc)
 	/* unmask all interrupts */
 	WRITE_REG(sc, TXP_IMR, TXP_INT_A2H_3);
 
-	txp_start(&sc->sc_arpcom.ec_if);
+	if_schedule_deferred_start(&sc->sc_arpcom.ec_if);
 
 	return (claimed);
 }
diff --git a/sys/dev/pci/if_vge.c b/sys/dev/pci/if_vge.c
index 206ac68..990c0c4 100644
--- a/sys/dev/pci/if_vge.c
+++ b/sys/dev/pci/if_vge.c
@@ -1067,6 +1067,7 @@ vge_attach(device_t parent, device_t self, void *aux)
 	 * Attach the interface.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, eaddr);
 	ether_set_ifflags_cb(&sc->sc_ethercom, vge_ifflags_cb);
 
@@ -1529,8 +1530,8 @@ vge_intr(void *arg)
 	/* Re-enable interrupts */
 	CSR_WRITE_1(sc, VGE_CRS3, VGE_CR3_INT_GMSK);
 
-	if (claim && !IFQ_IS_EMPTY(&ifp->if_snd))
-		vge_start(ifp);
+	if (claim)
+		if_schedule_deferred_start(ifp);
 
 	return claim;
 }
diff --git a/sys/dev/pci/if_vioif.c b/sys/dev/pci/if_vioif.c
index ed89412..c2568a2 100644
--- a/sys/dev/pci/if_vioif.c
+++ b/sys/dev/pci/if_vioif.c
@@ -672,6 +672,7 @@ skip:
 	sc->sc_ethercom.ec_capabilities |= ETHERCAP_VLAN_MTU;
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->sc_mac);
 
 	return;
@@ -1130,7 +1131,7 @@ vioif_tx_vq_done(struct virtqueue *vq)
 out:
 	VIOIF_TX_UNLOCK(sc);
 	if (r)
-		vioif_start(ifp);
+		if_schedule_deferred_start(ifp);
 	return r;
 }
 
diff --git a/sys/dev/pci/if_vr.c b/sys/dev/pci/if_vr.c
index 331f28b..4dd82e5 100644
--- a/sys/dev/pci/if_vr.c
+++ b/sys/dev/pci/if_vr.c
@@ -987,7 +987,7 @@ vr_intr(void *arg)
 	CSR_WRITE_2(sc, VR_IMR, VR_INTRS);
 
 	if (dotx)
-		vr_start(ifp);
+		if_schedule_deferred_start(ifp);
 
 	return (handled);
 }
@@ -1745,6 +1745,7 @@ vr_attach(device_t parent, device_t self, void *aux)
 	 * Call MI attach routines.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, sc->vr_enaddr);
 
 	rnd_attach_source(&sc->rnd_source, device_xname(self),
diff --git a/sys/dev/pci/if_wm.c b/sys/dev/pci/if_wm.c
index 1fdc9ae..49e28f8 100644
--- a/sys/dev/pci/if_wm.c
+++ b/sys/dev/pci/if_wm.c
@@ -696,6 +696,7 @@ static void	wm_nq_start_locked(struct ifnet *);
 static int	wm_nq_transmit(struct ifnet *, struct mbuf *);
 static void	wm_nq_transmit_locked(struct ifnet *, struct wm_txqueue *);
 static void	wm_nq_send_common_locked(struct ifnet *, struct wm_txqueue *, bool);
+static void	wm_deferred_start(struct ifnet *);
 /* Interrupt */
 static int	wm_txeof(struct wm_softc *, struct wm_txqueue *);
 static void	wm_rxeof(struct wm_rxqueue *);
@@ -1612,6 +1613,7 @@ wm_attach(device_t parent, device_t self, void *aux)
 	bool force_clear_smbi;
 	uint32_t link_mode;
 	uint32_t reg;
+	void (*deferred_start_func)(struct ifnet *) = NULL;
 
