PSARC/2008/242 Data Fast-Path for Softmac

6649224 fast-path needed to improve legacy network interface performance after UV
6649898 the smac_lock and smac_mutex fields in softmac_t should be given a more descriptive name
6799767 DLD capability is not correctly updated if it is renegotiated

14 files changed, 2236 insertions, 263 deletions

diff --git a/usr/src/uts/common/io/dld/dld_drv.c b/usr/src/uts/common/io/dld/dld_drv.c
index f833adce01..57721bb2ed 100644
--- a/usr/src/uts/common/io/dld/dld_drv.c
+++ b/usr/src/uts/common/io/dld/dld_drv.c
@@ -824,16 +824,19 @@ drv_ioc_usagelog(void *karg, intptr_t arg, int mode, cred_t *cred,
     int *rvalp)
 {
 	dld_ioc_usagelog_t	*log_info = (dld_ioc_usagelog_t *)karg;
+	int			err = 0;
 
 	if (log_info->ul_type < MAC_LOGTYPE_LINK ||
 	    log_info->ul_type > MAC_LOGTYPE_FLOW)
 		return (EINVAL);
 
-	if (log_info->ul_onoff)
-		mac_start_logusage(log_info->ul_type, log_info->ul_interval);
-	else
+	if (log_info->ul_onoff) {
+		err = mac_start_logusage(log_info->ul_type,
+		    log_info->ul_interval);
+	} else {
 		mac_stop_logusage(log_info->ul_type);
-	return (0);
+	}
+	return (err);
 }
 
 /*
diff --git a/usr/src/uts/common/io/dld/dld_proto.c b/usr/src/uts/common/io/dld/dld_proto.c
index b6faf7ada3..1f683c8591 100644
--- a/usr/src/uts/common/io/dld/dld_proto.c
+++ b/usr/src/uts/common/io/dld/dld_proto.c
@@ -430,8 +430,7 @@ proto_bind_req(dld_str_t *dsp, mblk_t *mp)
 
 	mac_perim_enter_by_mh(dsp->ds_mh, &mph);
 
-	if (dsp->ds_passivestate == DLD_UNINITIALIZED &&
-	    ((err = dls_active_set(dsp)) != 0)) {
+	if ((err = dls_active_set(dsp)) != 0) {
 		dl_err = DL_SYSERR;
 		goto failed2;
 	}
@@ -460,8 +459,7 @@ proto_bind_req(dld_str_t *dsp, mblk_t *mp)
 		}
 
 		dsp->ds_dlstate = DL_UNBOUND;
-		if (dsp->ds_passivestate == DLD_UNINITIALIZED)
-			dls_active_clear(dsp);
+		dls_active_clear(dsp, B_FALSE);
 		goto failed2;
 	}
 
@@ -489,9 +487,6 @@ proto_bind_req(dld_str_t *dsp, mblk_t *mp)
 	dlsap_addr_length += sizeof (uint16_t);
 
 	dsp->ds_dlstate = DL_IDLE;
-	if (dsp->ds_passivestate == DLD_UNINITIALIZED)
-		dsp->ds_passivestate = DLD_ACTIVE;
-
 	dlbindack(q, mp, sap, dlsap_addr, dlsap_addr_length, 0, 0);
 	return;
 
@@ -557,6 +552,7 @@ proto_unbind_req(dld_str_t *dsp, mblk_t *mp)
 	dsp->ds_mode = DLD_UNITDATA;
 	dsp->ds_dlstate = DL_UNBOUND;
 
+	dls_active_clear(dsp, B_FALSE);
 	mac_perim_exit(mph);
 	dlokack(dsp->ds_wq, mp, DL_UNBIND_REQ);
 	return;
@@ -609,8 +605,7 @@ proto_promiscon_req(dld_str_t *dsp, mblk_t *mp)
 
 	mac_perim_enter_by_mh(dsp->ds_mh, &mph);
 
-	if (dsp->ds_passivestate == DLD_UNINITIALIZED &&
-	    ((err = dls_active_set(dsp)) != 0)) {
+	if ((promisc_saved == 0) && (err = dls_active_set(dsp)) != 0) {
 		dsp->ds_promisc = promisc_saved;
 		dl_err = DL_SYSERR;
 		goto failed2;
@@ -624,15 +619,13 @@ proto_promiscon_req(dld_str_t *dsp, mblk_t *mp)
 	if (err != 0) {
 		dl_err = DL_SYSERR;
 		dsp->ds_promisc = promisc_saved;
-		if (dsp->ds_passivestate == DLD_UNINITIALIZED)
-			dls_active_clear(dsp);
+		if (promisc_saved == 0)
+			dls_active_clear(dsp, B_FALSE);
 		goto failed2;
 	}
 
 	mac_perim_exit(mph);
 
-	if (dsp->ds_passivestate == DLD_UNINITIALIZED)
-		dsp->ds_passivestate = DLD_ACTIVE;
 	dlokack(q, mp, DL_PROMISCON_REQ);
 	return;
 
@@ -702,12 +695,18 @@ proto_promiscoff_req(dld_str_t *dsp, mblk_t *mp)
 	 * Adjust channel promiscuity.
 	 */
 	err = dls_promisc(dsp, promisc_saved);
-	mac_perim_exit(mph);
 
 	if (err != 0) {
+		mac_perim_exit(mph);
 		dl_err = DL_SYSERR;
 		goto failed;
 	}
+
+	if (dsp->ds_promisc == 0)
+		dls_active_clear(dsp, B_FALSE);
+
+	mac_perim_exit(mph);
+
 	dlokack(q, mp, DL_PROMISCOFF_REQ);
 	return;
 failed:
@@ -741,14 +740,12 @@ proto_enabmulti_req(dld_str_t *dsp, mblk_t *mp)
 
 	mac_perim_enter_by_mh(dsp->ds_mh, &mph);
 
-	if (dsp->ds_passivestate == DLD_UNINITIALIZED &&
-	    ((err = dls_active_set(dsp)) != 0)) {
+	if ((dsp->ds_dmap == NULL) && (err = dls_active_set(dsp)) != 0) {
 		dl_err = DL_SYSERR;
 		goto failed2;
 	}
 
 	err = dls_multicst_add(dsp, mp->b_rptr + dlp->dl_addr_offset);
-
 	if (err != 0) {
 		switch (err) {
 		case EINVAL:
@@ -763,16 +760,13 @@ proto_enabmulti_req(dld_str_t *dsp, mblk_t *mp)
 			dl_err = DL_SYSERR;
 			break;
 		}
-		if (dsp->ds_passivestate == DLD_UNINITIALIZED)
-			dls_active_clear(dsp);
-
+		if (dsp->ds_dmap == NULL)
+			dls_active_clear(dsp, B_FALSE);
 		goto failed2;
 	}
 
 	mac_perim_exit(mph);
 
-	if (dsp->ds_passivestate == DLD_UNINITIALIZED)
-		dsp->ds_passivestate = DLD_ACTIVE;
 	dlokack(q, mp, DL_ENABMULTI_REQ);
 	return;
 
@@ -809,6 +803,8 @@ proto_disabmulti_req(dld_str_t *dsp, mblk_t *mp)
 
 	mac_perim_enter_by_mh(dsp->ds_mh, &mph);
 	err = dls_multicst_remove(dsp, mp->b_rptr + dlp->dl_addr_offset);
+	if ((err == 0) && (dsp->ds_dmap == NULL))
+		dls_active_clear(dsp, B_FALSE);
 	mac_perim_exit(mph);
 
 	if (err != 0) {
@@ -909,8 +905,7 @@ proto_setphysaddr_req(dld_str_t *dsp, mblk_t *mp)
 
 	mac_perim_enter_by_mh(dsp->ds_mh, &mph);
 
-	if (dsp->ds_passivestate == DLD_UNINITIALIZED &&
-	    ((err = dls_active_set(dsp)) != 0)) {
+	if ((err = dls_active_set(dsp)) != 0) {
 		dl_err = DL_SYSERR;
 		goto failed2;
 	}
@@ -928,17 +923,13 @@ proto_setphysaddr_req(dld_str_t *dsp, mblk_t *mp)
 			dl_err = DL_SYSERR;
 			break;
 		}
-		if (dsp->ds_passivestate == DLD_UNINITIALIZED)
-			dls_active_clear(dsp);
-
+		dls_active_clear(dsp, B_FALSE);
 		goto failed2;
 
 	}
 
 	mac_perim_exit(mph);
 
-	if (dsp->ds_passivestate == DLD_UNINITIALIZED)
-		dsp->ds_passivestate = DLD_ACTIVE;
 	dlokack(q, mp, DL_SET_PHYS_ADDR_REQ);
 	return;
 
diff --git a/usr/src/uts/common/io/dld/dld_str.c b/usr/src/uts/common/io/dld/dld_str.c
index f7f4266062..170e087a69 100644
--- a/usr/src/uts/common/io/dld/dld_str.c
+++ b/usr/src/uts/common/io/dld/dld_str.c
@@ -213,28 +213,20 @@ dld_getinfo(dev_info_t *dip, ddi_info_cmd_t cmd, void *arg, void **resp)
 	return (rc);
 }
 
-/*
- * qi_qopen: open(9e)
- */
-/*ARGSUSED*/
+void *
+dld_str_private(queue_t *q)
+{
+	return (((dld_str_t *)(q->q_ptr))->ds_private);
+}
+
 int
-dld_open(queue_t *rq, dev_t *devp, int flag, int sflag, cred_t *credp)
+dld_str_open(queue_t *rq, dev_t *devp, void *private)
 {
 	dld_str_t	*dsp;
 	major_t		major;
 	minor_t		minor;
 	int		err;
 
-	if (sflag == MODOPEN)
-		return (ENOTSUP);
-
-	/*
-	 * This is a cloning driver and therefore each queue should only
-	 * ever get opened once.
-	 */
-	if (rq->q_ptr != NULL)
-		return (EBUSY);
-
 	major = getmajor(*devp);
 	minor = getminor(*devp);
 
@@ -249,12 +241,14 @@ dld_open(queue_t *rq, dev_t *devp, int flag, int sflag, cred_t *credp)
 		return (ENOSR);
 
 	ASSERT(dsp->ds_dlstate == DL_UNATTACHED);
+	dsp->ds_private = private;
 	if (minor != 0) {
 		/*
 		 * Style 1 open
 		 */
 		if ((err = dld_str_attach(dsp, (t_uscalar_t)minor - 1)) != 0)
 			goto failed;
+
 		ASSERT(dsp->ds_dlstate == DL_UNBOUND);
 	} else {
 		(void) qassociate(rq, -1);
@@ -276,11 +270,8 @@ failed:
 	return (err);
 }
 
-/*
- * qi_qclose: close(9e)
- */
 int
-dld_close(queue_t *rq)
+dld_str_close(queue_t *rq)
 {
 	dld_str_t	*dsp = rq->q_ptr;
 
@@ -298,11 +289,6 @@ dld_close(queue_t *rq)
 		cv_wait(&dsp->ds_dlpi_pending_cv, &dsp->ds_lock);
 	mutex_exit(&dsp->ds_lock);
 
-	/*
-	 * Disable the queue srv(9e) routine.
-	 */
-	qprocsoff(rq);
-
 
 	/*
 	 * This stream was open to a provider node. Check to see
@@ -322,6 +308,40 @@ dld_close(queue_t *rq)
 }
 
 /*
+ * qi_qopen: open(9e)
+ */
+/*ARGSUSED*/
+int
+dld_open(queue_t *rq, dev_t *devp, int flag, int sflag, cred_t *credp)
+{
+	if (sflag == MODOPEN)
+		return (ENOTSUP);
+
+	/*
+	 * This is a cloning driver and therefore each queue should only
+	 * ever get opened once.
+	 */
+	if (rq->q_ptr != NULL)
+		return (EBUSY);
+
+	return (dld_str_open(rq, devp, NULL));
+}
+
+/*
+ * qi_qclose: close(9e)
+ */
+int
+dld_close(queue_t *rq)
+{
+	/*
+	 * Disable the queue srv(9e) routine.
+	 */
+	qprocsoff(rq);
+
+	return (dld_str_close(rq));
+}
+
+/*
  * qi_qputp: put(9e)
  */
 void
@@ -603,6 +623,7 @@ dld_str_destroy(dld_str_t *dsp)
 	ASSERT(dsp->ds_direct == B_FALSE);
 	ASSERT(dsp->ds_lso == B_FALSE);
 	ASSERT(dsp->ds_lso_max == 0);
+	ASSERT(dsp->ds_passivestate != DLD_ACTIVE);
 
 	/*
 	 * Reinitialize all the flags.
@@ -930,11 +951,10 @@ dld_str_attach(dld_str_t *dsp, t_uscalar_t ppa)
 	dev_t			dev;
 	int			err;
 	const char		*drvname;
-	mac_perim_handle_t	mph;
+	mac_perim_handle_t	mph = NULL;
 	boolean_t		qassociated = B_FALSE;
 	dls_link_t		*dlp = NULL;
 	dls_dl_handle_t		ddp = NULL;
-	boolean_t		entered_perim = B_FALSE;
 
 	if ((drvname = ddi_major_to_name(dsp->ds_major)) == NULL)
 		return (EINVAL);
@@ -959,7 +979,6 @@ dld_str_attach(dld_str_t *dsp, t_uscalar_t ppa)
 
 	if ((err = mac_perim_enter_by_macname(dls_devnet_mac(ddp), &mph)) != 0)
 		goto failed;
-	entered_perim = B_TRUE;
 
 	/*
 	 * Open a channel.
@@ -986,7 +1005,7 @@ dld_str_attach(dld_str_t *dsp, t_uscalar_t ppa)
 failed:
 	if (dlp != NULL)
 		dls_link_rele(dlp);
-	if (entered_perim)
+	if (mph != NULL)
 		mac_perim_exit(mph);
 	if (ddp != NULL)
 		dls_devnet_rele(ddp);
diff --git a/usr/src/uts/common/io/dls/dls.c b/usr/src/uts/common/io/dls/dls.c
index 72f1aecd6a..4cf2efcccf 100644
--- a/usr/src/uts/common/io/dls/dls.c
+++ b/usr/src/uts/common/io/dls/dls.c
@@ -46,8 +46,17 @@ dls_open(dls_link_t *dlp, dls_dl_handle_t ddh, dld_str_t *dsp)
 	if (zid != GLOBAL_ZONEID && dlp->dl_zid != zid)
 		return (ENOENT);
 
-	if ((err = mac_start(dlp->dl_mh)) != 0)
+	/*
+	 * mac_start() is required for non-legacy MACs to show accurate
+	 * kstats even before the interface is brought up. For legacy
+	 * drivers, this is not needed. Further, calling mac_start() for
+	 * legacy drivers would make the shared-lower-stream to stay in
+	 * the DL_IDLE state, which in turn causes performance regression.
+	 */
+	if (!mac_capab_get(dlp->dl_mh, MAC_CAPAB_LEGACY, NULL) &&
+	    ((err = mac_start(dlp->dl_mh)) != 0)) {
 		return (err);
+	}
 
 	local = (zid == dlp->dl_zid);
 	dlp->dl_zone_ref += (local ? 1 : 0);
@@ -96,7 +105,7 @@ dls_close(dld_str_t *dsp)
 	}
 	dsp->ds_dmap = NULL;
 
-	dls_active_clear(dsp);
+	dls_active_clear(dsp, B_TRUE);
 
 	/*
 	 * If the dld_str_t is bound then unbind it.
@@ -126,7 +135,8 @@ dls_close(dld_str_t *dsp)
 
 	dsp->ds_dlp = NULL;
 
-	mac_stop(dsp->ds_mh);
+	if (!mac_capab_get(dsp->ds_mh, MAC_CAPAB_LEGACY, NULL))
+		mac_stop(dsp->ds_mh);
 
 	/*
 	 * Release our reference to the dls_link_t allowing that to be
@@ -628,29 +638,50 @@ dls_active_set(dld_str_t *dsp)
 
 	ASSERT(MAC_PERIM_HELD(dsp->ds_mh));
 
-	/* If we're already active, then there's nothing more to do. */
-	if (dsp->ds_active)
+	if (dsp->ds_passivestate == DLD_PASSIVE)
 		return (0);
 
-	if ((err = dls_mac_active_set(dsp->ds_dlp)) != 0) {
+	/* If we're already active, then there's nothing more to do. */
+	if ((dsp->ds_nactive == 0) &&
+	    ((err = dls_mac_active_set(dsp->ds_dlp)) != 0)) {
 		/* except for ENXIO all other errors are mapped to EBUSY */
 		if (err != ENXIO)
 			return (EBUSY);
 		return (err);
 	}
 
-	dsp->ds_active = B_TRUE;
+	dsp->ds_passivestate = DLD_ACTIVE;
+	dsp->ds_nactive++;
 	return (0);
 }
 
