Implement true asynchronous signaling between processes and ports

28 files changed, 4686 insertions, 1535 deletions

diff --git a/erts/emulator/Makefile.in b/erts/emulator/Makefile.in
index 47089f7dd0..5381ae3bea 100644
--- a/erts/emulator/Makefile.in
+++ b/erts/emulator/Makefile.in
@@ -575,7 +575,8 @@ $(PRELOAD_SRC): $(ERL_TOP)/erts/preloaded/ebin/otp_ring0.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/zlib.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/prim_zip.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/erl_prim_loader.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/erlang.beam
+			$(ERL_TOP)/erts/preloaded/ebin/erlang.beam \
+			$(ERL_TOP)/erts/preloaded/ebin/erts_internal.beam
 	LANG=C $(PERL) utils/make_preload $(MAKE_PRELOAD_EXTRA) -rc $^ > $@
 else
 PRELOAD_OBJ = $(OBJDIR)/preload.o
@@ -587,7 +588,8 @@ $(PRELOAD_SRC): $(ERL_TOP)/erts/preloaded/ebin/otp_ring0.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/zlib.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/prim_zip.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/erl_prim_loader.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/erlang.beam
+			$(ERL_TOP)/erts/preloaded/ebin/erlang.beam \
+			$(ERL_TOP)/erts/preloaded/ebin/erts_internal.beam
 	LANG=C $(PERL) utils/make_preload -old $^ > $@
 endif
 
diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index d6d8633f6f..30b891be5d 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -94,6 +94,7 @@ atom asynchronous
 atom atom
 atom atom_used
 atom attributes
+atom await_port_send_result
 atom await_proc_exit
 atom await_sched_wall_time_modifications
 atom awaiting_load
@@ -152,6 +153,7 @@ atom connection_closed
 atom cons
 atom const
 atom context_switches
+atom control
 atom copy
 atom cpu
 atom cpu_timestamp
@@ -204,6 +206,7 @@ atom erlang
 atom ERROR='ERROR'
 atom error_handler
 atom error_logger
+atom erts_internal
 atom ets
 atom ETS_TRANSFER='ETS-TRANSFER'
 atom event
@@ -237,6 +240,7 @@ atom gc_end
 atom gc_start
 atom Ge='>='
 atom generational
+atom get_data
 atom get_seq_token
 atom get_tcw
 atom getenv
@@ -408,6 +412,7 @@ atom overlapped_io
 atom owner
 atom packet
 atom packet_size
+atom parallelism
 atom Plus='+'
 atom pause
 atom pending
@@ -482,6 +487,7 @@ atom sequential_trace_token
 atom serial
 atom set
 atom set_cpu_topology
+atom set_data
 atom set_on_first_link
 atom set_on_first_spawn
 atom set_on_link
diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index d8ccbacc26..106f742272 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -1135,7 +1135,7 @@ init_emulator(void)
 void
 dtrace_drvport_str(ErlDrvPort drvport, char *port_buf)
 {
-    Port *port = erts_drvport2port(drvport);
+    Port *port = erts_drvport2port(drvport, NULL);
 
     erts_snprintf(port_buf, DTRACE_TERM_BUF_SIZE, "#Port<%lu.%lu>",
                   port_channel_no(port->common.id),
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index dc0dcbabd6..3ab8fdb2c7 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -43,6 +43,7 @@
 static Export* flush_monitor_message_trap = NULL;
 static Export* set_cpu_topology_trap = NULL;
 static Export* await_proc_exit_trap = NULL;
+static Export* await_port_send_result_trap = NULL;
 Export* erts_format_cpu_topology_trap = NULL;
 
 static Export *await_sched_wall_time_mod_trap;
@@ -157,22 +158,37 @@ BIF_RETTYPE link_1(BIF_ALIST_1)
     }
 
     if (is_internal_port(BIF_ARG_1)) {
-	Port *pt = erts_id2port_sflgs(BIF_ARG_1,
-				      BIF_P,
-				      ERTS_PROC_LOCK_MAIN,
-				      ERTS_PORT_SFLGS_INVALID_LOOKUP);
-	if (!pt) {
+	int send_link_signal = 0;
+	Port *prt = erts_port_lookup(BIF_ARG_1, ERTS_PORT_SFLGS_INVALID_LOOKUP);
+	if (!prt) {
 	    goto res_no_proc;
 	}
 
 	erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_LINK);
 	
 	if (erts_add_link(&ERTS_P_LINKS(BIF_P), LINK_PID, BIF_ARG_1) >= 0)
-	    erts_add_link(&ERTS_P_LINKS(pt), LINK_PID, BIF_P->common.id);
+	    send_link_signal = 1;
 	/* else: already linked */
 
 	erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_LINK);
-	erts_port_release(pt);
+
+	if (send_link_signal) {
+	    Eterm ref;
+	    Eterm *refp = erts_port_synchronous_ops ? &ref : NULL;
+
+	    switch (erts_port_link(BIF_P, prt, BIF_P->common.id, refp)) {
+	    case ERTS_PORT_OP_DROPPED:
+	    case ERTS_PORT_OP_BADARG:
+		goto res_no_proc;
+	    case ERTS_PORT_OP_SCHEDULED:
+		if (refp) {
+		    ASSERT(is_internal_ref(ref));
+		    BIF_TRAP3(await_port_send_result_trap, BIF_P, ref, am_true, am_true);
+		}
+	    default:
+		break;
+	    }
+	}
 	BIF_RET(am_true);
     }
     else if (is_external_port(BIF_ARG_1)
@@ -944,36 +960,39 @@ BIF_RETTYPE unlink_1(BIF_ALIST_1)
     }
 
     if (is_internal_port(BIF_ARG_1)) {
-	Port *pt = erts_id2port_sflgs(BIF_ARG_1,
-				      BIF_P,
-				      ERTS_PROC_LOCK_MAIN,
-				      ERTS_PORT_SFLGS_DEAD);
-
 	erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_LINK|ERTS_PROC_LOCK_STATUS);
 #ifdef ERTS_SMP
-	if (ERTS_PROC_PENDING_EXIT(BIF_P)) {
-	    if (pt)
-		erts_port_release(pt);
+	if (ERTS_PROC_PENDING_EXIT(BIF_P))
 	    goto handle_pending_exit;
-	}
 #endif
 
 	l = erts_remove_link(&ERTS_P_LINKS(BIF_P), BIF_ARG_1);
 
-	ASSERT(pt || !l);
-
-	if (pt) {
-	    rl = erts_remove_link(&ERTS_P_LINKS(pt), BIF_P->common.id);
-	    erts_port_release(pt);
-	    if (rl)
-		erts_destroy_link(rl);
-	}
-
 	erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_LINK|ERTS_PROC_LOCK_STATUS);
 
-	if (l)
+	if (l) {
+	    Port *prt;
+
 	    erts_destroy_link(l);
 
+	    /* Send unlink signal */
+	    prt = erts_port_lookup(BIF_ARG_1, ERTS_PORT_SFLGS_DEAD);
+	    if (prt) {
+		ErtsPortOpResult res;
+		Eterm ref;
+		Eterm *refp = erts_port_synchronous_ops ? &ref : NULL;
+#ifdef DEBUG
+		ref = NIL;
+#endif
+		res = erts_port_unlink(BIF_P, prt, BIF_P->common.id, refp);
+
+		if (refp && res == ERTS_PORT_OP_SCHEDULED) {
+		    ASSERT(is_internal_ref(ref));
+		    BIF_TRAP3(await_port_send_result_trap, BIF_P, ref, am_true, am_true);
+		}
+	    }
+	}
+
 	BIF_RET(am_true);
     }
     else if (is_external_port(BIF_ARG_1)
@@ -1344,15 +1363,28 @@ BIF_RETTYPE exit_2(BIF_ALIST_2)
       */
 
      if (is_internal_port(BIF_ARG_1)) {
-	 Port *prt;
-	 erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_MAIN);
-	 prt = erts_id2port(BIF_ARG_1);
+	 Port *prt = erts_port_lookup(BIF_ARG_1, ERTS_PORT_SFLGS_INVALID_LOOKUP);
+
 	 if (prt) {
-	     erts_do_exit_port(prt, BIF_P->common.id, BIF_ARG_2);
-	     erts_port_release(prt);
+	     Eterm ref;
+	     Eterm *refp = erts_port_synchronous_ops ? &ref : NULL;
+	     ErtsPortOpResult res;
+
+#ifdef DEBUG
+	     ref = NIL;
+#endif
+
+	     res = erts_port_exit(BIF_P, 0, prt, BIF_P->common.id, BIF_ARG_2, refp);
+
+	     ERTS_BIF_CHK_EXITED(BIF_P);
+
+	     if (refp && res == ERTS_PORT_OP_SCHEDULED) {
+		 ASSERT(is_internal_ref(ref));
+		 BIF_TRAP3(await_port_send_result_trap, BIF_P, ref, am_true, am_true);
+	     }
+
 	 }
-	 erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_MAIN);
-	 ERTS_BIF_CHK_EXITED(BIF_P);
+
 	 BIF_RET(am_true);
      }
      else if(is_external_port(BIF_ARG_1)
@@ -1516,22 +1548,24 @@ BIF_RETTYPE process_flag_2(BIF_ALIST_2)
        }
        /*
 	* NOTE: It is important that we check for pending exit signals
-	*       and handle them before flag trap_exit is set to true.
-	*       For more info, see implementation of erts_send_exit_signal().
+	*       and handle them before returning if trap_exit is set to
+	*       true. For more info, see implementation of
+	*       erts_send_exit_signal().
 	*/
-       erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_STATUS);
-       ERTS_SMP_LC_ASSERT((ERTS_PROC_LOCK_MAIN|ERTS_PROC_LOCK_STATUS)
-			  & erts_proc_lc_my_proc_locks(BIF_P));
-       ERTS_SMP_BIF_CHK_PENDING_EXIT(BIF_P,
-				     ERTS_PROC_LOCK_MAIN|ERTS_PROC_LOCK_STATUS);
        if (trap_exit)
-	   state = erts_smp_atomic32_read_bor_nob(&BIF_P->state,
-						  ERTS_PSFLG_TRAP_EXIT);
+	   state = erts_smp_atomic32_read_bor_mb(&BIF_P->state,
+						 ERTS_PSFLG_TRAP_EXIT);
        else
-	   state = erts_smp_atomic32_read_band_nob(&BIF_P->state,
-						   ~ERTS_PSFLG_TRAP_EXIT);
+	   state = erts_smp_atomic32_read_band_mb(&BIF_P->state,
+						  ~ERTS_PSFLG_TRAP_EXIT);
+#ifdef ERTS_SMP
+       if (ERTS_PROC_PENDING_EXIT(BIF_P)) {
+	   erts_handle_pending_exit(BIF_P, ERTS_PROC_LOCK_MAIN);
+	   ERTS_BIF_EXITED(BIF_P);
+       }
+#endif
+
        old_value = (state & ERTS_PSFLG_TRAP_EXIT) ? am_true : am_false;
-       erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_STATUS);
        BIF_RET(old_value);
    }
    else if (BIF_ARG_1 == am_scheduler) {
@@ -1746,8 +1780,9 @@ ebif_bang_2(BIF_ALIST_2)
 #define SEND_BADARG		(-4)
 #define SEND_USER_ERROR		(-5)
 #define SEND_INTERNAL_ERROR	(-6)
+#define SEND_AWAIT_RESULT	(-7)
 
-Sint do_send(Process *p, Eterm to, Eterm msg, int suspend);
+Sint do_send(Process *p, Eterm to, Eterm msg, int suspend, Eterm *refp);
 
 static Sint remote_send(Process *p, DistEntry *dep,
 			Eterm to, Eterm full_to, Eterm msg, int suspend)
@@ -1801,7 +1836,7 @@ static Sint remote_send(Process *p, DistEntry *dep,
 }
 
 Sint
-do_send(Process *p, Eterm to, Eterm msg, int suspend) {
+do_send(Process *p, Eterm to, Eterm msg, int suspend, Eterm *refp) {
     Eterm portid;
     Port *pt;
     Process* rp;
@@ -1813,13 +1848,10 @@ do_send(Process *p, Eterm to, Eterm msg, int suspend) {
 	    trace_send(p, to, msg);
 	if (ERTS_PROC_GET_SAVED_CALLS_BUF(p))
 	    save_calls(p, &exp_send);
-	
-	rp = erts_proc_lookup_raw(to);
-	
-	if (!rp) {
-	    ERTS_SMP_ASSERT_IS_NOT_EXITING(p);
+
+	rp = erts_proc_lookup_raw(to);	
+	if (!rp)
 	    return 0;
-	}
     } else if (is_external_pid(to)) {
 	dep = external_pid_dist_entry(to);
 	if(dep == erts_this_dist_entry) {
@@ -1837,45 +1869,24 @@ do_send(Process *p, Eterm to, Eterm msg, int suspend) {
 	}
 	return remote_send(p, dep, to, to, msg, suspend);
     } else if (is_atom(to)) {
-	
-	/* Need to virtual schedule out sending process
-	 * because of lock wait. This is only necessary
-	 * for internal port calling but the lock is bundled
-	 * with name lookup.
-	 */
-	    
-	if (IS_TRACED_FL(p, F_TRACE_SCHED_PROCS)) {
-	    trace_virtual_sched(p, am_out);
-	}
-	if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-	    profile_runnable_proc(p, am_inactive);
-	}
-	erts_whereis_name(p, ERTS_PROC_LOCK_MAIN,
-			  to,
-			  &rp, 0, 0,
-			  &pt);
+	Eterm id = erts_whereis_name_to_id(p, to);
+
+	rp = erts_proc_lookup(id);
+	if (rp)
+	    goto send_message;
 
+	pt = erts_port_lookup(id, ERTS_PORT_SFLGS_INVALID_LOOKUP);
 	if (pt) {
-	    portid = pt->common.id;
+	    portid = id;
 	    goto port_common;
 	}
-	
-	/* Not a port virtually schedule the process back in */
-	if (IS_TRACED_FL(p, F_TRACE_SCHED_PROCS)) {
-	    trace_virtual_sched(p, am_in);
-	}
-	if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-	    profile_runnable_proc(p, am_active);
-	}
 
 	if (IS_TRACED(p))
 	    trace_send(p, to, msg);
 	if (ERTS_PROC_GET_SAVED_CALLS_BUF(p))
 	    save_calls(p, &exp_send);
 	
-	if (!rp) {
-	    return SEND_BADARG;
-	}
+	return SEND_BADARG;
     } else if (is_external_port(to)
 	       && (external_port_dist_entry(to)
 		   == erts_this_dist_entry)) {
@@ -1891,49 +1902,48 @@ do_send(Process *p, Eterm to, Eterm msg, int suspend) {
 	erts_send_error_to_logger(p->group_leader, dsbufp);
 	return 0;
     } else if (is_internal_port(to)) {
+	int ret_val;
 	portid = to;
-	/* schedule out calling process, waiting for lock*/
-	if (IS_TRACED_FL(p, F_TRACE_SCHED_PROCS)) {
-	    trace_virtual_sched(p, am_out);
-	}
-	if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-	    profile_runnable_proc(p, am_inactive);
-	}
-	pt = erts_id2port_sflgs(to,
-				p,
-				ERTS_PROC_LOCK_MAIN,
-				ERTS_PORT_SFLGS_INVALID_LOOKUP);
+
+	pt = erts_port_lookup(portid, ERTS_PORT_SFLGS_INVALID_LOOKUP);
+
       port_common:
-	ERTS_SMP_LC_ASSERT(!pt || erts_lc_is_port_locked(pt));
+	ret_val = 0;
         
-	/* We have waited for locks, trace schedule ports */
 	if (pt) {
-	    erts_aint32_t flags;
-	    if (IS_TRACED_FL(pt, F_TRACE_SCHED_PORTS)) {
-		trace_sched_ports_where(pt, am_in, am_command);
-	    }
-	    if (erts_system_profile_flags.runnable_ports && !erts_port_is_scheduled(pt)) {
-		profile_runnable_port(pt, am_active);
-	    }
-	
-	    flags = erts_atomic32_read_rb(&pt->sched.flags);
-	    /* XXX let port_command handle the busy stuff !!! */
-	    if (flags & ERTS_PTS_FLG_BUSY) {
+	    int ps_flags = suspend ? 0 : ERTS_PORT_SIG_FLG_NOSUSPEND;
+	    *refp = NIL;
+
+	    switch (erts_port_command(p, ps_flags, pt, msg, refp)) {
+	    case ERTS_PORT_OP_CALLER_EXIT:
+		/* We are exiting... */
+		return SEND_USER_ERROR;
+	    case ERTS_PORT_OP_BUSY:
+		/* Nothing has been sent */
+		if (suspend)
+		    erts_suspend(p, ERTS_PROC_LOCK_MAIN, pt);
+		return SEND_YIELD;
+	    case ERTS_PORT_OP_BUSY_SCHEDULED:
+		/* Message was sent */
 		if (suspend) {
 		    erts_suspend(p, ERTS_PROC_LOCK_MAIN, pt);
-		    if (erts_system_monitor_flags.busy_port) {
-			monitor_generic(p, am_busy_port, portid);
-		    }
-		}
-		/* Virtually schedule out the port before releasing */
-		if (IS_TRACED_FL(pt, F_TRACE_SCHED_PORTS)) {
-		    trace_sched_ports_where(pt, am_out, am_command);
+		    ret_val = SEND_YIELD_RETURN;
+		    break;
 		}
-		if (erts_system_profile_flags.runnable_ports && !erts_port_is_scheduled(pt)) {
-		    profile_runnable_port(pt, am_inactive);
+		/* Fall through */
+	    case ERTS_PORT_OP_SCHEDULED:
+		if (is_not_nil(*refp)) {
+		    ASSERT(is_internal_ref(*refp));
+		    ret_val = SEND_AWAIT_RESULT;
 		}
-		erts_port_release(pt);
-		return SEND_YIELD;
+		break;
+	    case ERTS_PORT_OP_DROPPED:
+	    case ERTS_PORT_OP_BADARG:
+	    case ERTS_PORT_OP_DONE:
+		break;
+	    default:
+		ERTS_INTERNAL_ERROR("Unexpected erts_port_command() result");
+		break;
 	    }
 	}
 	
@@ -1952,30 +1962,11 @@ do_send(Process *p, Eterm to, Eterm msg, int suspend) {
 			     SEQ_TRACE_SEND, portid, p);
 	}	    
 	
-	/* XXX NO GC in port command */
-	erts_port_command(p, p->common.id, pt, msg);
-	if (pt) {
-	    /* Virtually schedule out the port before releasing */
-	    if (IS_TRACED_FL(pt, F_TRACE_SCHED_PORTS)) {
-	    	trace_sched_ports_where(pt, am_out, am_command);
-	    }
-	    if (erts_system_profile_flags.runnable_ports && !erts_port_is_scheduled(pt)) {
-	    	profile_runnable_port(pt, am_inactive);
-	    }
-	    erts_port_release(pt);
-	}
-	/* Virtually schedule in process */
-	if (IS_TRACED_FL(p, F_TRACE_SCHED_PROCS)) {
-	    trace_virtual_sched(p, am_in);
-	}
-	if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-	    profile_runnable_proc(p, am_active);
-	}
 	if (ERTS_PROC_IS_EXITING(p)) {
 	    KILL_CATCHES(p); /* Must exit */
 	    return SEND_USER_ERROR;
 	}
-	return 0;
+	return ret_val;
     } else if (is_tuple(to)) { /* Remote send */
 	int ret;
 	tp = tuple_val(to);
@@ -1991,47 +1982,24 @@ do_send(Process *p, Eterm to, Eterm msg, int suspend) {
 	dep = erts_sysname_to_connected_dist_entry(tp[2]);
 
 	if (dep == erts_this_dist_entry) {
+	    Eterm id;
 	    erts_deref_dist_entry(dep);
 	    if (IS_TRACED(p))
 		trace_send(p, to, msg);
 	    if (ERTS_PROC_GET_SAVED_CALLS_BUF(p))
 		save_calls(p, &exp_send);
-	    
-	    /* Need to virtual schedule out sending process
-	     * because of lock wait. This is only necessary
-	     * for internal port calling but the lock is bundled.
-	     */
-	    
-	    if (IS_TRACED_FL(p, F_TRACE_SCHED_PROCS)) {
-	    	trace_virtual_sched(p, am_out);
-	    }
-	    if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-	    	profile_runnable_proc(p, am_inactive);
-	    }
 
-	    erts_whereis_name(p, ERTS_PROC_LOCK_MAIN,
-			      tp[1],
-			      &rp, 0, 0,
-			      &pt);
+	    id = erts_whereis_name_to_id(p, tp[1]);
+
+	    rp = erts_proc_lookup_raw(id);
+	    if (rp)
+		goto send_message;
+	    pt = erts_port_lookup(id, ERTS_PORT_SFLGS_INVALID_LOOKUP);
 	    if (pt) {
-		portid = pt->common.id;
+		portid = id;
 		goto port_common;
 	    }
-	    /* Port lookup failed, virtually schedule the process
-	     * back in.
-	     */
-
-	    if (IS_TRACED_FL(p, F_TRACE_SCHED_PROCS)) {
-	    	trace_virtual_sched(p, am_in);
-	    }
-	    if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-	    	profile_runnable_proc(p, am_active);
-	    }
-
-	    if (!rp) {
-		return 0;
-	    }
-	    goto send_message;
+	    return 0;
 	}
 
 	ret = remote_send(p, dep, tp[1], to, msg, suspend);
@@ -2070,6 +2038,7 @@ do_send(Process *p, Eterm to, Eterm msg, int suspend) {
 
 BIF_RETTYPE send_3(BIF_ALIST_3)
 {
+    Eterm ref;
     Process *p = BIF_P;
     Eterm to = BIF_ARG_1;
     Eterm msg = BIF_ARG_2;
@@ -2093,12 +2062,18 @@ BIF_RETTYPE send_3(BIF_ALIST_3)
     if(!is_nil(l)) {
 	BIF_ERROR(p, BADARG);
     }
-    
-    result = do_send(p, to, msg, suspend);
+
+#ifdef DEBUG
+    ref = NIL;
+#endif
+
+    result = do_send(p, to, msg, suspend, &ref);
     if (result > 0) {
 	ERTS_VBUMP_REDS(p, result);
 	BIF_RET(am_ok);
-    } else switch (result) {
+    }
+
+    switch (result) {
     case 0:
 	BIF_RET(am_ok); 
 	break;
@@ -2121,6 +2096,9 @@ BIF_RETTYPE send_3(BIF_ALIST_3)
 	    ERTS_BIF_YIELD_RETURN(p, am_ok);
 	else
 	    BIF_RET(am_nosuspend);
+    case SEND_AWAIT_RESULT:
+	ASSERT(is_internal_ref(ref));
+	BIF_TRAP3(await_port_send_result_trap, p, ref, am_nosuspend, am_ok);
     case SEND_BADARG:
 	BIF_ERROR(p, BADARG); 
 	break;
@@ -2145,12 +2123,21 @@ BIF_RETTYPE send_2(BIF_ALIST_2)
 
 Eterm erl_send(Process *p, Eterm to, Eterm msg)
 {
-    Sint result = do_send(p, to, msg, !0);
+    Eterm ref;
+    Sint result;
+
+#ifdef DEBUG
+    ref = NIL;
+#endif
+
+    result = do_send(p, to, msg, !0, &ref);
     
     if (result > 0) {
 	ERTS_VBUMP_REDS(p, result);
 	BIF_RET(msg);
-    } else switch (result) {
+    }
+
+    switch (result) {
     case 0:
 	BIF_RET(msg); 
 	break;
@@ -2162,6 +2149,9 @@ Eterm erl_send(Process *p, Eterm to, Eterm msg)
 	break;
     case SEND_YIELD_RETURN:
 	ERTS_BIF_YIELD_RETURN(p, msg);
+    case SEND_AWAIT_RESULT:
+	ASSERT(is_internal_ref(ref));
+	BIF_TRAP3(await_port_send_result_trap, p, ref, msg, msg);
     case SEND_BADARG:
 	BIF_ERROR(p, BADARG); 
 	break;
@@ -3166,11 +3156,9 @@ static erts_smp_spinlock_t make_ref_lock;
 static erts_smp_mtx_t ports_snapshot_mtx;
 erts_smp_atomic_t erts_dead_ports_ptr; /* To store dying ports during snapshot */
 
-Eterm erts_make_ref_in_buffer(Eterm buffer[REF_THING_SIZE])
+void
+erts_make_ref_in_array(Uint32 ref[ERTS_MAX_REF_NUMBERS])
 {
-    Eterm* hp = buffer;
-    Uint32 ref0, ref1, ref2;
-
     erts_smp_spin_lock(&make_ref_lock);
 
     reference0++;
@@ -3182,24 +3170,36 @@ Eterm erts_make_ref_in_buffer(Eterm buffer[REF_THING_SIZE])
 	}
     }
 
-    ref0 = reference0;
-    ref1 = reference1;
-    ref2 = reference2;
+    ref[0] = reference0;
+    ref[1] = reference1;
+    ref[2] = reference2;
 
     erts_smp_spin_unlock(&make_ref_lock);
+}
+
+Eterm erts_make_ref_in_buffer(Eterm buffer[REF_THING_SIZE])
+{
+    Eterm* hp = buffer;
+    Uint32 ref[ERTS_MAX_REF_NUMBERS];
 
-    write_ref_thing(hp, ref0, ref1, ref2);
+    erts_make_ref_in_array(ref);
+    write_ref_thing(hp, ref[0], ref[1], ref[2]);
     return make_internal_ref(hp);
 }
 
 Eterm erts_make_ref(Process *p)
 {
     Eterm* hp;
+    Uint32 ref[ERTS_MAX_REF_NUMBERS];
 
     ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_MAIN & erts_proc_lc_my_proc_locks(p));
 
     hp = HAlloc(p, REF_THING_SIZE);
-    return erts_make_ref_in_buffer(hp);
+
+    erts_make_ref_in_array(ref);
+    write_ref_thing(hp, ref[0], ref[1], ref[2]);
+
+    return make_internal_ref(hp);
 }
 