 	sc->sc_dev = self;
 	callout_init(&sc->sc_tick_ch, CALLOUT_FLAGS);
@@ -2514,12 +2516,16 @@ alloc_retry:
 	ifp->if_ioctl = wm_ioctl;
 	if ((sc->sc_flags & WM_F_NEWQUEUE) != 0) {
 		ifp->if_start = wm_nq_start;
-		if (sc->sc_nqueues > 1)
+		if (sc->sc_nqueues > 1) {
 			ifp->if_transmit = wm_nq_transmit;
+			deferred_start_func = wm_deferred_start;
+		}
 	} else {
 		ifp->if_start = wm_start;
-		if (sc->sc_nqueues > 1)
+		if (sc->sc_nqueues > 1) {
 			ifp->if_transmit = wm_transmit;
+			deferred_start_func = wm_deferred_start;
+		}
 	}
 	ifp->if_watchdog = wm_watchdog;
 	ifp->if_init = wm_init;
@@ -2620,6 +2626,7 @@ alloc_retry:
 	/* Attach the interface. */
 	if_initialize(ifp);
 	sc->sc_ipq = if_percpuq_create(&sc->sc_ethercom.ec_if);
+	if_deferred_start_init(ifp, deferred_start_func);
 	ether_ifattach(ifp, enaddr);
 	if_register(ifp);
 	ether_set_ifflags_cb(&sc->sc_ethercom, wm_ifflags_cb);
@@ -7245,6 +7252,53 @@ wm_nq_send_common_locked(struct ifnet *ifp, struct wm_txqueue *txq,
 	}
 }
 
+static void
+wm_deferred_start(struct ifnet *ifp)
+{
+	struct wm_softc *sc = ifp->if_softc;
+	int qid = 0;
+
+	/*
+	 * Try to transmit on all Tx queues. Passing a txq somehow and
+	 * transmitting only on the txq may be better.
+	 */
+restart:
+	WM_CORE_LOCK(sc);
+	if (sc->sc_core_stopping)
+		goto out;
+
+	for (; qid < sc->sc_nqueues; qid++) {
+		struct wm_txqueue *txq = &sc->sc_queue[qid].wmq_txq;
+
+		if (!mutex_tryenter(txq->txq_lock))
+			continue;
+
+		if (txq->txq_stopping) {
+			mutex_exit(txq->txq_lock);
+			continue;
+		}
+		WM_CORE_UNLOCK(sc);
+
+		if ((sc->sc_flags & WM_F_NEWQUEUE) != 0) {
+			/* XXX need for ALTQ */
+			if (qid == 0)
+				wm_nq_start_locked(ifp);
+			wm_nq_transmit_locked(ifp, txq);
+		} else {
+			/* XXX need for ALTQ */
+			if (qid == 0)
+				wm_start_locked(ifp);
+			wm_transmit_locked(ifp, txq);
+		}
+		mutex_exit(txq->txq_lock);
+
+		qid++;
+		goto restart;
+	}
+out:
+	WM_CORE_UNLOCK(sc);
+}
+
 /* Interrupt */
 
 /*
@@ -7926,7 +7980,7 @@ wm_intr_legacy(void *arg)
 
 	if (handled) {
 		/* Try to get more packets going. */
-		ifp->if_start(ifp);
+		if_schedule_deferred_start(ifp);
 	}
 
 	return handled;
@@ -7965,15 +8019,13 @@ wm_txrxintr_msix(void *arg)
 
 	/* Try to get more packets going. */
 	if (pcq_peek(txq->txq_interq) != NULL)
-		wm_nq_transmit_locked(ifp, txq);
+		if_schedule_deferred_start(ifp);
 	/*
 	 * There are still some upper layer processing which call
 	 * ifp->if_start(). e.g. ALTQ
 	 */
-	if (wmq->wmq_id == 0) {
-		if (!IFQ_IS_EMPTY(&ifp->if_snd))
-			wm_nq_start_locked(ifp);
-	}
+	if (wmq->wmq_id == 0)
+		if_schedule_deferred_start(ifp);
 
 	mutex_exit(txq->txq_lock);
 
diff --git a/sys/dev/pci/if_wpi.c b/sys/dev/pci/if_wpi.c
index cabe7bf..b8a510b 100644
--- a/sys/dev/pci/if_wpi.c
+++ b/sys/dev/pci/if_wpi.c
@@ -359,6 +359,7 @@ wpi_attach(device_t parent __unused, device_t self, void *aux)
 	memcpy(ifp->if_xname, device_xname(self), IFNAMSIZ);
 
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ieee80211_ifattach(ic);
 	/* override default methods */
 	ic->ic_node_alloc = wpi_node_alloc;
@@ -1630,7 +1631,7 @@ wpi_tx_intr(struct wpi_softc *sc, struct wpi_rx_desc *desc)
 
 	sc->sc_tx_timer = 0;
 	ifp->if_flags &= ~IFF_OACTIVE;
-	wpi_start(ifp);
+	if_schedule_deferred_start(ifp);
 }
 
 static void
diff --git a/sys/dev/pci/if_xge.c b/sys/dev/pci/if_xge.c
index 27acb76..18477a4 100644
--- a/sys/dev/pci/if_xge.c
+++ b/sys/dev/pci/if_xge.c
@@ -553,6 +553,7 @@ xge_attach(device_t parent, device_t self, void *aux)
 	 * Attach the interface.
 	 */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, enaddr);
 