+/*
+ * Note that dls_active_set() is called whenever an active operation
+ * (DL_BIND_REQ, DL_ENABMULTI_REQ ...) is processed and
+ * dls_active_clear(dsp, B_FALSE) is called whenever the active operation
+ * is being undone (DL_UNBIND_REQ, DL_DISABMULTI_REQ ...). In some cases,
+ * a stream is closed without every active operation being undone and we
+ * need to clear all the "active" states by calling
+ * dls_active_clear(dsp, B_TRUE).
+ */
 void
-dls_active_clear(dld_str_t *dsp)
+dls_active_clear(dld_str_t *dsp, boolean_t all)
 {
 	ASSERT(MAC_PERIM_HELD(dsp->ds_mh));
 
-	if (!dsp->ds_active)
+	if (dsp->ds_passivestate == DLD_PASSIVE)
+		return;
+
+	if (all && dsp->ds_nactive == 0)
+		return;
+
+	ASSERT(dsp->ds_nactive > 0);
+
+	dsp->ds_nactive -= (all ? dsp->ds_nactive : 1);
+	if (dsp->ds_nactive != 0)
 		return;
 
+	ASSERT(dsp->ds_passivestate == DLD_ACTIVE);
 	dls_mac_active_clear(dsp->ds_dlp);
-	dsp->ds_active = B_FALSE;
+	dsp->ds_passivestate = DLD_UNINITIALIZED;
 }
diff --git a/usr/src/uts/common/io/mac/mac.c b/usr/src/uts/common/io/mac/mac.c
index 6e6f451ca9..c700e500fe 100644
--- a/usr/src/uts/common/io/mac/mac.c
+++ b/usr/src/uts/common/io/mac/mac.c
@@ -2158,7 +2158,9 @@ uint32_t
 mac_no_notification(mac_handle_t mh)
 {
 	mac_impl_t *mip = (mac_impl_t *)mh;
-	return (mip->mi_unsup_note);
+
+	return (((mip->mi_state_flags & MIS_LEGACY) != 0) ?
+	    mip->mi_capab_legacy.ml_unsup_note : 0);
 }
 
 /*
@@ -2842,6 +2844,28 @@ mac_get_prop(mac_handle_t mh, mac_prop_t *macprop, void *val, uint_t valsize,
 	return (err);
 }
 
+int
+mac_fastpath_disable(mac_handle_t mh)
+{
+	mac_impl_t	*mip = (mac_impl_t *)mh;
+
+	if ((mip->mi_state_flags & MIS_LEGACY) == 0)
+		return (0);
+
+	return (mip->mi_capab_legacy.ml_fastpath_disable(mip->mi_driver));
+}
+
+void
+mac_fastpath_enable(mac_handle_t mh)
+{
+	mac_impl_t	*mip = (mac_impl_t *)mh;
+
+	if ((mip->mi_state_flags & MIS_LEGACY) == 0)
+		return;
+
+	mip->mi_capab_legacy.ml_fastpath_enable(mip->mi_driver);
+}
+
 void
 mac_register_priv_prop(mac_impl_t *mip, mac_priv_prop_t *mpp, uint_t nprop)
 {
@@ -4391,34 +4415,79 @@ mac_log_linkinfo(void *arg)
 	rw_exit(&i_mac_impl_lock);
 }
 
+typedef struct i_mac_fastpath_state_s {
+	boolean_t	mf_disable;
+	int		mf_err;
+} i_mac_fastpath_state_t;
+
+/*ARGSUSED*/
+static uint_t
+i_mac_fastpath_disable_walker(mod_hash_key_t key, mod_hash_val_t *val,
+    void *arg)
+{
+	i_mac_fastpath_state_t	*state = arg;
+	mac_handle_t		mh = (mac_handle_t)val;
+
+	if (state->mf_disable)
+		state->mf_err = mac_fastpath_disable(mh);
+	else
+		mac_fastpath_enable(mh);
+
+	return (state->mf_err == 0 ? MH_WALK_CONTINUE : MH_WALK_TERMINATE);
+}
+
 /*
  * Start the logging timer.
  */
-void
+int
 mac_start_logusage(mac_logtype_t type, uint_t interval)
 {
+	i_mac_fastpath_state_t state = {B_TRUE, 0};
+	int err;
+
 	rw_enter(&i_mac_impl_lock, RW_WRITER);
 	switch (type) {
 	case MAC_LOGTYPE_FLOW:
 		if (mac_flow_log_enable) {
 			rw_exit(&i_mac_impl_lock);
-			return;
+			return (0);
 		}
-		mac_flow_log_enable = B_TRUE;
 		/* FALLTHRU */
 	case MAC_LOGTYPE_LINK:
 		if (mac_link_log_enable) {
 			rw_exit(&i_mac_impl_lock);
-			return;
+			return (0);
 		}
-		mac_link_log_enable = B_TRUE;
 		break;
 	default:
 		ASSERT(0);
 	}
+
+	/* Disable fastpath */
+	mod_hash_walk(i_mac_impl_hash, i_mac_fastpath_disable_walker, &state);
+	if ((err = state.mf_err) != 0) {
+		/* Reenable fastpath  */
+		state.mf_disable = B_FALSE;
+		state.mf_err = 0;
+		mod_hash_walk(i_mac_impl_hash,
+		    i_mac_fastpath_disable_walker, &state);
+		rw_exit(&i_mac_impl_lock);
+		return (err);
+	}
+
+	switch (type) {
+	case MAC_LOGTYPE_FLOW:
+		mac_flow_log_enable = B_TRUE;
+		/* FALLTHRU */
+	case MAC_LOGTYPE_LINK:
+		mac_link_log_enable = B_TRUE;
+		break;
+	}
+
 	mac_logging_interval = interval;
 	rw_exit(&i_mac_impl_lock);
 	mac_log_linkinfo(NULL);
+	return (0);
 }
 
 /*
@@ -4428,6 +4497,7 @@ void
 mac_stop_logusage(mac_logtype_t type)
 {
 	i_mac_log_state_t	lstate;
+	i_mac_fastpath_state_t	state = {B_FALSE, 0};
 
 	rw_enter(&i_mac_impl_lock, RW_WRITER);
 	lstate.mi_fenable = mac_flow_log_enable;
@@ -4455,6 +4525,10 @@ mac_stop_logusage(mac_logtype_t type)
 	default:
 		ASSERT(0);
 	}
+
+	/* Reenable fastpath */
+	mod_hash_walk(i_mac_impl_hash, i_mac_fastpath_disable_walker, &state);
+
 	rw_exit(&i_mac_impl_lock);
 	(void) untimeout(mac_logging_timer);
 	mac_logging_timer = 0;
diff --git a/usr/src/uts/common/io/mac/mac_client.c b/usr/src/uts/common/io/mac/mac_client.c
index 85614bdd9e..8b4006a805 100644
--- a/usr/src/uts/common/io/mac/mac_client.c
+++ b/usr/src/uts/common/io/mac/mac_client.c
@@ -410,6 +410,12 @@ mac_devinfo_get(mac_handle_t mh)
 	return (((mac_impl_t *)mh)->mi_dip);
 }
 
+void *
+mac_driver(mac_handle_t mh)
+{
+	return (((mac_impl_t *)mh)->mi_driver);
+}
+
 const char *
 mac_name(mac_handle_t mh)
 {
@@ -1637,10 +1643,9 @@ i_mac_unicast_add(mac_client_handle_t mch, uint8_t *mac_addr, uint16_t flags,
 	boolean_t bcast_added = B_FALSE;
 	boolean_t nactiveclients_added = B_FALSE;
 	boolean_t mac_started = B_FALSE;
+	boolean_t fastpath_disabled = B_FALSE;
 	mac_resource_props_t mrp;
 
-	ASSERT(MAC_PERIM_HELD((mac_handle_t)mip));
-
 	/* when VID is non-zero, the underlying MAC can not be VNIC */
 	ASSERT(!((mip->mi_state_flags & MIS_IS_VNIC) && (vid != 0)));
 
@@ -1708,19 +1713,39 @@ i_mac_unicast_add(mac_client_handle_t mch, uint8_t *mac_addr, uint16_t flags,
 	}
 
 	/*
-	 * Return EBUSY if:
-	 *  - this is an exclusive active mac client and there already exist
-	 *    active mac clients, or
-	 *  - there already exist an exclusively active mac client.
+	 * If this is a VNIC/VLAN, disable softmac fast-path.
 	 */
-	if ((mcip->mci_state_flags & MCIS_EXCLUSIVE) &&
-	    (mip->mi_nactiveclients != 0) || (mip->mi_state_flags &
-	    MIS_EXCLUSIVE)) {
+	if (mcip->mci_state_flags & MCIS_IS_VNIC) {
+		err = mac_fastpath_disable((mac_handle_t)mip);
+		if (err != 0)
+			return (err);
+		fastpath_disabled = B_TRUE;
+	}
+
+	/*
+	 * Return EBUSY if:
+	 *  - there is an exclusively active mac client exists.
+	 *  - this is an exclusive active mac client but
+	 *	a. there is already active mac clients exist, or
+	 *	b. fastpath streams are already plumbed on this legacy device
+	 */
+	if (mip->mi_state_flags & MIS_EXCLUSIVE) {
+		if (fastpath_disabled)
+			mac_fastpath_enable((mac_handle_t)mip);
 		return (EBUSY);
 	}
 
-	if (mcip->mci_state_flags & MCIS_EXCLUSIVE)
+	if (mcip->mci_state_flags & MCIS_EXCLUSIVE) {
+		ASSERT(!fastpath_disabled);
+		if (mip->mi_nactiveclients != 0)
+			return (EBUSY);
+
+		if ((mip->mi_state_flags & MIS_LEGACY) &&
+		    !(mip->mi_capab_legacy.ml_active_set(mip->mi_driver))) {
+			return (EBUSY);
+		}
 		mip->mi_state_flags |= MIS_EXCLUSIVE;
+	}
 
 	bzero(&mrp, sizeof (mac_resource_props_t));
 	if (is_primary && !(mcip->mci_state_flags & (MCIS_IS_VNIC |
@@ -1970,8 +1995,15 @@ bail:
 	if (nactiveclients_added)
 		mip->mi_nactiveclients--;
 
-	if (mcip->mci_state_flags & MCIS_EXCLUSIVE)
+	if (mcip->mci_state_flags & MCIS_EXCLUSIVE) {
 		mip->mi_state_flags &= ~MIS_EXCLUSIVE;
+		if (mip->mi_state_flags & MIS_LEGACY)
+			mip->mi_capab_legacy.ml_active_clear(mip->mi_driver);
+	}
+
+	if (fastpath_disabled)
+		mac_fastpath_enable((mac_handle_t)mip);
+
 	kmem_free(muip, sizeof (mac_unicast_impl_t));
 	return (err);
 }
@@ -2087,10 +2119,10 @@ mac_unicast_remove(mac_client_handle_t mch, mac_unicast_handle_t mah)
 			mac_bcast_delete(mcip, mip->mi_type->mt_brdcst_addr,
 			    muip->mui_vid);
 		}
-		mac_stop((mac_handle_t)mip);
+
 		FLOW_FINAL_REFRELE(flent);
-		i_mac_perim_exit(mip);
-		return (0);
+		ASSERT(!(mcip->mci_state_flags & MCIS_EXCLUSIVE));
+		goto done;
 	}
 
 	/*
@@ -2170,8 +2202,14 @@ mac_unicast_remove(mac_client_handle_t mch, mac_unicast_handle_t mah)
 		mac_capab_update((mac_handle_t)mip);
 		mac_virtual_link_update(mip);
 	}
-	if (mcip->mci_state_flags & MCIS_EXCLUSIVE)
+
+	if (mcip->mci_state_flags & MCIS_EXCLUSIVE) {
 		mip->mi_state_flags &= ~MIS_EXCLUSIVE;
+
+		if (mip->mi_state_flags & MIS_LEGACY)
+			mip->mi_capab_legacy.ml_active_clear(mip->mi_driver);
+	}
+
 	mcip->mci_state_flags &= ~MCIS_UNICAST_HW;
 
 	if (mcip->mci_state_flags & MCIS_TAG_DISABLE)
@@ -2183,10 +2221,16 @@ mac_unicast_remove(mac_client_handle_t mch, mac_unicast_handle_t mah)
 	if (mcip->mci_state_flags & MCIS_DISABLE_TX_VID_CHECK)
 		mcip->mci_state_flags &= ~MCIS_DISABLE_TX_VID_CHECK;
 
-	mac_stop((mac_handle_t)mip);
+	kmem_free(muip, sizeof (mac_unicast_impl_t));
 
+done:
+	/*
+	 * Disable fastpath if this is a VNIC or a VLAN.
+	 */
+	if (mcip->mci_state_flags & MCIS_IS_VNIC)
+		mac_fastpath_enable((mac_handle_t)mip);
+	mac_stop((mac_handle_t)mip);
 	i_mac_perim_exit(mip);
-	kmem_free(muip, sizeof (mac_unicast_impl_t));
 	return (0);
 }
 
@@ -3149,16 +3193,17 @@ mac_capab_get(mac_handle_t mh, mac_capab_t cap, void *cap_data)
 	mac_impl_t *mip = (mac_impl_t *)mh;
 
 	/*
-	 * if mi_nactiveclients > 1, only MAC_CAPAB_HCKSUM,
-	 * MAC_CAPAB_NO_NATIVEVLAN, MAC_CAPAB_NO_ZCOPY can be advertised.
+	 * if mi_nactiveclients > 1, only MAC_CAPAB_LEGACY, MAC_CAPAB_HCKSUM,
+	 * MAC_CAPAB_NO_NATIVEVLAN and MAC_CAPAB_NO_ZCOPY can be advertised.
 	 */
 	if (mip->mi_nactiveclients > 1) {
 		switch (cap) {
-		case MAC_CAPAB_HCKSUM:
-			return (i_mac_capab_get(mh, cap, cap_data));
 		case MAC_CAPAB_NO_NATIVEVLAN:
 		case MAC_CAPAB_NO_ZCOPY:
 			return (B_TRUE);
+		case MAC_CAPAB_LEGACY:
+		case MAC_CAPAB_HCKSUM:
+			break;
 		default:
 			return (B_FALSE);
 		}
@@ -3303,7 +3348,8 @@ i_mac_set_resources(mac_handle_t mh, mac_resource_props_t *mrp)
 	mac_impl_t		*mip = (mac_impl_t *)mh;
 	mac_client_impl_t	*mcip;
 	int			err = 0;
-	mac_resource_props_t	tmrp;
+	uint32_t		resmask, newresmask;
+	mac_resource_props_t	tmrp, umrp;
 
 	ASSERT(MAC_PERIM_HELD((mac_handle_t)mip));
 
@@ -3311,6 +3357,20 @@ i_mac_set_resources(mac_handle_t mh, mac_resource_props_t *mrp)
 	if (err != 0)
 		return (err);
 
+	bcopy(&mip->mi_resource_props, &umrp, sizeof (mac_resource_props_t));
+	resmask = umrp.mrp_mask;
+	mac_update_resources(mrp, &umrp, B_FALSE);
+	newresmask = umrp.mrp_mask;
+
+	if (resmask == 0 && newresmask != 0) {
+		/*
+		 * Bandwidth, priority or cpu link properties configured,
+		 * must disable fastpath.
+		 */
+		if ((err = mac_fastpath_disable((mac_handle_t)mip)) != 0)
+			return (err);
+	}
+
 	/*
 	 * Since bind_cpu may be modified by mac_client_set_resources()
 	 * we use a copy of bind_cpu and finally cache bind_cpu in mip.
@@ -3322,9 +3382,20 @@ i_mac_set_resources(mac_handle_t mh, mac_resource_props_t *mrp)
 		err =
 		    mac_client_set_resources((mac_client_handle_t)mcip, &tmrp);
 	}
-	/* if mac_client_set_resources failed, do not update the values */
-	if (err == 0)
-		mac_update_resources(mrp, &mip->mi_resource_props, B_FALSE);
+
+	/* Only update the values if mac_client_set_resources succeeded */
+	if (err == 0) {
+		bcopy(&umrp, &mip->mi_resource_props,
+		    sizeof (mac_resource_props_t));
+		/*
+		 * If bankwidth, priority or cpu link properties cleared,
+		 * renable fastpath.
+		 */
+		if (resmask != 0 && newresmask == 0)
+			mac_fastpath_enable((mac_handle_t)mip);
+	} else if (resmask == 0 && newresmask != 0) {
+		mac_fastpath_enable((mac_handle_t)mip);
+	}
 	return (err);
 }
 
diff --git a/usr/src/uts/common/io/mac/mac_flow.c b/usr/src/uts/common/io/mac/mac_flow.c
index cb6560b1f7..fd4d13cf1b 100644
--- a/usr/src/uts/common/io/mac/mac_flow.c
+++ b/usr/src/uts/common/io/mac/mac_flow.c
@@ -335,8 +335,9 @@ mac_flow_rem_subflow(flow_entry_t *flent)
 {
 	flow_tab_t		*ft = flent->fe_flow_tab;
 	mac_client_impl_t	*mcip = ft->ft_mcip;
+	mac_handle_t		mh = (mac_handle_t)ft->ft_mip;
 