 BIF_RETTYPE make_ref_0(BIF_ALIST_0)
@@ -4507,6 +4507,8 @@ void erts_init_bif(void)
 						    am_format_cpu_topology,
 						    1);
     await_proc_exit_trap = erts_export_put(am_erlang,am_await_proc_exit,3);
+    await_port_send_result_trap
+	= erts_export_put(am_erts_internal, am_await_port_send_result, 3);
     await_sched_wall_time_mod_trap
 	= erts_export_put(am_erlang, am_await_sched_wall_time_modifications, 2);
     erts_smp_atomic32_init_nob(&sched_wall_time, 0);
@@ -4522,19 +4524,18 @@ bif erlang:send_to_logger/2
 BIF_RETTYPE send_to_logger_2(BIF_ALIST_2)
 {
     byte *buf;
-    int len;
+    ErlDrvSizeT len;
     if (!is_atom(BIF_ARG_1) || !(is_list(BIF_ARG_2) ||
 				 is_nil(BIF_ARG_1))) {
 	BIF_ERROR(BIF_P,BADARG);
     }
-    len = io_list_len(BIF_ARG_2);
-    if (len < 0)
+    if (erts_iolist_size(BIF_ARG_2, &len) != 0)
 	BIF_ERROR(BIF_P,BADARG);
     else if (len == 0)
 	buf = "";
     else {
 #ifdef DEBUG
-	int len2;
+	ErlDrvSizeT len2;
 #endif
 	buf = (byte *) erts_alloc(ERTS_ALC_T_TMP, len+1);
 #ifdef DEBUG
@@ -4542,7 +4543,7 @@ BIF_RETTYPE send_to_logger_2(BIF_ALIST_2)
 #else
 	(void)
 #endif
-	    io_list_to_buf(BIF_ARG_2, buf, len);
+	    erts_iolist_to_buf(BIF_ARG_2, buf, len);
 	ASSERT(len2 == len);
 	buf[len] = '\0';
 	switch (BIF_ARG_1) {
@@ -4636,7 +4637,6 @@ BIF_RETTYPE dt_prepend_vm_tag_data_1(BIF_ALIST_1)
 #ifdef USE_VM_PROBES
     Eterm b; 
     Eterm *hp;
-    hp = HAlloc(BIF_P,2);
     if (is_binary((DT_UTAG(BIF_P)))) {
 	Uint sz = binary_size(DT_UTAG(BIF_P));
 	int i;
@@ -4653,6 +4653,7 @@ BIF_RETTYPE dt_prepend_vm_tag_data_1(BIF_ALIST_1)
     } else {
 	b = new_binary(BIF_P,(byte *)"\0",1);
     }
+    hp = HAlloc(BIF_P,2);
     BIF_RET(CONS(hp,b,BIF_ARG_1));
 #else
     BIF_RET(BIF_ARG_1);
@@ -4663,7 +4664,6 @@ BIF_RETTYPE dt_append_vm_tag_data_1(BIF_ALIST_1)
 #ifdef USE_VM_PROBES
     Eterm b; 
     Eterm *hp;
-    hp = HAlloc(BIF_P,2);
     if (is_binary((DT_UTAG(BIF_P)))) {
 	Uint sz = binary_size(DT_UTAG(BIF_P));
 	int i;
@@ -4680,6 +4680,7 @@ BIF_RETTYPE dt_append_vm_tag_data_1(BIF_ALIST_1)
     } else {
 	b = new_binary(BIF_P,(byte *)"\0",1);
     }
+    hp = HAlloc(BIF_P,2);
     BIF_RET(CONS(hp,BIF_ARG_1,b));
 #else
     BIF_RET(BIF_ARG_1);
diff --git a/erts/emulator/beam/bif.h b/erts/emulator/beam/bif.h
index d20089a9fb..086dd9a5fd 100644
--- a/erts/emulator/beam/bif.h
+++ b/erts/emulator/beam/bif.h
@@ -322,27 +322,6 @@ do {					\
 	ERTS_BIF_EXITED((PROC));	\
 } while (0)
 
-#ifdef ERTS_SMP
-#define ERTS_SMP_BIF_CHK_PENDING_EXIT(P, L)				\
-do {									\
-    ERTS_SMP_LC_ASSERT((L) == erts_proc_lc_my_proc_locks((P)));		\
-    ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_MAIN & (L));			\
-    if (!((L) & ERTS_PROC_LOCK_STATUS))					\
-	erts_smp_proc_lock((P), ERTS_PROC_LOCK_STATUS);			\
-    if (ERTS_PROC_PENDING_EXIT((P))) {					\
-	erts_handle_pending_exit((P), (L)|ERTS_PROC_LOCK_STATUS);	\
-	erts_smp_proc_unlock((P),					\
-			     (((L)|ERTS_PROC_LOCK_STATUS)		\
-			      & ~ERTS_PROC_LOCK_MAIN));			\
-	ERTS_BIF_EXITED((P));						\
-    }									\
-    if (!((L) & ERTS_PROC_LOCK_STATUS))					\
-	erts_smp_proc_unlock((P), ERTS_PROC_LOCK_STATUS);		\
-} while (0)
-#else
-#define ERTS_SMP_BIF_CHK_PENDING_EXIT(P, L)
-#endif
-
 /*
  * The ERTS_BIF_*_AWAIT_X_*_TRAP makros either exits the caller, or
  * sets up a trap to erlang:await_proc_exit/3.
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index 8a85e102d1..c0a83c6f96 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -184,10 +184,6 @@ bif 'erl.lang.port':open/2		ebif_open_port_2 open_port_2
 
 bif erlang:pid_to_list/1
 bif 'erl.lang.proc':pid_to_string/1	ebif_pid_to_string_1 pid_to_list_1
-bif erlang:port_info/1
-bif 'erl.lang.port':info/1		ebif_port_info_1
-bif erlang:port_info/2
-bif 'erl.lang.port':info/2		ebif_port_info_2
 bif erlang:ports/0
 bif 'erl.lang.node':ports/0		ebif_ports_0
 bif erlang:pre_loaded/0
@@ -256,24 +252,16 @@ bif erlang:setnode/2
 bif erlang:setnode/3
 bif erlang:dist_exit/3
 
-bif erlang:port_call/2
-bif 'erl.lang.port':call/2		ebif_port_call_2
-bif erlang:port_call/3
-bif 'erl.lang.port':call/3		ebif_port_call_3
-bif erlang:port_command/2
-bif 'erl.lang.port':command/2		ebif_port_command_2
-bif erlang:port_command/3
-bif 'erl.lang.port':command/3		ebif_port_command_3
-bif erlang:port_control/3
-bif 'erl.lang.port':control/3		ebif_port_control_3
-bif erlang:port_close/1
-bif 'erl.lang.port':close/1		ebif_port_close_1
-bif erlang:port_connect/2
-bif 'erl.lang.port':connect/2		ebif_port_connect_2
-bif erlang:port_set_data/2
-bif 'erl.lang.port':set_data/2		ebif_port_set_data_2
-bif erlang:port_get_data/1
-bif 'erl.lang.port':get_data/1		ebif_port_get_data_1
+# Static native functions in erts_internal
+bif erts_internal:port_info/1
+bif erts_internal:port_info/2
+bif erts_internal:port_call/3
+bif erts_internal:port_command/3
+bif erts_internal:port_control/3
+bif erts_internal:port_close/1
+bif erts_internal:port_connect/2
+bif erts_internal:port_set_data/2
+bif erts_internal:port_get_data/1
 
 # Tracing & debugging.
 bif erlang:trace_pattern/2
diff --git a/erts/emulator/beam/binary.c b/erts/emulator/beam/binary.c
index 3d2725e239..4441dab181 100644
--- a/erts/emulator/beam/binary.c
+++ b/erts/emulator/beam/binary.c
@@ -355,10 +355,10 @@ BIF_RETTYPE bitstring_to_list_1(BIF_ALIST_1)
 BIF_RETTYPE erts_list_to_binary_bif(Process *p, Eterm arg)
 {
     Eterm bin;
-    Uint size;
+    ErlDrvSizeT size;
     byte* bytes;
 #ifdef DEBUG
-    int offset;
+    ErlDrvSizeT offset;
 #endif
 
     if (is_nil(arg)) {
@@ -377,7 +377,7 @@ BIF_RETTYPE erts_list_to_binary_bif(Process *p, Eterm arg)
 #ifdef DEBUG
     offset = 
 #endif
-	io_list_to_buf(arg, (char*) bytes, size);
+	erts_iolist_to_buf(arg, (char*) bytes, size);
 
     ASSERT(offset == 0);
     BIF_RET(bin);
diff --git a/erts/emulator/beam/dist.c b/erts/emulator/beam/dist.c
index f28d9dff09..a939b90eac 100644
--- a/erts/emulator/beam/dist.c
+++ b/erts/emulator/beam/dist.c
@@ -124,6 +124,13 @@ static void send_nodes_mon_msgs(Process *, Eterm, Eterm, Eterm, Eterm);
 static void init_nodes_monitors(void);
 
 static erts_smp_atomic_t no_caches;
+static erts_smp_atomic_t no_nodes;
+
+struct {
+    Eterm reason;
+    ErlHeapFragment *bp;
+} nodedown;
+
 
 static void
 delete_cache(ErtsAtomCache *cache)
@@ -393,6 +400,47 @@ static void doit_node_link_net_exits(ErtsLink *lnk, void *vnecp)
     erts_destroy_link(lnk);
 }
 
+static void
+set_node_not_alive(void *unused)
+{
+    ErlHeapFragment *bp;
+    Eterm nodename = erts_this_dist_entry->sysname;
+
+    ASSERT(erts_smp_atomic_read_nob(&no_nodes) == 0);
+
+    erts_smp_thr_progress_block();
+    erts_set_this_node(am_Noname, 0);
+    erts_is_alive = 0;
+    send_nodes_mon_msgs(NULL, am_nodedown, nodename, am_visible, nodedown.reason);
+    nodedown.reason = NIL;
+    bp = nodedown.bp;
+    nodedown.bp = NULL;
+    erts_smp_thr_progress_unblock();
+    if (bp)
+	free_message_buffer(bp);
+}
+
+static ERTS_INLINE void
+dec_no_nodes(void)
+{
+    erts_aint_t no = erts_smp_atomic_dec_read_mb(&no_nodes);
+    ASSERT(no >= 0);
+    ASSERT(erts_get_scheduler_id()); /* Need to be a scheduler */
+    if (no == 0)
+	erts_schedule_misc_aux_work(erts_get_scheduler_id(),
+				    set_node_not_alive,
+				    NULL);
+}
+
+static ERTS_INLINE void
+inc_no_nodes(void)
+{
+#ifdef DEBUG
+    erts_aint_t no = erts_smp_atomic_read_nob(&no_nodes);
+    ASSERT(erts_is_alive ? no > 0 : no == 0);
+#endif
+    erts_smp_atomic_inc_mb(&no_nodes);
+}
 	
 /*
  * proc is currently running or exiting process.
@@ -402,48 +450,76 @@ int erts_do_net_exits(DistEntry *dep, Eterm reason)
     Eterm nodename;
 
     if (dep == erts_this_dist_entry) {  /* Net kernel has died (clean up!!) */
+	DistEntry *tdep;
+	int no_dist_port = 0;
 	Eterm nd_reason = (reason == am_no_network
 			   ? am_no_network
 			   : am_net_kernel_terminated);
 	erts_smp_rwmtx_rwlock(&erts_dist_table_rwmtx);
 
+	for (tdep = erts_hidden_dist_entries; tdep; tdep = tdep->next)
+	    no_dist_port++;
+	for (tdep = erts_visible_dist_entries; tdep; tdep = tdep->next)
+	    no_dist_port++;
+
 	/* KILL all port controllers */
-	while(erts_visible_dist_entries || erts_hidden_dist_entries) {
-	    DistEntry *tdep;
-	    Eterm prt_id;
-	    Port *prt;
-	    if(erts_hidden_dist_entries)
-		tdep = erts_hidden_dist_entries;
+	if (no_dist_port == 0)
+	    erts_smp_rwmtx_rwunlock(&erts_dist_table_rwmtx);
+	else {
+	    Eterm def_buf[128];
+	    int i = 0;
+	    Eterm *dist_port;
+
+	    if (no_dist_port <= sizeof(def_buf)/sizeof(def_buf[0]))
+		dist_port = &def_buf[0];
 	    else
-		tdep = erts_visible_dist_entries;
-	    prt_id = tdep->cid;
-	    ASSERT(is_internal_port(prt_id));
+		dist_port = erts_alloc(ERTS_ALC_T_TMP,
+				       sizeof(Eterm)*no_dist_port);
+	    for (tdep = erts_hidden_dist_entries; tdep; tdep = tdep->next) {
+		ASSERT(is_internal_port(tdep->cid));
+		dist_port[i++] = tdep->cid;
+	    }
+	    for (tdep = erts_visible_dist_entries; tdep; tdep = tdep->next) {
+		ASSERT(is_internal_port(tdep->cid));
+		dist_port[i++] = tdep->cid;
+	    }
 	    erts_smp_rwmtx_rwunlock(&erts_dist_table_rwmtx);
 
-	    prt = erts_id2port(prt_id);
-	    if (prt) {
+	    for (i = 0; i < no_dist_port; i++) {
+		Port *prt = erts_port_lookup(dist_port[i],
+					     ERTS_PORT_SFLGS_INVALID_LOOKUP);
+		if (!prt)
+		    continue;
 		ASSERT(erts_atomic32_read_nob(&prt->state)
 		       & ERTS_PORT_SFLG_DISTRIBUTION);
-		ASSERT(prt->dist_entry);
-		/* will call do_net_exists !!! */
-		erts_do_exit_port(prt, prt_id, nd_reason);
-		erts_port_release(prt);
+
+		erts_port_exit(NULL, ERTS_PORT_SIG_FLG_FORCE_SCHED,
+			       prt, dist_port[i], nd_reason, NULL);
 	    }
 
-	    erts_smp_rwmtx_rwlock(&erts_dist_table_rwmtx);
+	    if (dist_port != &def_buf[0])
+		erts_free(ERTS_ALC_T_TMP, dist_port);
 	}
 
-	erts_smp_rwmtx_rwunlock(&erts_dist_table_rwmtx);
-
-	nodename = erts_this_dist_entry->sysname;
-	erts_smp_thr_progress_block();
-	erts_set_this_node(am_Noname, 0);
-	erts_is_alive = 0;
-	send_nodes_mon_msgs(NULL, am_nodedown, nodename, am_visible, nd_reason);
-	erts_smp_thr_progress_unblock();
-
+	/*
+	 * When last dist port exits, node will be taken
+	 * from alive to not alive.
+	 */
+	ASSERT(is_nil(nodedown.reason) && !nodedown.bp);
+	if (is_immed(nd_reason))
+	    nodedown.reason = nd_reason;
+	else {
+	    Eterm *hp;
+	    Uint sz = size_object(nd_reason);
+	    nodedown.bp = new_message_buffer(sz);
+	    hp = nodedown.bp->mem;
+	    nodedown.reason = copy_struct(nd_reason,
+					  sz,
+					  &hp,
+					  &nodedown.bp->off_heap);
+	}
     }
-    else { /* recursive call via erts_do_exit_port() will end up here */
+    else { /* Call from distribution port */
 	NetExitsContext nec = {dep};
 	ErtsLink *nlinks;
 	ErtsLink *node_links;
@@ -503,6 +579,9 @@ int erts_do_net_exits(DistEntry *dep, Eterm reason)
 	clear_dist_entry(dep);
 
     }
+
+    dec_no_nodes();
+
     return 1;
 }
 
@@ -516,6 +595,10 @@ void init_dist(void)
 {
     init_nodes_monitors();
 
+    nodedown.reason = NIL;
+    nodedown.bp = NULL;
+
+    erts_smp_atomic_init_nob(&no_nodes, 0);
     erts_smp_atomic_init_nob(&no_caches, 0);
 
     /* Lookup/Install all references to trap functions */
@@ -1601,7 +1684,7 @@ int erts_net_message(Port *prt,
     }
 #endif
     UnUseTmpHeapNoproc(DIST_CTL_DEFAULT_SIZE);
-    erts_do_exit_port(prt, dep->cid, am_killed);
+    erts_deliver_port_exit(prt, dep->cid, am_killed, 0);
     ERTS_SMP_CHK_NO_PROC_LOCKS;
     return -1;
 }
@@ -1924,7 +2007,7 @@ erts_dist_command(Port *prt, int reds_limit)
     erts_smp_de_runlock(dep);
 
     if (status & ERTS_DE_SFLG_EXITING) {
-	erts_do_exit_port(prt, prt->common.id, am_killed);
+	erts_deliver_port_exit(prt, prt->common.id, am_killed, 0);
 	erts_deref_dist_entry(dep);
 	return reds + ERTS_PORT_REDS_DIST_CMD_EXIT;
     }
@@ -2484,6 +2567,7 @@ BIF_RETTYPE setnode_2(BIF_ALIST_2)
 
     erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_MAIN);
     erts_smp_thr_progress_block();
+    inc_no_nodes();
     erts_set_this_node(BIF_ARG_1, (Uint32) creation);
     erts_is_alive = 1;
     send_nodes_mon_msgs(NULL, am_nodeup, BIF_ARG_1, am_visible, NIL);
@@ -2638,6 +2722,8 @@ BIF_RETTYPE setnode_3(BIF_ALIST_3)
     erts_smp_de_rwunlock(dep);
     dep = NULL; /* inc of refc transferred to port (dist_entry field) */
 
+    inc_no_nodes();
+
     send_nodes_mon_msgs(BIF_P,
 			am_nodeup,
 			BIF_ARG_1,
@@ -2723,11 +2809,17 @@ BIF_RETTYPE dist_exit_3(BIF_ALIST_3)
 #endif
 	erts_smp_proc_unlock(lp, lp_locks);
 	if (lp == BIF_P) {
+	    erts_aint32_t state = erts_smp_atomic32_read_acqb(&BIF_P->state);
 	    /*
 	     * We may have exited current process and may have to take action.
 	     */
-	    ERTS_BIF_CHK_EXITED(BIF_P);
-	    ERTS_SMP_BIF_CHK_PENDING_EXIT(BIF_P, ERTS_PROC_LOCK_MAIN);
+	    if (state & (ERTS_PSFLG_EXITING|ERTS_PSFLG_PENDING_EXIT)) {
+#ifdef ERTS_SMP
+		if (state & ERTS_PSFLG_PENDING_EXIT)
+		    erts_handle_pending_exit(BIF_P, ERTS_PROC_LOCK_MAIN);
+#endif
+		ERTS_BIF_EXITED(BIF_P);
+	    }
 	}
     }
     else if (is_external_pid(local)
diff --git a/erts/emulator/beam/erl_alloc.types b/erts/emulator/beam/erl_alloc.types
index 36beec9553..264cbf8efe 100644
--- a/erts/emulator/beam/erl_alloc.types
+++ b/erts/emulator/beam/erl_alloc.types
@@ -190,6 +190,9 @@ type	TIMER_WHEEL	LONG_LIVED	SYSTEM		timer_wheel
 type	DRV		DRIVER		SYSTEM		drv_internal
 type	DRV_BINARY	BINARY		BINARIES	drv_binary
 type	DRIVER		DRIVER		SYSTEM		driver
+type	DRV_CMD_DATA	DRIVER		SYSTEM		driver_command_data
+type	DRV_CTRL_DATA	DRIVER		SYSTEM		driver_control_data
+type	DRV_CALL_DATA	DRIVER		SYSTEM		driver_call_data
 type	NIF		DRIVER		SYSTEM		nif_internal
 type	BINARY		BINARY		BINARIES	binary
 type	NBIF_TABLE	SYSTEM		SYSTEM		nbif_tab
@@ -203,7 +206,6 @@ type	BITS_BUF	STANDARD	SYSTEM		bits_buf
 type	TMP_DIST_BUF	TEMPORARY	SYSTEM		tmp_dist_buf
 type	ASYNC_DATA	LONG_LIVED	SYSTEM		internal_async_data
 type	ESTACK		TEMPORARY	SYSTEM		estack
-type	PORT_CALL_BUF	TEMPORARY	SYSTEM		port_call_buf
 type	DB_TABLE	ETS		ETS		db_tab
 type	DB_FIXATION	SHORT_LIVED	ETS		db_fixation
 type	DB_FIX_DEL	SHORT_LIVED	ETS		fixed_del
@@ -233,6 +235,7 @@ type	DDLL_HANDLE	STANDARD	SYSTEM		ddll_handle
 type	DDLL_ERRCODES	LONG_LIVED	SYSTEM		ddll_errcodes
 type	DDLL_TMP_BUF	TEMPORARY	SYSTEM		ddll_tmp_buf
 type	PORT_TASK	SHORT_LIVED	SYSTEM		port_task
+type	PT_HNDL_LIST	SHORT_LIVED	SYSTEM		port_task_handle_list
 type	MISC_OP_LIST	SHORT_LIVED	SYSTEM		misc_op_list
 type	PORT_NAMES	SHORT_LIVED	SYSTEM		port_names
 type	PORT_DATA_LOCK	DRIVER		SYSTEM		port_data_lock
@@ -262,6 +265,8 @@ type	ZLIB		STANDARD	SYSTEM		zlib
 type	CPU_GRPS_MAP	LONG_LIVED	SYSTEM		cpu_groups_map
 type	AUX_WORK_TMO	LONG_LIVED	SYSTEM		aux_work_timeouts
 type	MISC_AUX_WORK_Q	LONG_LIVED	SYSTEM		misc_aux_work_q
+type    BUSY_CALLER_TAB	SHORT_LIVED	SYSTEM		busy_caller_table
+type    BUSY_CALLER	SHORT_LIVED	SYSTEM		busy_caller
 
 +if threads_no_smp
 # Need thread safe allocs, but std_alloc and fix_alloc are not;
diff --git a/erts/emulator/beam/erl_bif_ddll.c b/erts/emulator/beam/erl_bif_ddll.c
index 2b6deae7be..7cbea55eac 100644
--- a/erts/emulator/beam/erl_bif_ddll.c
+++ b/erts/emulator/beam/erl_bif_ddll.c
@@ -182,7 +182,7 @@ BIF_RETTYPE erl_ddll_try_load_3(BIF_ALIST_3)
     Eterm name_term = BIF_ARG_2;
     Eterm options = BIF_ARG_3;
     char *path = NULL;
-    Uint path_len;
+    ErlDrvSizeT path_len;
     char *name = NULL;
     DE_Handle *dh;
     erts_driver_t *drv;
@@ -261,7 +261,7 @@ BIF_RETTYPE erl_ddll_try_load_3(BIF_ALIST_3)
 	goto error;
     }
     path = erts_alloc(ERTS_ALC_T_DDLL_TMP_BUF, path_len + 1 /* might need path separator */ + sys_strlen(name) + 1);
-    if (io_list_to_buf(path_term, path, path_len) != 0) {
+    if (erts_iolist_to_buf(path_term, path, path_len) != 0) {
 	goto error;
     }
     while (path_len > 0 && (path[path_len-1] == '\\' || path[path_len-1] == '/')) {
@@ -1841,7 +1841,7 @@ static Eterm mkatom(char *str)
 static char *pick_list_or_atom(Eterm name_term)
 { 
     char *name = NULL;
-    Uint name_len;
+    ErlDrvSizeT name_len;
     if (is_atom(name_term)) {
 	Atom *ap = atom_tab(atom_val(name_term));
 	if (ap->len == 0) {
@@ -1857,7 +1857,7 @@ static char *pick_list_or_atom(Eterm name_term)
 	    goto error;
 	}
 	name = erts_alloc(ERTS_ALC_T_DDLL_TMP_BUF, name_len + 1);
-	if (io_list_to_buf(name_term, name, name_len) != 0) {
+	if (erts_iolist_to_buf(name_term, name, name_len) != 0) {
 	    goto error;
 	}
 	name[name_len] = '\0';
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 44c29252b2..f5a355a336 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -137,8 +137,6 @@ static char erts_system_version[] = ("Erlang " ERLANG_OTP_RELEASE
 static Eterm os_type_tuple;
 static Eterm os_version_tuple;
 
-static BIF_RETTYPE port_info(Process* p, Eterm portid, Eterm item);
-
 static Eterm
 current_function(Process* p, Process* rp, Eterm** hpp, int full_info);
 static Eterm current_stacktrace(Process* p, Process* rp, Eterm** hpp);
@@ -1864,17 +1862,17 @@ info_1_tuple(Process* BIF_P,	/* Pointer to current process. */
 #    define ERTS_ERROR_CHECKER_PRINTF_XML VALGRIND_PRINTF_XML
 #  endif
 #endif
-	    Uint buf_size = 8*1024; /* Try with 8KB first */
+	    ErlDrvSizeT buf_size = 8*1024; /* Try with 8KB first */
 	    char *buf = erts_alloc(ERTS_ALC_T_TMP, buf_size);
-	    int r = io_list_to_buf(*tp, (char*) buf, buf_size - 1);
-	    if (r < 0) {
+	    ErlDrvSizeT r = erts_iolist_to_buf(*tp, (char*) buf, buf_size - 1);
+	    if (ERTS_IOLIST_TO_BUF_FAILED(r)) {
 		erts_free(ERTS_ALC_T_TMP, (void *) buf);
 		if (erts_iolist_size(*tp, &buf_size)) {
 		    goto badarg;
 		}
 		buf_size++;
 		buf = erts_alloc(ERTS_ALC_T_TMP, buf_size);
-		r = io_list_to_buf(*tp, (char*) buf, buf_size - 1);
+		r = erts_iolist_to_buf(*tp, (char*) buf, buf_size - 1);
 		ASSERT(r == buf_size - 1);
 	    }
 	    buf[buf_size - 1 - r] = '\0';
@@ -2593,6 +2591,9 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
     } else if (ERTS_IS_ATOM_STR("run_queues", BIF_ARG_1)) {
 	res = make_small(erts_no_run_queues);
 	BIF_RET(res);
+    } else if (ERTS_IS_ATOM_STR("port_parallelism", BIF_ARG_1)) {
+	res = erts_port_parallelism ? am_true : am_false;
+	BIF_RET(res);
     } else if (ERTS_IS_ATOM_STR("c_compiler_used", BIF_ARG_1)) {
 	Eterm *hp = NULL;
 	Uint sz = 0;
@@ -2760,65 +2761,6 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
     BIF_ERROR(BIF_P, BADARG);
 }
 
-BIF_RETTYPE
-port_info_1(BIF_ALIST_1)
-{
-    Process* p = BIF_P;
-    Eterm pid = BIF_ARG_1;
-    static Eterm keys[] = {
-	am_name,
-	am_links,
-	am_id,
-	am_connected,
-	am_input,
-	am_output
-    };
-    Eterm items[ASIZE(keys)];
-    Eterm result = NIL;
-    Eterm reg_name;
-    Eterm* hp;
-    Uint need;
-    int i;
-
-    /*
-     * Collect all information about the port.
-     */
-
-    for (i = 0; i < ASIZE(keys); i++) {
-	Eterm item;
-
-	item = port_info(p, pid, keys[i]);
-	if (is_non_value(item)) {
-	    return THE_NON_VALUE;
-	}
-	if (item == am_undefined) {
-	    return am_undefined;
-	}
-	items[i] = item;
-    }
-    reg_name = port_info(p, pid, am_registered_name);
-
-    /*
-     * Build the resulting list.
-     */
-
-    need = 2*ASIZE(keys);
-    if (is_tuple(reg_name)) {
-	need += 2;
-    }
-    hp = HAlloc(p, need);
-    for (i = ASIZE(keys) - 1; i >= 0; i--) {
-	result = CONS(hp, items[i], result);
-	hp += 2;
-    }
-    if (is_tuple(reg_name)) {
-	result = CONS(hp, reg_name, result);
-    }
-
-    return result;
-}
-
-
 /**********************************************************************/ 
 /* Return information on ports */
 /* Info:
@@ -2830,41 +2772,20 @@ port_info_1(BIF_ALIST_1)
 **    output      Number of bytes output to the port program
 */
 
-BIF_RETTYPE port_info_2(BIF_ALIST_2)
-{
-    return port_info(BIF_P, BIF_ARG_1, BIF_ARG_2);
-}
-
-static BIF_RETTYPE port_info(Process* p, Eterm portid, Eterm item)
+Eterm
+erts_bld_port_info(Eterm **hpp, ErlOffHeap *ohp, Uint *szp, Port *prt, Eterm item)
 {
-    BIF_RETTYPE ret;
-    Port *prt;
-    Eterm res;
-    Eterm* hp;
-    int count;
-
-    if (is_internal_port(portid))
-	prt = erts_id2port_sflgs(portid,
-				 p,
-				 ERTS_PROC_LOCK_MAIN,
-				 ERTS_PORT_SFLGS_INVALID_LOOKUP);
-    else if (is_atom(portid))
-	erts_whereis_name(p, ERTS_PROC_LOCK_MAIN,
-			  portid, NULL, 0, 0, &prt);
-    else if (is_external_port(portid)
-	     && external_port_dist_entry(portid) == erts_this_dist_entry)
-	BIF_RET(am_undefined);
-    else {
-	BIF_ERROR(p, BADARG);
-    }
+    Eterm res = THE_NON_VALUE;
 