 	/*
@@ -750,7 +751,7 @@ xge_intr(void *pv)
 	if (sc->sc_lasttx != lasttx)
 		ifp->if_flags &= ~IFF_OACTIVE;
 
-	xge_start(ifp); /* Try to get more packets on the wire */
+	if_schedule_deferred_start(ifp); /* Try to get more packets on the wire */
 
 	if ((val = PIF_RCSR(RX_TRAFFIC_INT))) {
 		XGE_EVCNT_INCR(&sc->sc_rxintr);
diff --git a/sys/dev/pcmcia/if_cnw.c b/sys/dev/pcmcia/if_cnw.c
index 355a2f0..d7b5d20 100644
--- a/sys/dev/pcmcia/if_cnw.c
+++ b/sys/dev/pcmcia/if_cnw.c
@@ -558,6 +558,7 @@ cnw_attach(device_t parent, device_t self, void *aux)
 
 	/* Attach the interface */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, macaddr);
 
 	sc->sc_resource |= CNW_RES_NET;
@@ -975,7 +976,7 @@ cnw_intr(void *arg)
 			ifp->if_flags &= ~IFF_OACTIVE;
 
 			/* Continue to send packets from the queue */
-			cnw_start(&sc->sc_ethercom.ec_if);
+			if_schedule_deferred_start(&sc->sc_ethercom.ec_if);
 		}
 
 	}
diff --git a/sys/dev/pcmcia/if_malo_pcmcia.c b/sys/dev/pcmcia/if_malo_pcmcia.c
index b0d2b77..bfd46a0 100644
--- a/sys/dev/pcmcia/if_malo_pcmcia.c
+++ b/sys/dev/pcmcia/if_malo_pcmcia.c
@@ -356,6 +356,7 @@ cmalo_attach(void *arg)
 
 	/* attach interface */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ieee80211_ifattach(ic);
 
 	sc->sc_newstate = ic->ic_newstate;
@@ -1070,7 +1071,7 @@ cmalo_tx_done(struct malo_softc *sc)
 	ifp->if_opackets++;
 	ifp->if_flags &= ~IFF_OACTIVE;
 	ifp->if_timer = 0;
-	cmalo_start(ifp);
+	if_schedule_deferred_start(ifp);
 }
 
 static void
diff --git a/sys/dev/pcmcia/if_xi.c b/sys/dev/pcmcia/if_xi.c
index d3b177a..66b06c1 100644
--- a/sys/dev/pcmcia/if_xi.c
+++ b/sys/dev/pcmcia/if_xi.c
@@ -219,6 +219,7 @@ xi_attach(struct xi_softc *sc, u_int8_t *myea)
 
 	/* Attach the interface. */
 	if_attach(ifp);
+	if_deferred_start_init(ifp, NULL);
 	ether_ifattach(ifp, myea);
 
 	/*
@@ -360,8 +361,7 @@ xi_intr(void *arg)
 	}
 
 	/* Try to start more packets transmitting. */
-	if (IFQ_IS_EMPTY(&ifp->if_snd) == 0)
-		xi_start(ifp);
+	if_schedule_deferred_start(ifp);
 
 	/* Detected excessive collisions? */
 	if ((tx_status & EXCESSIVE_COLL) && ifp->if_opackets > 0) {
diff --git a/sys/net/if.c b/sys/net/if.c
index c9c1bfd..1894640 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -223,6 +223,16 @@ static int sysctl_percpuq_drops_handler(SYSCTLFN_PROTO);
 static void sysctl_percpuq_setup(struct sysctllog **, const char *,
     struct if_percpuq *);
 
+struct if_deferred_start {
+	struct ifnet	*ids_ifp;
+	void		(*ids_if_start)(struct ifnet *);
+	void		*ids_si;
+};
+
+static void if_deferred_start_softint(void *);
+static void if_deferred_start_common(struct ifnet *);
+static void if_deferred_start_destroy(struct ifnet *);
+
 #if defined(INET) || defined(INET6)
 static void sysctl_net_pktq_setup(struct sysctllog **, int);
 #endif
@@ -953,6 +963,99 @@ bad:
 	return;
 }
 