-	ASSERT(MAC_PERIM_HELD((mac_handle_t)ft->ft_mip));
+	ASSERT(MAC_PERIM_HELD(mh));
 
 	mac_flow_remove(ft, flent, B_FALSE);
 	if (flent->fe_mcip == NULL) {
@@ -348,10 +349,11 @@ mac_flow_rem_subflow(flow_entry_t *flent)
 			mac_flow_tab_destroy(ft);
 			mcip->mci_subflow_tab = NULL;
 		}
-		return;
+	} else {
+		mac_flow_wait(flent, FLOW_DRIVER_UPCALL);
+		mac_link_flow_clean((mac_client_handle_t)mcip, flent);
 	}
-	mac_flow_wait(flent, FLOW_DRIVER_UPCALL);
-	mac_link_flow_clean((mac_client_handle_t)mcip, flent);
+	mac_fastpath_enable(mh);
 }
 
 /*
@@ -363,13 +365,17 @@ mac_flow_add_subflow(mac_client_handle_t mch, flow_entry_t *flent,
     boolean_t instantiate_flow)
 {
 	mac_client_impl_t	*mcip = (mac_client_impl_t *)mch;
+	mac_handle_t		mh = (mac_handle_t)mcip->mci_mip;
 	flow_tab_info_t		*ftinfo;
 	flow_mask_t		mask;
 	flow_tab_t		*ft;
 	int			err;
 	boolean_t		ft_created = B_FALSE;
 
-	ASSERT(MAC_PERIM_HELD((mac_handle_t)mcip->mci_mip));
+	ASSERT(MAC_PERIM_HELD(mh));
+
+	if ((err = mac_fastpath_disable(mh)) != 0)
+		return (err);
 
 	/*
 	 * If the subflow table exists already just add the new subflow
@@ -382,8 +388,10 @@ mac_flow_add_subflow(mac_client_handle_t mch, flow_entry_t *flent,
 		 * Try to create a new table and then add the subflow to the
 		 * newly created subflow table
 		 */
-		if ((ftinfo = mac_flow_tab_info_get(mask)) == NULL)
+		if ((ftinfo = mac_flow_tab_info_get(mask)) == NULL) {
+			mac_fastpath_enable(mh);
 			return (EOPNOTSUPP);
+		}
 
 		mac_flow_tab_create(ftinfo->fti_ops, mask, ftinfo->fti_size,
 		    mcip->mci_mip, &ft);
@@ -394,6 +402,7 @@ mac_flow_add_subflow(mac_client_handle_t mch, flow_entry_t *flent,
 	if (err != 0) {
 		if (ft_created)
 			mac_flow_tab_destroy(ft);
+		mac_fastpath_enable(mh);
 		return (err);
 	}
 
@@ -405,6 +414,7 @@ mac_flow_add_subflow(mac_client_handle_t mch, flow_entry_t *flent,
 			mac_flow_remove(ft, flent, B_FALSE);
 			if (ft_created)
 				mac_flow_tab_destroy(ft);
+			mac_fastpath_enable(mh);
 			return (err);
 		}
 	} else {
diff --git a/usr/src/uts/common/io/mac/mac_provider.c b/usr/src/uts/common/io/mac/mac_provider.c
index 4d9d590457..0c9d6fddf2 100644
--- a/usr/src/uts/common/io/mac/mac_provider.c
+++ b/usr/src/uts/common/io/mac/mac_provider.c
@@ -131,7 +131,6 @@ mac_register(mac_register_t *mregp, mac_handle_t *mhp)
 	uint_t			instance;
 	boolean_t		style1_created = B_FALSE;
 	boolean_t		style2_created = B_FALSE;
-	mac_capab_legacy_t	legacy;
 	char			*driver;
 	minor_t			minor = 0;
 
@@ -298,14 +297,11 @@ mac_register(mac_register_t *mregp, mac_handle_t *mhp)
 	}
 	mip->mi_callbacks = mregp->m_callbacks;
 
-	if (i_mac_capab_get((mac_handle_t)mip, MAC_CAPAB_LEGACY, &legacy))
+	if (mac_capab_get((mac_handle_t)mip, MAC_CAPAB_LEGACY,
+	    &mip->mi_capab_legacy)) {
 		mip->mi_state_flags |= MIS_LEGACY;
-
-	if (mip->mi_state_flags & MIS_LEGACY) {
-		mip->mi_unsup_note = legacy.ml_unsup_note;
-		mip->mi_phy_dev = legacy.ml_dev;
+		mip->mi_phy_dev = mip->mi_capab_legacy.ml_dev;
 	} else {
-		mip->mi_unsup_note = 0;
 		mip->mi_phy_dev = makedevice(ddi_driver_major(mip->mi_dip),
 		    ddi_get_instance(mip->mi_dip) + 1);
 	}
@@ -505,6 +501,12 @@ mac_unregister(mac_handle_t mh)
 
 	i_mac_perim_enter(mip);
 
+	/*
+	 * There is still resource properties configured over this mac.
+	 */
+	if (mip->mi_resource_props.mrp_mask != 0)
+		mac_fastpath_enable((mac_handle_t)mip);
+
 	if (mip->mi_minor < MAC_MAX_MINOR + 1) {
 		ddi_remove_minor_node(mip->mi_dip, mip->mi_name);
 		ddi_remove_minor_node(mip->mi_dip,
diff --git a/usr/src/uts/common/io/softmac/softmac_ctl.c b/usr/src/uts/common/io/softmac/softmac_ctl.c
index 99c665aae6..d4c8afa8ce 100644
--- a/usr/src/uts/common/io/softmac/softmac_ctl.c
+++ b/usr/src/uts/common/io/softmac/softmac_ctl.c
@@ -19,7 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
@@ -70,6 +70,22 @@ softmac_send_bind_req(softmac_lower_t *slp, uint_t sap)
 }
 
 int
+softmac_send_unbind_req(softmac_lower_t *slp)
+{
+	mblk_t			*reqmp;
+
+	/*
+	 * create unbind req message and send it down
+	 */
+	reqmp = mexchange(NULL, NULL, DL_UNBIND_REQ_SIZE, M_PROTO,
+	    DL_UNBIND_REQ);
+	if (reqmp == NULL)
+		return (ENOMEM);
+
+	return (softmac_proto_tx(slp, reqmp, NULL));
+}
+
+int
 softmac_send_promisc_req(softmac_lower_t *slp, t_uscalar_t level, boolean_t on)
 {
 	mblk_t		*reqmp;
@@ -105,6 +121,7 @@ softmac_m_promisc(void *arg, boolean_t on)
 	softmac_t		*softmac = arg;
 	softmac_lower_t		*slp = softmac->smac_lower;
 
+	ASSERT(MAC_PERIM_HELD(softmac->smac_mh));
 	ASSERT(slp != NULL);
 	return (softmac_send_promisc_req(slp, DL_PROMISC_PHYS, on));
 }
@@ -120,6 +137,7 @@ softmac_m_multicst(void *arg, boolean_t add, const uint8_t *mca)
 	t_uscalar_t		dl_prim;
 	uint32_t		size, addr_length;
 
+	ASSERT(MAC_PERIM_HELD(softmac->smac_mh));
 	/*
 	 * create multicst message and send it down
 	 */
@@ -162,6 +180,7 @@ softmac_m_unicst(void *arg, const uint8_t *macaddr)
 	mblk_t			*reqmp;
 	size_t			size;
 
+	ASSERT(MAC_PERIM_HELD(softmac->smac_mh));
 	/*
 	 * create set_phys_addr message and send it down
 	 */
@@ -425,16 +444,72 @@ runt:
 }
 
 void
-softmac_rput_process_notdata(queue_t *rq, mblk_t *mp)
+softmac_rput_process_notdata(queue_t *rq, softmac_upper_t *sup, mblk_t *mp)
 {
-	softmac_lower_t	*slp = rq->q_ptr;
+	softmac_lower_t		*slp = rq->q_ptr;
+	union DL_primitives	*dlp;
+	ssize_t			len = MBLKL(mp);
 
 	switch (DB_TYPE(mp)) {
 	case M_PROTO:
 	case M_PCPROTO:
-		softmac_rput_process_proto(rq, mp);
-		break;
+		/*
+		 * If this is a shared-lower-stream, pass it to softmac to
+		 * process.
+		 */
+		if (sup == NULL) {
+			softmac_rput_process_proto(rq, mp);
+			break;
+		}
 
+		/*
+		 * Dedicated-lower-stream.
+		 */
+		dlp = (union DL_primitives *)mp->b_rptr;
+		ASSERT(len >= sizeof (dlp->dl_primitive));
+		switch (dlp->dl_primitive) {
+		case DL_OK_ACK:
+			if (len < DL_OK_ACK_SIZE)
+				goto runt;
+
+			/*
+			 * If this is a DL_OK_ACK for a DL_UNBIND_REQ, pass it
+			 * to softmac to process, otherwise directly pass it to
+			 * the upper stream.
+			 */
+			if (dlp->ok_ack.dl_correct_primitive == DL_UNBIND_REQ) {
+				softmac_rput_process_proto(rq, mp);
+				break;
+			}
+
+			putnext(sup->su_rq, mp);
+			break;
+		case DL_ERROR_ACK:
+			if (len < DL_ERROR_ACK_SIZE)
+				goto runt;
+
+			/*
+			 * If this is a DL_ERROR_ACK for a DL_UNBIND_REQ, pass
+			 * it to softmac to process, otherwise directly pass it
+			 * to the upper stream.
+			 */
+			if (dlp->error_ack.dl_error_primitive ==
+			    DL_UNBIND_REQ) {
+				softmac_rput_process_proto(rq, mp);
+				break;
+			}
+
+			putnext(sup->su_rq, mp);
+			break;
+		case DL_BIND_ACK:
+		case DL_CAPABILITY_ACK:
+			softmac_rput_process_proto(rq, mp);
+			break;
+		default:
+			putnext(sup->su_rq, mp);
+			break;
+		}
+		break;
 	case M_FLUSH:
 		if (*mp->b_rptr & FLUSHR)
 			flushq(rq, FLUSHDATA);
@@ -447,6 +522,11 @@ softmac_rput_process_notdata(queue_t *rq, mblk_t *mp)
 	case M_IOCNAK:
 	case M_COPYIN:
 	case M_COPYOUT:
+		if (sup != NULL) {
+			putnext(sup->su_rq, mp);
+			break;
+		}
+
 		mutex_enter(&slp->sl_mutex);
 		if (!slp->sl_pending_ioctl) {
 			mutex_exit(&slp->sl_mutex);
@@ -460,7 +540,7 @@ softmac_rput_process_notdata(queue_t *rq, mblk_t *mp)
 		slp->sl_ack_mp = mp;
 		cv_broadcast(&slp->sl_cv);
 		mutex_exit(&slp->sl_mutex);
-		return;
+		break;
 
 	default:
 		cmn_err(CE_NOTE, "softmac: got unsupported mblk type 0x%x",
@@ -468,4 +548,8 @@ softmac_rput_process_notdata(queue_t *rq, mblk_t *mp)
 		freemsg(mp);
 		break;
 	}
+	return;
+runt:
+	cmn_err(CE_WARN, "softmac: got runt %s", dl_primstr(dlp->dl_primitive));
+	freemsg(mp);
 }
diff --git a/usr/src/uts/common/io/softmac/softmac_dev.c b/usr/src/uts/common/io/softmac/softmac_dev.c
index f548df055d..37c5740846 100644
--- a/usr/src/uts/common/io/softmac/softmac_dev.c
+++ b/usr/src/uts/common/io/softmac/softmac_dev.c
@@ -19,28 +19,45 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
 
 #include <sys/types.h>
-#include <sys/dld.h>
 #include <inet/common.h>
 #include <sys/stropts.h>
 #include <sys/modctl.h>
-#include <sys/avl.h>
+#include <sys/dld.h>
 #include <sys/softmac_impl.h>
-#include <sys/softmac.h>
 
 dev_info_t		*softmac_dip = NULL;
+static kmem_cache_t	*softmac_upper_cachep;
+
+/*
+ * This function is a generic open(9E) entry point into the softmac for
+ * both the softmac module and the softmac driver.
+ */
+static int softmac_cmn_open(queue_t *, dev_t *, int, int, cred_t *);
+
+/*
+ * The following softmac_mod_xxx() functions are (9E) entry point functions for
+ * the softmac module.
+ */
+static int softmac_mod_close(queue_t *);
+static void softmac_mod_rput(queue_t *, mblk_t *);
+static void softmac_mod_wput(queue_t *, mblk_t *);
+static void softmac_mod_wsrv(queue_t *);
+
+/*
+ * The following softmac_drv_xxx() functions are (9E) entry point functions for
+ * the softmac driver.
+ */
+static int softmac_drv_open(queue_t *, dev_t *, int, int, cred_t *);
+static int softmac_drv_close(queue_t *);
+static void softmac_drv_wput(queue_t *, mblk_t *);
+static void softmac_drv_wsrv(queue_t *);
 
-static int softmac_open(queue_t *, dev_t *, int, int, cred_t *);
-static int softmac_close(queue_t *);
-static void softmac_rput(queue_t *, mblk_t *);
-static void softmac_rsrv(queue_t *);
-static void softmac_wput(queue_t *, mblk_t *);
-static void softmac_wsrv(queue_t *);
 static int softmac_attach(dev_info_t *, ddi_attach_cmd_t);
 static int softmac_detach(dev_info_t *, ddi_detach_cmd_t);
 static int softmac_info(dev_info_t *, ddi_info_cmd_t, void *, void **);
@@ -68,21 +85,21 @@ static struct module_info softmac_dld_modinfo = {
 };
 
 static struct qinit softmac_urinit = {
-	(pfi_t)softmac_rput,	/* qi_putp */
-	(pfi_t)softmac_rsrv,	/* qi_srvp */
-	softmac_open,		/* qi_qopen */
-	softmac_close,		/* qi_qclose */
-	NULL,			/* qi_qadmin */
-	&softmac_modinfo	/* qi_minfo */
+	(pfi_t)softmac_mod_rput,	/* qi_putp */
+	(pfi_t)NULL,			/* qi_srvp */
+	softmac_cmn_open,		/* qi_qopen */
+	softmac_mod_close,		/* qi_qclose */
+	NULL,				/* qi_qadmin */
+	&softmac_modinfo		/* qi_minfo */
 };
 
 static struct qinit softmac_uwinit = {
-	(pfi_t)softmac_wput,	/* qi_putp */
-	(pfi_t)softmac_wsrv,	/* qi_srvp */
-	NULL,			/* qi_qopen */
-	NULL,			/* qi_qclose */
-	NULL,			/* qi_qadmin */
-	&softmac_modinfo	/* qi_minfo */
+	(pfi_t)softmac_mod_wput,	/* qi_putp */
+	(pfi_t)softmac_mod_wsrv,	/* qi_srvp */
+	NULL,				/* qi_qopen */
+	NULL,				/* qi_qclose */
+	NULL,				/* qi_qadmin */
+	&softmac_modinfo		/* qi_minfo */
 };
 
 static struct streamtab softmac_tab = {
@@ -95,11 +112,12 @@ DDI_DEFINE_STREAM_OPS(softmac_ops, nulldev, nulldev, softmac_attach,
     ddi_quiesce_not_supported);
 
 static struct qinit softmac_dld_r_qinit = {
-	NULL, NULL, dld_open, dld_close, NULL, &softmac_dld_modinfo
+	NULL, NULL, softmac_drv_open, softmac_drv_close, NULL,
+	&softmac_dld_modinfo
 };
 
 static struct qinit softmac_dld_w_qinit = {
-	(pfi_t)dld_wput, (pfi_t)dld_wsrv, NULL, NULL, NULL,
+	(pfi_t)softmac_drv_wput, (pfi_t)softmac_drv_wsrv, NULL, NULL, NULL,
 	&softmac_dld_modinfo
 };
 
@@ -128,6 +146,49 @@ static struct modlinkage softmac_modlinkage = {
 	NULL
 };
 
+/*ARGSUSED*/
+static int
+softmac_upper_constructor(void *buf, void *arg, int kmflag)
+{
+	softmac_upper_t	*sup = buf;
+
+	bzero(buf, sizeof (softmac_upper_t));
+
+	mutex_init(&sup->su_mutex, NULL, MUTEX_DEFAULT, NULL);
+	cv_init(&sup->su_cv, NULL, CV_DEFAULT, NULL);
+	mutex_init(&sup->su_disp_mutex, NULL, MUTEX_DEFAULT, NULL);
+	cv_init(&sup->su_disp_cv, NULL, CV_DEFAULT, NULL);
+	list_create(&sup->su_req_list, sizeof (softmac_switch_req_t),
+	    offsetof(softmac_switch_req_t, ssq_req_list_node));
+	return (0);
+}
+
+/*ARGSUSED*/
+static void
+softmac_upper_destructor(void *buf, void *arg)
+{
+	softmac_upper_t	*sup = buf;
+
+	ASSERT(sup->su_slp == NULL);
+	ASSERT(sup->su_pending_head == NULL && sup->su_pending_tail == NULL);
+	ASSERT(!sup->su_dlpi_pending);
+	ASSERT(!sup->su_active);
+	ASSERT(!sup->su_closing);
+	ASSERT(sup->su_tx_flow_mp == NULL);
+	ASSERT(sup->su_tx_inprocess == 0);
+	ASSERT(sup->su_mode == SOFTMAC_UNKNOWN);
+	ASSERT(!sup->su_tx_busy);
+	ASSERT(!sup->su_bound);
+	ASSERT(!sup->su_taskq_scheduled);
+	ASSERT(list_is_empty(&sup->su_req_list));
+
+	list_destroy(&sup->su_req_list);
+	mutex_destroy(&sup->su_mutex);
+	cv_destroy(&sup->su_cv);
+	mutex_destroy(&sup->su_disp_mutex);
+	cv_destroy(&sup->su_disp_cv);
+}
+
 int
 _init(void)
 {
@@ -135,6 +196,11 @@ _init(void)
 
 	softmac_init();
 