-    if (!prt) {
-	BIF_RET(am_undefined);
-    }
+    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
 
     if (item == am_id) {
-	hp = HAlloc(p, 3);
-	res = make_small(internal_port_number(portid));
+	if (hpp)
+	    res = make_small(internal_port_index(prt->common.id));
+	if (szp) {
+	    res = am_true;
+	    goto done;
+	}
     }
     else if (item == am_links) {
 	MonitorInfoCollection mic;
@@ -2875,15 +2796,24 @@ static BIF_RETTYPE port_info(Process* p, Eterm portid, Eterm item)
 
 	erts_doforall_links(ERTS_P_LINKS(prt), &collect_one_link, &mic);
 
-	hp = HAlloc(p, 3 + mic.sz);
-	res = NIL;
-	for (i = 0; i < mic.mi_i; i++) {
-	    item = STORE_NC(&hp, &MSO(p), mic.mi[i].entity);
-	    res = CONS(hp, item, res);
-	    hp += 2;
+	if (szp)
+	    *szp += mic.sz;
+
+	if (hpp) {
+	    res = NIL;
+	    for (i = 0; i < mic.mi_i; i++) {
+		item = STORE_NC(hpp, ohp, mic.mi[i].entity);
+		res = CONS(*hpp, item, res);
+		*hpp += 2;
+	    }
 	}
+
 	DESTROY_MONITOR_INFOS(mic);
 
+	if (szp) {
+	    res = am_true;
+	    goto done;
+	}
     }
     else if (item == am_monitors) {
 	MonitorInfoCollection mic;
@@ -2894,64 +2824,84 @@ static BIF_RETTYPE port_info(Process* p, Eterm portid, Eterm item)
 
 	erts_doforall_monitors(ERTS_P_MONITORS(prt), &collect_one_origin_monitor, &mic);
 
-	hp = HAlloc(p, 3 + mic.sz);
-	res = NIL;
-	for (i = 0; i < mic.mi_i; i++) {
-	    Eterm t;
-	    item = STORE_NC(&hp, &MSO(p), mic.mi[i].entity);
-	    t = TUPLE2(hp, am_process, item);
-	    hp += 3;
-	    res = CONS(hp, t, res);
-	    hp += 2;
+	if (szp)
+	    *szp += mic.sz;
+
+	if (hpp) {
+	    res = NIL;
+	    for (i = 0; i < mic.mi_i; i++) {
+		Eterm t;
+		item = STORE_NC(hpp, ohp, mic.mi[i].entity);
+		t = TUPLE2(*hpp, am_process, item);
+		*hpp += 3;
+		res = CONS(*hpp, t, res);
+		*hpp += 2;
+	    }
 	}
+
 	DESTROY_MONITOR_INFOS(mic);
 
+	if (szp) {
+	    res = am_true;
+	    goto done;
+	}
     }
     else if (item == am_name) {
-	count = sys_strlen(prt->name);
+	int count = sys_strlen(prt->name);
 
-	hp = HAlloc(p, 3 + 2*count);
-	res = buf_to_intlist(&hp, prt->name, count, NIL);
+	if (hpp)
+	    res = buf_to_intlist(hpp, prt->name, count, NIL);
+
+	if (szp) {
+	    *szp += 2*count;
+	    res = am_true;
+	    goto done;
+	}
     }
     else if (item == am_connected) {
-	hp = HAlloc(p, 3);
-	res = ERTS_PORT_GET_CONNECTED(prt); /* internal pid */
+	if (hpp)
+	    res = ERTS_PORT_GET_CONNECTED(prt); /* internal pid */
+	if (szp) {
+	    res = am_true;
+	    goto done;
+	}
     }
     else if (item == am_input) {
-	Uint hsz = 3;
-	Uint n = prt->bytes_in;
-	(void) erts_bld_uint(NULL, &hsz, n);
-	hp = HAlloc(p, hsz);
-	res = erts_bld_uint(&hp, NULL, n);
+	res = erts_bld_uint(hpp, szp, prt->bytes_in);
+	if (szp) {
+	    res = am_true;
+	    goto done;
+	}
     }
     else if (item == am_output) {
-	Uint hsz = 3;
-	Uint n = prt->bytes_out;
-	(void) erts_bld_uint(NULL, &hsz, n);
-	hp = HAlloc(p, hsz);
-	res = erts_bld_uint(&hp, NULL, n);
+	res = erts_bld_uint(hpp, szp, prt->bytes_out);
+	if (szp) {
+	    res = am_true;
+	    goto done;
+	}
     }
     else if (item == am_registered_name) {
-	RegProc *reg;
-	reg = prt->common.u.alive.reg;
-	if (reg == NULL) {
-	    ERTS_BIF_PREP_RET(ret, NIL);
-	    goto done;
-	} else {
-	    hp = HAlloc(p, 3);
+	RegProc *reg = prt->common.u.alive.reg;
+	if (reg) {
 	    res = reg->name;
+	    if (szp) {
+		res = am_true;
+		goto done;
+	    }
+	}
+	else {
+	    if (szp)
+		return am_undefined;
+	    return NIL;
 	}
     }
     else if (item == am_memory) {
 	/* All memory consumed in bytes (the Port struct should not be
 	   included though).
 	 */
-	Uint hsz = 3;
 	Uint size = 0;
 	ErlHeapFragment* bp;
 
-	hp = HAlloc(p, 3);
-
 	erts_doforall_links(ERTS_P_LINKS(prt), &one_link_size, &size);
 
 	for (bp = prt->bp; bp; bp = bp->next)
@@ -2966,52 +2916,72 @@ static BIF_RETTYPE port_info(Process* p, Eterm portid, Eterm item)
 	/* All memory allocated by the driver should be included, but it is
 	   hard to retrieve... */
 	
-	(void) erts_bld_uint(NULL, &hsz, size);
-	hp = HAlloc(p, hsz);
-	res = erts_bld_uint(&hp, NULL, size);
+	res = erts_bld_uint(hpp, szp, size);
+	if (szp) {
+	    res = am_true;
+	    goto done;
+	}
     }
     else if (item == am_queue_size) {
 	Uint ioq_size = erts_port_ioq_size(prt);
-	Uint hsz = 3;
-	(void) erts_bld_uint(NULL, &hsz, ioq_size);
-	hp = HAlloc(p, hsz);
-	res = erts_bld_uint(&hp, NULL, ioq_size);
+	res = erts_bld_uint(hpp, szp, ioq_size);
+	if (szp) {
+	    res = am_true;
+	    goto done;
+	}
     }
     else if (ERTS_IS_ATOM_STR("locking", item)) {
-	hp = HAlloc(p, 3);
+	if (hpp) {
 #ifndef ERTS_SMP
-	res = am_false;
+	    res = am_false;
 #else
-	if (erts_atomic32_read_nob(&prt->state)
-	    & ERTS_PORT_SFLG_PORT_SPECIFIC_LOCK) {
-	    DECL_AM(port_level);
-	    ASSERT(prt->drv_ptr->flags
-		   & ERL_DRV_FLAG_USE_PORT_LOCKING);
-	    res = AM_port_level;
+	    if (erts_atomic32_read_nob(&prt->state)
+		& ERTS_PORT_SFLG_PORT_SPECIFIC_LOCK) {
+		DECL_AM(port_level);
+		ASSERT(prt->drv_ptr->flags
+		       & ERL_DRV_FLAG_USE_PORT_LOCKING);
+		res = AM_port_level;
+	    }
+	    else {
+		DECL_AM(driver_level);
+		ASSERT(!(prt->drv_ptr->flags
+			 & ERL_DRV_FLAG_USE_PORT_LOCKING));
+		res = AM_driver_level;
+	    }
+#endif
 	}
-	else {
-	    DECL_AM(driver_level);
-	    ASSERT(!(prt->drv_ptr->flags
-		     & ERL_DRV_FLAG_USE_PORT_LOCKING));
-	    res = AM_driver_level;
+	if (szp) {
+	    res = am_true;
+	    goto done;
 	}
-#endif
+    }
+    else if (item == am_parallelism) {
+	if (szp) {
+	    res = am_true;
+	    goto done;
+	}
+	res = ((ERTS_PTS_FLG_PARALLELISM &
+		erts_smp_atomic32_read_nob(&prt->sched.flags))
+	       ? am_true
+	       : am_false);
     }
     else {
-	ERTS_BIF_PREP_ERROR(ret, p, BADARG);
-	goto done;
+	if (szp)
+	    return am_false;
+	return THE_NON_VALUE;
     }
 
-    ERTS_BIF_PREP_RET(ret, TUPLE2(hp, item, res));
-
- done:
-
-    erts_port_release(prt);
+done:
+    if (szp)
+	*szp += 3;
+    if (hpp) {
+	res = TUPLE2(*hpp, item, res);
+	*hpp += 3;
+    }
 
-    return ret;
+    return res;
 }
 
-
 BIF_RETTYPE
 fun_info_2(BIF_ALIST_2)
 {
diff --git a/erts/emulator/beam/erl_bif_port.c b/erts/emulator/beam/erl_bif_port.c
index 0d0733b8d0..97f147132e 100644
--- a/erts/emulator/beam/erl_bif_port.c
+++ b/erts/emulator/beam/erl_bif_port.c
@@ -49,9 +49,6 @@ static void free_args(char **);
 
 char *erts_default_arg0 = "default";
 
-static BIF_RETTYPE
-port_call(Process* p, Eterm arg1, Eterm arg2, Eterm arg3);
-
 BIF_RETTYPE open_port_2(BIF_ALIST_2)
 {
     Port *port;
@@ -86,539 +83,397 @@ BIF_RETTYPE open_port_2(BIF_ALIST_2)
     BIF_RET(port_id);
 }
 
-/****************************************************************************
-
-  PORT BIFS:
-
-           port_command/2   -- replace Port ! {..., {command, Data}}
-               port_command(Port, Data) -> true
-               when port(Port), io-list(Data)
-
-           port_control/3   -- new port_control(Port, Ctl, Data) -> Reply
-	      port_control(Port, Ctl, Data) -> Reply
-              where integer(Ctl), io-list(Data), io-list(Reply)
-
-           port_close/1     -- replace Port ! {..., close}
-             port_close(Port) -> true
-             when port(Port)
-
-           port_connect/2   -- replace Port ! {..., {connect, Pid}}
-              port_connect(Port, Pid) 
-              when port(Port), pid(Pid)
-
- ***************************************************************************/
-
-static Port*
-id_or_name2port(Process *c_p, Eterm id)
+static ERTS_INLINE Port *
+lookup_port(Process *c_p, Eterm id_or_name)
 {
-    Port *port;
-    if (is_not_atom(id))
-	port = erts_id2port_sflgs(id,
-				  c_p,
-				  ERTS_PROC_LOCK_MAIN,
-				  ERTS_PORT_SFLGS_INVALID_LOOKUP);
+    /* TODO: Implement nicer lookup in register... */
+    Eterm id;
+    if (is_atom(id_or_name))
+	id = erts_whereis_name_to_id(c_p, id_or_name);
     else
-	erts_whereis_name(c_p, ERTS_PROC_LOCK_MAIN, id, NULL, 0, 0, &port);
-    return port;
+	id = id_or_name;
+    return erts_port_lookup(id, ERTS_PORT_SFLGS_INVALID_LOOKUP);
 }
 
-#define ERTS_PORT_COMMAND_FLAG_FORCE		(((Uint32) 1) << 0)
-#define ERTS_PORT_COMMAND_FLAG_NOSUSPEND	(((Uint32) 1) << 1)
+/*
+ * erts_internal:port_command/3 is used by the
+ * erlang:port_command/2 and erlang:port_command/3
+ * BIFs.
+ */
 
-static BIF_RETTYPE
-do_port_command(Process *BIF_P, Eterm arg1, Eterm arg2, Eterm arg3,
-		Uint32 flags)
+BIF_RETTYPE erts_internal_port_command_3(BIF_ALIST_3)
 {
     BIF_RETTYPE res;
-    Port *p;
-
-    /* Trace sched out before lock check wait */    
-    if (IS_TRACED_FL(BIF_P, F_TRACE_SCHED_PROCS)) {
-	trace_virtual_sched(BIF_P, am_out);
-    }
-    
-    if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-    	profile_runnable_proc(BIF_P, am_inactive);
-    }
-
-    p = id_or_name2port(BIF_P, arg1);
-    if (!p) {
-    	if (IS_TRACED_FL(BIF_P, F_TRACE_SCHED_PROCS)) {
-	    trace_virtual_sched(BIF_P, am_in);
+    Port *prt;
+    int flags = 0;
+    Eterm ref;
+
+    if (is_not_nil(BIF_ARG_3)) {
+	Eterm l = BIF_ARG_3;
+	while (is_list(l)) {
+	    Eterm* cons = list_val(l);
+	    Eterm car = CAR(cons);
+	    if (car == am_force)
+		flags |= ERTS_PORT_SIG_FLG_FORCE;
+	    else if (car == am_nosuspend)
+		flags |= ERTS_PORT_SIG_FLG_NOSUSPEND;
+	    else
+		BIF_RET(am_badarg);
+	    l = CDR(cons);
 	}
-    	if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-    	    profile_runnable_proc(BIF_P, am_active);
-    	}
-	BIF_ERROR(BIF_P, BADARG);
+	if (!is_nil(l))
+	    BIF_RET(am_badarg);
     }
-    
-    /* Trace port in, id_or_name2port causes wait */
 
-    if (IS_TRACED_FL(p, F_TRACE_SCHED_PORTS)) {
-	trace_sched_ports_where(p, am_in, am_command);
-    }
-    if (erts_system_profile_flags.runnable_ports && !erts_port_is_scheduled(p)) {
-    	profile_runnable_port(p, am_active);
+    prt = lookup_port(BIF_P, BIF_ARG_1);
+    if (!prt)
+	BIF_RET(am_badarg);
+
+    if (flags & ERTS_PORT_SIG_FLG_FORCE) {
+	if (!(prt->drv_ptr->flags & ERL_DRV_FLAG_SOFT_BUSY))
+	    BIF_RET(am_notsup);
     }
 
-    ERTS_BIF_PREP_RET(res, am_true);
+#ifdef DEBUG
+    ref = NIL;
+#endif
 
-    if ((flags & ERTS_PORT_COMMAND_FLAG_FORCE)
-	&& !(p->drv_ptr->flags & ERL_DRV_FLAG_SOFT_BUSY)) {
-	ERTS_BIF_PREP_ERROR(res, BIF_P, EXC_NOTSUP);
-    }
-    else if (!(flags & ERTS_PORT_COMMAND_FLAG_FORCE)
-	     && (erts_smp_atomic32_read_nob(&p->sched.flags)
-		 & ERTS_PTS_FLG_BUSY)) {
-	if (flags & ERTS_PORT_COMMAND_FLAG_NOSUSPEND) {
+    switch (erts_port_output(BIF_P, flags, prt, prt->common.id, BIF_ARG_2, &ref)) {
+    case ERTS_PORT_OP_CALLER_EXIT:
+    case ERTS_PORT_OP_BADARG:
+    case ERTS_PORT_OP_DROPPED:
+ 	ERTS_BIF_PREP_RET(res, am_badarg);
+	break;
+    case ERTS_PORT_OP_BUSY:
+	ASSERT(!(flags & ERTS_PORT_SIG_FLG_FORCE));
+	if (flags & ERTS_PORT_SIG_FLG_NOSUSPEND)
 	    ERTS_BIF_PREP_RET(res, am_false);
-	}
 	else {
-	    erts_suspend(BIF_P, ERTS_PROC_LOCK_MAIN, p);
-	    if (erts_system_monitor_flags.busy_port) {
-		monitor_generic(BIF_P, am_busy_port, p->common.id);
-	    }
-	    ERTS_BIF_PREP_YIELD3(res, bif_export[BIF_port_command_3], BIF_P,
-				 arg1, arg2, arg3);
-	}
-    } else {
-	int wres;
-	erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_MAIN);
-	ERTS_SMP_CHK_NO_PROC_LOCKS;
-	wres = erts_write_to_port(BIF_P->common.id, p, arg2);
-	erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_MAIN);
-	if (wres != 0) {
-	    ERTS_BIF_PREP_ERROR(res, BIF_P, BADARG);
+	    erts_suspend(BIF_P, ERTS_PROC_LOCK_MAIN, prt);
+	    ERTS_BIF_PREP_YIELD3(res, bif_export[BIF_erts_internal_port_command_3],
+				 BIF_P, BIF_ARG_1, BIF_ARG_2, BIF_ARG_3);
 	}
-    }
-    
-    if (IS_TRACED_FL(p, F_TRACE_SCHED_PORTS)) {
-	trace_sched_ports_where(p, am_out, am_command);
-    }
-    if (erts_system_profile_flags.runnable_ports && !erts_port_is_scheduled(p)) {
-    	profile_runnable_port(p, am_inactive);
+	break;
+    case ERTS_PORT_OP_BUSY_SCHEDULED:
+	ASSERT(!(flags & ERTS_PORT_SIG_FLG_FORCE));
+	/* Fall through... */
+    case ERTS_PORT_OP_SCHEDULED:
+	ASSERT(is_internal_ref(ref));
+	ERTS_BIF_PREP_RET(res, ref);
+	break;
+    case ERTS_PORT_OP_DONE:
+	ERTS_BIF_PREP_RET(res, am_true);
+	break;
+    default:
+	ERTS_INTERNAL_ERROR("Unexpected erts_port_output() result");
+	break;
     }
 
-    erts_port_release(p);
-    /* Trace sched in after port release */
-    if (IS_TRACED_FL(BIF_P, F_TRACE_SCHED_PROCS)) {
-	trace_virtual_sched(BIF_P, am_in);
-    }
-    if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-    	profile_runnable_proc(BIF_P, am_active);
-    }
-    
     if (ERTS_PROC_IS_EXITING(BIF_P)) {
 	KILL_CATCHES(BIF_P);	/* Must exit */
 	ERTS_BIF_PREP_ERROR(res, BIF_P, EXC_ERROR);
     }
-    return res;
-}
 
-BIF_RETTYPE port_command_2(BIF_ALIST_2)
-{
-    return do_port_command(BIF_P, BIF_ARG_1, BIF_ARG_2, NIL, 0);
+    return res;
 }
 
-BIF_RETTYPE port_command_3(BIF_ALIST_3)
+BIF_RETTYPE erts_internal_port_call_3(BIF_ALIST_3)
 {
-    Eterm l = BIF_ARG_3;
-    Uint32 flags = 0;
-    while (is_list(l)) {
-	Eterm* cons = list_val(l);
-	Eterm car = CAR(cons);
-	if (car == am_force) {
-	    flags |= ERTS_PORT_COMMAND_FLAG_FORCE;
-	} else if (car == am_nosuspend) {
-	    flags |= ERTS_PORT_COMMAND_FLAG_NOSUSPEND;
-	} else {
-	    BIF_ERROR(BIF_P, BADARG);
-	}
-	l = CDR(cons);
-    }
-    if(!is_nil(l)) {
-	BIF_ERROR(BIF_P, BADARG);
+    Port* prt;
+    Eterm retval;
+    Uint uint_op;
+    unsigned int op;
+    erts_aint32_t state;
+
+    prt = lookup_port(BIF_P, BIF_ARG_1);
+    if (!prt)
+	BIF_RET(am_badarg);
+
+    if (!term_to_Uint(BIF_ARG_2, &uint_op))
+	BIF_RET(am_badarg);
+
+    if (uint_op > (Uint) UINT_MAX)
+	BIF_RET(am_badarg);
+
+    op = (unsigned int) uint_op;
+
+    switch (erts_port_call(BIF_P, prt, op, BIF_ARG_3, &retval)) {
+    case ERTS_PORT_OP_CALLER_EXIT:
+    case ERTS_PORT_OP_DROPPED:
+    case ERTS_PORT_OP_BADARG:
+	retval = am_badarg;
+	break;
+    case ERTS_PORT_OP_SCHEDULED:
+	ASSERT(is_internal_ref(retval));
+	break;
+    case ERTS_PORT_OP_DONE:
+	ASSERT(is_not_internal_ref(retval));
+	break;
+    default:
+	ERTS_INTERNAL_ERROR("Unexpected erts_port_call() result");
+	retval = am_internal_error;
+	break;
     }
-    return do_port_command(BIF_P, BIF_ARG_1, BIF_ARG_2, BIF_ARG_3, flags);
-}
 
-BIF_RETTYPE port_call_2(BIF_ALIST_2)
-{
-    return port_call(BIF_P,BIF_ARG_1, make_small(0), BIF_ARG_2);
-}
+    state = erts_smp_atomic32_read_acqb(&BIF_P->state);
+    if (state & (ERTS_PSFLG_EXITING|ERTS_PSFLG_PENDING_EXIT)) {
+#ifdef ERTS_SMP
+	if (state & ERTS_PSFLG_PENDING_EXIT)
+	    erts_handle_pending_exit(BIF_P, ERTS_PROC_LOCK_MAIN);
+#endif
+	ERTS_BIF_EXITED(BIF_P);
+    }
 
-BIF_RETTYPE port_call_3(BIF_ALIST_3)
-{
-    return port_call(BIF_P, BIF_ARG_1, BIF_ARG_2, BIF_ARG_3);
+    BIF_RET(retval);
 }
 
-static BIF_RETTYPE
-port_call(Process* c_p, Eterm arg1, Eterm arg2, Eterm arg3)
+BIF_RETTYPE erts_internal_port_control_3(BIF_ALIST_3)
 {
-    Uint op;
-    Port *p;
-    Uint size;
-    byte *bytes;
-    byte *endp;
-    ErlDrvSizeT real_size;
-    erts_driver_t *drv;
-    byte port_input[256];	/* Default input buffer to encode in */
-    byte port_result[256];	/* Buffer for result from port. */
-    byte* port_resp;		/* Pointer to result buffer. */
-    char *prc;
-    ErlDrvSSizeT ret;
-    Eterm res;
-    Sint result_size;
-    Eterm *hp;
-    Eterm *hp_end;              /* To satisfy hybrid heap architecture */
-    unsigned ret_flags = 0U;
-    int fpe_was_unmasked;
-
-    bytes = &port_input[0];
-    port_resp = port_result;
-    /* trace of port scheduling with virtual process descheduling
-     * lock wait 
-     */
-    if (IS_TRACED_FL(c_p, F_TRACE_SCHED_PROCS)) {
-	trace_virtual_sched(c_p, am_out);
-    }
-
-    if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-	profile_runnable_proc(c_p, am_inactive);
+    Port* prt;
+    Eterm retval;
+    Uint uint_op;
+    unsigned int op;
+    erts_aint32_t state;
+
+    prt = lookup_port(BIF_P, BIF_ARG_1);
+    if (!prt)
+	BIF_RET(am_badarg);
+
+    if (!term_to_Uint(BIF_ARG_2, &uint_op))
+	BIF_RET(am_badarg);
+
+    if (uint_op > (Uint) UINT_MAX)
+	BIF_RET(am_badarg);
+
+    op = (unsigned int) uint_op;
+
+    switch (erts_port_control(BIF_P, prt, op, BIF_ARG_3, &retval)) {
+    case ERTS_PORT_OP_CALLER_EXIT:
+    case ERTS_PORT_OP_BADARG:
+    case ERTS_PORT_OP_DROPPED:
+	retval = am_badarg;
+	break;
+    case ERTS_PORT_OP_SCHEDULED:
+	ASSERT(is_internal_ref(retval));
+	break;
+    case ERTS_PORT_OP_DONE:
+	ASSERT(is_not_internal_ref(retval));
+	break;
+    default:
+	ERTS_INTERNAL_ERROR("Unexpected erts_port_control() result");
+	retval = am_internal_error;
+	break;
     }
 
-    p = id_or_name2port(c_p, arg1);
-    if (!p) {
-    error:
-	if (port_resp != port_result && 
-	    !(ret_flags & DRIVER_CALL_KEEP_BUFFER)) {
-	    driver_free(port_resp);
-	}
-	if (bytes != &port_input[0])
-	    erts_free(ERTS_ALC_T_PORT_CALL_BUF, bytes);
-	/* Need to virtual schedule in the process if there
-	 * was an error.
-	 */
-	if (IS_TRACED_FL(c_p, F_TRACE_SCHED_PROCS)) {
-	    trace_virtual_sched(c_p, am_in);
-    	}
-
-	if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-	    profile_runnable_proc(c_p, am_active);
-    	}
-
-	if (p)
-	    erts_port_release(p);
+    state = erts_smp_atomic32_read_acqb(&BIF_P->state);
+    if (state & (ERTS_PSFLG_EXITING|ERTS_PSFLG_PENDING_EXIT)) {
 #ifdef ERTS_SMP
-	ERTS_SMP_BIF_CHK_PENDING_EXIT(c_p, ERTS_PROC_LOCK_MAIN);
-#else
-	ERTS_BIF_CHK_EXITED(c_p);
+	if (state & ERTS_PSFLG_PENDING_EXIT)
+	    erts_handle_pending_exit(BIF_P, ERTS_PROC_LOCK_MAIN);
 #endif
-	BIF_ERROR(c_p, BADARG);
+	ERTS_BIF_EXITED(BIF_P);
     }
 
-    if ((drv = p->drv_ptr) == NULL) {
-	goto error;
-    }
-    if (drv->call == NULL) {
-	goto error;
-    }
-    if (!term_to_Uint(arg2, &op)) {
-	goto error;
-    }
-    p->caller = c_p->common.id;
-    
-    /* Lock taken, virtual schedule of port */
-    if (IS_TRACED_FL(p, F_TRACE_SCHED_PORTS)) {
-    	trace_sched_ports_where(p, am_in, am_call);
-    }
-    
-    if (erts_system_profile_flags.runnable_ports && !erts_port_is_scheduled(p)) {
-    	profile_runnable_port(p, am_active);
-    }
-    size = erts_encode_ext_size(arg3);
-    if (size > sizeof(port_input))
-	bytes = erts_alloc(ERTS_ALC_T_PORT_CALL_BUF, size);
-
-    endp = bytes;
-    erts_encode_ext(arg3, &endp);
+    BIF_RET(retval);
+}
 
-    real_size = endp - bytes;
-    if (real_size > size) {
-	erl_exit(1, "%s, line %d: buffer overflow: %d word(s)\n",
-		 __FILE__, __LINE__, endp - (bytes + size));
-    }
-    erts_smp_proc_unlock(c_p, ERTS_PROC_LOCK_MAIN);
-#ifdef USE_VM_PROBES
-    if (DTRACE_ENABLED(driver_call)) {
-        DTRACE_CHARBUF(process_str, DTRACE_TERM_BUF_SIZE);
-        DTRACE_CHARBUF(port_str, DTRACE_TERM_BUF_SIZE);
+/*
+ * erts_internal:port_close/1 is used by the
+ * erlang:port_close/1 BIF.
+ */
+BIF_RETTYPE erts_internal_port_close_1(BIF_ALIST_1)
+{
+    Eterm ref;
+    Port *prt;
 