+/*
+ * The deferred if_start framework
+ *
+ * The common APIs to defer if_start to softint when if_start is requested
+ * from a device driver running in hardware interrupt context.
+ */
+/*
+ * Call ifp->if_start (or equivalent) in a dedicated softint for
+ * deferred if_start.
+ */
+static void
+if_deferred_start_softint(void *arg)
+{
+	struct if_deferred_start *ids = arg;
+	struct ifnet *ifp = ids->ids_ifp;
+
+#ifdef DEBUG
+	log(LOG_DEBUG, "%s: deferred start on %s\n", __func__,
+	    ifp->if_xname);
+#endif
+
+	ids->ids_if_start(ifp);
+}
+
+/*
+ * The default callback function for deferred if_start.
+ */
+static void
+if_deferred_start_common(struct ifnet *ifp)
+{
+
+	if_start_lock(ifp);
+}
+
+static inline bool
+if_snd_is_used(struct ifnet *ifp)
+{
+
+	return ifp->if_transmit == NULL || ifp->if_transmit == if_nulltransmit ||
+	    ALTQ_IS_ENABLED(&ifp->if_snd);
+}
+
+/*
+ * Schedule deferred if_start.
+ */
+void
+if_schedule_deferred_start(struct ifnet *ifp)
+{
+
+	KASSERT(ifp->if_deferred_start != NULL);
+
+	if (if_snd_is_used(ifp) && IFQ_IS_EMPTY(&ifp->if_snd))
+		return;
+
+	softint_schedule(ifp->if_deferred_start->ids_si);
+}
+
+/*
+ * Create an instance of deferred if_start. A driver should call the function
+ * only if the driver needs deferred if_start. Drivers can setup their own
+ * deferred if_start function via 2nd argument.
+ */
+void
+if_deferred_start_init(struct ifnet *ifp, void (*func)(struct ifnet *))
+{
+	struct if_deferred_start *ids;
+
+	ids = kmem_zalloc(sizeof(*ids), KM_SLEEP);
+	if (ids == NULL)
+		panic("kmem_zalloc failed");
+
+	ids->ids_ifp = ifp;
+	ids->ids_si = softint_establish(SOFTINT_NET|SOFTINT_MPSAFE,
+	    if_deferred_start_softint, ids);
+	if (func != NULL)
+		ids->ids_if_start = func;
+	else
+		ids->ids_if_start = if_deferred_start_common;
+
+	ifp->if_deferred_start = ids;
+}
+
+static void
+if_deferred_start_destroy(struct ifnet *ifp)
+{
+
+	if (ifp->if_deferred_start == NULL)
+		return;
+
+	softint_disestablish(ifp->if_deferred_start->ids_si);
+	kmem_free(ifp->if_deferred_start, sizeof(*ifp->if_deferred_start));
+	ifp->if_deferred_start = NULL;
+}
 
 /*
  * The common interface input routine that is called by device drivers,
@@ -1194,6 +1297,7 @@ if_detach(struct ifnet *ifp)
 		callout_destroy(ifp->if_slowtimo_ch);
 		kmem_free(ifp->if_slowtimo_ch, sizeof(*ifp->if_slowtimo_ch));
 	}
+	if_deferred_start_destroy(ifp);
 
 	/*
 	 * Do an if_down() to give protocols a chance to do something.
diff --git a/sys/net/if.h b/sys/net/if.h
index 0599d1e..fd1b259 100644
--- a/sys/net/if.h
+++ b/sys/net/if.h
@@ -230,6 +230,7 @@ struct bridge_iflist;
 struct callout;
 struct krwlock;
 struct if_percpuq;
+struct if_deferred_start;
 
 typedef unsigned short if_index_t;
 
@@ -342,6 +343,7 @@ typedef struct ifnet {
 	struct pslist_entry	if_pslist_entry;
 	struct psref_target     if_psref;
 	struct pslist_head	if_addr_pslist;
+	struct if_deferred_start	*if_deferred_start;
 #endif
 } ifnet_t;
  
@@ -989,6 +991,9 @@ void	if_percpuq_destroy(struct if_percpuq *);
 void
 	if_percpuq_enqueue(struct if_percpuq *, struct mbuf *);
 
+void	if_deferred_start_init(struct ifnet *, void (*)(struct ifnet *));
+void	if_schedule_deferred_start(struct ifnet *);
+
 void ifa_insert(struct ifnet *, struct ifaddr *);
 void ifa_remove(struct ifnet *, struct ifaddr *);