+	softmac_upper_cachep = kmem_cache_create("softmac_upper_cache",
+	    sizeof (softmac_upper_t), 0, softmac_upper_constructor,
+	    softmac_upper_destructor, NULL, NULL, NULL, 0);
+	ASSERT(softmac_upper_cachep != NULL);
+
 	if ((err = mod_install(&softmac_modlinkage)) != 0) {
 		softmac_fini();
 		return (err);
@@ -154,6 +220,7 @@ _fini(void)
 	if ((err = mod_remove(&softmac_modlinkage)) != 0)
 		return (err);
 
+	kmem_cache_destroy(softmac_upper_cachep);
 	softmac_fini();
 
 	return (0);
@@ -166,7 +233,7 @@ _info(struct modinfo *modinfop)
 }
 
 static int
-softmac_open(queue_t *rq, dev_t *devp, int flag, int sflag, cred_t *credp)
+softmac_cmn_open(queue_t *rq, dev_t *devp, int flag, int sflag, cred_t *credp)
 {
 	softmac_lower_t	*slp;
 	/*
@@ -198,16 +265,15 @@ softmac_open(queue_t *rq, dev_t *devp, int flag, int sflag, cred_t *credp)
 	/*
 	 * Regular device open of a softmac DLPI node.  We modify
 	 * the queues' q_qinfo pointer such that all future STREAMS
-	 * operations will go through dld's entry points (including
-	 * dld_close()).
+	 * operations will go through another set of entry points
 	 */
 	rq->q_qinfo = &softmac_dld_r_qinit;
 	WR(rq)->q_qinfo = &softmac_dld_w_qinit;
-	return (dld_open(rq, devp, flag, sflag, credp));
+	return (softmac_drv_open(rq, devp, flag, sflag, credp));
 }
 
 static int
-softmac_close(queue_t *rq)
+softmac_mod_close(queue_t *rq)
 {
 	softmac_lower_t	*slp = rq->q_ptr;
 
@@ -237,10 +303,11 @@ softmac_close(queue_t *rq)
 }
 
 static void
-softmac_rput(queue_t *rq, mblk_t *mp)
+softmac_mod_rput(queue_t *rq, mblk_t *mp)
 {
-	softmac_lower_t *slp = rq->q_ptr;
-	union DL_primitives *dlp;
+	softmac_lower_t		*slp = rq->q_ptr;
+	softmac_lower_rxinfo_t	*rxinfo;
+	union DL_primitives	*dlp;
 
 	/*
 	 * This is the softmac module.
@@ -249,11 +316,21 @@ softmac_rput(queue_t *rq, mblk_t *mp)
 	ASSERT((mp->b_next == NULL) && (mp->b_prev == NULL));
 
 	switch (DB_TYPE(mp)) {
-	case M_DATA:
+	case M_DATA: {
+
+		/*
+		 * If sl_rxinfo is non-NULL. This is dedicated-lower-stream
+		 * created for fastpath. Directly call the rx callback.
+		 */
+		if ((rxinfo = slp->sl_rxinfo) != NULL) {
+			rxinfo->slr_rx(rxinfo->slr_arg, NULL, mp, NULL);
+			break;
+		}
+
 		/*
-		 * Some drivers start to send up packets even if not in the
-		 * DL_IDLE state, where sl_softmac is not set yet.  Drop the
-		 * packet in this case.
+		 * A shared-lower-stream. Some driver starts to send up
+		 * packets even it not in the DL_IDLE state, where
+		 * sl_softmac is not set yet. Drop the packet in this case.
 		 */
 		if (slp->sl_softmac == NULL) {
 			freemsg(mp);
@@ -275,18 +352,13 @@ softmac_rput(queue_t *rq, mblk_t *mp)
 		 */
 		if (DB_REF(mp) == 1) {
 			ASSERT(slp->sl_softmac != NULL);
-			/*
-			 * We don't need any locks to protect sl_handle
-			 * because ip_input() can tolerate if sl_handle
-			 * is reset to NULL when DL_CAPAB_POLL is
-			 * disabled.
-			 */
 			mac_rx(slp->sl_softmac->smac_mh, NULL, mp);
 			return;
 		} else {
 			softmac_rput_process_data(slp, mp);
 		}
 		break;
+	}
 	case M_PROTO:
 	case M_PCPROTO:
 		if (MBLKL(mp) < sizeof (dlp->dl_primitive)) {
@@ -295,6 +367,12 @@ softmac_rput(queue_t *rq, mblk_t *mp)
 		}
 		dlp = (union DL_primitives *)mp->b_rptr;
 		if (dlp->dl_primitive == DL_UNITDATA_IND) {
+
+			if ((rxinfo = slp->sl_rxinfo) != NULL) {
+				rxinfo->slr_rx(rxinfo->slr_arg, NULL, mp, NULL);
+				break;
+			}
+
 			cmn_err(CE_WARN, "got unexpected %s message",
 			    dl_primstr(DL_UNITDATA_IND));
 			freemsg(mp);
@@ -302,19 +380,13 @@ softmac_rput(queue_t *rq, mblk_t *mp)
 		}
 		/*FALLTHROUGH*/
 	default:
-		softmac_rput_process_notdata(rq, mp);
+		softmac_rput_process_notdata(rq, slp->sl_sup, mp);
 		break;
 	}
 }
 
-/* ARGSUSED */
-static void
-softmac_rsrv(queue_t *rq)
-{
-}
-
 static void
-softmac_wput(queue_t *wq, mblk_t *mp)
+softmac_mod_wput(queue_t *wq, mblk_t *mp)
 {
 	/*
 	 * This is the softmac module
@@ -342,7 +414,6 @@ softmac_wput(queue_t *wq, mblk_t *mp)
 			 */
 			arg = (smac_ioc_start_t *)mp->b_cont->b_rptr;
 			arg->si_slp = slp;
-
 			miocack(wq, mp, sizeof (*arg), 0);
 			break;
 		}
@@ -359,7 +430,7 @@ softmac_wput(queue_t *wq, mblk_t *mp)
 }
 
 static void
-softmac_wsrv(queue_t *wq)
+softmac_mod_wsrv(queue_t *wq)
 {
 	softmac_lower_t *slp = wq->q_ptr;
 
@@ -372,7 +443,9 @@ softmac_wsrv(queue_t *wq)
 	 * Inform that the tx resource is available; mac_tx_update() will
 	 * inform all the upper streams sharing this lower stream.
 	 */
-	if (slp->sl_softmac != NULL)
+	if (slp->sl_sup != NULL)
+		qenable(slp->sl_sup->su_wq);
+	else if (slp->sl_softmac != NULL)
 		mac_tx_update(slp->sl_softmac->smac_mh);
 }
 
@@ -420,3 +493,179 @@ softmac_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
 