-        dtrace_pid_str(ERTS_PORT_GET_CONNECTED(p), process_str);
-        dtrace_port_str(p, port_str);
-        DTRACE5(driver_call, process_str, port_str, p->name, op, real_size);
-    }
-#endif
-    prc  = (char *) port_resp;
-    fpe_was_unmasked = erts_block_fpe();
-    ret = drv->call((ErlDrvData)p->drv_data, 
-		    (unsigned) op,
-		    (char *) bytes, 
-		    (int) real_size,
-		    &prc, 
-		    (int) sizeof(port_result),
-		    &ret_flags);
-    erts_unblock_fpe(fpe_was_unmasked);
-    if (IS_TRACED_FL(p, F_TRACE_SCHED_PORTS)) {
-    	trace_sched_ports_where(p, am_out, am_call);
-    }
-    
-    if (erts_system_profile_flags.runnable_ports && !erts_port_is_scheduled(p)) {
-    	profile_runnable_port(p, am_inactive);
-    }
-   
-    port_resp = (byte *) prc;
-    p->caller = NIL;
-    erts_smp_proc_lock(c_p, ERTS_PROC_LOCK_MAIN);
-#ifdef HARDDEBUG
-    { 
-	ErlDrvSizeT z;
-	printf("real_size = %ld,%d, ret = %ld,%d\r\n", (unsigned long) real_size,
-	       (int) real_size, (unsigned long)ret, (int) ret);
-	printf("[");
-	for(z = 0; z < real_size; ++z) {
-	    printf("%d, ",(int) bytes[z]);
-	}
-	printf("]\r\n");
-	printf("[");
-	for(z = 0; z < ret; ++z) {
-	    printf("%d, ",(int) port_resp[z]);
-	}
-	printf("]\r\n");
-    }
-#endif
-    if (ret <= 0 || port_resp[0] != VERSION_MAGIC) { 
-	/* Error or a binary without magic/ with wrong magic */
-	goto error;
-    }
-    result_size = erts_decode_ext_size(port_resp, ret);
-    if (result_size < 0) {
-	goto error;
-    }
-    hp = HAlloc(c_p, result_size);
-    hp_end = hp + result_size;
-    endp = port_resp;
-    res = erts_decode_ext(&hp, &MSO(c_p), &endp);
-    if (res == THE_NON_VALUE) {
-	goto error;
-    }
-    HRelease(c_p, hp_end, hp);
-    if (port_resp != port_result && !(ret_flags & DRIVER_CALL_KEEP_BUFFER)) {
-	driver_free(port_resp);
-    }
-    if (bytes != &port_input[0])
-	erts_free(ERTS_ALC_T_PORT_CALL_BUF, bytes);
-    if (p)
-	erts_port_release(p);
-#ifdef ERTS_SMP
-    ERTS_SMP_BIF_CHK_PENDING_EXIT(c_p, ERTS_PROC_LOCK_MAIN);
-#else
-    ERTS_BIF_CHK_EXITED(c_p);
+#ifdef DEBUG
+    ref = NIL;
 #endif
-    if (IS_TRACED_FL(c_p, F_TRACE_SCHED_PROCS)) {
-	trace_virtual_sched(c_p, am_in);
-    }
 
-    if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-	profile_runnable_proc(c_p, am_active);
+    prt = lookup_port(BIF_P, BIF_ARG_1);
+    if (!prt)
+	BIF_RET(am_badarg);
+
+
+    switch (erts_port_exit(BIF_P, 0, prt, prt->common.id, am_normal, &ref)) {
+    case ERTS_PORT_OP_CALLER_EXIT:
+    case ERTS_PORT_OP_BADARG:
+    case ERTS_PORT_OP_DROPPED:
+	BIF_RET(am_badarg);
+    case ERTS_PORT_OP_SCHEDULED:
+	ASSERT(is_internal_ref(ref));
+	BIF_RET(ref);
+    case ERTS_PORT_OP_DONE:
+	BIF_RET(am_true);
+    default:
+	ERTS_INTERNAL_ERROR("Unexpected erts_port_exit() result");
+	BIF_RET(am_internal_error);
     }
-  
-    return res;
 }
-    
-BIF_RETTYPE port_control_3(BIF_ALIST_3)
+
+/*
+ * erts_internal:port_connect/2 is used by the
+ * erlang:port_connect/2 BIF.
+ */
+BIF_RETTYPE erts_internal_port_connect_2(BIF_ALIST_2)
 {
-    Port* p;
-    Uint op;
-    Eterm res = THE_NON_VALUE;
-    
-    /* Virtual schedule out calling process before lock wait */
-    if (IS_TRACED_FL(BIF_P, F_TRACE_SCHED_PROCS)) {
-	trace_virtual_sched(BIF_P, am_out);
-    }
+    Eterm ref;
+    Port* prt;
 
-    if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-    	profile_runnable_proc(BIF_P, am_inactive);
-    }
+    prt = lookup_port(BIF_P, BIF_ARG_1);
+    if (!prt)
+	BIF_RET(am_badarg);
 
-    p = id_or_name2port(BIF_P, BIF_ARG_1);
-    if (!p) {
-    	/* Schedule the process before exiting */
-    	if (IS_TRACED_FL(BIF_P, F_TRACE_SCHED_PROCS)) {
-	    trace_virtual_sched(BIF_P, am_in);
-    	}
-	
-	if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-    	    profile_runnable_proc(BIF_P, am_active);
-	}
-	
-	BIF_ERROR(BIF_P, BADARG);
-    }
-
-    /* Trace the port for scheduling in */
-    if (IS_TRACED_FL(p, F_TRACE_SCHED_PORTS)) {
-    	trace_sched_ports_where(p, am_in, am_control);
-    }
-    
-    if (erts_system_profile_flags.runnable_ports && !erts_port_is_scheduled(p)) {
-    	profile_runnable_port(p, am_active);
-    }
+#ifdef DEBUG
+    ref = NIL;
+#endif
 
-    if (term_to_Uint(BIF_ARG_2, &op))
-	res = erts_port_control(BIF_P, p, op, BIF_ARG_3);
-    
-    /* Trace the port for scheduling out */
-    if (IS_TRACED_FL(p, F_TRACE_SCHED_PORTS)) {
-    	trace_sched_ports_where(p, am_out, am_control);
+    switch (erts_port_connect(BIF_P, 0, prt, prt->common.id, BIF_ARG_2, &ref)) {
+    case ERTS_PORT_OP_CALLER_EXIT:
+    case ERTS_PORT_OP_BADARG:
+    case ERTS_PORT_OP_DROPPED:
+	BIF_RET(am_badarg);
+    case ERTS_PORT_OP_SCHEDULED:
+	ASSERT(is_internal_ref(ref));
+	BIF_RET(ref);
+	break;
+    case ERTS_PORT_OP_DONE:
+	BIF_RET(am_true);
+	break;
+    default:
+	ERTS_INTERNAL_ERROR("Unexpected erts_port_connect() result");
+	BIF_RET(am_internal_error);
     }
+}
 
-    if (erts_system_profile_flags.runnable_ports && !erts_port_is_scheduled(p)) {
-    	profile_runnable_port(p, am_inactive);
-    }
+BIF_RETTYPE erts_internal_port_info_1(BIF_ALIST_1)
+{
+    Eterm retval;
+    Port* prt;
 
-    erts_port_release(p);
-#ifdef ERTS_SMP
-    ERTS_SMP_BIF_CHK_PENDING_EXIT(BIF_P, ERTS_PROC_LOCK_MAIN);
-#else
-    ERTS_BIF_CHK_EXITED(BIF_P);
-#endif
-    
-    if (IS_TRACED_FL(BIF_P, F_TRACE_SCHED_PROCS)) {
-	trace_virtual_sched(BIF_P, am_in);
+    if (is_internal_port(BIF_ARG_1) || is_atom(BIF_ARG_1)) {
+	prt = lookup_port(BIF_P, BIF_ARG_1);
+	if (!prt)
+	    BIF_RET(am_undefined);
     }
-    
-    if (erts_system_profile_flags.runnable_procs && erts_system_profile_flags.exclusive) {
-    	profile_runnable_proc(BIF_P, am_active);
+    else if (is_external_port(BIF_ARG_1)) {
+	if (external_port_dist_entry(BIF_ARG_1) == erts_this_dist_entry)
+	    BIF_RET(am_undefined);
+	else
+	    BIF_RET(am_badarg);
     }
-    
-    if (is_non_value(res)) {
-	BIF_ERROR(BIF_P, BADARG);
+    else {
+	BIF_RET(am_badarg);
+    }
+
+    switch (erts_port_info(BIF_P, prt, THE_NON_VALUE, &retval)) {
+    case ERTS_PORT_OP_CALLER_EXIT:
+    case ERTS_PORT_OP_BADARG:
+	BIF_RET(am_badarg);
+    case ERTS_PORT_OP_DROPPED:
+	BIF_RET(am_undefined);
+    case ERTS_PORT_OP_SCHEDULED:
+	ASSERT(is_internal_ref(retval));
+	BIF_RET(retval);
+    case ERTS_PORT_OP_DONE:
+	ASSERT(is_not_internal_ref(retval));
+	BIF_RET(retval);
+    default:
+	ERTS_INTERNAL_ERROR("Unexpected erts_port_info() result");
+	BIF_RET(am_internal_error);
     }
-    BIF_RET(res);
 }
 
-BIF_RETTYPE port_close_1(BIF_ALIST_1)
-{
-    Port* p;
-    erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_MAIN);
-    p = id_or_name2port(NULL, BIF_ARG_1);
-    if (!p) {
-	erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_MAIN);
-	BIF_ERROR(BIF_P, BADARG);
-    }
-    erts_do_exit_port(p, ERTS_PORT_GET_CONNECTED(p), am_normal);
-    /* if !ERTS_SMP: since we terminate port with reason normal 
-       we SHOULD never get an exit signal ourselves
-       */
-    erts_port_release(p);
-    erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_MAIN);
-    BIF_RET(am_true);
-}
 
-BIF_RETTYPE port_connect_2(BIF_ALIST_2)
+BIF_RETTYPE erts_internal_port_info_2(BIF_ALIST_2)
 {
+    Eterm retval;
     Port* prt;
-    Process* rp;
-    Eterm pid = BIF_ARG_2;
 
-    if (is_not_internal_pid(pid)) {
-    error:
-	BIF_ERROR(BIF_P, BADARG);
-    }
-    prt = id_or_name2port(BIF_P, BIF_ARG_1);
-    if (!prt) {
-	goto error;
+    if (is_internal_port(BIF_ARG_1) || is_atom(BIF_ARG_1)) {
+	prt = lookup_port(BIF_P, BIF_ARG_1);
+	if (!prt)
+	    BIF_RET(am_undefined);
     }
-
-    rp = erts_pid2proc(BIF_P, ERTS_PROC_LOCK_MAIN,
-		       pid, ERTS_PROC_LOCK_LINK);
-    if (!rp) {
-	erts_port_release(prt);
-	ERTS_SMP_ASSERT_IS_NOT_EXITING(BIF_P);
-	goto error;
+    else if (is_external_port(BIF_ARG_1)) {
+	if (external_port_dist_entry(BIF_ARG_1) == erts_this_dist_entry)
+	    BIF_RET(am_undefined);
+	else
+	    BIF_RET(am_badarg);
     }
-
-    erts_add_link(&ERTS_P_LINKS(rp), LINK_PID, prt->common.id);
-    erts_add_link(&ERTS_P_LINKS(prt), LINK_PID, pid);
-
-    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
-
-    ERTS_PORT_SET_CONNECTED_RELB(prt, pid); /* internal pid */
-    erts_port_release(prt);
-#ifdef USE_VM_PROBES
-    if (DTRACE_ENABLED(port_connect)) {
-        DTRACE_CHARBUF(process_str, DTRACE_TERM_BUF_SIZE);
-        DTRACE_CHARBUF(port_str, DTRACE_TERM_BUF_SIZE);
-        DTRACE_CHARBUF(newprocess_str, DTRACE_TERM_BUF_SIZE);
-
-        dtrace_pid_str(pid, process_str);
-        erts_snprintf(port_str, sizeof(port_str), "%T", prt->id);
-        dtrace_proc_str(rp, newprocess_str);
-        DTRACE4(port_connect, process_str, port_str, prt->name, newprocess_str);
+    else {
+	BIF_RET(am_badarg);
+    }
+
+    switch (erts_port_info(BIF_P, prt, BIF_ARG_2, &retval)) {
+    case ERTS_PORT_OP_CALLER_EXIT:
+    case ERTS_PORT_OP_BADARG:
+	BIF_RET(am_badarg);
+    case ERTS_PORT_OP_DROPPED:
+	BIF_RET(am_undefined);
+    case ERTS_PORT_OP_SCHEDULED:
+	ASSERT(is_internal_ref(retval));
+	BIF_RET(retval);
+    case ERTS_PORT_OP_DONE:
+	ASSERT(is_not_internal_ref(retval));
+	BIF_RET(retval);
+    default:
+	ERTS_INTERNAL_ERROR("Unexpected erts_port_info() result");
+	BIF_RET(am_internal_error);
     }
-#endif
-    BIF_RET(am_true);
 }
 
-BIF_RETTYPE port_set_data_2(BIF_ALIST_2)
+
+BIF_RETTYPE erts_internal_port_set_data_2(BIF_ALIST_2)
 {
+    Eterm ref;
     Port* prt;
-    Eterm portid = BIF_ARG_1;
-    Eterm data   = BIF_ARG_2;
 
-    prt = id_or_name2port(BIF_P, portid);
-    if (!prt) {
-	BIF_ERROR(BIF_P, BADARG);
-    }
-    if (prt->bp != NULL) {
-	free_message_buffer(prt->bp);
-	prt->bp = NULL;
-    }
-    if (IS_CONST(data)) {
-	prt->data = data;
-    } else {
-	Uint size;
-	ErlHeapFragment* bp;
-	Eterm* hp;
-
-	size = size_object(data);
-	prt->bp = bp = new_message_buffer(size);
-	hp = bp->mem;
-	prt->data = copy_struct(data, size, &hp, &bp->off_heap);
+    prt = lookup_port(BIF_P, BIF_ARG_1);
+    if (!prt)
+	BIF_RET(am_badarg);
+
+    switch (erts_port_set_data(BIF_P, prt, BIF_ARG_2, &ref)) {
+    case ERTS_PORT_OP_CALLER_EXIT:
+    case ERTS_PORT_OP_BADARG:
+    case ERTS_PORT_OP_DROPPED:
+	BIF_RET(am_badarg);
+    case ERTS_PORT_OP_SCHEDULED:
+	ASSERT(is_internal_ref(ref));
+	BIF_RET(ref);
+    case ERTS_PORT_OP_DONE:
+	BIF_RET(am_true);
+    default:
+	ERTS_INTERNAL_ERROR("Unexpected erts_port_set_data() result");
+	BIF_RET(am_internal_error);
     }
-    erts_port_release(prt);
-    BIF_RET(am_true);
 }
 
 
-BIF_RETTYPE port_get_data_1(BIF_ALIST_1)
+BIF_RETTYPE erts_internal_port_get_data_1(BIF_ALIST_1)
 {
-    BIF_RETTYPE res;
+    Eterm retval;
     Port* prt;
-    Eterm portid = BIF_ARG_1;
 
-    prt = id_or_name2port(BIF_P, portid);
-    if (!prt) {
-	BIF_ERROR(BIF_P, BADARG);
-    }
-    if (prt->bp == NULL) {	/* MUST be CONST! */
-	res = prt->data;
-    } else {
-	Eterm* hp = HAlloc(BIF_P, prt->bp->used_size);
-	res = copy_struct(prt->data, prt->bp->used_size, &hp, &MSO(BIF_P));
+    prt = lookup_port(BIF_P, BIF_ARG_1);
+    if (!prt)
+	BIF_RET(am_badarg);
+
+    switch (erts_port_get_data(BIF_P, prt, &retval)) {
+    case ERTS_PORT_OP_CALLER_EXIT:
+    case ERTS_PORT_OP_BADARG:
+    case ERTS_PORT_OP_DROPPED:
+	BIF_RET(am_badarg);
+    case ERTS_PORT_OP_SCHEDULED:
+	ASSERT(is_internal_ref(retval));
+	BIF_RET(retval);
+    case ERTS_PORT_OP_DONE:
+	ASSERT(is_not_internal_ref(retval));
+	BIF_RET(retval);
+    default:
+	ERTS_INTERNAL_ERROR("Unexpected erts_port_get_data() result");
+	BIF_RET(am_internal_error);
     }
-    erts_port_release(prt);
-    BIF_RET(res);
 }
 
 /* 
@@ -659,6 +514,7 @@ open_port(Process* p, Eterm name, Eterm settings, int *err_typep, int *err_nump)
     opts.overlapped_io = 0; 
     opts.spawn_type = ERTS_SPAWN_ANY; 
     opts.argv = NULL;
+    opts.parallelism = erts_port_parallelism;
     linebuf = 0;
 
     *err_nump = 0;
@@ -736,6 +592,13 @@ open_port(Process* p, Eterm name, Eterm settings, int *err_typep, int *err_nump)
 		    }
 		} else if (option == am_cd) {
 		    edir = *tp;
+		} else if (option == am_parallelism) {
+		    if (*tp == am_true)
+			opts.parallelism = 1;
+		    else if (*tp == am_false)
+			opts.parallelism = 0;
+		    else
+			goto badarg;
 		} else {
 		    goto badarg;
 		}
@@ -904,9 +767,9 @@ open_port(Process* p, Eterm name, Eterm settings, int *err_typep, int *err_nump)
 	    heap[2] = make_small(0);
 	    heap[3] = NIL;
 	    iolist = make_list(heap);
-	    r = io_list_to_buf(iolist, (char*) dir, MAXPATHLEN);
+	    r = erts_iolist_to_buf(iolist, (char*) dir, MAXPATHLEN);
 	    UnUseTmpHeap(4,p);
-	    if (r < 0) {
+	    if (ERTS_IOLIST_TO_BUF_FAILED(r)) {
 		goto badarg;
 	    }
 	    opts.wd = (char *) dir;
@@ -1035,7 +898,7 @@ static byte* convert_environment(Process* p, Eterm env)
     Eterm* hp;
     Uint heap_size;
     int n;
-    Uint size;
+    ErlDrvSizeT size;
     byte* bytes;
 
     if ((n = list_length(env)) < 0) {
@@ -1087,7 +950,7 @@ static byte* convert_environment(Process* p, Eterm env)
      * Put the result in a binary (no risk for a memory leak that way).
      */
     (void) erts_new_heap_binary(p, NULL, size, &bytes);
-    io_list_to_buf(all, (char*)bytes, size);
+    erts_iolist_to_buf(all, (char*)bytes, size);
 
  done:
     erts_free(ERTS_ALC_T_TMP, temp_heap);
diff --git a/erts/emulator/beam/erl_bif_re.c b/erts/emulator/beam/erl_bif_re.c
index 6b843d2e08..ace128f045 100644
--- a/erts/emulator/beam/erl_bif_re.c
+++ b/erts/emulator/beam/erl_bif_re.c
@@ -418,7 +418,7 @@ build_compile_result(Process *p, Eterm error_tag, pcre *result, int errcode, con
 static BIF_RETTYPE
 re_compile(Process* p, Eterm arg1, Eterm arg2)
 {
-    Uint slen;
+    ErlDrvSizeT slen;
     char *expr;
     pcre *result;
     int errcode = 0;
@@ -449,7 +449,7 @@ re_compile(Process* p, Eterm arg1, Eterm arg2)
         BIF_ERROR(p,BADARG);
     }
     expr = erts_alloc(ERTS_ALC_T_RE_TMP_BUF, slen + 1);
-    if (io_list_to_buf(arg1, expr, slen) != 0) {
+    if (erts_iolist_to_buf(arg1, expr, slen) != 0) {
 	erts_free(ERTS_ALC_T_RE_TMP_BUF, expr);
 	BIF_ERROR(p,BADARG);
     }
@@ -802,7 +802,7 @@ build_capture(Eterm capture_spec[CAPSPEC_SIZE], const pcre *code)
 			memcpy(tmpb,ap->name,ap->len);
 			tmpb[ap->len] = '\0';
 		    } else {
-			Uint slen;
+			ErlDrvSizeT slen;
 			if (erts_iolist_size(val, &slen)) {
 			    goto error;
 			}
@@ -814,7 +814,7 @@ build_capture(Eterm capture_spec[CAPSPEC_SIZE], const pcre *code)
 						    (tmpbsiz = slen + 1));
 			    }
 			}
-			if (io_list_to_buf(val, tmpb, slen) != 0) {
+			if (erts_iolist_to_buf(val, tmpb, slen) != 0) {
 			    goto error;
 			}
 			tmpb[slen] = '\0';
@@ -858,7 +858,7 @@ re_run(Process *p, Eterm arg1, Eterm arg2, Eterm arg3)
     const pcre *code_tmp;
     RestartContext restart;
     byte *temp_alloc = NULL;
-    Uint slength;
+    ErlDrvSizeT slength;
     int startoffset = 0;
     int options = 0, comp_options = 0;
     int ovsize;
@@ -882,7 +882,7 @@ re_run(Process *p, Eterm arg1, Eterm arg2, Eterm arg3)
     if (is_not_tuple(arg2) || (arityval(*tuple_val(arg2)) != 4)) {
 	if (is_binary(arg2) || is_list(arg2) || is_nil(arg2)) {
 	    /* Compile from textual RE */
-	    Uint slen;
+	    ErlDrvSizeT slen;
 	    char *expr;
 	    pcre *result;
 	    int errcode = 0;
@@ -901,7 +901,7 @@ re_run(Process *p, Eterm arg1, Eterm arg2, Eterm arg3)
 	    }
 	    
 	    expr = erts_alloc(ERTS_ALC_T_RE_TMP_BUF, slen + 1);
-	    if (io_list_to_buf(arg2, expr, slen) != 0) {
+	    if (erts_iolist_to_buf(arg2, expr, slen) != 0) {
 		erts_free(ERTS_ALC_T_RE_TMP_BUF, expr);
 		BIF_ERROR(p,BADARG);
 	    }
@@ -1044,7 +1044,7 @@ handle_iolist:
 	}
 	restart.subject = erts_alloc(ERTS_ALC_T_RE_SUBJECT, slength);
 
-	if (io_list_to_buf(arg1, restart.subject, slength) != 0) {
+	if (erts_iolist_to_buf(arg1, restart.subject, slength) != 0) {
 	    erts_free(ERTS_ALC_T_RE_SUBJECT, restart.ovector);
 	    erts_free(ERTS_ALC_T_RE_SUBJECT, restart.code);
 	    erts_free(ERTS_ALC_T_RE_SUBJECT, restart.subject);
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index f83e380b02..af7c2b91a0 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -564,7 +564,8 @@ void erts_usage(void)
     /*    erts_fprintf(stderr, "-i module  set the boot module (default init)\n"); */
 
     erts_fprintf(stderr, "-K boolean  enable or disable kernel poll\n");
-
+    erts_fprintf(stderr, "-n[s|a|d]   Control behavior of signals to ports\n");
+    erts_fprintf(stderr, "            Note that this flag is deprecated!\n");
     erts_fprintf(stderr, "-M<X> <Y>   memory allocator switches,\n");
     erts_fprintf(stderr, "            see the erts_alloc(3) documentation for more info.\n");
 
@@ -592,6 +593,7 @@ void erts_usage(void)
     erts_fprintf(stderr, "            valid range is [%d-%d]\n",
 		 ERTS_SCHED_THREAD_MIN_STACK_SIZE,
 		 ERTS_SCHED_THREAD_MAX_STACK_SIZE);
+    erts_fprintf(stderr, "-spp Bool   set port parallelism scheduling hint\n");
     erts_fprintf(stderr, "-S n1:n2    set number of schedulers (n1), and number of\n");
     erts_fprintf(stderr, "            schedulers online (n2), valid range for both\n");
     erts_fprintf(stderr, "            numbers are [1-%d]\n",
@@ -1228,6 +1230,30 @@ erl_start(int argc, char **argv)
 		       arg);
 	    break;
 
+	case 'n':
+	    arg = get_arg(argv[i]+2, argv[i+1], &i);
+	    switch (arg[0]) {
+	    case 's': /* synchronous */
+		erts_port_synchronous_ops = 1;
+		erts_port_schedule_all_ops = 0;
+		break;
+	    case 'a': /* asynchronous */
+		erts_port_synchronous_ops = 0;
+		erts_port_schedule_all_ops = 1;
+		break;
+	    case 'd': /* Default - schedule on conflict (asynchronous) */
+		erts_port_synchronous_ops = 0;
+		erts_port_schedule_all_ops = 0;
+		break;
+	    default:
+	    bad_n_option:
+		erts_fprintf(stderr, "bad -n option %s\n", arg);
+		erts_usage();
+	    }
+	    if (arg[1] != '\0')
+		goto bad_n_option;
+	    break;
+
 	case 'P': /* set maximum number of processes */
 	    arg = get_arg(argv[i]+2, argv[i+1], &i);
 	    errno = 0;
@@ -1342,6 +1368,19 @@ erl_start(int argc, char **argv)
 		    erts_usage();
 		}
 	    }
+	    else if (has_prefix("pp", sub_param)) {
+		arg = get_arg(sub_param+2, argv[i+1], &i);
+		if (sys_strcmp(arg, "true") == 0)
+		    erts_port_parallelism = 1;
+		else if (sys_strcmp(arg, "false") == 0)
+		    erts_port_parallelism = 0;
+		else {
+		    erts_fprintf(stderr,
+				 "bad port parallelism scheduling hint %s\n",
+				 arg);
+		    erts_usage();
+		}
+	    }
 	    else if (sys_strcmp("nsp", sub_param) == 0)
 		erts_use_sender_punish = 0;
 	    else if (sys_strcmp("wt", sub_param) == 0) {
@@ -1467,8 +1506,6 @@ erl_start(int argc, char **argv)
 	    }
 	    break;
 	}
-	case 'n':   /* XXX obsolete */
-	    break;
 	case 'c':
 	    if (argv[i][2] == 0) { /* -c: documented option */
 		erts_disable_tolerant_timeofday = 1;
diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index 8ef6e8f846..04721cee7c 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -501,7 +501,7 @@ int enif_inspect_iolist_as_binary(ErlNifEnv* env, Eterm term, ErlNifBinary* bin)
 {
     struct enif_tmp_obj_t* tobj;
     ErtsAlcType_t allocator;
-    Uint sz;
+    ErlDrvSizeT sz;
     if (is_binary(term)) {
 	return enif_inspect_binary(env,term,bin);
     }
@@ -527,7 +527,7 @@ int enif_inspect_iolist_as_binary(ErlNifEnv* env, Eterm term, ErlNifBinary* bin)
     bin->size = sz;
     bin->bin_term = THE_NON_VALUE;
     bin->ref_bin = NULL;
-    io_list_to_buf(term, (char*) bin->data, sz);
+    erts_iolist_to_buf(term, (char*) bin->data, sz);
     ADD_READONLY_CHECK(env, bin->data, bin->size); 
     return 1;
 }
diff --git a/erts/emulator/beam/erl_port.h b/erts/emulator/beam/erl_port.h
index 6ad92dcd7d..beeddd09a0 100644
--- a/erts/emulator/beam/erl_port.h
+++ b/erts/emulator/beam/erl_port.h
@@ -20,6 +20,7 @@
 #ifndef ERL_PORT_TYPE__
 #define ERL_PORT_TYPE__
 typedef struct _erl_drv_port Port;
+typedef struct ErtsProc2PortSigData_ ErtsProc2PortSigData;
 #endif
 
 #if !defined(ERL_PORT_H__) && !defined(ERL_PORT_GET_PORT_TYPE_ONLY__)
@@ -33,6 +34,10 @@ typedef struct _erl_drv_port Port;
 #define ERTS_DEFAULT_MAX_PORTS (1 << 16)
 #define ERTS_MIN_PORTS 1024
 
+extern int erts_port_synchronous_ops;
+extern int erts_port_schedule_all_ops;
+extern int erts_port_parallelism;
+
 typedef struct erts_driver_t_ erts_driver_t;
 
 #define ERTS_INVALID_ERL_DRV_PORT ((ErlDrvPort) (SWord) -1)
@@ -63,6 +68,19 @@ typedef struct line_buf {  /* Buffer used in line oriented I/O */
 			      The rest is the overflow buffer. */
 } LineBuf;
 
+/*
+ * Items part of erlang:port_info/1 result. Note am_registered_name
+ * *need* to be first.
+ */
+
+#define ERTS_PORT_INFO_1_ITEMS				\
+    {	am_registered_name,	/* Needs to be first */	\
+	am_name,					\
+	am_links,					\
+	am_id,						\
+	am_connected,					\
+	am_input,					\
+	am_output }
 