 	return (DDI_FAILURE);
 }
+
+/*ARGSUSED*/
+static void
+softmac_dedicated_rx(void *arg, mac_resource_handle_t mrh, mblk_t *mp,
+    mac_header_info_t *mhip)
+{
+	queue_t *rq = ((softmac_upper_t *)arg)->su_rq;
+
+	if (canputnext(rq))
+		putnext(rq, mp);
+	else
+		freemsg(mp);
+}
+
+/*ARGSUSED*/
+static int
+softmac_drv_open(queue_t *rq, dev_t *devp, int flag, int sflag, cred_t *credp)
+{
+	softmac_upper_t	*sup = NULL;
+	softmac_t	*softmac;
+	int		err = 0;
+
+	/*
+	 * This is a softmac device created for a legacy device, find the
+	 * associated softmac and initialize the softmac_upper_t structure.
+	 */
+	if ((err = softmac_hold(*devp, &softmac)) != 0)
+		return (err);
+
+	sup = kmem_cache_alloc(softmac_upper_cachep, KM_NOSLEEP);
+	if (sup == NULL) {
+		err = ENOMEM;
+		goto fail;
+	}
+
+	ASSERT(list_is_empty(&sup->su_req_list));
+
+	if ((sup->su_tx_flow_mp = allocb(1, BPRI_HI)) == NULL) {
+		err = ENOMEM;
+		goto fail;
+	}
+
+	sup->su_rq = rq;
+	sup->su_wq = WR(rq);
+	sup->su_softmac = softmac;
+	sup->su_mode = SOFTMAC_UNKNOWN;
+
+	sup->su_rxinfo.slr_arg = sup;
+	sup->su_rxinfo.slr_rx = softmac_dedicated_rx;
+	sup->su_direct_rxinfo.slr_arg = sup;
+	sup->su_direct_rxinfo.slr_rx = softmac_dedicated_rx;
+
+	if ((err = dld_str_open(rq, devp, sup)) != 0) {
+		freeb(sup->su_tx_flow_mp);
+		sup->su_tx_flow_mp = NULL;
+		goto fail;
+	}
+
+	return (0);
+
+fail:
+	if (sup != NULL)
+		kmem_cache_free(softmac_upper_cachep, sup);
+	softmac_rele(softmac);
+	return (err);
+}
+
+static int
+softmac_drv_close(queue_t *rq)
+{
+	softmac_upper_t	*sup = dld_str_private(rq);
+	softmac_t	*softmac = sup->su_softmac;
+
+	ASSERT(WR(rq)->q_next == NULL);
+
+	qprocsoff(rq);
+
+	ASSERT(sup->su_tx_inprocess == 0);
+
+	/*
+	 * Wait until the pending request are processed by the worker thread.
+	 */
+	mutex_enter(&sup->su_disp_mutex);
+	sup->su_closing = B_TRUE;
+	while (sup->su_dlpi_pending)
+		cv_wait(&sup->su_disp_cv, &sup->su_disp_mutex);
+	mutex_exit(&sup->su_disp_mutex);
+
+	softmac_upperstream_close(sup);
+
+	if (sup->su_tx_flow_mp != NULL) {
+		freeb(sup->su_tx_flow_mp);
+		sup->su_tx_flow_mp = NULL;
+	}
+
+	if (sup->su_active) {
+		mutex_enter(&softmac->smac_active_mutex);
+		softmac->smac_nactive--;
+		mutex_exit(&softmac->smac_active_mutex);
+		sup->su_active = B_FALSE;
+	}
+
+	sup->su_bound = B_FALSE;
+	sup->su_softmac = NULL;
+	sup->su_closing = B_FALSE;
+
+	kmem_cache_free(softmac_upper_cachep, sup);
+
+	softmac_rele(softmac);
+	return (dld_str_close(rq));
+}
+
+static void
+softmac_drv_wput(queue_t *wq, mblk_t *mp)
+{
+	softmac_upper_t	*sup = dld_str_private(wq);
+	t_uscalar_t	prim;
+
+	ASSERT(wq->q_next == NULL);
+
+	switch (DB_TYPE(mp)) {
+	case M_DATA:
+	case M_MULTIDATA:
+		softmac_wput_data(sup, mp);
+		break;
+	case M_PROTO:
+	case M_PCPROTO:
+
+		if (MBLKL(mp) < sizeof (t_uscalar_t)) {
+			freemsg(mp);
+			return;
+		}
+
+		prim = ((union DL_primitives *)mp->b_rptr)->dl_primitive;
+		if (prim == DL_UNITDATA_REQ) {
+			softmac_wput_data(sup, mp);
+			return;
+		}
+
+		softmac_wput_nondata(sup, mp);
+		break;
+	default:
+		softmac_wput_nondata(sup, mp);
+		break;
+	}
+}
+
+static void
+softmac_drv_wsrv(queue_t *wq)
+{
+	softmac_upper_t	*sup = dld_str_private(wq);
+
+	ASSERT(wq->q_next == NULL);
+
+	mutex_enter(&sup->su_mutex);
+	if (sup->su_mode != SOFTMAC_FASTPATH) {
+		/*
+		 * Bump su_tx_inprocess so that su_mode won't change.
+		 */
+		sup->su_tx_inprocess++;
+		mutex_exit(&sup->su_mutex);
+		dld_wsrv(wq);
+		mutex_enter(&sup->su_mutex);
+		if (--sup->su_tx_inprocess == 0)
+			cv_signal(&sup->su_cv);
+	} else if (sup->su_tx_busy && SOFTMAC_CANPUTNEXT(sup->su_slp->sl_wq)) {
+		/*
+		 * The flow-conctol of the dedicated-lower-stream is
+		 * relieved, relieve the flow-control of the
+		 * upper-stream too.
+		 */
+		sup->su_tx_flow_mp = getq(wq);
+		sup->su_tx_busy = B_FALSE;
+	}
+	mutex_exit(&sup->su_mutex);
+}
diff --git a/usr/src/uts/common/io/softmac/softmac_fp.c b/usr/src/uts/common/io/softmac/softmac_fp.c
new file mode 100644
index 0000000000..a012aa32a4
--- /dev/null
+++ b/usr/src/uts/common/io/softmac/softmac_fp.c
@@ -0,0 +1,1252 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+/*
+ * Softmac data-path switching:
+ *
+ * - Fast-path model
+ *
+ * When the softmac fast-path is used, a dedicated lower-stream
+ * will be opened over the legacy device for each IP/ARP (upper-)stream
+ * over the softMAC, and all DLPI messages (including control messages
+ * and data messages) will be exchanged between the upper-stream and
+ * the corresponding lower-stream directly. Therefore, the data
+ * demultiplexing, filtering and classification processing will be done
+ * by the lower-stream, and the GLDv3 DLS/MAC layer processing will be
+ * no longer needed.
+ *
+ * - Slow-path model
+ *
+ * Some GLDv3 features requires the GLDv3 DLS/MAC layer processing to
+ * not be bypassed to assure its function correctness. For example,
+ * softmac fast-path must be disabled to support GLDv3 VNIC functionality.
+ * In this case, a shared lower-stream will be opened over the legacy
+ * device, which is responsible for implementing the GLDv3 callbacks
+ * and passing RAW data messages between the legacy devices and the GLDv3
+ * framework.
+ *
+ * By default, the softmac fast-path mode will be used to assure the
+ * performance; MAC clients will be able to request to disable the softmac
+ * fast-path mode to support certain features, and if that succeeds,
+ * the system will fallback to the slow-path softmac data-path model.
+ *
+ *
+ * The details of the softmac data fast-path model is stated as below
+ *
+ * 1. When a stream is opened on a softMAC, the softmac module will takes
+ *    over the DLPI processing on this stream;
+ *
+ * 2. For IP/ARP streams over a softMAC, softmac data fast-path will be
+ *    used by default, unless fast-path is disabled by any MAC client
+ *    explicitly. The softmac module first identifies an IP/ARP stream
+ *    by seeing whether there is a SIOCSLIFNAME ioctl sent from upstream,
+ *    if there is one, this stream is either an IP or an ARP stream
+ *    and will use fast-path potentially;
+ *
+ * 3. When the softmac fast-path is used, an dedicated lower-stream will
+ *    be setup for each IP/ARP stream (1-1 mapping). From that point on,
+ *    all control and data messages will be exchanged between the IP/ARP
+ *    upper-stream and the legacy device through this dedicated
+ *    lower-stream. As a result, the DLS/MAC layer processing in GLDv3
+ *    will be skipped, and this greatly improves the performance;
+ *
+ * 4. When the softmac data fast-path is disabled by a MAC client (e.g.,
+ *    by a VNIC), all the IP/ARP upper streams will try to switch from
+ *    the fast-path to the slow-path. The dedicated lower-stream will be
+ *    destroyed, and all the control and data-messages will go through the
+ *    existing GLDv3 code path and (in the end) the shared lower-stream;
+ *
+ * 5. On the other hand, when the last MAC client cancels its fast-path
+ *    disable request, all the IP/ARP streams will try to switch back to
+ *    the fast-path mode;
+ *
+ * Step 5 and 6 both rely on the data-path mode switching process
+ * described below:
+ *
+ * 1) To switch the softmac data-path mode (between fast-path and slow-path),
+ *    softmac will first send a DL_NOTE_REPLUMB DL_NOTIFY_IND message
+ *    upstream over each IP/ARP streams that needs data-path mode switching;
+ *
+ * 2) When IP receives this DL_NOTE_REPLUMB message, it will bring down
+ *    all the IP interfaces on the corresponding ill (IP Lower level
+ *    structure), and bring up those interfaces over again; this will in
+ *    turn cause the ARP to "replumb" the interface.
+ *
+ *    During the replumb process, both IP and ARP will send downstream the
+ *    necessary DL_DISABMULTI_REQ and DL_UNBIND_REQ messages and cleanup
+ *    the old state of the underlying softMAC, following with the necessary
+ *    DL_BIND_REQ and DL_ENABMULTI_REQ messages to setup the new state.
+ *    Between the cleanup and re-setup process, IP/ARP will also send down
+ *    a DL_NOTE_REPLUMB_DONE DL_NOTIFY_CONF messages to the softMAC to
+ *    indicate the *switching point*;
+ *
+ * 3) When softmac receives the DL_NOTE_REPLUMB_DONE message, it either
+ *    creates or destroys the dedicated lower-stream (depending on which
+ *    data-path mode the softMAC switches to), and change the softmac
+ *    data-path mode. From then on, softmac will process all the succeeding
+ *    control messages (including the DL_BIND_REQ and DL_ENABMULTI_REQ
+ *    messages) and data messages based on new data-path mode.
+ */
+
+#include <sys/types.h>
+#include <sys/disp.h>
+#include <sys/callb.h>
+#include <sys/sysmacros.h>
+#include <sys/file.h>
+#include <sys/vlan.h>
+#include <sys/dld.h>
+#include <sys/sockio.h>
+#include <sys/softmac_impl.h>
+
+static kmutex_t		softmac_taskq_lock;
+static kcondvar_t	softmac_taskq_cv;
+static list_t		softmac_taskq_list;	/* List of softmac_upper_t */
+boolean_t		softmac_taskq_quit;
+boolean_t		softmac_taskq_done;
+
+static void		softmac_taskq_dispatch();
+static int		softmac_fastpath_setup(softmac_upper_t *);
+static mac_tx_cookie_t	softmac_fastpath_wput_data(softmac_upper_t *, mblk_t *,
+			    uintptr_t, uint16_t);
+static void		softmac_datapath_switch_done(softmac_upper_t *);
+
+void
+softmac_fp_init()
+{
+	mutex_init(&softmac_taskq_lock, NULL, MUTEX_DRIVER, NULL);
+	cv_init(&softmac_taskq_cv, NULL, CV_DRIVER, NULL);
+
+	softmac_taskq_quit = B_FALSE;
+	softmac_taskq_done = B_FALSE;
+	list_create(&softmac_taskq_list, sizeof (softmac_upper_t),
+	    offsetof(softmac_upper_t, su_taskq_list_node));
+	(void) thread_create(NULL, 0, softmac_taskq_dispatch, NULL, 0,
+	    &p0, TS_RUN, minclsyspri);
+}
+
+void
+softmac_fp_fini()
+{
+	/*
+	 * Request the softmac_taskq thread to quit and wait for it to be done.
+	 */
+	mutex_enter(&softmac_taskq_lock);
+	softmac_taskq_quit = B_TRUE;
+	cv_signal(&softmac_taskq_cv);
+	while (!softmac_taskq_done)
+		cv_wait(&softmac_taskq_cv, &softmac_taskq_lock);
+	mutex_exit(&softmac_taskq_lock);
+	list_destroy(&softmac_taskq_list);
+
+	mutex_destroy(&softmac_taskq_lock);
+	cv_destroy(&softmac_taskq_cv);
+}
+
+static boolean_t
+check_ip_above(queue_t *q)
+{
+	queue_t		*next_q;
+	boolean_t	ret = B_TRUE;
+
+	claimstr(q);
+	next_q = q->q_next;
+	if (strcmp(next_q->q_qinfo->qi_minfo->mi_idname, "ip") != 0)
+		ret = B_FALSE;
+	releasestr(q);
+	return (ret);
+}
+
+/* ARGSUSED */
+static int
+softmac_capab_perim(softmac_upper_t *sup, void *data, uint_t flags)
+{
+	switch (flags) {
+	case DLD_ENABLE:
+		mutex_enter(&sup->su_mutex);
+		break;
+	case DLD_DISABLE:
+		mutex_exit(&sup->su_mutex);
+		break;
+	case DLD_QUERY:
+		return (MUTEX_HELD(&sup->su_mutex));
+	}
+	return (0);
+}
+
+/* ARGSUSED */
+static mac_tx_notify_handle_t
+softmac_client_tx_notify(void *txcb, mac_tx_notify_t func, void *arg)
+{
+	return (NULL);
+}
+
+static int
+softmac_capab_direct(softmac_upper_t *sup, void *data, uint_t flags)
+{
+	dld_capab_direct_t	*direct = data;
+	softmac_lower_t		*slp = sup->su_slp;
+
+	ASSERT(MUTEX_HELD(&sup->su_mutex));
+
+	ASSERT(sup->su_mode == SOFTMAC_FASTPATH);
+
+	switch (flags) {
+	case DLD_ENABLE:
+		if (sup->su_direct)
+			return (0);
+
+		sup->su_direct_rxinfo.slr_rx = (softmac_rx_t)direct->di_rx_cf;
+		sup->su_direct_rxinfo.slr_arg = direct->di_rx_ch;
+		slp->sl_rxinfo = &sup->su_direct_rxinfo;
+		direct->di_tx_df = (uintptr_t)softmac_fastpath_wput_data;
+		direct->di_tx_dh = sup;
+
+		/*
+		 * We relying on the STREAM flow-control to backenable
+		 * the IP stream. Therefore, no notify callback needs to
+		 * be registered. But IP requires this to be a valid function
+		 * pointer.
+		 */
+		direct->di_tx_cb_df = (uintptr_t)softmac_client_tx_notify;
+		direct->di_tx_cb_dh = NULL;
+		sup->su_direct = B_TRUE;
+		return (0);
+
+	case DLD_DISABLE:
+		if (!sup->su_direct)
+			return (0);
+
+		slp->sl_rxinfo = &sup->su_rxinfo;
+		sup->su_direct = B_FALSE;
+		return (0);
+	}
+	return (ENOTSUP);
+}
+
+static int
+softmac_dld_capab(softmac_upper_t *sup, uint_t type, void *data, uint_t flags)
+{
+	int	err;
+
+	/*
+	 * Don't enable direct callback capabilities unless the caller is
+	 * the IP client. When a module is inserted in a stream (_I_INSERT)
+	 * the stack initiates capability disable, but due to races, the
+	 * module insertion may complete before the capability disable
+	 * completes. So we limit the check to DLD_ENABLE case.
+	 */
+	if ((flags == DLD_ENABLE && type != DLD_CAPAB_PERIM) &&
+	    !check_ip_above(sup->su_rq)) {
+		return (ENOTSUP);
+	}
+
+	switch (type) {
+	case DLD_CAPAB_DIRECT:
+		err = softmac_capab_direct(sup, data, flags);
+		break;
+
+	case DLD_CAPAB_PERIM:
+		err = softmac_capab_perim(sup, data, flags);
+		break;
+
+	default:
+		err = ENOTSUP;
+		break;
+	}
+	return (err);
+}
+
+static void
+softmac_capability_advertise(softmac_upper_t *sup, mblk_t *mp)
+{
+	dl_capability_ack_t	*dlap;
+	dl_capability_sub_t	*dlsp;
+	t_uscalar_t		subsize;
+	uint8_t			*ptr;
+	queue_t			*q = sup->su_wq;
+	mblk_t			*mp1;
+	softmac_t		*softmac = sup->su_softmac;
+	boolean_t		dld_capable = B_FALSE;
+	boolean_t		hcksum_capable = B_FALSE;
+	boolean_t		zcopy_capable = B_FALSE;
+	boolean_t		mdt_capable = B_FALSE;
+
+	ASSERT(sup->su_mode == SOFTMAC_FASTPATH);
+
+	/*
+	 * Initially assume no capabilities.
+	 */
+	subsize = 0;
+
+	/*
+	 * Direct capability negotiation interface between IP and softmac
+	 */
+	if (check_ip_above(sup->su_rq)) {
+		dld_capable = B_TRUE;
+		subsize += sizeof (dl_capability_sub_t) +
+		    sizeof (dl_capab_dld_t);
+	}
+
+	/*
+	 * Check if checksum offload is supported on this MAC.
+	 */
+	if (softmac->smac_capab_flags & MAC_CAPAB_HCKSUM) {
+		hcksum_capable = B_TRUE;
+		subsize += sizeof (dl_capability_sub_t) +
+		    sizeof (dl_capab_hcksum_t);
+	}
+
+	/*
+	 * Check if zerocopy is supported on this interface.
+	 */
+	if (!(softmac->smac_capab_flags & MAC_CAPAB_NO_ZCOPY)) {
+		zcopy_capable = B_TRUE;
+		subsize += sizeof (dl_capability_sub_t) +
+		    sizeof (dl_capab_zerocopy_t);
+	}
+
+	if (softmac->smac_mdt) {
+		mdt_capable = B_TRUE;
+		subsize += sizeof (dl_capability_sub_t) +
+		    sizeof (dl_capab_mdt_t);
+	}
+
+	/*
+	 * If there are no capabilities to advertise or if we
+	 * can't allocate a response, send a DL_ERROR_ACK.
+	 */
+	if ((subsize == 0) || (mp1 = reallocb(mp,
+	    sizeof (dl_capability_ack_t) + subsize, 0)) == NULL) {
+		dlerrorack(q, mp, DL_CAPABILITY_REQ, DL_NOTSUPPORTED, 0);
+		return;
+	}
+
+	mp = mp1;
+	DB_TYPE(mp) = M_PROTO;
+	mp->b_wptr = mp->b_rptr + sizeof (dl_capability_ack_t) + subsize;
+	bzero(mp->b_rptr, MBLKL(mp));
+	dlap = (dl_capability_ack_t *)mp->b_rptr;
+	dlap->dl_primitive = DL_CAPABILITY_ACK;
+	dlap->dl_sub_offset = sizeof (dl_capability_ack_t);
+	dlap->dl_sub_length = subsize;
+	ptr = (uint8_t *)&dlap[1];
+
+	/*
+	 * IP polling interface.
+	 */
+	if (dld_capable) {
+		dl_capab_dld_t		dld;
+
+		dlsp = (dl_capability_sub_t *)ptr;
+		dlsp->dl_cap = DL_CAPAB_DLD;
+		dlsp->dl_length = sizeof (dl_capab_dld_t);
+		ptr += sizeof (dl_capability_sub_t);
+
+		bzero(&dld, sizeof (dl_capab_dld_t));
+		dld.dld_version = DLD_CURRENT_VERSION;
+		dld.dld_capab = (uintptr_t)softmac_dld_capab;
+		dld.dld_capab_handle = (uintptr_t)sup;
+
+		dlcapabsetqid(&(dld.dld_mid), sup->su_rq);
+		bcopy(&dld, ptr, sizeof (dl_capab_dld_t));
+		ptr += sizeof (dl_capab_dld_t);
+	}
+
+	/*
+	 * TCP/IP checksum offload.
+	 */
+	if (hcksum_capable) {
+		dl_capab_hcksum_t	hcksum;
+
+		dlsp = (dl_capability_sub_t *)ptr;
+
+		dlsp->dl_cap = DL_CAPAB_HCKSUM;
+		dlsp->dl_length = sizeof (dl_capab_hcksum_t);
+		ptr += sizeof (dl_capability_sub_t);
+
+		bzero(&hcksum, sizeof (dl_capab_hcksum_t));
+		hcksum.hcksum_version = HCKSUM_VERSION_1;
+		hcksum.hcksum_txflags = softmac->smac_hcksum_txflags;
+		dlcapabsetqid(&(hcksum.hcksum_mid), sup->su_rq);
+		bcopy(&hcksum, ptr, sizeof (dl_capab_hcksum_t));
+		ptr += sizeof (dl_capab_hcksum_t);
+	}
+
+	/*
+	 * Zero copy
+	 */
+	if (zcopy_capable) {
+		dl_capab_zerocopy_t	zcopy;
+
+		dlsp = (dl_capability_sub_t *)ptr;
+
+		dlsp->dl_cap = DL_CAPAB_ZEROCOPY;
+		dlsp->dl_length = sizeof (dl_capab_zerocopy_t);
+		ptr += sizeof (dl_capability_sub_t);
+
+		bzero(&zcopy, sizeof (dl_capab_zerocopy_t));
+		zcopy.zerocopy_version = ZEROCOPY_VERSION_1;
+		zcopy.zerocopy_flags = DL_CAPAB_VMSAFE_MEM;
+		dlcapabsetqid(&(zcopy.zerocopy_mid), sup->su_rq);
+		bcopy(&zcopy, ptr, sizeof (dl_capab_zerocopy_t));
+		ptr += sizeof (dl_capab_zerocopy_t);
+	}
+
+	/*
+	 * MDT
+	 */
+	if (mdt_capable) {
+		dl_capab_mdt_t mdt;
+
+		dlsp = (dl_capability_sub_t *)ptr;
+
+		dlsp->dl_cap = DL_CAPAB_MDT;
+		dlsp->dl_length = sizeof (dl_capab_mdt_t);
+		ptr += sizeof (dl_capability_sub_t);
+
+		bzero(&mdt, sizeof (dl_capab_mdt_t));
+		mdt.mdt_version = MDT_VERSION_2;
+		mdt.mdt_flags = DL_CAPAB_MDT_ENABLE;
+		mdt.mdt_hdr_head = softmac->smac_mdt_capab.mdt_hdr_head;
+		mdt.mdt_hdr_tail = softmac->smac_mdt_capab.mdt_hdr_tail;
+		mdt.mdt_max_pld = softmac->smac_mdt_capab.mdt_max_pld;
+		mdt.mdt_span_limit = softmac->smac_mdt_capab.mdt_span_limit;
+		dlcapabsetqid(&(mdt.mdt_mid), sup->su_rq);
+		bcopy(&mdt, ptr, sizeof (dl_capab_mdt_t));
+		ptr += sizeof (dl_capab_mdt_t);
+	}
+
+	ASSERT(ptr == mp->b_rptr + sizeof (dl_capability_ack_t) + subsize);
+	qreply(q, mp);
+}
+
+static void
+softmac_capability_req(softmac_upper_t *sup, mblk_t *mp)
+{
+	dl_capability_req_t	*dlp = (dl_capability_req_t *)mp->b_rptr;
+	dl_capability_sub_t	*sp;
+	size_t			size, len;
+	offset_t		off, end;
+	t_uscalar_t		dl_err;
+	queue_t			*q = sup->su_wq;
+
+	ASSERT(sup->su_mode == SOFTMAC_FASTPATH);
+	if (MBLKL(mp) < sizeof (dl_capability_req_t)) {
+		dl_err = DL_BADPRIM;
+		goto failed;
+	}
+
+	if (!sup->su_bound) {
+		dl_err = DL_OUTSTATE;
+		goto failed;
+	}
+
+	/*
+	 * This request is overloaded. If there are no requested capabilities
+	 * then we just want to acknowledge with all the capabilities we
+	 * support. Otherwise we enable the set of capabilities requested.
+	 */
+	if (dlp->dl_sub_length == 0) {
+		softmac_capability_advertise(sup, mp);
+		return;
+	}
+
+	if (!MBLKIN(mp, dlp->dl_sub_offset, dlp->dl_sub_length)) {
+		dl_err = DL_BADPRIM;
+		goto failed;
+	}
+
+	dlp->dl_primitive = DL_CAPABILITY_ACK;
+
+	off = dlp->dl_sub_offset;
+	len = dlp->dl_sub_length;
+
+	/*
+	 * Walk the list of capabilities to be enabled.
+	 */
+	for (end = off + len; off < end; ) {
+		sp = (dl_capability_sub_t *)(mp->b_rptr + off);
+		size = sizeof (dl_capability_sub_t) + sp->dl_length;
+
+		if (off + size > end ||
+		    !IS_P2ALIGNED(off, sizeof (uint32_t))) {
+			dl_err = DL_BADPRIM;
+			goto failed;
+		}
+
+		switch (sp->dl_cap) {
+		/*
+		 * TCP/IP checksum offload to hardware.
+		 */
+		case DL_CAPAB_HCKSUM: {
+			dl_capab_hcksum_t *hcksump;
+			dl_capab_hcksum_t hcksum;
+
+			hcksump = (dl_capab_hcksum_t *)&sp[1];
+			/*
+			 * Copy for alignment.
+			 */
+			bcopy(hcksump, &hcksum, sizeof (dl_capab_hcksum_t));
+			dlcapabsetqid(&(hcksum.hcksum_mid), sup->su_rq);
+			bcopy(&hcksum, hcksump, sizeof (dl_capab_hcksum_t));
+			break;
+		}
+
+		default:
+			break;
+		}
+
+		off += size;
+	}
+	qreply(q, mp);
+	return;
+failed:
+	dlerrorack(q, mp, DL_CAPABILITY_REQ, dl_err, 0);
+}
+
+static void
+softmac_bind_req(softmac_upper_t *sup, mblk_t *mp)
+{
+	softmac_lower_t	*slp = sup->su_slp;
+	softmac_t	*softmac = sup->su_softmac;
+	mblk_t		*ackmp, *mp1;
+	int		err;
+
+	if (MBLKL(mp) < DL_BIND_REQ_SIZE) {
+		freemsg(mp);
+		return;
+	}
+
+	/*
+	 * Allocate ackmp incase the underlying driver does not ack timely.
+	 */
+	if ((mp1 = allocb(sizeof (dl_error_ack_t), BPRI_HI)) == NULL) {
+		dlerrorack(sup->su_wq, mp, DL_BIND_REQ, DL_SYSERR, ENOMEM);
+		return;
+	}
+
+	err = softmac_output(slp, mp, DL_BIND_REQ, DL_BIND_ACK, &ackmp);
+	if (ackmp != NULL) {
+		freemsg(mp1);
+	} else {
+		/*
+		 * The driver does not ack timely.
+		 */
+		ASSERT(err == ENOMSG);
+		ackmp = mp1;
+	}
+	if (err != 0)
+		goto failed;
+
+	/*
+	 * Enable capabilities the underlying driver claims to support.
+	 */
+	if ((err = softmac_capab_enable(slp)) != 0)
+		goto failed;
+
+	/*
+	 * Check whether this softmac is already marked as exclusively used,
+	 * e.g., an aggregation is created over it. Fail the BIND_REQ if so.
+	 */
+	mutex_enter(&softmac->smac_active_mutex);
+	if (softmac->smac_active) {
+		mutex_exit(&softmac->smac_active_mutex);
+		err = EBUSY;
+		goto failed;
+	}
+	softmac->smac_nactive++;
+	sup->su_active = B_TRUE;
+	mutex_exit(&softmac->smac_active_mutex);
+	sup->su_bound = B_TRUE;
+
+	qreply(sup->su_wq, ackmp);
+	return;
+failed:
+	if (err != 0) {
+		dlerrorack(sup->su_wq, ackmp, DL_BIND_REQ, DL_SYSERR, err);
+		return;
+	}
+}
+
+static void
+softmac_unbind_req(softmac_upper_t *sup, mblk_t *mp)
+{
+	softmac_lower_t	*slp = sup->su_slp;
+	softmac_t	*softmac = sup->su_softmac;
+	mblk_t		*ackmp, *mp1;
+	int		err;
+
+	if (MBLKL(mp) < DL_UNBIND_REQ_SIZE) {
+		freemsg(mp);
+		return;
+	}
+
+	if (!sup->su_bound) {
+		dlerrorack(sup->su_wq, mp, DL_UNBIND_REQ, DL_OUTSTATE, 0);
+		return;
+	}
+
+	/*
+	 * Allocate ackmp incase the underlying driver does not ack timely.
+	 */
+	if ((mp1 = allocb(sizeof (dl_error_ack_t), BPRI_HI)) == NULL) {
+		dlerrorack(sup->su_wq, mp, DL_UNBIND_REQ, DL_SYSERR, ENOMEM);
+		return;
+	}
+
+	err = softmac_output(slp, mp, DL_UNBIND_REQ, DL_OK_ACK, &ackmp);
+	if (ackmp != NULL) {
+		freemsg(mp1);
+	} else {
+		/*
+		 * The driver does not ack timely.
+		 */
+		ASSERT(err == ENOMSG);
+		ackmp = mp1;
+	}
+	if (err != 0) {
+		dlerrorack(sup->su_wq, ackmp, DL_UNBIND_REQ, DL_SYSERR, err);
+		return;
+	}
+
+	sup->su_bound = B_FALSE;
+
+	mutex_enter(&softmac->smac_active_mutex);
+	if (sup->su_active) {
+		ASSERT(!softmac->smac_active);
+		softmac->smac_nactive--;
+		sup->su_active = B_FALSE;
+	}
+	mutex_exit(&softmac->smac_active_mutex);
+
+done:
+	qreply(sup->su_wq, ackmp);
+}
+
+/*
+ * Process the non-data mblk.
+ */
+static void
+softmac_wput_single_nondata(softmac_upper_t *sup, mblk_t *mp)
+{
+	softmac_t *softmac = sup->su_softmac;
+	softmac_lower_t	*slp = sup->su_slp;
+	unsigned char	dbtype;
+	t_uscalar_t	prim;
+
+	dbtype = DB_TYPE(mp);
+	switch (dbtype) {
+	case M_IOCTL:
+	case M_CTL: {
+		uint32_t	expected_mode;
+
+		if (((struct iocblk *)(mp->b_rptr))->ioc_cmd != SIOCSLIFNAME)
+			break;
+
+		/*
+		 * Nak the M_IOCTL based on the STREAMS specification.
+		 */
+		if (dbtype == M_IOCTL)
+			miocnak(sup->su_wq, mp, 0, EINVAL);
+
+		/*
+		 * This stream is either IP or ARP. See whether
+		 * we need to setup a dedicated-lower-stream for it.
+		 */
+		mutex_enter(&softmac->smac_fp_mutex);
+
+		expected_mode = DATAPATH_MODE(softmac);
+		if (expected_mode == SOFTMAC_SLOWPATH)
+			sup->su_mode = SOFTMAC_SLOWPATH;
+		list_insert_head(&softmac->smac_sup_list, sup);
+		mutex_exit(&softmac->smac_fp_mutex);
+
+		/*
+		 * Setup the fast-path dedicated lower stream if fast-path
+		 * is expected. Note that no lock is held here, and if
+		 * smac_expected_mode is changed from SOFTMAC_FASTPATH to
+		 * SOFTMAC_SLOWPATH, the DL_NOTE_REPLUMB message used for
+		 * data-path switching would already be queued and will
+		 * be processed by softmac_wput_single_nondata() later.
+		 */
+		if (expected_mode == SOFTMAC_FASTPATH)
+			(void) softmac_fastpath_setup(sup);
+		return;
+	}
+	case M_PROTO:
+	case M_PCPROTO:
+		if (MBLKL(mp) < sizeof (t_uscalar_t)) {
+			freemsg(mp);
+			return;
+		}
+		prim = ((union DL_primitives *)mp->b_rptr)->dl_primitive;
+		switch (prim) {
+		case DL_NOTIFY_IND:
+			if (MBLKL(mp) < sizeof (dl_notify_ind_t) ||
+			    ((dl_notify_ind_t *)mp->b_rptr)->dl_notification !=
+			    DL_NOTE_REPLUMB) {
+				freemsg(mp);
+				return;
+			}
+			/*
+			 * This DL_NOTE_REPLUMB message is initiated
+			 * and queued by the softmac itself, when the
+			 * sup is trying to switching its datapath mode
+			 * between SOFTMAC_SLOWPATH and SOFTMAC_FASTPATH.
+			 * Send this message upstream.
+			 */
+			qreply(sup->su_wq, mp);
+			return;
+		case DL_NOTIFY_CONF:
+			if (MBLKL(mp) < sizeof (dl_notify_conf_t) ||
+			    ((dl_notify_conf_t *)mp->b_rptr)->dl_notification !=
+			    DL_NOTE_REPLUMB_DONE) {
+				freemsg(mp);
+				return;
+			}
+			/*
+			 * This is an indication from IP/ARP that the
+			 * fastpath->slowpath switch is done.
+			 */
+			freemsg(mp);
+			softmac_datapath_switch_done(sup);
+			return;
+		}
+		break;
+	}
+
+	/*
+	 * No need to hold lock to check su_mode, since su_mode updating only
+	 * operation is is serialized by softmac_wput_nondata_task().
+	 */
+	if (sup->su_mode != SOFTMAC_FASTPATH) {
+		dld_wput(sup->su_wq, mp);
+		return;
+	}
+
+	/*
+	 * Fastpath non-data message processing. Most of non-data messages
+	 * can be directly passed down to the dedicated-lower-stream, aside
+	 * from the following M_PROTO/M_PCPROTO messages.
+	 */
+	switch (dbtype) {
+	case M_PROTO:
+	case M_PCPROTO:
+		switch (prim) {
+		case DL_BIND_REQ:
+			softmac_bind_req(sup, mp);
+			break;
+		case DL_UNBIND_REQ:
+			softmac_unbind_req(sup, mp);
+			break;
+		case DL_CAPABILITY_REQ:
+			softmac_capability_req(sup, mp);
+			break;
+		default:
+			putnext(slp->sl_wq, mp);
+			break;
+		}
+		break;
+	default:
+		putnext(slp->sl_wq, mp);
+		break;
+	}
+}
+
+/*
+ * The worker thread which processes non-data messages. Note we only process
+ * one message at one time in order to be able to "flush" the queued message
+ * and serialize the processing.
+ */
+static void
+softmac_wput_nondata_task(void *arg)
+{
+	softmac_upper_t	*sup = arg;
+	mblk_t		*mp;
+
+	mutex_enter(&sup->su_disp_mutex);
+
+	while (sup->su_pending_head != NULL) {
+		if (sup->su_closing)
+			break;
+
+		SOFTMAC_DQ_PENDING(sup, &mp);
+		mutex_exit(&sup->su_disp_mutex);
+		softmac_wput_single_nondata(sup, mp);
+		mutex_enter(&sup->su_disp_mutex);
+	}
+
+	/*
+	 * If the stream is closing, flush all queued messages and inform
+	 * the stream to be closed.
+	 */
+	freemsgchain(sup->su_pending_head);
+	sup->su_pending_head = sup->su_pending_tail = NULL;
+	sup->su_dlpi_pending = B_FALSE;
+	cv_signal(&sup->su_disp_cv);
+	mutex_exit(&sup->su_disp_mutex);
+}
+
+/*
+ * Kernel thread to handle taskq dispatch failures in softmac_wput_nondata().
+ * This thread is started when the softmac module is first loaded.
+ */
+static void
+softmac_taskq_dispatch(void)
+{
+	callb_cpr_t	cprinfo;
+	softmac_upper_t	*sup;
+
+	CALLB_CPR_INIT(&cprinfo, &softmac_taskq_lock, callb_generic_cpr,
+	    "softmac_taskq_dispatch");
+	mutex_enter(&softmac_taskq_lock);
+
+	while (!softmac_taskq_quit) {
+		sup = list_head(&softmac_taskq_list);
+		while (sup != NULL) {
+			list_remove(&softmac_taskq_list, sup);
+			sup->su_taskq_scheduled = B_FALSE;
+			mutex_exit(&softmac_taskq_lock);
+			VERIFY(taskq_dispatch(system_taskq,
+			    softmac_wput_nondata_task, sup, TQ_SLEEP) != NULL);
+			mutex_enter(&softmac_taskq_lock);
+			sup = list_head(&softmac_taskq_list);
+		}
+
+		CALLB_CPR_SAFE_BEGIN(&cprinfo);
+		cv_wait(&softmac_taskq_cv, &softmac_taskq_lock);
+		CALLB_CPR_SAFE_END(&cprinfo, &softmac_taskq_lock);
+	}
+
+	softmac_taskq_done = B_TRUE;
+	cv_signal(&softmac_taskq_cv);
+	CALLB_CPR_EXIT(&cprinfo);
+	thread_exit();
+}
+
+void
+softmac_wput_nondata(softmac_upper_t *sup, mblk_t *mp)
+{
+	/*
+	 * The processing of the message might block. Enqueue the
+	 * message for later processing.
+	 */
+	mutex_enter(&sup->su_disp_mutex);
+
+	if (sup->su_closing) {
+		mutex_exit(&sup->su_disp_mutex);
+		freemsg(mp);
+		return;
+	}
+
+	SOFTMAC_EQ_PENDING(sup, mp);
+
+	if (sup->su_dlpi_pending) {
+		mutex_exit(&sup->su_disp_mutex);
+		return;
+	}
+	sup->su_dlpi_pending = B_TRUE;
+	mutex_exit(&sup->su_disp_mutex);
+
+	if (taskq_dispatch(system_taskq, softmac_wput_nondata_task,
+	    sup, TQ_NOSLEEP) != NULL) {
+		return;
+	}
+
+	mutex_enter(&softmac_taskq_lock);
+	if (!sup->su_taskq_scheduled) {
+		list_insert_tail(&softmac_taskq_list, sup);
+		cv_signal(&softmac_taskq_cv);
+	}
+	sup->su_taskq_scheduled = B_TRUE;
+	mutex_exit(&softmac_taskq_lock);
+}
+
+/*
+ * Setup the dedicated-lower-stream (fast-path) for the IP/ARP upperstream.
+ */
+static int
+softmac_fastpath_setup(softmac_upper_t *sup)
+{
+	softmac_t	*softmac = sup->su_softmac;
+	softmac_lower_t	*slp;
+	int		err;
+
+	err = softmac_lower_setup(softmac, sup, &slp);
+
+	mutex_enter(&sup->su_mutex);
+	/*
+	 * Wait for all data messages to be processed so that we can change
+	 * the su_mode.
+	 */
+	while (sup->su_tx_inprocess != 0)
+		cv_wait(&sup->su_cv, &sup->su_mutex);
+
+	ASSERT(sup->su_mode != SOFTMAC_FASTPATH);
+	ASSERT(sup->su_slp == NULL);
+	if (err != 0) {
+		sup->su_mode = SOFTMAC_SLOWPATH;
+	} else {
+		sup->su_slp = slp;
+		sup->su_mode = SOFTMAC_FASTPATH;
+	}
+	mutex_exit(&sup->su_mutex);
+	return (err);
+}
+
+/*
+ * Tear down the dedicated-lower-stream (fast-path) for the IP/ARP upperstream.
+ */
+static void
+softmac_fastpath_tear(softmac_upper_t *sup)
+{
+	mutex_enter(&sup->su_mutex);
+	/*
+	 * Wait for all data messages in the dedicated-lower-stream
+	 * to be processed.
+	 */
+	while (sup->su_tx_inprocess != 0)
+		cv_wait(&sup->su_cv, &sup->su_mutex);
+
+	if (sup->su_tx_busy) {
+		ASSERT(sup->su_tx_flow_mp == NULL);
+		sup->su_tx_flow_mp = getq(sup->su_wq);
+		sup->su_tx_busy = B_FALSE;
+	}
+
+	sup->su_mode = SOFTMAC_SLOWPATH;
+
+	/*
+	 * Destroy the dedicated-lower-stream. Note that slp is destroyed
+	 * when lh is closed.
+	 */
+	(void) ldi_close(sup->su_slp->sl_lh, FREAD|FWRITE, kcred);
+	sup->su_slp = NULL;
+	mutex_exit(&sup->su_mutex);
+}
+
+void
+softmac_wput_data(softmac_upper_t *sup, mblk_t *mp)
+{
+	/*
+	 * No lock is required to access the su_mode field since the data
+	 * traffic is quiesce by IP when the data-path mode is in the
+	 * process of switching.
+	 */
+	if (sup->su_mode != SOFTMAC_FASTPATH)
+		dld_wput(sup->su_wq, mp);
+	else
+		(void) softmac_fastpath_wput_data(sup, mp, NULL, 0);
+}
+
+/*ARGSUSED*/
+static mac_tx_cookie_t
+softmac_fastpath_wput_data(softmac_upper_t *sup, mblk_t *mp, uintptr_t f_hint,
+    uint16_t flag)
+{
+	queue_t		*wq = sup->su_slp->sl_wq;
+
+	/*
+	 * This function is called from IP, only the MAC_DROP_ON_NO_DESC
+	 * flag can be specified.
+	 */
+	ASSERT((flag & ~MAC_DROP_ON_NO_DESC) == 0);
+	ASSERT(mp->b_next == NULL);
+
+	/*
+	 * Check wether the dedicated-lower-stream is able to handle more
+	 * messages, and enable the flow-control if it is not.
+	 *
+	 * Note that in order not to introduce any packet reordering, we
+	 * always send the message down to the dedicated-lower-stream:
+	 *
+	 * If the flow-control is already enabled, but we still get
+	 * the messages from the upper-stream, it means that the upper
+	 * stream does not respect STREAMS flow-control (e.g., TCP). Simply
+	 * pass the message down to the lower-stream in that case.
+	 */
+	if (SOFTMAC_CANPUTNEXT(wq)) {
+		putnext(wq, mp);
+		return (NULL);
+	}
+
+	if ((flag & MAC_DROP_ON_NO_DESC) != 0) {
+		freemsg(mp);
+		return ((mac_tx_cookie_t)wq);
+	}
+
+	if (sup->su_tx_busy) {
+		putnext(wq, mp);
+		return ((mac_tx_cookie_t)wq);
+	}
+
+	mutex_enter(&sup->su_mutex);
+	if (!sup->su_tx_busy) {
+		ASSERT(sup->su_tx_flow_mp != NULL);
+		(void) putq(sup->su_wq, sup->su_tx_flow_mp);
+		sup->su_tx_flow_mp = NULL;
+		sup->su_tx_busy = B_TRUE;
+		qenable(wq);
+	}
+	mutex_exit(&sup->su_mutex);
+	putnext(wq, mp);
+	return ((mac_tx_cookie_t)wq);
+}
+
+boolean_t
+softmac_active_set(void *arg)
+{
+	softmac_t	*softmac = arg;
+
+	mutex_enter(&softmac->smac_active_mutex);
+	if (softmac->smac_nactive != 0) {
+		mutex_exit(&softmac->smac_active_mutex);
+		return (B_FALSE);
+	}
+	softmac->smac_active = B_TRUE;
+	mutex_exit(&softmac->smac_active_mutex);
+	return (B_TRUE);
+}
+
+void
+softmac_active_clear(void *arg)
+{
+	softmac_t	*softmac = arg;
+
+	mutex_enter(&softmac->smac_active_mutex);
+	ASSERT(softmac->smac_active && (softmac->smac_nactive == 0));
+	softmac->smac_active = B_FALSE;
+	mutex_exit(&softmac->smac_active_mutex);
+}
+
+/*
+ * Disable/reenable fastpath on given softmac. This request could come from a
+ * MAC client or directly from administrators.
+ */
+int
+softmac_datapath_switch(softmac_t *softmac, boolean_t disable, boolean_t admin)
+{
+	softmac_upper_t		*sup;
+	mblk_t			*head = NULL, *tail = NULL, *mp;
+	list_t			reqlist;
+	softmac_switch_req_t	*req;
+	uint32_t		current_mode, expected_mode;
+	int			err = 0;
+
+	mutex_enter(&softmac->smac_fp_mutex);
+
+	current_mode = DATAPATH_MODE(softmac);
+	if (admin) {
+		if (softmac->smac_fastpath_admin_disabled == disable) {
+			mutex_exit(&softmac->smac_fp_mutex);
+			return (0);
+		}
+		softmac->smac_fastpath_admin_disabled = disable;
+	} else if (disable) {
+		softmac->smac_fp_disable_clients++;
+	} else {
+		ASSERT(softmac->smac_fp_disable_clients != 0);
+		softmac->smac_fp_disable_clients--;
+	}
+
+	expected_mode = DATAPATH_MODE(softmac);
+	if (current_mode == expected_mode) {
+		mutex_exit(&softmac->smac_fp_mutex);
+		return (0);
+	}
+
+	/*
+	 * The expected mode is different from whatever datapath mode
+	 * this softmac is expected from last request, enqueue the data-path
+	 * switch request.
+	 */
+	list_create(&reqlist, sizeof (softmac_switch_req_t),
+	    offsetof(softmac_switch_req_t, ssq_req_list_node));
+
+	/*
+	 * Allocate all DL_NOTIFY_IND messages and request structures that
+	 * are required to switch each IP/ARP stream to the expected mode.
+	 */
+	for (sup = list_head(&softmac->smac_sup_list); sup != NULL;
+	    sup = list_next(&softmac->smac_sup_list, sup)) {
+		dl_notify_ind_t	*dlip;
+
+		req = kmem_alloc(sizeof (softmac_switch_req_t), KM_NOSLEEP);
+		if (req == NULL)
+			break;
+
+		req->ssq_expected_mode = expected_mode;
+
+		/*
+		 * Allocate the DL_NOTE_REPLUMB message.
+		 */
+		if ((mp = allocb(sizeof (dl_notify_ind_t), BPRI_LO)) == NULL) {
+			kmem_free(req, sizeof (softmac_switch_req_t));
+			break;
+		}
+
+		list_insert_tail(&reqlist, req);
+
+		mp->b_wptr = mp->b_rptr + sizeof (dl_notify_ind_t);
+		mp->b_datap->db_type = M_PROTO;
+		bzero(mp->b_rptr, sizeof (dl_notify_ind_t));
+		dlip = (dl_notify_ind_t *)mp->b_rptr;
+		dlip->dl_primitive = DL_NOTIFY_IND;
+		dlip->dl_notification = DL_NOTE_REPLUMB;
+		if (head == NULL) {
+			head = tail = mp;
+		} else {
+			tail->b_next = mp;
+			tail = mp;
+		}
+	}
+
+	/*
+	 * Note that it is fine if the expected data-path mode is fast-path
+	 * and some of streams fails to switch. Only return failure if we
+	 * are expected to switch to the slow-path.
+	 */
+	if (sup != NULL && expected_mode == SOFTMAC_SLOWPATH) {
+		err = ENOMEM;
+		goto fail;
+	}
+
+	/*
+	 * Start switching for each IP/ARP stream. The switching operation
+	 * will eventually succeed and there is no need to wait for it
+	 * to finish.
+	 */
+	for (sup = list_head(&softmac->smac_sup_list); sup != NULL;
+	    sup = list_next(&softmac->smac_sup_list, sup)) {
+		mp = head->b_next;
+		head->b_next = NULL;
+
+		/*
+		 * Add the swtich request to the requests list of the stream.
+		 */
+		req = list_head(&reqlist);
+		ASSERT(req != NULL);
+		list_remove(&reqlist, req);
+		list_insert_tail(&sup->su_req_list, req);
+		softmac_wput_nondata(sup, head);
+		head = mp;
+	}
+
+	mutex_exit(&softmac->smac_fp_mutex);
+	ASSERT(list_is_empty(&reqlist));
+	list_destroy(&reqlist);
+	return (0);
+fail:
+	if (admin) {
+		softmac->smac_fastpath_admin_disabled = !disable;
+	} else if (disable) {
+		softmac->smac_fp_disable_clients--;
+	} else {
+		softmac->smac_fp_disable_clients++;
+	}
+
+	mutex_exit(&softmac->smac_fp_mutex);
+	while ((req = list_head(&reqlist)) != NULL) {
+		list_remove(&reqlist, req);
+		kmem_free(req, sizeof (softmac_switch_req_t));
+	}
+	freemsgchain(head);
+	list_destroy(&reqlist);
+	return (err);
+}
+
+int
+softmac_fastpath_disable(void *arg)
+{
+	return (softmac_datapath_switch((softmac_t *)arg, B_TRUE, B_FALSE));
+}
+
+void
+softmac_fastpath_enable(void *arg)
+{
+	VERIFY(softmac_datapath_switch((softmac_t *)arg, B_FALSE,
+	    B_FALSE) == 0);
+}
+
+void
+softmac_upperstream_close(softmac_upper_t *sup)
+{
+	softmac_t		*softmac = sup->su_softmac;
+	softmac_switch_req_t	*req;
+
+	mutex_enter(&softmac->smac_fp_mutex);
+
+	if (sup->su_mode == SOFTMAC_FASTPATH)
+		softmac_fastpath_tear(sup);
+
+	if (sup->su_mode != SOFTMAC_UNKNOWN) {
+		list_remove(&softmac->smac_sup_list, sup);
+		sup->su_mode = SOFTMAC_UNKNOWN;
+	}
+
+	/*
+	 * Cleanup all the switch requests queueed on this stream.
+	 */
+	while ((req = list_head(&sup->su_req_list)) != NULL) {
+		list_remove(&sup->su_req_list, req);
+		kmem_free(req, sizeof (softmac_switch_req_t));
+	}
+	mutex_exit(&softmac->smac_fp_mutex);
+}
+
+/*
+ * Handle the DL_NOTE_REPLUMB_DONE indication from IP/ARP. Change the upper
+ * stream from the fastpath mode to the slowpath mode.
+ */
+static void
+softmac_datapath_switch_done(softmac_upper_t *sup)
+{
+	softmac_t		*softmac = sup->su_softmac;
+	softmac_switch_req_t	*req;
+	uint32_t		expected_mode;
+
+	mutex_enter(&softmac->smac_fp_mutex);
+	req = list_head(&sup->su_req_list);
+	list_remove(&sup->su_req_list, req);
+	expected_mode = req->ssq_expected_mode;
+	kmem_free(req, sizeof (softmac_switch_req_t));
+
+	if (expected_mode == sup->su_mode) {
+		mutex_exit(&softmac->smac_fp_mutex);
+		return;
+	}
+
+	ASSERT(!sup->su_bound);
+	mutex_exit(&softmac->smac_fp_mutex);
+
+	/*
+	 * It is fine if the expected mode is fast-path and we fail
+	 * to enable fastpath on this stream.
+	 */
+	if (expected_mode == SOFTMAC_SLOWPATH)
+		softmac_fastpath_tear(sup);
+	else
+		(void) softmac_fastpath_setup(sup);
+}
diff --git a/usr/src/uts/common/io/softmac/softmac_main.c b/usr/src/uts/common/io/softmac/softmac_main.c
index a44856c849..bfdf3ee851 100644
--- a/usr/src/uts/common/io/softmac/softmac_main.c
+++ b/usr/src/uts/common/io/softmac/softmac_main.c
@@ -69,6 +69,8 @@ static mod_hash_t	*softmac_hash;
 static kmutex_t		smac_global_lock;
 static kcondvar_t	smac_global_cv;
 