 /*
  * Port Specific Data.
@@ -113,7 +131,7 @@ struct _erl_drv_port {
     erts_atomic32_t refc;
     int cleanup;
 #endif
-    erts_smp_atomic_t connected;/* A connected process */
+    erts_atomic_t connected;	/* A connected process */
     Eterm caller;		/* Current caller. */
     Eterm data;			/* Data associated with port. */
     ErlHeapFragment* bp;	/* Heap fragment holding data (NULL if imm data). */
@@ -135,6 +153,13 @@ struct _erl_drv_port {
     ErtsPrtSD *psd;		 /* Port specific data */
 };
 
+#define ERTS_PORT_GET_CONNECTED(PRT) \
+    ((Eterm) erts_atomic_read_nob(&(PRT)->connected))
+#define ERTS_PORT_SET_CONNECTED(PRT, PID) \
+    erts_atomic_set_relb(&(PRT)->connected, (erts_aint_t) (PID))
+#define ERTS_PORT_INIT_CONNECTED(PRT, PID) \
+    erts_atomic_init_nob(&(PRT)->connected, (erts_aint_t) (PID))
+
 
 struct erl_drv_port_data_lock {
     erts_mtx_t mtx;
@@ -240,6 +265,7 @@ extern erts_smp_atomic_t erts_bytes_in;		/* no bytes sent into the system */
   (ERTS_PORT_SFLGS_DEAD | ERTS_PORT_SFLG_INVALID)
 #define ERTS_PORT_SFLGS_INVALID_LOOKUP					\
   (ERTS_PORT_SFLGS_INVALID_DRIVER_LOOKUP				\
+   | ERTS_PORT_SFLG_EXITING						\
    | ERTS_PORT_SFLG_CLOSING)
 #define ERTS_PORT_SFLGS_INVALID_TRACER_LOOKUP				\
   (ERTS_PORT_SFLGS_INVALID_LOOKUP					\
@@ -358,17 +384,6 @@ erts_smp_port_unlock(Port *prt)
 #define ERTS_PORT_SCHED_ID(P, ID) \
   ((Uint) (UWord) erts_prtsd_set((P), ERTS_PSD_SCHED_ID, (void *) (UWord) (ID)))
 
-#define ERTS_PORT_INIT_CONNECTED(PRT, PID) \
-    erts_smp_atomic_init_nob(&(PRT)->connected, (erts_aint_t) (PID))
-#define ERTS_PORT_SET_CONNECTED(PRT, PID) \
-    erts_smp_atomic_set_nob(&(PRT)->connected, (erts_aint_t) (PID))
-#define ERTS_PORT_SET_CONNECTED_RELB(PRT, PID) \
-    erts_smp_atomic_set_relb(&(PRT)->connected, (erts_aint_t) (PID))
-#define ERTS_PORT_GET_CONNECTED(PRT) \
-    ((Eterm) erts_smp_atomic_read_nob(&(PRT)->connected))
-#define ERTS_PORT_GET_CONNECTED_ACQB(PRT) \
-    ((Eterm) erts_smp_atomic_read_acqb(&(PRT)->connected))
-
 extern const Port erts_invalid_port;
 #define ERTS_PORT_LOCK_BUSY ((Port *) &erts_invalid_port)
 
@@ -424,8 +439,11 @@ ERTS_GLB_INLINE Port *
 erts_port_lookup(Eterm id, Uint32 invalid_sflgs)
 {
     Port *prt = erts_port_lookup_raw(id);
-    erts_aint32_t state = erts_atomic32_read_nob(&prt->state);
-    return (state & invalid_sflgs) ? NULL : prt;
+    return (!prt
+	    ? NULL
+	    : ((invalid_sflgs & erts_atomic32_read_nob(&prt->state))
+	       ? NULL
+	       : prt));
 }
 
 
@@ -584,14 +602,16 @@ erts_thr_drvport2port_raw(ErlDrvPort drvport)
     else {
 	Port *prt = (Port *) drvport;
 #if ERTS_ENABLE_LOCK_CHECK
-	if (emu_thread) {
-	    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
-	    ERTS_LC_ASSERT(!prt->port_data_lock
-			   || erts_lc_mtx_is_locked(&prt->port_data_lock->mtx));
-	}
-	else {
-	    ERTS_LC_ASSERT(prt->port_data_lock);
-	    ERTS_LC_ASSERT(erts_lc_mtx_is_locked(&prt->port_data_lock->mtx));
+	if (!ERTS_IS_CRASH_DUMPING) {
+	    if (emu_thread) {
+		ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
+		ERTS_LC_ASSERT(!prt->port_data_lock
+			       || erts_lc_mtx_is_locked(&prt->port_data_lock->mtx));
+	    }
+	    else {
+		ERTS_LC_ASSERT(prt->port_data_lock);
+		ERTS_LC_ASSERT(erts_lc_mtx_is_locked(&prt->port_data_lock->mtx));
+	    }
 	}
 #endif
 	return prt;
@@ -606,7 +626,8 @@ erts_drvport2port_raw(ErlDrvPort drvport)
 	return NULL;
     else {
 	Port *prt = (Port *) drvport;
-	ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
+	ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt)
+			   || ERTS_IS_CRASH_DUMPING);
 	return prt;
     }
 }
@@ -637,7 +658,8 @@ erts_drvportid2port(Eterm id)
 					    internal_port_index(id));
     if (!prt)
 	return NULL;
-    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
+    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt)
+		       || ERTS_IS_CRASH_DUMPING);
     if (prt->common.id != id)
 	return NULL;
     state = erts_atomic32_read_nob(&prt->state);
@@ -680,4 +702,141 @@ erts_is_valid_tracer_port(Eterm id)
 }
 #endif /* #if ERTS_GLB_INLINE_INCL_FUNC_DEF */
 
+struct binary;
+
+#define ERTS_P2P_SIG_DATA_FLG_BANG_OP		(1 << 0)
+#define ERTS_P2P_SIG_DATA_FLG_REPLY		(1 << 1)
+#define ERTS_P2P_SIG_DATA_FLG_NOSUSPEND		(1 << 2)
+#define ERTS_P2P_SIG_DATA_FLG_FORCE		(1 << 3)
+#define ERTS_P2P_SIG_DATA_FLG_BAD_OUTPUT	(1 << 4)
+#define ERTS_P2P_SIG_DATA_FLG_BROKEN_LINK	(1 << 5)
+#define ERTS_P2P_SIG_DATA_FLG_SCHED		(1 << 6)
+
+struct ErtsProc2PortSigData_ {
+    int flags;
+    Eterm caller;
+    Uint32 ref[ERTS_MAX_REF_NUMBERS];
+    union {
+	struct {
+	    Eterm from;
+	    ErlIOVec *evp;
+	    ErlDrvBinary *cbinp;
+	} outputv;
+	struct {
+	    Eterm from;
+	    char *bufp;
+	    ErlDrvSizeT size;
+	} output;
+	struct {
+	    Eterm from;
+	    Eterm connected;
+	} connect;
+	struct {
+	    Eterm from;
+	    Eterm reason;
+	    ErlHeapFragment *bp;
+	} exit;
+	struct {
+	    struct binary *binp;
+	    unsigned int command;
+	    char *bufp;
+	    ErlDrvSizeT size;
+	} control;
+	struct {
+	    unsigned int command;
+	    char *bufp;
+	    ErlDrvSizeT size;
+	} call;
+	struct {
+	    Eterm item;
+	} info;
+	struct {
+	    Eterm port;
+	    Eterm to;
+	} link;
+	struct {
+	    Eterm from;
+	} unlink;
+	struct {
+	    ErlHeapFragment *bp;
+	    Eterm data;
+	} set_data;
+    } u;
+} ;
+
+#define ERTS_PROC2PORT_SIG_EXEC			0
+#define ERTS_PROC2PORT_SIG_ABORT		1
+#define ERTS_PROC2PORT_SIG_ABORT_NOSUSPEND	2
+#define ERTS_PROC2PORT_SIG_ABORT_CLOSED		3
+
+typedef int (*ErtsProc2PortSigCallback)(Port *,
+					erts_aint32_t,
+					int,
+					ErtsProc2PortSigData *);
+
+#define ERTS_PORT_REDS_CMD_OUTPUTV	400
+#define ERTS_PORT_REDS_CMD_OUTPUT	400
+#define ERTS_PORT_REDS_EXIT		300
+#define ERTS_PORT_REDS_CONNECT		40
+#define ERTS_PORT_REDS_UNLINK		40
+#define ERTS_PORT_REDS_LINK		40
+#define ERTS_PORT_REDS_BADSIG		40
+#define ERTS_PORT_REDS_CONTROL		400
+#define ERTS_PORT_REDS_CALL		400
+#define ERTS_PORT_REDS_INFO		100
+#define ERTS_PORT_REDS_SET_DATA		40
+#define ERTS_PORT_REDS_GET_DATA		40
+
+typedef enum {
+    ERTS_PORT_OP_BADARG,
+    ERTS_PORT_OP_CALLER_EXIT,
+    ERTS_PORT_OP_BUSY,
+    ERTS_PORT_OP_BUSY_SCHEDULED,
+    ERTS_PORT_OP_SCHEDULED,
+    ERTS_PORT_OP_DROPPED,
+    ERTS_PORT_OP_DONE
+} ErtsPortOpResult;
+
+ErtsPortOpResult
+erts_schedule_proc2port_signal(Process *,
+			       Port *,
+			       Eterm,
+			       Eterm *,
+			       ErtsProc2PortSigData *,
+			       int,
+			       ErtsProc2PortSigCallback);
+
+int erts_deliver_port_exit(Port *, Eterm, Eterm, int);
+
+/*
+ * Port signal flags
+ */
+#define ERTS_PORT_SIG_FLG_BANG_OP		ERTS_P2P_SIG_DATA_FLG_BANG_OP
+#define ERTS_PORT_SIG_FLG_NOSUSPEND		ERTS_P2P_SIG_DATA_FLG_NOSUSPEND
+#define ERTS_PORT_SIG_FLG_FORCE			ERTS_P2P_SIG_DATA_FLG_FORCE
+#define ERTS_PORT_SIG_FLG_BROKEN_LINK		ERTS_P2P_SIG_DATA_FLG_BROKEN_LINK
+#define ERTS_PORT_SIG_FLG_BAD_OUTPUT		ERTS_P2P_SIG_DATA_FLG_BAD_OUTPUT
+#define ERTS_PORT_SIG_FLG_FORCE_SCHED		ERTS_P2P_SIG_DATA_FLG_SCHED
+
+/*
+ * Port ! {Owner, {command, Data}}
+ * Port ! {Owner, {connect, NewOwner}}
+ * Port ! {Owner, close}
+ */
+ErtsPortOpResult erts_port_command(Process *, int, Port *, Eterm, Eterm *);
+
+/*
+ * Signals from processes to ports.
+ */
+ErtsPortOpResult erts_port_output(Process *, int, Port *, Eterm, Eterm, Eterm *);
+ErtsPortOpResult erts_port_exit(Process *, int, Port *, Eterm, Eterm, Eterm *);
+ErtsPortOpResult erts_port_connect(Process *, int, Port *, Eterm, Eterm, Eterm *);
+ErtsPortOpResult erts_port_link(Process *, Port *, Eterm, Eterm *);
+ErtsPortOpResult erts_port_unlink(Process *, Port *, Eterm, Eterm *);
+ErtsPortOpResult erts_port_control(Process *, Port *, unsigned int, Eterm, Eterm *);
+ErtsPortOpResult erts_port_call(Process *, Port *, unsigned int, Eterm, Eterm *);
+ErtsPortOpResult erts_port_info(Process *, Port *, Eterm, Eterm *);
+ErtsPortOpResult erts_port_set_data(Process *, Port *, Eterm, Eterm *);
+ErtsPortOpResult erts_port_get_data(Process *, Port *, Eterm *);
+
 #endif
diff --git a/erts/emulator/beam/erl_port_task.c b/erts/emulator/beam/erl_port_task.c
index e613ad0144..e8ed00daee 100644
--- a/erts/emulator/beam/erl_port_task.c
+++ b/erts/emulator/beam/erl_port_task.c
@@ -36,9 +36,20 @@
 #include <stdarg.h>
 
 #if defined(DEBUG) && 0
-#define HARD_DEBUG
+#define ERTS_HARD_DEBUG_TASK_QUEUES
+#else
+#undef ERTS_HARD_DEBUG_TASK_QUEUES
+#endif
+
+#ifdef ERTS_HARD_DEBUG_TASK_QUEUES
+static void chk_task_queues(Port *pp, ErtsPortTask *execq, int processing_busy_queue);
+#define ERTS_PT_DBG_CHK_TASK_QS(PP, EQ, PBQ) \
+    chk_task_queues((PP), (EQ), (PBQ))
+#else
+#define ERTS_PT_DBG_CHK_TASK_QS(PP, EQ, PBQ)
 #endif
 
+
 /*
  * Costs in reductions for some port operations.
  */
@@ -52,7 +63,7 @@
 
 #ifdef USE_VM_PROBES
 #define DTRACE_DRIVER(PROBE_NAME, PP)                              \
-    if (DTRACE_ENABLED(driver_ready_input)) {                      \
+    if (DTRACE_ENABLED(PROBE_NAME)) {                              \
         DTRACE_CHARBUF(process_str, DTRACE_TERM_BUF_SIZE);         \
         DTRACE_CHARBUF(port_str, DTRACE_TERM_BUF_SIZE);            \
                                                                    \
@@ -70,6 +81,17 @@ erts_smp_atomic_t erts_port_task_outstanding_io_tasks;
 #define ERTS_PT_STATE_ABORTED		1
 #define ERTS_PT_STATE_EXECUTING		2
 
+typedef union {
+    struct { /* I/O tasks */
+	ErlDrvEvent event;
+	ErlDrvEventData event_data;
+    } io;
+    struct {
+	ErtsProc2PortSigCallback callback;
+	ErtsProc2PortSigData data;
+    } psig;
+} ErtsPortTaskTypeData;
+
 struct ErtsPortTask_ {
     erts_smp_atomic32_t state;
     ErtsPortTaskType type;
@@ -77,17 +99,39 @@ struct ErtsPortTask_ {
 	struct {
 	    ErtsPortTask *next;
 	    ErtsPortTaskHandle *handle;
-	    union {
-		struct { /* I/O tasks */
-		    ErlDrvEvent event;
-		    ErlDrvEventData event_data;
-		} io;
-	    } u;
+	    int flags;
+	    Uint32 ref[ERTS_MAX_REF_NUMBERS];
+	    ErtsPortTaskTypeData td;
 	} alive;
 	ErtsThrPrgrLaterOp release;
     } u;
 };
 
+struct ErtsPortTaskHandleList_ {
+    ErtsPortTaskHandle handle;
+    union {
+	ErtsPortTaskHandleList *next;
+#ifdef ERTS_SMP
+	ErtsThrPrgrLaterOp release;
+#endif
+    } u;
+};
+
+typedef struct ErtsPortTaskBusyCaller_ ErtsPortTaskBusyCaller;
+struct ErtsPortTaskBusyCaller_ {
+    ErtsPortTaskBusyCaller *next;
+    Eterm caller;
+    SWord count;
+    ErtsPortTask *last;
+};
+
+#define ERTS_PORT_TASK_BUSY_CALLER_TABLE_BUCKETS 17
+struct ErtsPortTaskBusyCallerTable_ {
+    ErtsPortTaskBusyCaller *bucket[ERTS_PORT_TASK_BUSY_CALLER_TABLE_BUCKETS];
+    ErtsPortTaskBusyCaller pre_alloc_busy_caller;
+};
+
+
 static void begin_port_cleanup(Port *pp, ErtsPortTask **execq);
 
 ERTS_SCHED_PREF_QUICK_ALLOC_IMPL(port_task,
@@ -95,6 +139,11 @@ ERTS_SCHED_PREF_QUICK_ALLOC_IMPL(port_task,
 				 1000,
 				 ERTS_ALC_T_PORT_TASK)
 
+ERTS_SCHED_PREF_QUICK_ALLOC_IMPL(busy_caller_table,
+				 ErtsPortTaskBusyCallerTable,
+				 50,
+				 ERTS_ALC_T_BUSY_CALLER_TAB)
+
 #ifdef ERTS_SMP
 static void
 call_port_task_free(void *vptp)
@@ -115,6 +164,358 @@ schedule_port_task_free(ErtsPortTask *ptp)
 #endif
 }
 
+static ERTS_INLINE ErtsPortTask *
+p2p_sig_data_to_task(ErtsProc2PortSigData *sigdp)
+{
+    ErtsPortTask *ptp;
+    char *ptr = (char *) sigdp;
+    ptr -= offsetof(ErtsPortTask, u.alive.td.psig.data);
+    ptp = (ErtsPortTask *) ptr;
+    ASSERT(ptp->type == ERTS_PORT_TASK_PROC_SIG);
+    return ptp;
+}
+
+ErtsProc2PortSigData *
+erts_port_task_alloc_p2p_sig_data(void)
+{
+    ErtsPortTask *ptp = port_task_alloc();
+
+    ptp->type = ERTS_PORT_TASK_PROC_SIG;
+    ptp->u.alive.flags = ERTS_PT_FLG_SIG_DEP;
+    erts_smp_atomic32_init_nob(&ptp->state, ERTS_PT_STATE_SCHEDULED);
+
+    ASSERT(ptp == p2p_sig_data_to_task(&ptp->u.alive.td.psig.data));
+
+    return &ptp->u.alive.td.psig.data;
+}
+
+static ERTS_INLINE Eterm
+task_caller(ErtsPortTask *ptp)
+{
+    Eterm caller;
+
+    ASSERT(ptp->type == ERTS_PORT_TASK_PROC_SIG);
+
+    caller = ptp->u.alive.td.psig.data.caller;
+
+    ASSERT(is_internal_pid(caller) || is_internal_port(caller));
+
+    return caller;
+}
+
+/*
+ * Busy queue management
+ */
+
+static ERTS_INLINE int
+caller2bix(Eterm caller)
+{
+    ASSERT(is_internal_pid(caller) || is_internal_port(caller));
+    return (int) (_GET_PID_DATA(caller) % ERTS_PORT_TASK_BUSY_CALLER_TABLE_BUCKETS);
+}
+
+
+static void
+popped_from_busy_queue(Port *pp, ErtsPortTask *ptp, int last)
+{
+    ErtsPortTaskBusyCaller **prev_bcpp = NULL, *bcp;
+    ErtsPortTaskBusyCallerTable *tabp = pp->sched.taskq.local.busy.table;
+    Eterm caller = task_caller(ptp);
+    int bix = caller2bix(caller);
+
+    ASSERT(is_internal_pid(caller));
+
+    ASSERT(tabp);
+    bcp = tabp->bucket[bix];
+    prev_bcpp = &tabp->bucket[bix];
+    ASSERT(bcp);
+    while (bcp->caller != caller) {
+	prev_bcpp = &bcp->next;
+	bcp = bcp->next;
+	ASSERT(bcp);
+    }
+    ASSERT(bcp->count > 0);
+    if (--bcp->count != 0) {
+	ASSERT(!last);
+    }
+    else {
+	*prev_bcpp = bcp->next;
+	if (bcp == &tabp->pre_alloc_busy_caller)
+	    bcp->caller = am_undefined;
+	else
+	    erts_free(ERTS_ALC_T_BUSY_CALLER, bcp);
+	if (last) {
+#ifdef DEBUG
+	    erts_aint32_t flags =
+#endif
+		erts_smp_atomic32_read_band_nob(
+		    &pp->sched.flags,
+		    ~ERTS_PTS_FLG_HAVE_BUSY_TASKS);
+	    ASSERT(flags & ERTS_PTS_FLG_HAVE_BUSY_TASKS);
+#ifdef DEBUG
+	    for (bix = 0; bix < ERTS_PORT_TASK_BUSY_CALLER_TABLE_BUCKETS; bix++) {
+		ASSERT(!tabp->bucket[bix]);
+	    }
+#endif
+	    busy_caller_table_free(tabp);
+	    pp->sched.taskq.local.busy.first = NULL;
+	    pp->sched.taskq.local.busy.last = NULL;
+	    pp->sched.taskq.local.busy.table = NULL;
+	}
+    }
+}
+
+static void
+busy_wait_move_to_busy_queue(Port *pp, ErtsPortTask *ptp)
+{
+    ErtsPortTaskBusyCallerTable *tabp = pp->sched.taskq.local.busy.table;
+    Eterm caller = task_caller(ptp);
+    ErtsPortTaskBusyCaller *bcp;
+    int bix;
+
+    ASSERT(is_internal_pid(caller));
+    /*
+     * Port is busy and this task type needs to wait until not busy.
+     */
+
+    ASSERT(ptp->u.alive.flags & ERTS_PT_FLG_WAIT_BUSY);
+
+    ptp->u.alive.next = NULL;
+    if (pp->sched.taskq.local.busy.last) {
+	ASSERT(pp->sched.taskq.local.busy.first);
+	pp->sched.taskq.local.busy.last->u.alive.next = ptp;
+    }
+    else {
+	int i;
+	erts_aint32_t flags;
+
+	pp->sched.taskq.local.busy.first = ptp;
+	flags = erts_smp_atomic32_read_bor_nob(&pp->sched.flags,
+					       ERTS_PTS_FLG_HAVE_BUSY_TASKS);
+	ASSERT(!(flags & ERTS_PTS_FLG_HAVE_BUSY_TASKS));
+
+	ASSERT(!tabp);
+
+	tabp = busy_caller_table_alloc();
+	pp->sched.taskq.local.busy.table = tabp;
+	for (i = 0; i < ERTS_PORT_TASK_BUSY_CALLER_TABLE_BUCKETS; i++)
+	    tabp->bucket[i] = NULL;
+	tabp->pre_alloc_busy_caller.caller = am_undefined;
+    }
+    pp->sched.taskq.local.busy.last = ptp;
+
+    bix = caller2bix(caller);
+    ASSERT(tabp);
+    bcp = tabp->bucket[bix];
+
+    while (bcp && bcp->caller != caller)
+	bcp = bcp->next;
+
+    if (bcp)
+	bcp->count++;
+    else {
+	if (tabp->pre_alloc_busy_caller.caller == am_undefined)
+	    bcp = &tabp->pre_alloc_busy_caller;
+	else
+	    bcp = erts_alloc(ERTS_ALC_T_BUSY_CALLER,
+			     sizeof(ErtsPortTaskBusyCaller));
+	bcp->caller = caller;
+	bcp->count = 1;
+	bcp->next = tabp->bucket[bix];
+	tabp->bucket[bix] = bcp;
+    }
+
+    bcp->last = ptp;
+}
+
+static ERTS_INLINE int
+check_sig_dep_move_to_busy_queue(Port *pp, ErtsPortTask *ptp)
+{
+    ErtsPortTaskBusyCallerTable *tabp = pp->sched.taskq.local.busy.table;
+    ErtsPortTask *last_ptp;
+    ErtsPortTaskBusyCaller *bcp;
+    int bix;
+    Eterm caller;
+
+    ASSERT(ptp->u.alive.flags & ERTS_PT_FLG_SIG_DEP);
+    ASSERT(pp->sched.taskq.local.busy.last);
+    ASSERT(tabp);
+
+
+    /*
+     * We are either not busy, or the task does not imply wait on busy port.
+     * However, due to the signaling order requirements the task might depend
+     * on other tasks in the busy queue.
+     */
+
+    caller = task_caller(ptp);
+    bix = caller2bix(caller);
+    bcp = tabp->bucket[bix];
+    while (bcp && bcp->caller != caller)
+	bcp = bcp->next;
+
+    if (!bcp)
+	return 0;
+
+    /*
+     * There are other tasks that we depend on in the busy queue;
+     * move into busy queue.
+     */
+
+    bcp->count++;
+    last_ptp = bcp->last;
+    ptp->u.alive.next = last_ptp->u.alive.next;
+    if (!ptp->u.alive.next) {
+	ASSERT(pp->sched.taskq.local.busy.last == last_ptp);
+	pp->sched.taskq.local.busy.last = ptp;
+    }
+    last_ptp->u.alive.next = ptp;
+    bcp->last = ptp;
+
+    return 1;
+}
+
+static void
+no_sig_dep_move_from_busyq(Port *pp)
+{
+    ErtsPortTaskBusyCallerTable *tabp = pp->sched.taskq.local.busy.table;
+    ErtsPortTask *first_ptp, *last_ptp, *ptp;
+    ErtsPortTaskBusyCaller **prev_bcpp = NULL, *bcp = NULL;
+
+    /*
+     * Move tasks at the head of the busy queue that no longer
+     * have any dependencies to busy wait tasks into the ordinary
+     * queue.
+     */
+
+    first_ptp = ptp = pp->sched.taskq.local.busy.first;
+
+    ASSERT(ptp && !(ptp->u.alive.flags & ERTS_PT_FLG_WAIT_BUSY));
+    ASSERT(tabp);
+
+    do {
+	Eterm caller = task_caller(ptp);
+
+	if (!bcp || bcp->caller != caller) {
+	    int bix = caller2bix(caller);
+
+	    prev_bcpp = &tabp->bucket[bix];
+	    bcp = tabp->bucket[bix];
+	    ASSERT(bcp);
+	    while (bcp->caller != caller) {
+		ASSERT(bcp);
+		prev_bcpp = &bcp->next;
+		bcp = bcp->next;
+	    }
+	}
+
+	ASSERT(bcp->caller == caller);
+	ASSERT(bcp->count > 0);
+
+	if (--bcp->count == 0) {
+	    *prev_bcpp = bcp->next;
+	    if (bcp == &tabp->pre_alloc_busy_caller)
+		bcp->caller = am_undefined;
+	    else
+		erts_free(ERTS_ALC_T_BUSY_CALLER, bcp);
+	}
+
+	last_ptp = ptp;
+	ptp = ptp->u.alive.next;
+    } while (ptp && !(ptp->u.alive.flags & ERTS_PT_FLG_WAIT_BUSY));
+
+    pp->sched.taskq.local.busy.first = last_ptp->u.alive.next;
+    if (!pp->sched.taskq.local.busy.first) {
+#ifdef DEBUG
+	int bix;
+	erts_aint32_t flags =
+#endif
+	    erts_smp_atomic32_read_band_nob(
+		&pp->sched.flags,
+		~ERTS_PTS_FLG_HAVE_BUSY_TASKS);
+	ASSERT(flags & ERTS_PTS_FLG_HAVE_BUSY_TASKS);
+#ifdef DEBUG
+	for (bix = 0; bix < ERTS_PORT_TASK_BUSY_CALLER_TABLE_BUCKETS; bix++) {
+	    ASSERT(!tabp->bucket[bix]);
+	}
+#endif
+	busy_caller_table_free(tabp);
+	pp->sched.taskq.local.busy.last = NULL;
+	pp->sched.taskq.local.busy.table = NULL;
+    }
+    last_ptp->u.alive.next = pp->sched.taskq.local.first;
+    pp->sched.taskq.local.first = first_ptp;
+}
+
+#ifdef ERTS_HARD_DEBUG_TASK_QUEUES
+
+static void
+chk_task_queues(Port *pp, ErtsPortTask *execq, int processing_busy_queue)
+{
+    Sint tot_count, tot_table_count;
+    int bix;
+    ErtsPortTask *ptp, *last;
+    ErtsPortTask *first = processing_busy_queue ? execq : pp->sched.taskq.local.busy.first;
+    ErtsPortTask *nb_task_queue = processing_busy_queue ? pp->sched.taskq.local.first : execq;
+    ErtsPortTaskBusyCallerTable *tabp = pp->sched.taskq.local.busy.table;
+    ErtsPortTaskBusyCaller *bcp;
+
+    if (!first) {
+	ASSERT(!tabp);
+	ASSERT(!pp->sched.taskq.local.busy.last);
+	ASSERT(!(erts_smp_atomic32_read_nob(&pp->sched.flags) & ERTS_PTS_FLG_HAVE_BUSY_TASKS));
+	return;
+    }
+
+    ASSERT(erts_smp_atomic32_read_nob(&pp->sched.flags) & ERTS_PTS_FLG_HAVE_BUSY_TASKS);
+    ASSERT(tabp);
+
+    tot_count = 0;
+    ptp = first;
+    while (ptp) {
+	Sint count = 0;
+	Eterm caller = task_caller(ptp);
+	int bix = caller2bix(caller);
+	for (bcp = tabp->bucket[bix]; bcp; bcp = bcp->next)
+	    if (bcp->caller == caller)
+		break;
+	ASSERT(bcp && bcp->caller == caller);
+
+	ASSERT(bcp->last);
+	while (1) {
+	    ErtsPortTask *ptp2;
+
+	    ASSERT(caller == task_caller(ptp));
+	    count++;
+	    tot_count++;
+	    last = ptp;
+
+	    for (ptp2 = nb_task_queue; ptp2; ptp2 = ptp2->u.alive.next) {
+		ASSERT(ptp != ptp2);
+	    }
+
+	    if (ptp == bcp->last)
+		break;
+	    ptp = ptp->u.alive.next;
+	}
+
+	ASSERT(count == bcp->count);
+	ptp = ptp->u.alive.next;
+    }
+
+    tot_table_count = 0;
+    for (bix = 0; bix < ERTS_PORT_TASK_BUSY_CALLER_TABLE_BUCKETS; bix++) {
+	for (bcp = tabp->bucket[bix]; bcp; bcp = bcp->next)
+	    tot_table_count += bcp->count;
+    }
+
+    ASSERT(tot_count == tot_table_count);
+
+    ASSERT(last == pp->sched.taskq.local.busy.last);
+}
+
+#endif /* ERTS_HARD_DEBUG_TASK_QUEUES */
+
 /*
  * Task handle manipulation.
  */
@@ -151,6 +552,141 @@ set_handle(ErtsPortTask *ptp, ErtsPortTaskHandle *pthp)
 }
 