+static kmem_cache_t	*softmac_cachep;
+
 #define	SOFTMAC_HASHSZ		64
 
 static void softmac_create_task(void *);
@@ -79,9 +81,14 @@ static void softmac_m_stop(void *);
 static int softmac_m_open(void *);
 static void softmac_m_close(void *);
 static boolean_t softmac_m_getcapab(void *, mac_capab_t, void *);
+static int softmac_m_setprop(void *, const char *, mac_prop_id_t,
+    uint_t, const void *);
+static int softmac_m_getprop(void *, const char *, mac_prop_id_t,
+    uint_t, uint_t, void *, uint_t *);
+
 
 #define	SOFTMAC_M_CALLBACK_FLAGS	\
-	(MC_IOCTL | MC_GETCAPAB | MC_OPEN | MC_CLOSE)
+	(MC_IOCTL | MC_GETCAPAB | MC_OPEN | MC_CLOSE | MC_SETPROP | MC_GETPROP)
 
 static mac_callbacks_t softmac_m_callbacks = {
 	SOFTMAC_M_CALLBACK_FLAGS,
@@ -95,9 +102,57 @@ static mac_callbacks_t softmac_m_callbacks = {
 	softmac_m_ioctl,
 	softmac_m_getcapab,
 	softmac_m_open,
-	softmac_m_close
+	softmac_m_close,
+	softmac_m_setprop,
+	softmac_m_getprop
 };
 
+/*ARGSUSED*/
+static int
+softmac_constructor(void *buf, void *arg, int kmflag)
+{
+	softmac_t	*softmac = buf;
+
+	bzero(buf, sizeof (softmac_t));
+	mutex_init(&softmac->smac_mutex, NULL, MUTEX_DEFAULT, NULL);
+	mutex_init(&softmac->smac_active_mutex, NULL, MUTEX_DEFAULT, NULL);
+	mutex_init(&softmac->smac_fp_mutex, NULL, MUTEX_DEFAULT, NULL);
+	cv_init(&softmac->smac_cv, NULL, CV_DEFAULT, NULL);
+	cv_init(&softmac->smac_fp_cv, NULL, CV_DEFAULT, NULL);
+	list_create(&softmac->smac_sup_list, sizeof (softmac_upper_t),
+	    offsetof(softmac_upper_t, su_list_node));
+	return (0);
+}
+
+/*ARGSUSED*/
+static void
+softmac_destructor(void *buf, void *arg)
+{
+	softmac_t	*softmac = buf;
+
+	ASSERT(softmac->smac_fp_disable_clients == 0);
+	ASSERT(!softmac->smac_fastpath_admin_disabled);
+
+	ASSERT(!(softmac->smac_flags & SOFTMAC_ATTACH_DONE));
+	ASSERT(softmac->smac_hold_cnt == 0);
+	ASSERT(softmac->smac_attachok_cnt == 0);
+	ASSERT(softmac->smac_mh == NULL);
+	ASSERT(softmac->smac_softmac[0] == NULL &&
+	    softmac->smac_softmac[1] == NULL);
+	ASSERT(softmac->smac_state == SOFTMAC_INITIALIZED);
+	ASSERT(softmac->smac_lower == NULL);
+	ASSERT(softmac->smac_active == B_FALSE);
+	ASSERT(softmac->smac_nactive == 0);
+	ASSERT(list_is_empty(&softmac->smac_sup_list));
+
+	list_destroy(&softmac->smac_sup_list);
+	mutex_destroy(&softmac->smac_mutex);
+	mutex_destroy(&softmac->smac_active_mutex);
+	mutex_destroy(&softmac->smac_fp_mutex);
+	cv_destroy(&softmac->smac_cv);
+	cv_destroy(&softmac->smac_fp_cv);
+}
+
 void
 softmac_init()
 {
@@ -108,11 +163,19 @@ softmac_init()
 	rw_init(&softmac_hash_lock, NULL, RW_DEFAULT, NULL);
 	mutex_init(&smac_global_lock, NULL, MUTEX_DRIVER, NULL);
 	cv_init(&smac_global_cv, NULL, CV_DRIVER, NULL);
+
+	softmac_cachep = kmem_cache_create("softmac_cache",
+	    sizeof (softmac_t), 0, softmac_constructor,
+	    softmac_destructor, NULL, NULL, NULL, 0);
+	ASSERT(softmac_cachep != NULL);
+	softmac_fp_init();
 }
 
 void
 softmac_fini()
 {
+	softmac_fp_fini();
+	kmem_cache_destroy(softmac_cachep);
 	rw_destroy(&softmac_hash_lock);
 	mod_hash_destroy_hash(softmac_hash);
 	mutex_destroy(&smac_global_lock);
@@ -281,16 +344,12 @@ softmac_create(dev_info_t *dip, dev_t dev)
 	 * Check whether the softmac for the specified device already exists
 	 */
 	rw_enter(&softmac_hash_lock, RW_WRITER);
-	if ((err = mod_hash_find(softmac_hash, (mod_hash_key_t)devname,
+	if ((mod_hash_find(softmac_hash, (mod_hash_key_t)devname,
 	    (mod_hash_val_t *)&softmac)) != 0) {
 
-		softmac = kmem_zalloc(sizeof (softmac_t), KM_SLEEP);
-		mutex_init(&softmac->smac_mutex, NULL, MUTEX_DRIVER, NULL);
-		cv_init(&softmac->smac_cv, NULL, CV_DRIVER, NULL);
+		softmac = kmem_cache_alloc(softmac_cachep, KM_SLEEP);
 		(void) strlcpy(softmac->smac_devname, devname, MAXNAMELEN);
-		/*
-		 * Insert the softmac into the hash table.
-		 */
+
 		err = mod_hash_insert(softmac_hash,
 		    (mod_hash_key_t)softmac->smac_devname,
 		    (mod_hash_val_t)softmac);
@@ -413,8 +472,18 @@ softmac_m_getcapab(void *arg, mac_capab_t cap, void *cap_data)
 	case MAC_CAPAB_LEGACY: {
 		mac_capab_legacy_t *legacy = cap_data;
 
+		/*
+		 * The caller is not interested in the details.
+		 */
+		if (legacy == NULL)
+			break;
+
 		legacy->ml_unsup_note = ~softmac->smac_notifications &
 		    (DL_NOTE_LINK_UP | DL_NOTE_LINK_DOWN | DL_NOTE_SPEED);
+		legacy->ml_active_set = softmac_active_set;
+		legacy->ml_active_clear = softmac_active_clear;
+		legacy->ml_fastpath_disable = softmac_fastpath_disable;
+		legacy->ml_fastpath_enable = softmac_fastpath_enable;
 		legacy->ml_dev = makedevice(softmac->smac_umajor,
 		    softmac->smac_uppa + 1);
 		break;
@@ -816,22 +885,23 @@ softmac_mac_register(softmac_t *softmac)
 	 * Try to create the datalink for this softmac.
 	 */
 	if ((err = softmac_create_datalink(softmac)) != 0) {
-		if (!(softmac->smac_flags & SOFTMAC_NOSUPP)) {
+		if (!(softmac->smac_flags & SOFTMAC_NOSUPP))
 			(void) mac_unregister(softmac->smac_mh);
-			softmac->smac_mh = NULL;
-		}
+		mutex_enter(&softmac->smac_mutex);
+		softmac->smac_mh = NULL;
+		goto done;
 	}
 	/*
 	 * If succeed, create the thread which handles the DL_NOTIFY_IND from
 	 * the lower stream.
 	 */
+	mutex_enter(&softmac->smac_mutex);
 	if (softmac->smac_mh != NULL) {
 		softmac->smac_notify_thread = thread_create(NULL, 0,
 		    softmac_notify_thread, softmac, 0, &p0,
 		    TS_RUN, minclsyspri);
 	}
 
-	mutex_enter(&softmac->smac_mutex);
 done:
 	ASSERT(softmac->smac_state == SOFTMAC_ATTACH_INPROG &&
 	    softmac->smac_attachok_cnt == softmac->smac_cnt);
@@ -967,7 +1037,6 @@ softmac_destroy(dev_info_t *dip, dev_t dev)
 			rw_exit(&softmac_hash_lock);
 			return (0);
 		}
-
 		err = mod_hash_remove(softmac_hash,
 		    (mod_hash_key_t)devname,
 		    (mod_hash_val_t *)&hashval);
@@ -975,10 +1044,9 @@ softmac_destroy(dev_info_t *dip, dev_t dev)
 
 		mutex_exit(&softmac->smac_mutex);
 		rw_exit(&softmac_hash_lock);
-
-		mutex_destroy(&softmac->smac_mutex);
-		cv_destroy(&softmac->smac_cv);
-		kmem_free(softmac, sizeof (softmac_t));
+		ASSERT(softmac->smac_fp_disable_clients == 0);
+		softmac->smac_fastpath_admin_disabled = B_FALSE;
+		kmem_cache_free(softmac_cachep, softmac);
 		return (0);
 	}
 	mutex_exit(&softmac->smac_mutex);
@@ -1119,27 +1187,84 @@ softmac_recreate()
 	} while (smw.smw_retry);
 }
 
-/* ARGSUSED */
 static int
 softmac_m_start(void *arg)
 {
-	return (0);
+	softmac_t	*softmac = arg;
+	softmac_lower_t	*slp = softmac->smac_lower;
+	int		err;
+
+	ASSERT(MAC_PERIM_HELD(softmac->smac_mh));
+	/*
+	 * Bind to SAP 2 on token ring, 0 on other interface types.
+	 * (SAP 0 has special significance on token ring).
+	 * Note that the receive-side packets could come anytime after bind.
+	 */
+	err = softmac_send_bind_req(slp, softmac->smac_media == DL_TPR ? 2 : 0);
+	if (err != 0)
+		return (err);
+
+	/*
+	 * Put the lower stream to the DL_PROMISC_SAP mode in order to receive
+	 * all packets of interest.
+	 *
+	 * some driver (e.g. the old legacy eri driver) incorrectly passes up
+	 * packets to DL_PROMISC_SAP stream when the lower stream is not bound,
+	 * so that we send DL_PROMISON_REQ after DL_BIND_REQ.
+	 */
+	err = softmac_send_promisc_req(slp, DL_PROMISC_SAP, B_TRUE);
+	if (err != 0) {
+		(void) softmac_send_unbind_req(slp);
+		return (err);
+	}
+
+	/*
+	 * Enable capabilities the underlying driver claims to support.
+	 * Some driver requires this being called after the stream is bound.
+	 */
+	if ((err = softmac_capab_enable(slp)) != 0) {
+		(void) softmac_send_promisc_req(slp, DL_PROMISC_SAP, B_FALSE);
+		(void) softmac_send_unbind_req(slp);
+	}
+
+	return (err);
 }
 
 /* ARGSUSED */
 static void
 softmac_m_stop(void *arg)
 {
+	softmac_t	*softmac = arg;
+	softmac_lower_t	*slp = softmac->smac_lower;
+
+	ASSERT(MAC_PERIM_HELD(softmac->smac_mh));
+
+	/*
+	 * It is not needed to reset zerocopy, MDT or HCKSUM capabilities.
+	 */
+	(void) softmac_send_promisc_req(slp, DL_PROMISC_SAP, B_FALSE);
+	(void) softmac_send_unbind_req(slp);
 }
 
 /*
- * Set up the lower stream above the legacy device which is shared by
- * GLDv3 MAC clients. Put the lower stream into DLIOCRAW mode to send
- * and receive the raw data. Further, put the lower stream into
+ * Set up the lower stream above the legacy device. There are two different
+ * type of lower streams:
+ *
+ * - Shared lower-stream
+ *
+ * Shared by all GLDv3 MAC clients. Put the lower stream to the DLIOCRAW
+ * mode to send and receive the raw data. Further, put the lower stream into
  * DL_PROMISC_SAP mode to receive all packets of interest.
+ *
+ * - Dedicated lower-stream
+ *
+ * The lower-stream which is dedicated to upper IP/ARP stream. This is used
+ * as fast-path for IP. In this case, the second argument is the pointer to
+ * the softmac upper-stream.
  */
-static int
-softmac_lower_setup(softmac_t *softmac, softmac_lower_t **slpp)
+int
+softmac_lower_setup(softmac_t *softmac, softmac_upper_t *sup,
+    softmac_lower_t **slpp)
 {
 	ldi_ident_t		li;
 	dev_t			dev;
@@ -1153,7 +1278,13 @@ softmac_lower_setup(softmac_t *softmac, softmac_lower_t **slpp)
 	if ((err = ldi_ident_from_dip(softmac_dip, &li)) != 0)
 		return (err);
 
+	/*
+	 * The GLDv3 framework makes sure that mac_unregister(), mac_open(),
+	 * and mac_close() cannot be called at the same time. So we don't
+	 * need any protection to access softmac here.
+	 */
 	dev = softmac->smac_dev;
+
 	err = ldi_open_by_dev(&dev, OTYP_CHR, FREAD|FWRITE, kcred, &lh, li);
 	ldi_ident_release(li);
 	if (err != 0)
@@ -1172,10 +1303,13 @@ softmac_lower_setup(softmac_t *softmac, softmac_lower_t **slpp)
 	}
 
 	/*
-	 * Put the lower stream into DLIOCRAW mode to send/receive raw data.
+	 * If this is the shared-lower-stream, put the lower stream to
+	 * the DLIOCRAW mode to send/receive raw data.
 	 */
-	if ((err = ldi_ioctl(lh, DLIOCRAW, 0, FKIOCTL, kcred, &rval)) != 0)
+	if ((sup == NULL) && (err = ldi_ioctl(lh, DLIOCRAW, 0, FKIOCTL,
+	    kcred, &rval)) != 0) {
 		goto done;
+	}
 
 	/*
 	 * Then push the softmac shim layer atop the lower stream.
@@ -1198,50 +1332,25 @@ softmac_lower_setup(softmac_t *softmac, softmac_lower_t **slpp)
 		goto done;
 	}
 	slp = start_arg.si_slp;
+	slp->sl_sup = sup;
 	slp->sl_lh = lh;
 	slp->sl_softmac = softmac;
 	*slpp = slp;
 
-	/*
-	 * Bind to SAP 2 on token ring, 0 on other interface types.
-	 * (SAP 0 has special significance on token ring).
-	 * Note that the receive-side packets could come anytime after bind.
-	 */
-	if (softmac->smac_media == DL_TPR)
-		err = softmac_send_bind_req(slp, 2);
-	else
-		err = softmac_send_bind_req(slp, 0);
-	if (err != 0)
-		goto done;
-
-	/*
-	 * Put the lower stream into DL_PROMISC_SAP mode to receive all
-	 * packets of interest.
-	 *
-	 * Some drivers (e.g. the old legacy eri driver) incorrectly pass up
-	 * packets to DL_PROMISC_SAP stream when the lower stream is not bound,
-	 * so we send DL_PROMISON_REQ after DL_BIND_REQ.
-	 */
-	if ((err = softmac_send_promisc_req(slp, DL_PROMISC_SAP, B_TRUE)) != 0)
-		goto done;
-
-	/*
-	 * Enable the capabilities the underlying driver claims to support.
-	 * Some drivers require this to be called after the stream is bound.
-	 */
-	if ((err = softmac_capab_enable(slp)) != 0)
-		goto done;
-
-	/*
-	 * Send the DL_NOTIFY_REQ to enable certain DL_NOTIFY_IND.
-	 * We don't have to wait for the ack.
-	 */
-	notifications = DL_NOTE_PHYS_ADDR | DL_NOTE_LINK_UP |
-	    DL_NOTE_LINK_DOWN | DL_NOTE_PROMISC_ON_PHYS |
-	    DL_NOTE_PROMISC_OFF_PHYS;
+	if (sup != NULL) {
+		slp->sl_rxinfo = &sup->su_rxinfo;
+	} else {
+		/*
+		 * Send DL_NOTIFY_REQ to enable certain DL_NOTIFY_IND.
+		 * We don't have to wait for the ack.
+		 */
+		notifications = DL_NOTE_PHYS_ADDR | DL_NOTE_LINK_UP |
+		    DL_NOTE_LINK_DOWN | DL_NOTE_PROMISC_ON_PHYS |
+		    DL_NOTE_PROMISC_OFF_PHYS;
 
-	(void) softmac_send_notify_req(slp,
-	    (notifications & softmac->smac_notifications));
+		(void) softmac_send_notify_req(slp,
+		    (notifications & softmac->smac_notifications));
+	}
 
 done:
 	if (err != 0)
@@ -1257,13 +1366,11 @@ softmac_m_open(void *arg)
 	int		err;
 
 	ASSERT(MAC_PERIM_HELD(softmac->smac_mh));
-	ASSERT(softmac->smac_lower_state == SOFTMAC_INITIALIZED);
 
-	if ((err = softmac_lower_setup(softmac, &slp)) != 0)
+	if ((err = softmac_lower_setup(softmac, NULL, &slp)) != 0)
 		return (err);
 
 	softmac->smac_lower = slp;
-	softmac->smac_lower_state = SOFTMAC_READY;
 	return (0);
 }
 
@@ -1274,7 +1381,6 @@ softmac_m_close(void *arg)
 	softmac_lower_t	*slp;
 
 	ASSERT(MAC_PERIM_HELD(softmac->smac_mh));
-	ASSERT(softmac->smac_lower_state == SOFTMAC_READY);
 	slp = softmac->smac_lower;
 	ASSERT(slp != NULL);
 
@@ -1282,10 +1388,74 @@ softmac_m_close(void *arg)
 	 * Note that slp is destroyed when lh is closed.
 	 */
 	(void) ldi_close(slp->sl_lh, FREAD|FWRITE, kcred);
-	softmac->smac_lower_state = SOFTMAC_INITIALIZED;
 	softmac->smac_lower = NULL;
 }
 
+/*
+ * Softmac supports two priviate link properteis:
+ *
+ * - "_fastpath"
+ *
+ *    This is a read-only link property which points out the current data-path
+ *    model of the given legacy link. The possible values are "disabled" and
+ *    "enabled".
+ *
+ * - "_disable_fastpath"
+ *
+ *    This is a read-write link property which can be used to disable or enable
+ *    the fast-path of the given legacy link. The possible values are "true"
+ *    and "false". Note that even when "_disable_fastpath" is set to be
+ *    "false", the fast-path may still not be enabled since there may be
+ *    other mac cleints that request the fast-path to be disabled.
+ */
+/* ARGSUSED */
+static int
+softmac_m_setprop(void *arg, const char *name, mac_prop_id_t id,
+    uint_t valsize, const void *val)
+{
+	softmac_t	*softmac = arg;
+
+	if (id != MAC_PROP_PRIVATE || strcmp(name, "_disable_fastpath") != 0)
+		return (ENOTSUP);
+
+	if (strcmp(val, "true") == 0)
+		return (softmac_datapath_switch(softmac, B_TRUE, B_TRUE));
+	else if (strcmp(val, "false") == 0)
+		return (softmac_datapath_switch(softmac, B_FALSE, B_TRUE));
+	else
+		return (EINVAL);
+}
+
+static int
+softmac_m_getprop(void *arg, const char *name, mac_prop_id_t id, uint_t flags,
+    uint_t valsize, void *val, uint_t *perm)
+{
+	softmac_t	*softmac = arg;
+	char		*fpstr;
+
+	if (id != MAC_PROP_PRIVATE)
+		return (ENOTSUP);
+
+	if (strcmp(name, "_fastpath") == 0) {
+		if ((flags & MAC_PROP_DEFAULT) != 0)
+			return (ENOTSUP);
+
+		*perm = MAC_PROP_PERM_READ;
+		mutex_enter(&softmac->smac_fp_mutex);
+		fpstr = (DATAPATH_MODE(softmac) == SOFTMAC_SLOWPATH) ?
+		    "disabled" : "enabled";
+		mutex_exit(&softmac->smac_fp_mutex);
+	} else if (strcmp(name, "_disable_fastpath") == 0) {
+		*perm = MAC_PROP_PERM_RW;
+		fpstr = ((flags & MAC_PROP_DEFAULT) != 0) ? "false" :
+		    (softmac->smac_fastpath_admin_disabled ? "true" : "false");
+	} else {
+		return (ENOTSUP);
+	}
+
+	return (strlcpy(val, fpstr, valsize) >= valsize ? EINVAL : 0);
+}
+
 int
 softmac_hold_device(dev_t dev, dls_dev_handle_t *ddhp)
 {
@@ -1367,12 +1537,39 @@ again:
 void
 softmac_rele_device(dls_dev_handle_t ddh)
 {
+	if (ddh != NULL)
+		softmac_rele((softmac_t *)ddh);
+}
+
+int
+softmac_hold(dev_t dev, softmac_t **softmacp)
+{
 	softmac_t	*softmac;
+	char		*drv;
+	mac_handle_t	mh;
+	char		mac[MAXNAMELEN];
+	int		err;
 
-	if (ddh == NULL)
-		return;
+	if ((drv = ddi_major_to_name(getmajor(dev))) == NULL)
+		return (EINVAL);
 
-	softmac = (softmac_t *)ddh;
+	(void) snprintf(mac, MAXNAMELEN, "%s%d", drv, getminor(dev) - 1);
+	if ((err = mac_open(mac, &mh)) != 0)
+		return (err);
+
+	softmac = (softmac_t *)mac_driver(mh);
+
+	mutex_enter(&softmac->smac_mutex);
+	softmac->smac_hold_cnt++;
+	mutex_exit(&softmac->smac_mutex);
+	mac_close(mh);
+	*softmacp = softmac;
+	return (0);
+}
+
+void
+softmac_rele(softmac_t *softmac)
+{
 	mutex_enter(&softmac->smac_mutex);
 	softmac->smac_hold_cnt--;
 	mutex_exit(&softmac->smac_mutex);
diff --git a/usr/src/uts/common/io/softmac/softmac_pkt.c b/usr/src/uts/common/io/softmac/softmac_pkt.c
index 4a856f4f58..b0d613b9be 100644
--- a/usr/src/uts/common/io/softmac/softmac_pkt.c
+++ b/usr/src/uts/common/io/softmac/softmac_pkt.c
@@ -27,16 +27,6 @@
 #include <inet/led.h>
 #include <sys/softmac_impl.h>
 
-/*
- * Macro to check whether the write-queue of the lower stream is full.
- *
- * Because softmac is pushed right above the underlying device and
- * _I_INSERT/_I_REMOVE is not processed in the lower stream, it is
- * safe to directly access the q_next pointer.
- */
-#define	CANPUTNEXT(q)	\
-	(!((q)->q_next->q_nfsrv->q_flag & QFULL) || canput((q)->q_next))
-
 mblk_t *
 softmac_m_tx(void *arg, mblk_t *mp)
 {
@@ -46,7 +36,7 @@ softmac_m_tx(void *arg, mblk_t *mp)
 	 * Optimize for the most common case.
 	 */
 	if (mp->b_next == NULL) {
-		if (!CANPUTNEXT(wq))
+		if (!SOFTMAC_CANPUTNEXT(wq))
 			return (mp);
 
 		mp->b_flag |= MSGNOLOOP;
@@ -57,7 +47,7 @@ softmac_m_tx(void *arg, mblk_t *mp)
 	while (mp != NULL) {
 		mblk_t *next = mp->b_next;
 
-		if (!CANPUTNEXT(wq))
+		if (!SOFTMAC_CANPUTNEXT(wq))
 			break;
 		mp->b_next = NULL;
 		mp->b_flag |= MSGNOLOOP;
@@ -67,7 +57,6 @@ softmac_m_tx(void *arg, mblk_t *mp)
 	return (mp);
 }
 
-
 void
 softmac_rput_process_data(softmac_lower_t *slp, mblk_t *mp)
 {
@@ -141,7 +130,7 @@ dlpi_get_errno(t_uscalar_t error, t_uscalar_t unix_errno)
 	return (error == DL_SYSERR ? unix_errno : EINVAL);
 }
 
-static int
+int
 softmac_output(softmac_lower_t *slp, mblk_t *mp, t_uscalar_t dl_prim,
     t_uscalar_t ack, mblk_t **mpp)
 {
@@ -227,7 +216,7 @@ softmac_ioctl_tx(softmac_lower_t *slp, mblk_t *mp, mblk_t **mpp)
 	softmac_serialize_exit(slp);
 }
 
-static int
+int
 softmac_mexchange_error_ack(mblk_t **mpp, t_uscalar_t error_primitive,
 	t_uscalar_t error, t_uscalar_t unix_errno)
 {
diff --git a/usr/src/uts/common/io/sundlpi.c b/usr/src/uts/common/io/sundlpi.c
index d537f8127b..a322634fb6 100644
--- a/usr/src/uts/common/io/sundlpi.c
+++ b/usr/src/uts/common/io/sundlpi.c
@@ -491,6 +491,7 @@ dl_primstr(t_uscalar_t prim)
 	case DL_NOTIFY_REQ:		return ("DL_NOTIFY_REQ");
 	case DL_NOTIFY_ACK:		return ("DL_NOTIFY_ACK");
 	case DL_NOTIFY_IND:		return ("DL_NOTIFY_IND");
+	case DL_NOTIFY_CONF:		return ("DL_NOTIFY_CONF");
 	case DL_CAPABILITY_REQ:		return ("DL_CAPABILITY_REQ");
 	case DL_CAPABILITY_ACK:		return ("DL_CAPABILITY_ACK");
 	case DL_CONTROL_REQ:		return ("DL_CONTROL_REQ");