 /*
+ * No-suspend handles.
+ */
+
+#ifdef ERTS_SMP
+static void
+free_port_task_handle_list(void *vpthlp)
+{
+    erts_free(ERTS_ALC_T_PT_HNDL_LIST, vpthlp);
+}
+#endif
+
+static void
+schedule_port_task_handle_list_free(ErtsPortTaskHandleList *pthlp)
+{
+#ifdef ERTS_SMP
+    erts_schedule_thr_prgr_later_op(free_port_task_handle_list,
+				    (void *) pthlp,
+				    &pthlp->u.release);
+#else
+    erts_free(ERTS_ALC_T_PT_HNDL_LIST, pthlp);
+#endif
+}
+
+static ERTS_INLINE void
+abort_nosuspend_task(ErtsPortTaskType type,
+		     ErtsPortTaskTypeData *tdp)
+{
+
+    if (type != ERTS_PORT_TASK_PROC_SIG)
+	ERTS_INTERNAL_ERROR("Invalid no-suspend port task type");
+
+    tdp->psig.callback(NULL,
+		       ERTS_PORT_SFLG_INVALID,
+		       ERTS_PROC2PORT_SIG_ABORT_NOSUSPEND,
+		       &tdp->psig.data);
+}
+
+
+static void
+save_nosuspend_handle(Port *pp, ErtsPortTask *ptp)
+{
+    erts_aint32_t act;
+    ErtsPortTaskHandleList *pthlp = erts_alloc(ERTS_ALC_T_PT_HNDL_LIST,
+					       sizeof(ErtsPortTaskHandleList));
+
+    set_handle(ptp, &pthlp->handle);
+
+    ASSERT(ptp == handle2task(&pthlp->handle));
+    ASSERT(ptp->u.alive.handle == &pthlp->handle);
+
+    act = erts_smp_atomic32_read_nob(&pp->sched.flags);
+
+    if (!(act & ERTS_PTS_FLG_BUSY)) {
+
+	erts_port_task_sched_lock(&pp->sched);
+	pthlp->u.next = pp->sched.taskq.local.busy.nosuspend;
+	pp->sched.taskq.local.busy.nosuspend = pthlp;
+	erts_port_task_sched_unlock(&pp->sched);
+
+	act = erts_smp_atomic32_read_nob(&pp->sched.flags);
+
+	while (1) {
+	    erts_aint32_t exp, new;
+
+	    if ((act & (ERTS_PTS_FLG_BUSY|ERTS_PTS_FLG_HAVE_NS_TASKS))
+		== ERTS_PTS_FLG_HAVE_NS_TASKS)
+		return;
+
+	    if (act & ERTS_PTS_FLG_BUSY) {
+		erts_aint32_t s;
+		s = erts_smp_atomic32_cmpxchg_nob(&ptp->state,
+						  ERTS_PT_STATE_ABORTED,
+						  ERTS_PT_STATE_SCHEDULED);
+		if (s == ERTS_PT_STATE_SCHEDULED) {
+		    reset_port_task_handle(&pthlp->handle);
+		    break; /* Abort task */
+		}
+		/* Else: someone else handled it */
+		return;
+	    }
+
+	    new = exp = act;
+
+	    new |= ERTS_PTS_FLG_HAVE_NS_TASKS;
+
+	    act = erts_smp_atomic32_cmpxchg_relb(&pp->sched.flags, new, exp);
+	    if (act == exp)
+		return;
+
+	}
+    }
+
+
+    abort_nosuspend_task(ptp->type, &ptp->u.alive.td);
+}
+
+
+static ErtsPortTaskHandleList *
+get_free_nosuspend_handles(Port *pp)
+{
+    ErtsPortTaskHandleList *nshp, *last_nshp = NULL;
+
+    ERTS_SMP_LC_ASSERT(erts_port_task_sched_lock_is_locked(&pp->sched));
+
+    nshp = pp->sched.taskq.local.busy.nosuspend;
+
+    while (nshp && !erts_port_task_is_scheduled(&nshp->handle)) {
+	last_nshp = nshp;
+	nshp = nshp->u.next;
+    }
+
+    if (!last_nshp)
+	nshp = NULL;
+    else {
+	nshp = pp->sched.taskq.local.busy.nosuspend;
+	pp->sched.taskq.local.busy.nosuspend = last_nshp->u.next;
+	last_nshp->u.next = NULL;
+	if (!pp->sched.taskq.local.busy.nosuspend)
+	    erts_smp_atomic32_read_band_nob(&pp->sched.flags,
+					    ~ERTS_PTS_FLG_HAVE_NS_TASKS);
+    }
+    return nshp;
+}
+
+static void
+free_nosuspend_handles(ErtsPortTaskHandleList *free_nshp)
+{
+    while (free_nshp) {
+	ErtsPortTaskHandleList *nshp = free_nshp;
+	free_nshp = free_nshp->u.next;
+	schedule_port_task_handle_list_free(nshp);
+    }
+}
+
+/*
  * Port queue operations
  */
 
@@ -225,42 +761,21 @@ enqueue_task(Port *pp, ErtsPortTask *ptp)
     return flags;
 }
 
-static ERTS_INLINE ErtsPortTask *
-pop_task(Port *pp, ErtsPortTask **execqp)
+static ERTS_INLINE void
+prepare_exec(Port *pp, ErtsPortTask **execqp, int *processing_busy_q_p)
 {
-    ErtsPortTask *ptp;
+    erts_aint32_t act = erts_smp_atomic32_read_nob(&pp->sched.flags);
 
-    ptp = *execqp;
-    if (ptp) {
-	*execqp = ptp->u.alive.next;
-	return ptp;
+    if (!pp->sched.taskq.local.busy.first || (act & ERTS_PTS_FLG_BUSY)) {
+	*execqp = pp->sched.taskq.local.first;
+	*processing_busy_q_p = 0;
+    }
+    else {
+	*execqp = pp->sched.taskq.local.busy.first;
+	*processing_busy_q_p = 1;
     }
 
-    ASSERT(!pp->sched.taskq.local);
-
-    erts_port_task_sched_lock(&pp->sched);
-    ptp = pp->sched.taskq.in.first;
-    pp->sched.taskq.in.first = NULL;
-    pp->sched.taskq.in.last = NULL;
-    if (ptp)
-	*execqp = ptp->u.alive.next;
-    else
-	erts_smp_atomic32_read_band_nob(&pp->sched.flags,
-					~ERTS_PTS_FLG_HAVE_TASKS);
-    erts_port_task_sched_unlock(&pp->sched);
-
-
-    return ptp;
-}
-
-static ERTS_INLINE void
-prepare_exec(Port *pp, ErtsPortTask **execqp)
-{
-    erts_aint32_t act;
-    *execqp = pp->sched.taskq.local;
-
-    /* guess a likely value */
-    act = ERTS_PTS_FLG_HAVE_TASKS|ERTS_PTS_FLG_IN_RUNQ;
+    ERTS_PT_DBG_CHK_TASK_QS(pp, *execqp, *processing_busy_q_p);
 
     while (1) {
 	erts_aint32_t new, exp;
@@ -281,11 +796,19 @@ prepare_exec(Port *pp, ErtsPortTask **execqp)
 
 /* finalize_exec() return value != 0 if port should remain active */
 static ERTS_INLINE int
-finalize_exec(Port *pp, ErtsPortTask **execq)
+finalize_exec(Port *pp, ErtsPortTask **execq, int processing_busy_q)
 {
     erts_aint32_t act;
 
-    pp->sched.taskq.local = *execq;
+    if (!processing_busy_q)
+	pp->sched.taskq.local.first = *execq;
+    else {
+	pp->sched.taskq.local.busy.first = *execq;
+	ASSERT(*execq);
+    }
+
+    ERTS_PT_DBG_CHK_TASK_QS(pp, *execq, processing_busy_q);
+
     *execq = NULL;
 
     /* guess a likely value */
@@ -313,6 +836,155 @@ finalize_exec(Port *pp, ErtsPortTask **execq)
     return (act & ERTS_PTS_FLG_HAVE_TASKS) != 0;
 }
 
+static ERTS_INLINE erts_aint32_t
+select_queue_for_exec(Port *pp, ErtsPortTask **execqp, int *processing_busy_q_p)
+{
+    erts_aint32_t flags = erts_smp_atomic32_read_nob(&pp->sched.flags);
+
+    ERTS_PT_DBG_CHK_TASK_QS(pp, *execqp, *processing_busy_q_p);
+
+    if (flags & ERTS_PTS_FLG_BUSY) {
+	if (*processing_busy_q_p) {
+	    ErtsPortTask *ptp;
+
+	    ptp = pp->sched.taskq.local.busy.first = *execqp;
+	    if (!ptp)
+		pp->sched.taskq.local.busy.last = NULL;
+	    else if (!(ptp->u.alive.flags & ERTS_PT_FLG_WAIT_BUSY))
+		no_sig_dep_move_from_busyq(pp);
+
+	    *execqp = pp->sched.taskq.local.first;
+	    *processing_busy_q_p = 0;
+
+	    ERTS_PT_DBG_CHK_TASK_QS(pp, *execqp, *processing_busy_q_p);
+	}
+
+	return flags;
+    }
+
+    /* Not busy */
+
+    if (!*processing_busy_q_p && pp->sched.taskq.local.busy.first) {
+	pp->sched.taskq.local.first = *execqp;
+	*execqp = pp->sched.taskq.local.busy.first;
+	*processing_busy_q_p = 1;
+
+	ERTS_PT_DBG_CHK_TASK_QS(pp, *execqp, *processing_busy_q_p);
+    }
+
+    return flags;
+}
+
+/*
+ * check_task_for_exec() returns a value !0 if the task
+ * is ok to execute; otherwise 0.
+ */
+static ERTS_INLINE int
+check_task_for_exec(Port *pp,
+		    erts_aint32_t flags,
+		    ErtsPortTask **execqp,
+		    int *processing_busy_q_p,
+		    ErtsPortTask *ptp)
+{
+
+    if (!*processing_busy_q_p) {
+	/* Processing normal queue */
+
+	ERTS_PT_DBG_CHK_TASK_QS(pp, ptp, *processing_busy_q_p);
+
+	if ((flags & ERTS_PTS_FLG_BUSY)
+	    && (ptp->u.alive.flags & ERTS_PT_FLG_WAIT_BUSY)) {
+
+	    busy_wait_move_to_busy_queue(pp, ptp);
+	    ERTS_PT_DBG_CHK_TASK_QS(pp, *execqp, *processing_busy_q_p);
+
+	    return 0;
+	}
+
+	if (pp->sched.taskq.local.busy.last
+	    && (ptp->u.alive.flags & ERTS_PT_FLG_SIG_DEP)) {
+
+	    int res = !check_sig_dep_move_to_busy_queue(pp, ptp);
+	    ERTS_PT_DBG_CHK_TASK_QS(pp, *execqp, *processing_busy_q_p);
+
+	    return res;
+	}
+
+    }
+    else {
+	/* Processing busy queue */
+
+	ASSERT(!(flags & ERTS_PTS_FLG_BUSY));
+
+	ERTS_PT_DBG_CHK_TASK_QS(pp, ptp, *processing_busy_q_p);
+
+	popped_from_busy_queue(pp, ptp, !*execqp);
+
+	if (!*execqp) {
+	    *execqp = pp->sched.taskq.local.first;
+	    *processing_busy_q_p = 0;
+	}
+
+	ERTS_PT_DBG_CHK_TASK_QS(pp, *execqp, *processing_busy_q_p);
+
+    }
+
+    return 1;
+}
+
+static ErtsPortTask *
+fetch_in_queue(Port *pp, ErtsPortTask **execqp)
+{
+    ErtsPortTask *ptp;
+    ErtsPortTaskHandleList *free_nshp = NULL;
+
+    erts_port_task_sched_lock(&pp->sched);
+
+    ptp = pp->sched.taskq.in.first;
+    pp->sched.taskq.in.first = NULL;
+    pp->sched.taskq.in.last = NULL;
+    if (ptp)
+	*execqp = ptp->u.alive.next;
+    else
+	erts_smp_atomic32_read_band_nob(&pp->sched.flags,
+					~ERTS_PTS_FLG_HAVE_TASKS);
+
+    
+    if (pp->sched.taskq.local.busy.nosuspend)
+	free_nshp = get_free_nosuspend_handles(pp);
+
+    erts_port_task_sched_unlock(&pp->sched);
+
+    if (free_nshp)
+	free_nosuspend_handles(free_nshp);
+
+    return ptp;
+}
+
+static ERTS_INLINE ErtsPortTask *
+select_task_for_exec(Port *pp,
+		     ErtsPortTask **execqp,
+		     int *processing_busy_q_p)
+{
+    ErtsPortTask *ptp;
+    erts_aint32_t flags;
+
+    flags = select_queue_for_exec(pp, execqp, processing_busy_q_p);
+
+    while (1) {
+	ptp = *execqp;
+	if (ptp)
+	    *execqp = ptp->u.alive.next;
+	else {
+	    ptp = fetch_in_queue(pp, execqp);
+	    if (!ptp)
+		return NULL;
+	}
+	if (check_task_for_exec(pp, flags, execqp, processing_busy_q_p, ptp))
+	    return ptp;
+    }
+}
+
 /*
  * Abort a scheduled task.
  */
@@ -358,6 +1030,12 @@ erts_port_task_abort(ErtsPortTaskHandle *pthp)
 			   &erts_port_task_outstanding_io_tasks) > 0);
 		erts_smp_atomic_dec_relb(&erts_port_task_outstanding_io_tasks);
 		break;
+	    case ERTS_PORT_TASK_PROC_SIG:
+		ptp->u.alive.td.psig.callback(NULL,
+					      ERTS_PORT_SFLG_INVALID,
+					      ERTS_PROC2PORT_SIG_ABORT,
+					      &ptp->u.alive.td.psig.data);
+		break;
 	    default:
 		break;
 	    }
@@ -373,6 +1051,88 @@ erts_port_task_abort(ErtsPortTaskHandle *pthp)
     return res;
 }
 
+void
+erts_port_task_abort_nosuspend_tasks(Port *pp)
+{
+    ErtsPortTaskHandleList *abort_list;
+#ifdef ERTS_SMP
+    ErtsThrPrgrDelayHandle dhndl = ERTS_THR_PRGR_DHANDLE_INVALID;
+#endif
+
+    erts_port_task_sched_lock(&pp->sched);
+    erts_smp_atomic32_read_band_nob(&pp->sched.flags,
+				    ~ERTS_PTS_FLG_HAVE_NS_TASKS);
+    abort_list = pp->sched.taskq.local.busy.nosuspend;
+    pp->sched.taskq.local.busy.nosuspend = NULL;
+    erts_port_task_sched_unlock(&pp->sched);
+
+    while (abort_list) {
+#ifdef DEBUG
+	ErtsPortTaskHandle *saved_pthp;
+#endif
+	ErtsPortTaskType type;
+	ErtsPortTaskTypeData td;
+	ErtsPortTaskHandle *pthp;
+	ErtsPortTask *ptp;
+	ErtsPortTaskHandleList *pthlp;
+	erts_aint32_t old_state;
+
+	pthlp = abort_list;
+	abort_list = pthlp->u.next;
+
+#ifdef ERTS_SMP
+	if (dhndl != ERTS_THR_PRGR_DHANDLE_MANAGED)
+	    dhndl = erts_thr_progress_unmanaged_delay();
+#endif
+
+	pthp = &pthlp->handle;
+	ptp = handle2task(pthp);
+	if (!ptp) {
+#ifdef ERTS_SMP
+	    if (dhndl != ERTS_THR_PRGR_DHANDLE_MANAGED)
+		erts_thr_progress_unmanaged_continue(dhndl);
+#endif
+	    schedule_port_task_handle_list_free(pthlp);
+	    continue;
+	}
+
+#ifdef DEBUG
+	saved_pthp = ptp->u.alive.handle;
+	ERTS_SMP_READ_MEMORY_BARRIER;
+	old_state = erts_smp_atomic32_read_nob(&ptp->state);
+	if (old_state == ERTS_PT_STATE_SCHEDULED) {
+	    ASSERT(saved_pthp == pthp);
+	}
+#endif
+
+	old_state = erts_smp_atomic32_cmpxchg_nob(&ptp->state,
+						  ERTS_PT_STATE_ABORTED,
+						  ERTS_PT_STATE_SCHEDULED);
+	if (old_state != ERTS_PT_STATE_SCHEDULED) {
+	    /* Task already aborted, executing, or executed */
+#ifdef ERTS_SMP
+	    if (dhndl != ERTS_THR_PRGR_DHANDLE_MANAGED)
+		erts_thr_progress_unmanaged_continue(dhndl);
+#endif
+	    schedule_port_task_handle_list_free(pthlp);
+	    continue;
+	}
+
+	reset_port_task_handle(pthp);
+
+	type = ptp->type;
+	td = ptp->u.alive.td;
+
+#ifdef ERTS_SMP
+	if (dhndl != ERTS_THR_PRGR_DHANDLE_MANAGED)
+	    erts_thr_progress_unmanaged_continue(dhndl);
+#endif
+	schedule_port_task_handle_list_free(pthlp);
+
+	abort_nosuspend_task(type, &td);
+    }
+}
+
 /*
  * Schedule a task.
  */
@@ -416,18 +1176,23 @@ erts_port_task_schedule(Eterm id,
     if (!pp)
 	goto fail;
 
-    ptp = port_task_alloc();
+    if (type != ERTS_PORT_TASK_PROC_SIG) {
+	ptp = port_task_alloc();
 
-    ptp->type = type;
+	ptp->type = type;
+	ptp->u.alive.flags = 0;
 
-    erts_smp_atomic32_init_nob(&ptp->state, ERTS_PT_STATE_SCHEDULED);
+	erts_smp_atomic32_init_nob(&ptp->state, ERTS_PT_STATE_SCHEDULED);
+
+	set_handle(ptp, pthp);
+    }
 
     switch (type) {
     case ERTS_PORT_TASK_INPUT:
     case ERTS_PORT_TASK_OUTPUT: {
 	va_list argp;
 	va_start(argp, type);
-	ptp->u.alive.u.io.event = va_arg(argp, ErlDrvEvent);
+	ptp->u.alive.td.io.event = va_arg(argp, ErlDrvEvent);
 	va_end(argp);
 	erts_smp_atomic_inc_relb(&erts_port_task_outstanding_io_tasks);
 	break;
@@ -435,18 +1200,32 @@ erts_port_task_schedule(Eterm id,
     case ERTS_PORT_TASK_EVENT: {
 	va_list argp;
 	va_start(argp, type);
-	ptp->u.alive.u.io.event = va_arg(argp, ErlDrvEvent);
-	ptp->u.alive.u.io.event_data = va_arg(argp, ErlDrvEventData);
+	ptp->u.alive.td.io.event = va_arg(argp, ErlDrvEvent);
+	ptp->u.alive.td.io.event_data = va_arg(argp, ErlDrvEventData);
 	va_end(argp);
 	erts_smp_atomic_inc_relb(&erts_port_task_outstanding_io_tasks);
 	break;
     }
+    case ERTS_PORT_TASK_PROC_SIG: {
+	ErtsProc2PortSigData *sigdp;
+	va_list argp;
+	ASSERT(!pthp);
+	va_start(argp, type);
+	sigdp = va_arg(argp, ErtsProc2PortSigData *);
+	ptp = p2p_sig_data_to_task(sigdp);
+	ptp->u.alive.td.psig.callback = va_arg(argp, ErtsProc2PortSigCallback);
+ 	ptp->u.alive.flags |= va_arg(argp, int);
+	va_end(argp);
+	if (ptp->u.alive.flags & ERTS_PT_FLG_NOSUSPEND)
+	    save_nosuspend_handle(pp, ptp);
+	else
+	    set_handle(ptp, pthp);
+	break;
+    }
     default:
 	break;
     }
 
-    set_handle(ptp, pthp);
-
     act = enqueue_task(pp, ptp);
     if (act & ERTS_PTS_FLG_EXIT) {
 	reset_handle(ptp);
@@ -572,6 +1351,7 @@ erts_port_task_execute(ErtsRunQueue *runq, Port **curr_port_pp)
 {
     Port *pp;
     ErtsPortTask *execq;
+    int processing_busy_q;
     int res = 0;
     int reds = ERTS_PORT_REDS_EXECUTE;
     erts_aint_t io_tasks_executed = 0;
@@ -606,7 +1386,7 @@ erts_port_task_execute(ErtsRunQueue *runq, Port **curr_port_pp)
 	erts_smp_spin_unlock(&erts_sched_stat.lock);
     }
 
-    prepare_exec(pp, &execq);
+    prepare_exec(pp, &execq, &processing_busy_q);
 
     erts_smp_port_lock(pp);
 
@@ -617,14 +1397,14 @@ erts_port_task_execute(ErtsRunQueue *runq, Port **curr_port_pp)
 
     fpe_was_unmasked = erts_block_fpe();
 
-    state = erts_atomic_read_nob(&pp->state);
+    state = erts_atomic32_read_nob(&pp->state);
     goto begin_handle_tasks;
 
     while (1) {
 	erts_aint32_t task_state;
 	ErtsPortTask *ptp;
 
-	ptp = pop_task(pp, &execq);
+	ptp = select_task_for_exec(pp, &execq, &processing_busy_q);
 	if (!ptp)
 	    break;
 
@@ -645,40 +1425,44 @@ erts_port_task_execute(ErtsRunQueue *runq, Port **curr_port_pp)
 	switch (ptp->type) {
 	case ERTS_PORT_TASK_TIMEOUT:
 	    reds += ERTS_PORT_REDS_TIMEOUT;
-	    if (!(erts_atomic32_read_nob(&pp->state) & ERTS_PORT_SFLGS_DEAD)) {
+	    if (!(state & ERTS_PORT_SFLGS_DEAD)) {
                 DTRACE_DRIVER(driver_timeout, pp);
 		(*pp->drv_ptr->timeout)((ErlDrvData) pp->drv_data);
             }
 	    break;
 	case ERTS_PORT_TASK_INPUT:
 	    reds += ERTS_PORT_REDS_INPUT;
-	    ASSERT((erts_atomic32_read_nob(&pp->state)
-		    & ERTS_PORT_SFLGS_DEAD) == 0);
+	    ASSERT((state & ERTS_PORT_SFLGS_DEAD) == 0);
             DTRACE_DRIVER(driver_ready_input, pp);
 	    /* NOTE some windows drivers use ->ready_input for input and output */
 	    (*pp->drv_ptr->ready_input)((ErlDrvData) pp->drv_data,
-					ptp->u.alive.u.io.event);
+					ptp->u.alive.td.io.event);
 	    io_tasks_executed++;
 	    break;
 	case ERTS_PORT_TASK_OUTPUT:
 	    reds += ERTS_PORT_REDS_OUTPUT;
-	    ASSERT((erts_atomic32_read_nob(&pp->state)
-		    & ERTS_PORT_SFLGS_DEAD) == 0);
+	    ASSERT((state & ERTS_PORT_SFLGS_DEAD) == 0);
             DTRACE_DRIVER(driver_ready_output, pp);
 	    (*pp->drv_ptr->ready_output)((ErlDrvData) pp->drv_data,
-					 ptp->u.alive.u.io.event);
+					 ptp->u.alive.td.io.event);
 	    io_tasks_executed++;
 	    break;
 	case ERTS_PORT_TASK_EVENT:
 	    reds += ERTS_PORT_REDS_EVENT;
-	    ASSERT((erts_atomic32_read_nob(&pp->state)
-		    & ERTS_PORT_SFLGS_DEAD) == 0);
+	    ASSERT((state & ERTS_PORT_SFLGS_DEAD) == 0);
             DTRACE_DRIVER(driver_event, pp);
 	    (*pp->drv_ptr->event)((ErlDrvData) pp->drv_data,
-				  ptp->u.alive.u.io.event,
-				  ptp->u.alive.u.io.event_data);
+				  ptp->u.alive.td.io.event,
+				  ptp->u.alive.td.io.event_data);
 	    io_tasks_executed++;
 	    break;
+	case ERTS_PORT_TASK_PROC_SIG:
+	    ASSERT((state & ERTS_PORT_SFLGS_DEAD) == 0);
+	    reds += ptp->u.alive.td.psig.callback(pp,
+						  state,
+						  ERTS_PROC2PORT_SIG_EXEC,
+						  &ptp->u.alive.td.psig.data);
+	    break;
 	case ERTS_PORT_TASK_DIST_CMD:
 	    reds += erts_dist_command(pp, CONTEXT_REDS-reds);
 	    break;
@@ -740,7 +1524,7 @@ erts_port_task_execute(ErtsRunQueue *runq, Port **curr_port_pp)
     ASSERT(runq == (ErtsRunQueue *) erts_smp_atomic_read_nob(&pp->run_queue));
 #endif
 
-    active = finalize_exec(pp, &execq);
+    active = finalize_exec(pp, &execq, processing_busy_q);
 
     erts_port_release(pp);
 
@@ -858,24 +1642,30 @@ begin_port_cleanup(Port *pp, ErtsPortTask **execqp)
 		break;
 	    case ERTS_PORT_TASK_INPUT:
 		erts_stale_drv_select(pp->common.id,
-				      ptp->u.alive.u.io.event,
+				      ptp->u.alive.td.io.event,
 				      DO_READ,
 				      1);
 		break;
 	    case ERTS_PORT_TASK_OUTPUT:
 		erts_stale_drv_select(pp->common.id,
-				      ptp->u.alive.u.io.event,
+				      ptp->u.alive.td.io.event,
 				      DO_WRITE,
 				      1);
 		break;
 	    case ERTS_PORT_TASK_EVENT:
 		erts_stale_drv_select(pp->common.id,
-				      ptp->u.alive.u.io.event,
+				      ptp->u.alive.td.io.event,
 				      0,
 				      1);
 		break;
 	    case ERTS_PORT_TASK_DIST_CMD:
 		break;
+	    case ERTS_PORT_TASK_PROC_SIG:
+		ptp->u.alive.td.psig.callback(NULL,
+					      ERTS_PORT_SFLG_INVALID,
+					      ERTS_PROC2PORT_SIG_ABORT_CLOSED,
+					      &ptp->u.alive.td.psig.data);
+		break;
 	    default:
 		erl_exit(ERTS_ABORT_EXIT,
 			 "Invalid port task type: %d\n",
@@ -944,4 +1734,5 @@ erts_port_task_init(void)
     erts_smp_atomic_init_nob(&erts_port_task_outstanding_io_tasks,
 			     (erts_aint_t) 0);
     init_port_task_alloc();
+    init_busy_caller_table_alloc();
 }
diff --git a/erts/emulator/beam/erl_port_task.h b/erts/emulator/beam/erl_port_task.h
index 71b1cc6e25..c41f8104c7 100644
--- a/erts/emulator/beam/erl_port_task.h
+++ b/erts/emulator/beam/erl_port_task.h
@@ -27,6 +27,9 @@
 #define ERTS_PORT_TASK_H_BASIC_TYPES__
 #include "erl_sys_driver.h"
 #include "erl_smp.h"
+#define ERL_PORT_GET_PORT_TYPE_ONLY__
+#include "erl_port.h"
+#undef ERL_PORT_GET_PORT_TYPE_ONLY__
 typedef erts_smp_atomic_t ErtsPortTaskHandle;
 #endif
 
@@ -43,12 +46,19 @@ typedef erts_smp_atomic_t ErtsPortTaskHandle;
 #define ERTS_INCLUDE_SCHEDULER_INTERNALS
 #endif
 
+#define ERTS_PT_FLG_WAIT_BUSY		(1 << 0)
+#define ERTS_PT_FLG_SIG_DEP		(1 << 1)
+#define ERTS_PT_FLG_NOSUSPEND		(1 << 2)
+#define ERTS_PT_FLG_REF			(1 << 3)
+#define ERTS_PT_FLG_BAD_OUTPUT		(1 << 4)
+
 typedef enum {
     ERTS_PORT_TASK_INPUT,
     ERTS_PORT_TASK_OUTPUT,
     ERTS_PORT_TASK_EVENT,
     ERTS_PORT_TASK_TIMEOUT,
-    ERTS_PORT_TASK_DIST_CMD
+    ERTS_PORT_TASK_DIST_CMD,
+    ERTS_PORT_TASK_PROC_SIG
 } ErtsPortTaskType;
 
 #ifdef ERTS_INCLUDE_SCHEDULER_INTERNALS
@@ -61,14 +71,35 @@ extern erts_smp_atomic_t erts_port_task_outstanding_io_tasks;
 #define ERTS_PTS_FLG_HAVE_TASKS		(((erts_aint32_t) 1) << 2)
 #define ERTS_PTS_FLG_EXIT		(((erts_aint32_t) 1) << 3)
 #define ERTS_PTS_FLG_BUSY		(((erts_aint32_t) 1) << 4)
+#define ERTS_PTS_FLG_HAVE_BUSY_TASKS	(((erts_aint32_t) 1) << 5)
+#define ERTS_PTS_FLG_HAVE_NS_TASKS	(((erts_aint32_t) 1) << 6)
+#define ERTS_PTS_FLG_PARALLELISM	(((erts_aint32_t) 1) << 7)
+#define ERTS_PTS_FLG_FORCE_SCHED	(((erts_aint32_t) 1) << 8)
+
 
+#define ERTS_PTS_FLGS_FORCE_SCHEDULE_OP		\
+    (ERTS_PTS_FLG_EXIT				\
+     | ERTS_PTS_FLG_HAVE_BUSY_TASKS		\
+     | ERTS_PTS_FLG_HAVE_TASKS			\
+     | ERTS_PTS_FLG_EXEC			\
+     | ERTS_PTS_FLG_FORCE_SCHED)
 
 typedef struct ErtsPortTask_ ErtsPortTask;
+typedef struct ErtsPortTaskBusyCallerTable_ ErtsPortTaskBusyCallerTable;
+typedef struct ErtsPortTaskHandleList_ ErtsPortTaskHandleList;
 
 typedef struct {
     Port *next;
     struct {
-	ErtsPortTask *local;
+	struct {
+	    struct {
+		ErtsPortTask *first;
+		ErtsPortTask *last;
+		ErtsPortTaskBusyCallerTable *table;
+		ErtsPortTaskHandleList *nosuspend;
+	    } busy;
+	    ErtsPortTask *first;
+	} local;
 	struct {
 	    ErtsPortTask *first;
 	    ErtsPortTask *last;
@@ -87,6 +118,7 @@ ERTS_GLB_INLINE void erts_port_task_init_sched(ErtsPortTaskSched *ptsp,
 ERTS_GLB_INLINE void erts_port_task_fini_sched(ErtsPortTaskSched *ptsp);
 ERTS_GLB_INLINE void erts_port_task_sched_lock(ErtsPortTaskSched *ptsp);
 ERTS_GLB_INLINE void erts_port_task_sched_unlock(ErtsPortTaskSched *ptsp);
+ERTS_GLB_INLINE int erts_port_task_sched_lock_is_locked(ErtsPortTaskSched *ptsp);
 
 #ifdef ERTS_INCLUDE_SCHEDULER_INTERNALS
 ERTS_GLB_INLINE int erts_port_task_have_outstanding_io_tasks(void);
@@ -110,7 +142,11 @@ ERTS_GLB_INLINE void
 erts_port_task_init_sched(ErtsPortTaskSched *ptsp, Eterm instr_id)
 {
     ptsp->next = NULL;
-    ptsp->taskq.local = NULL;
+    ptsp->taskq.local.busy.first = NULL;
+    ptsp->taskq.local.busy.last = NULL;
+    ptsp->taskq.local.busy.table = NULL;
+    ptsp->taskq.local.busy.nosuspend = NULL;
+    ptsp->taskq.local.first = NULL;
     ptsp->taskq.in.first = NULL;
     ptsp->taskq.in.last = NULL;
     erts_smp_atomic32_init_nob(&ptsp->flags, 0);
@@ -135,6 +171,17 @@ erts_port_task_sched_unlock(ErtsPortTaskSched *ptsp)
 #endif
 }
 
+ERTS_GLB_INLINE int
+erts_port_task_sched_lock_is_locked(ErtsPortTaskSched *ptsp)
+{
+#if defined(ERTS_SMP) && defined(ERTS_ENABLE_LOCK_CHECK)
+    return erts_lc_mtx_is_locked(&ptsp->mtx);
+#else
+    return 0;
+#endif
+}
+
+
 ERTS_GLB_INLINE void
 erts_port_task_fini_sched(ErtsPortTaskSched *ptsp)
 {
@@ -162,12 +209,15 @@ void erts_port_task_init(void);
 #endif
 
 int erts_port_task_abort(ErtsPortTaskHandle *);
+void erts_port_task_abort_nosuspend_tasks(Port *);
+
 int erts_port_task_schedule(Eterm,
 			    ErtsPortTaskHandle *,
 			    ErtsPortTaskType,
 			    ...);
 void erts_port_task_free_port(Port *);
 int erts_port_is_scheduled(Port *);
+ErtsProc2PortSigData *erts_port_task_alloc_p2p_sig_data(void);
 
 #ifdef ERTS_SMP
 void erts_enqueue_port(ErtsRunQueue *rq, Port *pp);
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 6cf267b01e..332cc81d48 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -1490,7 +1490,7 @@ handle_reap_ports(ErtsAuxWorkData *awdp, erts_aint32_t aux_work)
 						    ERTS_PORT_SFLG_HALT);
 		erts_smp_atomic32_inc_nob(&erts_halt_progress);
 		if (!(state & (ERTS_PORT_SFLG_EXITING|ERTS_PORT_SFLG_CLOSING)))
-		    erts_do_exit_port(prt, prt->common.id, am_killed);
+		    erts_deliver_port_exit(prt, prt->common.id, am_killed, 0);
 	    }
 
 	    erts_port_release(prt);
@@ -6086,6 +6086,8 @@ erts_suspend(Process* c_p, ErtsProcLocks c_p_locks, Port *busy_port)
     if (!(c_p_locks & ERTS_PROC_LOCK_STATUS))
 	erts_smp_proc_unlock(c_p, ERTS_PROC_LOCK_STATUS);
 
+    if (suspend && busy_port && erts_system_monitor_flags.busy_port)
+	monitor_generic(c_p, am_busy_port, busy_port->common.id);
 }
 
 void
@@ -8183,14 +8185,15 @@ static void doit_exit_link(ErtsLink *lnk, void *vpcontext)
     switch(lnk->type) {
     case LINK_PID:
 	if(is_internal_port(item)) {
-	    Port *prt = erts_id2port(item);
-	    if (prt) {
-		rlnk = erts_remove_link(&ERTS_P_LINKS(prt), p->common.id);
-		if (rlnk)
-		    erts_destroy_link(rlnk);
-		erts_do_exit_port(prt, p->common.id, reason);
-		erts_port_release(prt);
-	    }
+	    Port *prt = erts_port_lookup(item, ERTS_PORT_SFLGS_INVALID_LOOKUP);
+	    if (prt)
+		erts_port_exit(NULL,
+			       (ERTS_PORT_SIG_FLG_FORCE_SCHED
+				| ERTS_PORT_SIG_FLG_BROKEN_LINK),
+			       prt,
+			       p->common.id,
+			       reason,
+			       NULL);
 	}
 	else if(is_external_port(item)) {
 	    erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
diff --git a/erts/emulator/beam/erl_thr_progress.h b/erts/emulator/beam/erl_thr_progress.h
index 0e63d41fda..1416aa6166 100644
--- a/erts/emulator/beam/erl_thr_progress.h
+++ b/erts/emulator/beam/erl_thr_progress.h
@@ -134,6 +134,7 @@ typedef struct {
 typedef int ErtsThrPrgrDelayHandle;
 #define ERTS_THR_PRGR_DHANDLE_MANAGED ((ErtsThrPrgrDelayHandle) -1)
 /* ERTS_THR_PRGR_DHANDLE_MANAGED implies managed thread */
+#define ERTS_THR_PRGR_DHANDLE_INVALID ((ErtsThrPrgrDelayHandle) -2)
 
 extern ErtsThrPrgr erts_thr_prgr__;
 
diff --git a/erts/emulator/beam/erl_trace.h b/erts/emulator/beam/erl_trace.h
new file mode 100644
index 0000000000..0d6df699ff
--- /dev/null
+++ b/erts/emulator/beam/erl_trace.h
@@ -0,0 +1,138 @@
+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2012. All Rights Reserved.
+ *
+ * The contents of this file are subject to the Erlang Public License,
+ * Version 1.1, (the "License"); you may not use this file except in
+ * compliance with the License. You should have received a copy of the
+ * Erlang Public License along with this software. If not, it can be
+ * retrieved online at http://www.erlang.org/.
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ *
+ * %CopyrightEnd%
+ */
+
+
+#ifndef ERL_TRACE_H__
+#define ERL_TRACE_H__
+
+struct binary;
+
+/* erl_bif_trace.c */
+Eterm erl_seq_trace_info(Process *p, Eterm arg1);
+void erts_system_monitor_clear(Process *c_p);
+void erts_system_profile_clear(Process *c_p);
+
+/* erl_trace.c */
+void erts_init_trace(void);
+void erts_trace_check_exiting(Eterm exiting);
+Eterm erts_set_system_seq_tracer(Process *c_p,
+				 ErtsProcLocks c_p_locks,
+				 Eterm new);
+Eterm erts_get_system_seq_tracer(void);
+void erts_change_default_tracing(int setflags, Uint *flagsp, Eterm *tracerp);
+void erts_get_default_tracing(Uint *flagsp, Eterm *tracerp);
+void erts_set_system_monitor(Eterm monitor);
+Eterm erts_get_system_monitor(void);
+
+#ifdef ERTS_SMP
+void erts_check_my_tracer_proc(Process *);
+void erts_block_sys_msg_dispatcher(void);
+void erts_release_sys_msg_dispatcher(void);
+void erts_foreach_sys_msg_in_q(void (*func)(Eterm,
+					    Eterm,
+					    Eterm,
+					    ErlHeapFragment *));
+void erts_queue_error_logger_message(Eterm, Eterm, ErlHeapFragment *);
+#endif
+
+void erts_send_sys_msg_proc(Eterm, Eterm, Eterm, ErlHeapFragment *);
+void trace_send(Process*, Eterm, Eterm);
+void trace_receive(Process*, Eterm);
+Uint32 erts_call_trace(Process *p, BeamInstr mfa[], struct binary *match_spec, Eterm* args,
+		       int local, Eterm *tracer_pid);
+void erts_trace_return(Process* p, BeamInstr* fi, Eterm retval, Eterm *tracer_pid);
+void erts_trace_exception(Process* p, BeamInstr mfa[], Eterm class, Eterm value,
+			  Eterm *tracer);
+void erts_trace_return_to(Process *p, BeamInstr *pc);
+void trace_sched(Process*, Eterm);
+void trace_proc(Process*, Process*, Eterm, Eterm);
+void trace_proc_spawn(Process*, Eterm pid, Eterm mod, Eterm func, Eterm args);
+void save_calls(Process *p, Export *);
+void trace_gc(Process *p, Eterm what);
+/* port tracing */
+void trace_virtual_sched(Process*, Eterm);
+void trace_sched_ports(Port *pp, Eterm);
+void trace_sched_ports_where(Port *pp, Eterm, Eterm);
+void trace_port(Port *, Eterm what, Eterm data);
+void trace_port_open(Port *, Eterm calling_pid, Eterm drv_name);
+
+/* system_profile */
+void erts_set_system_profile(Eterm profile);
+Eterm erts_get_system_profile(void);
+void profile_scheduler(Eterm scheduler_id, Eterm);
+void profile_scheduler_q(Eterm scheduler_id, Eterm state, Eterm no_schedulers, Uint Ms, Uint s, Uint us);
+void profile_runnable_proc(Process* p, Eterm status);
+void profile_runnable_port(Port* p, Eterm status);
+void erts_system_profile_setup_active_schedulers(void);
+
+/* system_monitor */
+void monitor_long_gc(Process *p, Uint time);
+void monitor_large_heap(Process *p);
+void monitor_generic(Process *p, Eterm type, Eterm spec);
+Uint erts_trace_flag2bit(Eterm flag);
+int erts_trace_flags(Eterm List, 
+		 Uint *pMask, Eterm *pTracer, int *pCpuTimestamp);
+Eterm erts_bif_trace(int bif_index, Process* p, Eterm* args, BeamInstr *I);
+
+#ifdef ERTS_SMP
+void erts_send_pending_trace_msgs(ErtsSchedulerData *esdp);
+#define ERTS_SMP_CHK_PEND_TRACE_MSGS(ESDP)				\
+do {									\
+    if ((ESDP)->pending_trace_msgs)					\
+	erts_send_pending_trace_msgs((ESDP));				\
+} while (0)
+#else
+#define ERTS_SMP_CHK_PEND_TRACE_MSGS(ESDP)
+#endif
+
+#define seq_trace_output(token, msg, type, receiver, process) \
+seq_trace_output_generic((token), (msg), (type), (receiver), (process), NIL)
+#define seq_trace_output_exit(token, msg, type, receiver, exitfrom) \
+seq_trace_output_generic((token), (msg), (type), (receiver), NULL, (exitfrom))
+void seq_trace_output_generic(Eterm token, Eterm msg, Uint type, 
+			      Eterm receiver, Process *process, Eterm exitfrom);
+
+int seq_trace_update_send(Process *process);
+
+Eterm erts_seq_trace(Process *process, 
+		     Eterm atom_type, Eterm atom_true_or_false, 
+		     int build_result);
+
+struct trace_pattern_flags {
+    unsigned int breakpoint : 1; /* Set if any other is set */
+    unsigned int local      : 1; /* Local call trace breakpoint */
+    unsigned int meta       : 1; /* Metadata trace breakpoint */
+    unsigned int call_count : 1; /* Fast call count breakpoint */
+    unsigned int call_time  : 1; /* Fast call time breakpoint */
+};
+extern const struct trace_pattern_flags erts_trace_pattern_flags_off;
+extern int erts_call_time_breakpoint_tracing;
+int erts_set_trace_pattern(Eterm* mfa, int specified, 
+			   struct binary* match_prog_set, struct binary *meta_match_prog_set,
+			   int on, struct trace_pattern_flags,
+			   Eterm meta_tracer_pid);
+void
+erts_get_default_trace_pattern(int *trace_pattern_is_on,
+			       struct binary **match_spec,
+			       struct binary **meta_match_spec,
+			       struct trace_pattern_flags *trace_pattern_flags,
+			       Eterm *meta_tracer_pid);
+void erts_bif_trace_init(void);
+
+#endif /* ERL_TRACE_H__ */
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 6713481a04..d91dd7d9ec 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -578,11 +578,35 @@ Eterm erts_realloc_binary(Eterm bin, size_t size);
 
 /* erl_bif_info.c */
 
+Eterm
+erts_bld_port_info(Eterm **hpp,
+		   ErlOffHeap *ohp,
+		   Uint *szp,
+		   Port *prt,
+		   Eterm item); 
+
 void erts_bif_info_init(void);
 
 /* bif.c */
 Eterm erts_make_ref(Process *);
 Eterm erts_make_ref_in_buffer(Eterm buffer[REF_THING_SIZE]);
+void erts_make_ref_in_array(Uint32 ref[ERTS_MAX_REF_NUMBERS]);
+
+ERTS_GLB_INLINE Eterm
+erts_proc_store_ref(Process *c_p, Uint32 ref[ERTS_MAX_REF_NUMBERS]);
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_INLINE Eterm
+erts_proc_store_ref(Process *c_p, Uint32 ref[ERTS_MAX_REF_NUMBERS])
+{
+    Eterm *hp = HAlloc(c_p, REF_THING_SIZE);
+    write_ref_thing(hp, ref[0], ref[1], ref[2]);
+    return make_internal_ref(hp);
+}
+
+#endif
+
 void erts_queue_monitor_message(Process *,
 				ErtsProcLocks*,
 				Eterm,
@@ -596,13 +620,6 @@ Eterm erl_send(Process *p, Eterm to, Eterm msg);
 
 Eterm erl_is_function(Process* p, Eterm arg1, Eterm arg2);
 
-/* erl_bif_port.c */
-
-/* erl_bif_trace.c */
-Eterm erl_seq_trace_info(Process *p, Eterm arg1);
-void erts_system_monitor_clear(Process *c_p);
-void erts_system_profile_clear(Process *c_p);
-
 /* beam_load.c */
 typedef struct {
     BeamInstr* current;		/* Pointer to: Mod, Name, Arity */
@@ -892,7 +909,6 @@ typedef struct {
 #define ERTS_SPAWN_DRIVER 1
 #define ERTS_SPAWN_EXECUTABLE 2
 #define ERTS_SPAWN_ANY (ERTS_SPAWN_DRIVER | ERTS_SPAWN_EXECUTABLE)
-
 int erts_add_driver_entry(ErlDrvEntry *drv, DE_Handle *handle, int driver_list_locked);
 void erts_destroy_driver(erts_driver_t *drv);
 int erts_save_suspend_process_on_port(Port*, Process*);
@@ -900,10 +916,6 @@ Port *erts_open_driver(erts_driver_t*, Eterm, char*, SysDriverOpts*, int *, int
 int erts_is_port_ioq_empty(Port *);
 void erts_terminate_port(Port *);
 void erts_init_io(int, int);
-void erts_do_exit_port(Port *, Eterm, Eterm);
-void erts_port_command(Process *, Eterm, Port *, Eterm);
-Eterm erts_port_control(Process*, Port*, Uint, Eterm);
-int erts_write_to_port(Eterm caller_id, Port *p, Eterm list);
 void erts_raw_port_command(Port*, byte*, Uint);
 void driver_report_exit(ErlDrvPort, int);
 LineBuf* allocate_linebuf(int);
@@ -963,79 +975,6 @@ char *erts_convert_filename_to_native(Eterm name, ErtsAlcType_t alloc_type, int
 #define ERTS_UTF8_ERROR 2
 #define ERTS_UTF8_ANALYZE_MORE 3
 
-/* erl_trace.c */
-void erts_init_trace(void);
-void erts_trace_check_exiting(Eterm exiting);
-Eterm erts_set_system_seq_tracer(Process *c_p,
-				 ErtsProcLocks c_p_locks,
-				 Eterm new);
-Eterm erts_get_system_seq_tracer(void);
-void erts_change_default_tracing(int setflags, Uint *flagsp, Eterm *tracerp);
-void erts_get_default_tracing(Uint *flagsp, Eterm *tracerp);
-void erts_set_system_monitor(Eterm monitor);
-Eterm erts_get_system_monitor(void);
-
-#ifdef ERTS_SMP
-void erts_check_my_tracer_proc(Process *);
-void erts_block_sys_msg_dispatcher(void);
-void erts_release_sys_msg_dispatcher(void);
-void erts_foreach_sys_msg_in_q(void (*func)(Eterm,
-					    Eterm,
-					    Eterm,
-					    ErlHeapFragment *));
-void erts_queue_error_logger_message(Eterm, Eterm, ErlHeapFragment *);
-#endif
-
-void erts_send_sys_msg_proc(Eterm, Eterm, Eterm, ErlHeapFragment *);
-void trace_send(Process*, Eterm, Eterm);
-void trace_receive(Process*, Eterm);
-Uint32 erts_call_trace(Process *p, BeamInstr mfa[], Binary *match_spec, Eterm* args,
-		       int local, Eterm *tracer_pid);
-void erts_trace_return(Process* p, BeamInstr* fi, Eterm retval, Eterm *tracer_pid);
-void erts_trace_exception(Process* p, BeamInstr mfa[], Eterm class, Eterm value,
-			  Eterm *tracer);
-void erts_trace_return_to(Process *p, BeamInstr *pc);
-void trace_sched(Process*, Eterm);
-void trace_proc(Process*, Process*, Eterm, Eterm);
-void trace_proc_spawn(Process*, Eterm pid, Eterm mod, Eterm func, Eterm args);
-void save_calls(Process *p, Export *);
-void trace_gc(Process *p, Eterm what);
-/* port tracing */
-void trace_virtual_sched(Process*, Eterm);
-void trace_sched_ports(Port *pp, Eterm);
-void trace_sched_ports_where(Port *pp, Eterm, Eterm);
-void trace_port(Port *, Eterm what, Eterm data);
-void trace_port_open(Port *, Eterm calling_pid, Eterm drv_name);
-
-/* system_profile */
-void erts_set_system_profile(Eterm profile);
-Eterm erts_get_system_profile(void);
-void profile_scheduler(Eterm scheduler_id, Eterm);
-void profile_scheduler_q(Eterm scheduler_id, Eterm state, Eterm no_schedulers, Uint Ms, Uint s, Uint us);
-void profile_runnable_proc(Process* p, Eterm status);
-void profile_runnable_port(Port* p, Eterm status);
-void erts_system_profile_setup_active_schedulers(void);
-
-/* system_monitor */
-void monitor_long_gc(Process *p, Uint time);
-void monitor_large_heap(Process *p);
-void monitor_generic(Process *p, Eterm type, Eterm spec);
-Uint erts_trace_flag2bit(Eterm flag);
-int erts_trace_flags(Eterm List, 
-		 Uint *pMask, Eterm *pTracer, int *pCpuTimestamp);
-Eterm erts_bif_trace(int bif_index, Process* p, Eterm* args, BeamInstr *I);
-
-#ifdef ERTS_SMP
-void erts_send_pending_trace_msgs(ErtsSchedulerData *esdp);
-#define ERTS_SMP_CHK_PEND_TRACE_MSGS(ESDP)				\
-do {									\
-    if ((ESDP)->pending_trace_msgs)					\
-	erts_send_pending_trace_msgs((ESDP));				\
-} while (0)
-#else
-#define ERTS_SMP_CHK_PEND_TRACE_MSGS(ESDP)
-#endif
-
 void bin_write(int, void*, byte*, size_t);
 int intlist_to_buf(Eterm, char*, int); /* most callers pass plain char*'s */
 
@@ -1053,9 +992,16 @@ char* Sint_to_buf(Sint, struct Sint_buf*);
 #define ERTS_IOLIST_TYPE 2
 
 Eterm buf_to_intlist(Eterm**, char*, size_t, Eterm); /* most callers pass plain char*'s */
-int io_list_to_buf(Eterm, char*, int);
-int io_list_to_buf2(Eterm, char*, int);
-int erts_iolist_size(Eterm, Uint *);
+
+#define ERTS_IOLIST_TO_BUF_OVERFLOW	(~((ErlDrvSizeT) 0))
+#define ERTS_IOLIST_TO_BUF_TYPE_ERROR	(~((ErlDrvSizeT) 1))
+#define ERTS_IOLIST_TO_BUF_FAILED(R) \
+    (((R) & (~((ErlDrvSizeT) 1))) == (~((ErlDrvSizeT) 1)))
+#define ERTS_IOLIST_TO_BUF_SUCCEEDED(R) \
+    (!ERTS_IOLIST_TO_BUF_FAILED((R)))
+
+ErlDrvSizeT erts_iolist_to_buf(Eterm, char*, ErlDrvSizeT);
+int erts_iolist_size(Eterm, ErlDrvSizeT *);
 int is_string(Eterm);
 void erl_at_exit(void (*) (void*), void*);
 Eterm collect_memory(Process *);
@@ -1100,39 +1046,6 @@ Uint erts_current_reductions(Process* current, Process *p);
 int erts_print_system_version(int to, void *arg, Process *c_p);
 
 int erts_hibernate(Process* c_p, Eterm module, Eterm function, Eterm args, Eterm* reg);
-#define seq_trace_output(token, msg, type, receiver, process) \
-seq_trace_output_generic((token), (msg), (type), (receiver), (process), NIL)
-#define seq_trace_output_exit(token, msg, type, receiver, exitfrom) \
-seq_trace_output_generic((token), (msg), (type), (receiver), NULL, (exitfrom))
-void seq_trace_output_generic(Eterm token, Eterm msg, Uint type, 
-			      Eterm receiver, Process *process, Eterm exitfrom);
-
-int seq_trace_update_send(Process *process);
-
-Eterm erts_seq_trace(Process *process, 
-		     Eterm atom_type, Eterm atom_true_or_false, 
-		     int build_result);
-
-struct trace_pattern_flags {
-    unsigned int breakpoint : 1; /* Set if any other is set */
-    unsigned int local      : 1; /* Local call trace breakpoint */
-    unsigned int meta       : 1; /* Metadata trace breakpoint */
-    unsigned int call_count : 1; /* Fast call count breakpoint */
-    unsigned int call_time  : 1; /* Fast call time breakpoint */
-};
-extern const struct trace_pattern_flags erts_trace_pattern_flags_off;
-extern int erts_call_time_breakpoint_tracing;
-int erts_set_trace_pattern(Eterm* mfa, int specified, 
-			   Binary* match_prog_set, Binary *meta_match_prog_set,
-			   int on, struct trace_pattern_flags,
-			   Eterm meta_tracer_pid);
-void
-erts_get_default_trace_pattern(int *trace_pattern_is_on,
-			       Binary **match_spec,
-			       Binary **meta_match_spec,
-			       struct trace_pattern_flags *trace_pattern_flags,
-			       Eterm *meta_tracer_pid);
-void erts_bif_trace_init(void);
 
 /*
 ** Call_trace uses this API for the parameter matching functions
diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.c
index 6776f72894..2a55a7c09f 100644
--- a/erts/emulator/beam/io.c
+++ b/erts/emulator/beam/io.c
@@ -43,6 +43,8 @@
 #include "erl_version.h"
 #include "error.h"
 #include "erl_async.h"
+#define ERTS_WANT_EXTERNAL_TAGS
+#include "external.h"
 #include "dtrace-wrapper.h"
 
 extern ErlDrvEntry fd_driver_entry;
@@ -69,6 +71,11 @@ erts_driver_t vanilla_driver;
 erts_driver_t spawn_driver;
 erts_driver_t fd_driver;
 
+int erts_port_synchronous_ops = 0;
+int erts_port_schedule_all_ops = 0;
+int erts_port_parallelism = 0;
+
+static void deliver_result(Eterm sender, Eterm pid, Eterm res);
 static int init_driver(erts_driver_t *, ErlDrvEntry *, DE_Handle *);
 static void terminate_port(Port *p);
 static void pdl_init(void);
@@ -254,9 +261,12 @@ static void insert_port_struct(void *vprt, Eterm data)
     erts_atomic32_init_relb(&prt->state, ERTS_PORT_SFLG_INITIALIZING);
 }
 
+#define ERTS_CREATE_PORT_FLAG_PARALLELISM		(1 << 0)
+
 static Port *create_port(char *name,
 			 erts_driver_t *driver,
 			 erts_mtx_t *driver_lock,
+			 int create_flags,
 			 Eterm pid,
 			 int *enop)
 {
@@ -264,6 +274,7 @@ static Port *create_port(char *name,
     char *p;
     size_t port_size, size;
     erts_aint32_t state = ERTS_PORT_SFLG_CONNECTED;
+    erts_aint32_t x_pts_flgs = 0;
 #ifdef DEBUG
     /* Make sure the debug flags survives until port is freed */
     state |= ERTS_PORT_SFLG_PORT_DEBUG;
@@ -373,6 +384,15 @@ static Port *create_port(char *name,
 
     ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
 
+    if (erts_port_schedule_all_ops)
+	x_pts_flgs |= ERTS_PTS_FLG_FORCE_SCHED;
+
+    if (create_flags & ERTS_CREATE_PORT_FLAG_PARALLELISM)
+	x_pts_flgs |= ERTS_PTS_FLG_PARALLELISM;
+
+    if (x_pts_flgs)
+	erts_smp_atomic32_read_bor_nob(&prt->sched.flags, x_pts_flgs);
+
     erts_atomic32_set_relb(&prt->state, state);
     return prt;
 }
@@ -525,6 +545,7 @@ erts_open_driver(erts_driver_t* driver,	/* Pointer to driver. */
     int error_type, error_number;
     int port_errno = 0;
     erts_mtx_t *driver_lock = NULL;
+    int cprt_flgs = 0;
 
     ERTS_SMP_CHK_NO_PROC_LOCKS;
 
@@ -599,7 +620,10 @@ erts_open_driver(erts_driver_t* driver,	/* Pointer to driver. */
      * to allow message sending and setting timers in the start function.
      */
 
-    port = create_port(name, driver, driver_lock, pid, &port_errno);
+    if (opts->parallelism)
+	cprt_flgs |= ERTS_CREATE_PORT_FLAG_PARALLELISM;
+
+    port = create_port(name, driver, driver_lock, cprt_flgs, pid, &port_errno);
     if (!port) {
 	if (driver->handle) {
 	    erts_smp_rwmtx_rlock(&erts_driver_list_lock);
@@ -713,6 +737,7 @@ driver_create_port(ErlDrvPort creator_port_ix, /* Creating port */
 		   char* name,            /* Driver name */
 		   ErlDrvData drv_data)   /* Driver data */
 {
+    int cprt_flgs = 0;
     Port *creator_port;
     Port* port;
     erts_driver_t *driver;
@@ -753,7 +778,11 @@ driver_create_port(ErlDrvPort creator_port_ix, /* Creating port */
 
     erts_smp_rwmtx_runlock(&erts_driver_list_lock);
 
-    port = create_port(name, driver, driver_lock, pid, NULL);
+    /* Inherit parallelism flag from parent */
+    if (ERTS_PTS_FLG_PARALLELISM &
+	erts_smp_atomic32_read_nob(&creator_port->sched.flags))
+	cprt_flgs |= ERTS_CREATE_PORT_FLAG_PARALLELISM;
+    port = create_port(name, driver, driver_lock, cprt_flgs, pid, NULL);
     if (!port) {
 	if (driver->handle) {
 	    erts_smp_rwmtx_rlock(&erts_driver_list_lock);
@@ -806,10 +835,15 @@ erts_smp_xports_unlock(Port *prt)
     xplp = prt->xports;
     ASSERT(xplp);
     while (xplp) {
+	Port *rprt = xplp->port;
 	ErtsXPortsList *free_xplp;
-	if (xplp->port->xports)
-	    erts_smp_xports_unlock(xplp->port);
-	erts_port_release(xplp->port);
+	erts_aint32_t state;
+	if (rprt->xports)
+	    erts_smp_xports_unlock(rprt);
+	state = erts_atomic32_read_nob(&rprt->state);
+	if ((state & ERTS_PORT_SFLG_CLOSING) && erts_is_port_ioq_empty(rprt))
+	    terminate_port(rprt);
+	erts_port_release(rprt);
 	free_xplp = xplp;
 	xplp = xplp->next;
 	xports_list_free(free_xplp);
@@ -849,8 +883,8 @@ io_list_to_vec(Eterm obj,	/* io-list */
     DECLARE_ESTACK(s);
     Eterm* objp;
     char *buf  = cbin->orig_bytes;
-    ErlDrvSizeT len = cbin->orig_size;
-    ErlDrvSizeT csize  = 0;
+    Uint len = cbin->orig_size;
+    Uint csize  = 0;
     int vlen   = 0;
     char* cptr = buf;
 
@@ -965,7 +999,7 @@ io_list_to_vec(Eterm obj,	/* io-list */
 
 #define IO_LIST_VEC_COUNT(obj)						\
 do {									\
-    ErlDrvSizeT _size = binary_size(obj);				\
+    Uint _size = binary_size(obj);					\
     Eterm _real;							\
     ERTS_DECLARE_DUMMY(Uint _offset);					\
     int _bitoffs;							\
@@ -1016,8 +1050,9 @@ do {									\
  */
 
 static int 
-io_list_vec_len(Eterm obj, Uint* vsize, Uint* csize,
-		Uint* pvsize, Uint* pcsize, Uint* total_size)
+io_list_vec_len(Eterm obj, int* vsize, Uint* csize,
+		Uint* pvsize, Uint* pcsize,
+		ErlDrvSizeT* total_size)
 {
     DECLARE_ESTACK(s);
     Eterm* objp;
@@ -1028,7 +1063,7 @@ io_list_vec_len(Eterm obj, Uint* vsize, Uint* csize,
     Uint p_v_size = 0;
     Uint p_c_size = 0;
     Uint p_in_clist = 0;
-    Uint total;
+    Uint total; /* Uint due to halfword emulator */
 
     goto L_jump_start;  /* avoid a push */
 
@@ -1088,7 +1123,7 @@ io_list_vec_len(Eterm obj, Uint* vsize, Uint* csize,
     if (total < c_size) {
 	goto L_overflow_error;
     }
-    *total_size = total;
+    *total_size = (ErlDrvSizeT) total;
 
     DESTROY_ESTACK(s);
     *vsize = v_size;
@@ -1103,56 +1138,691 @@ io_list_vec_len(Eterm obj, Uint* vsize, Uint* csize,
     return 1;
 }
 
-/* write data to a port */
-int erts_write_to_port(Eterm caller_id, Port *p, Eterm list)
-{
-    char *buf;
-    erts_driver_t *drv = p->drv_ptr;
-    Uint size;
+typedef enum {
+    ERTS_TRY_IMM_DRV_CALL_OK,
+    ERTS_TRY_IMM_DRV_CALL_BUSY_LOCK,
+    ERTS_TRY_IMM_DRV_CALL_INVALID_PORT,
+    ERTS_TRY_IMM_DRV_CALL_INVALID_SCHED_FLAGS
+} ErtsTryImmDrvCallResult;
+
+typedef struct {
+    Process *c_p; /* Currently executing process (unlocked) */
+    Port *port; /* Port to operate on */
+    Eterm port_op; /* port operation as an atom */
+    erts_aint32_t state; /* in: invalid state; out: read state (if read) */
+    erts_aint32_t sched_flags; /* in: invalid flags; out: read flags (if read) */
+    int async; /* Asynchronous operation */
+    int pre_chk_sched_flags; /* Check sched flags before lock? */
     int fpe_was_unmasked;
-    
-    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(p));
+} ErtsTryImmDrvCallState;
+
+#define ERTS_INIT_TRY_IMM_DRV_CALL_STATE(C_P, PRT, SFLGS, PTS_FLGS, A, PRT_OP) \
+    {(C_P), (PRT), (PRT_OP), (SFLGS), (PTS_FLGS), (A), 1, 0}
+
+/*
+ * Try doing an immediate driver callback call from a process. If
+ * this fail, the operation should be scheduled in the normal case...
+ *
+ */
+static ERTS_INLINE ErtsTryImmDrvCallResult
+try_imm_drv_call(ErtsTryImmDrvCallState *sp)
+{
+    ErtsTryImmDrvCallResult res;
+    erts_aint32_t invalid_state, invalid_sched_flags;
+    Port *prt = sp->port;
+    Process *c_p = sp->c_p;
+
+    ASSERT(is_atom(sp->port_op));
+
+    invalid_sched_flags = ERTS_PTS_FLGS_FORCE_SCHEDULE_OP;
+    invalid_sched_flags |= sp->sched_flags;
+    if (sp->async)
+	invalid_sched_flags |= ERTS_PTS_FLG_PARALLELISM;
+
+    if (sp->pre_chk_sched_flags) {
+	sp->sched_flags = erts_smp_atomic32_read_nob(&prt->sched.flags);
+	if (sp->sched_flags & invalid_sched_flags)
+	    return ERTS_TRY_IMM_DRV_CALL_INVALID_SCHED_FLAGS;
+    }
+
+    if (erts_smp_port_trylock(prt) == EBUSY)
+	return ERTS_TRY_IMM_DRV_CALL_BUSY_LOCK;
+
+    invalid_state = sp->state;
+    sp->state = erts_atomic32_read_nob(&prt->state);
+    if (sp->state & invalid_state) {
+	res = ERTS_TRY_IMM_DRV_CALL_INVALID_PORT;
+	goto locked_fail;
+    }
+
+    sp->sched_flags = erts_smp_atomic32_read_nob(&prt->sched.flags);
+    if (sp->sched_flags & invalid_sched_flags) {
+	res = ERTS_TRY_IMM_DRV_CALL_INVALID_SCHED_FLAGS;
+	goto locked_fail;
+    }
+
+    if (c_p) {
+	if (IS_TRACED_FL(c_p, F_TRACE_SCHED_PROCS))
+	    trace_virtual_sched(c_p, am_out);
+	if (erts_system_profile_flags.runnable_procs
+	    && erts_system_profile_flags.exclusive)
+	    profile_runnable_proc(c_p, am_inactive);
+
+	erts_smp_proc_unlock(c_p, ERTS_PROC_LOCK_MAIN);
+    }
+
     ERTS_SMP_CHK_NO_PROC_LOCKS;
 
-    p->caller = caller_id;
-    if (drv->outputv != NULL) {
-	Uint vsize;
-	Uint csize;
-	Uint pvsize;
-	Uint pcsize;
-	ErlDrvSizeT blimit;
+    if (IS_TRACED_FL(prt, F_TRACE_SCHED_PORTS))
+	trace_sched_ports_where(prt, am_in, sp->port_op);
+    if (erts_system_profile_flags.runnable_ports
+	&& !erts_port_is_scheduled(prt))
+    	profile_runnable_port(prt, am_active);
+
+    sp->fpe_was_unmasked = erts_block_fpe();
+
+    return ERTS_TRY_IMM_DRV_CALL_OK;
+
+locked_fail:
+    erts_port_release(prt);
+    return res;
+}
+
+static ERTS_INLINE void
+finalize_imm_drv_call(ErtsTryImmDrvCallState *sp)
+{
+    Port *prt = sp->port;
+    Process *c_p = sp->c_p;
+
+    erts_unblock_fpe(sp->fpe_was_unmasked);
+
+#ifdef ERTS_SMP
+    if (prt->xports)
+	erts_smp_xports_unlock(prt);
+    ASSERT(!prt->xports);
+#endif
+
+    if (IS_TRACED_FL(prt, F_TRACE_SCHED_PORTS))
+	trace_sched_ports_where(prt, am_out, sp->port_op);
+    if (erts_system_profile_flags.runnable_ports
+	&& !erts_port_is_scheduled(prt))
+    	profile_runnable_port(prt, am_inactive);
+
+    erts_port_release(prt);
+
+    if (c_p) {
+	erts_smp_proc_lock(c_p, ERTS_PROC_LOCK_MAIN);
+
+	if (IS_TRACED_FL(c_p, F_TRACE_SCHED_PROCS))
+	    trace_virtual_sched(c_p, am_in);
+	if (erts_system_profile_flags.runnable_procs
+	    && erts_system_profile_flags.exclusive)
+	    profile_runnable_proc(c_p, am_active);
+    }
+}
+
+#define ERTS_QUEUE_PORT_SCHED_OP_REPLY_SIZE (REF_THING_SIZE + 3)
+
+static ERTS_INLINE void
+queue_port_sched_op_reply(Process *rp,
+			  ErtsProcLocks *rp_locksp,
+			  Eterm *hp_start,
+			  Eterm *hp,
+			  Uint h_size,
+			  ErlHeapFragment* bp,
+			  Uint32 *ref_num,
+			  Eterm msg)
+{
+    Eterm ref = make_internal_ref(hp);
+    write_ref_thing(hp, ref_num[0], ref_num[1], ref_num[2]);
+    hp += REF_THING_SIZE;
+
+    msg = TUPLE2(hp, ref, msg);
+    hp += 3;
+
+    if (!bp) {
+	HRelease(rp, hp_start + h_size, hp);
+    }
+    else {
+	Uint used_h_size = hp - hp_start;
+	ASSERT(h_size >= used_h_size);
+	if (h_size > used_h_size)
+	    bp = erts_resize_message_buffer(bp, used_h_size, &msg, 1);
+    }
+
+    erts_queue_message(rp,
+		       rp_locksp,
+		       bp,
+		       msg,
+		       NIL
+#ifdef USE_VM_PROBES
+		       , NIL
+#endif
+	);
+}
+
+static void
+port_sched_op_reply(Eterm to, Uint32 *ref_num, Eterm msg)
+{
+    Process *rp = erts_proc_lookup_raw(to);
+    if (rp) {
+	ErlOffHeap *ohp;
+	ErlHeapFragment* bp;
+	Eterm msg_copy;
+	Uint hsz, msg_sz;
+	Eterm *hp, *hp_start;
+	ErtsProcLocks rp_locks = 0;
+
+	hsz = ERTS_QUEUE_PORT_SCHED_OP_REPLY_SIZE;
+	if (is_immed(msg))
+	    msg_sz = 0;
+	else {
+	    msg_sz = size_object(msg);
+	    hsz += msg_sz;
+	}
+
+	hp_start = hp = erts_alloc_message_heap(hsz,
+						&bp,
+						&ohp,
+						rp,
+						&rp_locks);
+	if (is_immed(msg))
+	    msg_copy = msg;
+	else
+	    msg_copy = copy_struct(msg, msg_sz, &hp, ohp);
+
+	queue_port_sched_op_reply(rp,
+				  &rp_locks,
+				  hp_start,
+				  hp,
+				  hsz,
+				  bp,
+				  ref_num,
+				  msg_copy);
+
+	if (rp_locks)
+	    erts_smp_proc_unlock(rp, rp_locks);
+    }
+}
+
+
+ErtsPortOpResult
+erts_schedule_proc2port_signal(Process *c_p,
+			       Port *prt,
+			       Eterm caller,
+			       Eterm *refp,
+			       ErtsProc2PortSigData *sigdp,
+			       int task_flags,
+			       ErtsProc2PortSigCallback callback)
+{
+    int sched_res;
+    if (!refp) {
+	if (c_p)
+	    erts_smp_proc_unlock(c_p, ERTS_PROC_LOCK_MAIN);
+    }
+    else {
+	ASSERT(c_p);
+	sigdp->flags |= ERTS_P2P_SIG_DATA_FLG_REPLY;
+	erts_make_ref_in_array(sigdp->ref);
+	*refp = erts_proc_store_ref(c_p, sigdp->ref);
+
+	/*
+	 * Caller needs to wait for a message containing
+	 * the ref that we just created. No such message
+	 * can exist in callers message queue at this time.
+	 * We therefore move the save pointer of the
+	 * callers message queue to the end of the queue.
+	 *
+	 * NOTE: It is of vital importance that the caller
+	 *       immediately do a receive unconditionaly
+	 *       waiting for the message with the reference;
+	 *       otherwise, next receive will *not* work
+	 *       as expected!
+	 */
+	erts_smp_proc_lock(c_p, ERTS_PROC_LOCKS_MSG_RECEIVE);
+
+	if (ERTS_PROC_PENDING_EXIT(c_p)) {
+	    /* need to exit caller instead */
+	    erts_smp_proc_unlock(c_p, ERTS_PROC_LOCKS_MSG_RECEIVE);
+	    KILL_CATCHES(c_p);
+	    c_p->freason = EXC_EXIT;
+	    return ERTS_PORT_OP_CALLER_EXIT;
+	}
+
+	ERTS_SMP_MSGQ_MV_INQ2PRIVQ(c_p);
+	c_p->msg.save = c_p->msg.last;
+
+	erts_smp_proc_unlock(c_p,
+			     (ERTS_PROC_LOCK_MAIN
+			      | ERTS_PROC_LOCKS_MSG_RECEIVE));
+    }
+
+
+    sigdp->caller = caller;
+
+    /* Schedule port close call for later execution... */
+    sched_res = erts_port_task_schedule(prt->common.id,
+					NULL,
+					ERTS_PORT_TASK_PROC_SIG,
+					sigdp,
+					callback,
+					task_flags);
+
+    if (c_p)
+	erts_smp_proc_lock(c_p, ERTS_PROC_LOCK_MAIN);
+
+    if (sched_res != 0) {
+	if (refp)
+	    *refp = NIL;
+	return ERTS_PORT_OP_DROPPED;
+    }
+    return ERTS_PORT_OP_SCHEDULED;
+}
+
+static ERTS_INLINE void
+send_badsig(Port *prt)
+{
+    ErtsProcLocks rp_locks = ERTS_PROC_LOCKS_XSIG_SEND;
+    Process* rp;
+    Eterm connected = ERTS_PORT_GET_CONNECTED(prt);
+
+    ERTS_SMP_CHK_NO_PROC_LOCKS;
+    ERTS_LC_ASSERT(erts_get_scheduler_id());
+
+    ASSERT(is_internal_pid(connected));
+
+    rp = erts_proc_lookup_raw(connected);
+    if (rp) {
+	erts_smp_proc_lock(rp, rp_locks);
+	if (!ERTS_PROC_IS_EXITING(rp))
+	    (void) erts_send_exit_signal(NULL,
+					 prt->common.id,
+					 rp,
+					 &rp_locks, 
+					 am_badsig,
+					 NIL,
+					 NULL,
+					 0);
+	if (rp_locks)
+	    erts_smp_proc_unlock(rp, rp_locks);
+    }
+}
+
+static void
+badsig_received(int bang_op,
+		Port *prt,
+		erts_aint32_t state,
+		int bad_output_value)
+{
+    /*
+     * if (bang_op)
+     *   we are part of a "Prt ! Something" operation
+     * else
+     *   we are part of a call to a port BIF
+     * behave accordingly...
+     */
+    if (!(state & ERTS_PORT_SFLGS_INVALID_LOOKUP)) {
+	if (bad_output_value) {
+	    erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
+	    erts_dsprintf(dsbufp, "Bad value on output port '%s'\n", prt->name);
+	    erts_send_error_to_logger_nogl(dsbufp);
+	}
+	if (bang_op)
+	    send_badsig(prt);
+    }
+}
+
+static int
+port_badsig(Port *prt, erts_aint32_t state, int op, ErtsProc2PortSigData *sigdp)
+{
+    if (op == ERTS_PROC2PORT_SIG_EXEC)
+	badsig_received(sigdp->flags & ERTS_P2P_SIG_DATA_FLG_BANG_OP,
+			prt,
+			state,
+			sigdp->flags & ERTS_P2P_SIG_DATA_FLG_BAD_OUTPUT);
+    if (sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY)
+	port_sched_op_reply(sigdp->caller, sigdp->ref, am_badarg);
+    return ERTS_PORT_REDS_BADSIG;
+}
+
+
+/*
+ * bad_port_signal() will
+ * - preserve signal order of signals.
+ * - send a 'badsig' exit signal to connected process if 'from' is an
+ *   internal pid and the port is alive when the bad signal reaches
+ *   it.
+ */
+static ErtsPortOpResult
+bad_port_signal(Process *c_p,
+		int flags,
+		Port *prt,
+		Eterm from,
+		Eterm *refp,
+		Eterm port_op)
+{
+    ErtsProc2PortSigData *sigdp;
+    ErtsTryImmDrvCallResult try_call_res;
+    ErtsTryImmDrvCallState try_call_state
+	= ERTS_INIT_TRY_IMM_DRV_CALL_STATE(
+	    c_p,
+	    prt,
+	    ERTS_PORT_SFLGS_INVALID_LOOKUP,
+	    0,
+	    !refp,
+	    port_op);
+
+    try_call_res = try_imm_drv_call(&try_call_state);
+    switch (try_call_res) {
+    case ERTS_TRY_IMM_DRV_CALL_OK:
+	badsig_received(flags & ERTS_PORT_SIG_FLG_BANG_OP,
+			prt,
+			try_call_state.state,
+			flags & ERTS_PORT_SIG_FLG_BAD_OUTPUT);
+	finalize_imm_drv_call(&try_call_state);
+	return ERTS_PORT_OP_BADARG;
+    case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+	return ERTS_PORT_OP_DROPPED;
+    case ERTS_TRY_IMM_DRV_CALL_INVALID_SCHED_FLAGS:
+    case ERTS_TRY_IMM_DRV_CALL_BUSY_LOCK:
+	/* Schedule badsig() call instead... */
+	break;
+    }
+
+    sigdp = erts_port_task_alloc_p2p_sig_data();
+    sigdp->flags = flags;
+
+    return erts_schedule_proc2port_signal(c_p,
+					  prt,
+					  c_p->common.id,
+					  refp,
+					  sigdp,
+					  0,
+					  port_badsig);
+}
+
+
+/*
+ * Driver outputv() callback
+ */
+
+static ERTS_INLINE void
+call_driver_outputv(int bang_op,
+		    Eterm caller,
+		    Eterm from,
+		    Port *prt,
+		    erts_driver_t *drv,
+		    ErlIOVec *evp)
+{
+    /*
+     * if (bang_op)
+     *   we are part of a "Prt ! {From, {command, Data}}" operation
+     * else
+     *   we are part of a call to port_command/[2,3]
+     * behave accordingly...
+     */
+    if (bang_op && from != ERTS_PORT_GET_CONNECTED(prt))
+	send_badsig(prt);
+    else {
+	ErlDrvSizeT size = evp->size;
+
+	ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
+
+#ifdef USE_VM_PROBES
+	if (DTRACE_ENABLED(driver_outputv)) {
+	    DTRACE_FORMAT_COMMON_PID_AND_PORT(caller, prt);
+	    DTRACE4(driver_outputv, process_str, port_str, prt->name, size);
+	}
+#endif
+
+	prt->caller = caller;
+	(*drv->outputv)((ErlDrvData) prt->drv_data, evp);
+	prt->caller = NIL;
+
+	prt->bytes_out += size;
+	erts_smp_atomic_add_nob(&erts_bytes_out, size);
+    }
+}
+
+static ERTS_INLINE void
+cleanup_scheduled_outputv(ErlIOVec *ev, ErlDrvBinary *cbinp)
+{
+    int i;
+    /* Need to free all binaries */
+    for (i = 1; i < ev->vsize; i++)
+	if (ev->binv[i])
+	    driver_free_binary(ev->binv[i]);
+    if (cbinp)
+	driver_free_binary(cbinp);
+    erts_free(ERTS_ALC_T_DRV_CMD_DATA, ev);
+}
+
+static int
+port_sig_outputv(Port *prt, erts_aint32_t state, int op, ErtsProc2PortSigData *sigdp)
+{
+    Eterm reply;
+
+    switch (op) {
+    case ERTS_PROC2PORT_SIG_EXEC:
+	/* Execution of a scheduled outputv() call */
+
+	ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
+
+	if (state & ERTS_PORT_SFLGS_INVALID_LOOKUP)
+	    reply = am_badarg;
+	else {
+	    call_driver_outputv(sigdp->flags & ERTS_P2P_SIG_DATA_FLG_BANG_OP,
+				sigdp->caller,
+				sigdp->u.outputv.from,
+				prt,
+				prt->drv_ptr,
+				sigdp->u.outputv.evp);
+	    reply = am_true;
+	}
+	break;
+    case ERTS_PROC2PORT_SIG_ABORT_NOSUSPEND:
+	reply = am_false;
+	break;
+    default:
+	reply = am_badarg;
+	break;
+    }
+
+    if (sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY)
+	port_sched_op_reply(sigdp->caller, sigdp->ref, reply);
+
+    cleanup_scheduled_outputv(sigdp->u.outputv.evp,
+			      sigdp->u.outputv.cbinp);
+
+    return ERTS_PORT_REDS_CMD_OUTPUTV;
+}
+
+/*
+ * Driver output() callback
+ */
+
+static ERTS_INLINE void
+call_driver_output(int bang_op,
+		   Eterm caller,
+		   Eterm from,
+		   Port *prt,
+		   erts_driver_t *drv,
+		   char *bufp,
+		   ErlDrvSizeT size)
+{
+    /*
+     * if (bang_op)
+     *   we are part of a "Prt ! {From, {command, Data}}" operation
+     * else
+     *   we are part of a call to port_command/[2,3]
+     * behave accordingly...
+     */
+    if (bang_op && from != ERTS_PORT_GET_CONNECTED(prt))
+	send_badsig(prt);
+    else {
+
+#ifdef USE_VM_PROBES
+	if (DTRACE_ENABLED(driver_output)) {
+	    DTRACE_FORMAT_COMMON_PID_AND_PORT(caller, prt);
+	    DTRACE4(driver_output, process_str, port_str, prt->name, size);
+	}
+#endif
+
+	prt->caller = caller;
+	(*drv->output)((ErlDrvData) prt->drv_data, bufp, size);
+	prt->caller = NIL;
+
+	prt->bytes_out += size;
+	erts_smp_atomic_add_nob(&erts_bytes_out, size);
+    }
+}
+
+static ERTS_INLINE void
+cleanup_scheduled_output(char *bufp)
+{
+    erts_free(ERTS_ALC_T_DRV_CMD_DATA, bufp);
+}
+
+static int
+port_sig_output(Port *prt, erts_aint32_t state, int op, ErtsProc2PortSigData *sigdp)
+{
+    Eterm reply;
+
+    switch (op) {
+    case ERTS_PROC2PORT_SIG_EXEC:
+	/* Execution of a scheduled output() call */
+
+	ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
+
+	if (state & ERTS_PORT_SFLGS_INVALID_LOOKUP)
+	    reply = am_badarg;
+	else {
+	    call_driver_output(sigdp->flags & ERTS_P2P_SIG_DATA_FLG_BANG_OP,
+			       sigdp->caller,
+			       sigdp->u.output.from,
+			       prt,
+			       prt->drv_ptr,
+			       sigdp->u.output.bufp,
+			       sigdp->u.output.size);
+	    reply = am_true;
+	}
+	break;
+    case ERTS_PROC2PORT_SIG_ABORT_NOSUSPEND:
+	reply = am_false;
+	break;
+    default:
+	reply = am_badarg;
+	break;
+    }
+
+    if (sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY)
+	port_sched_op_reply(sigdp->caller, sigdp->ref, reply);
+
+    cleanup_scheduled_output(sigdp->u.output.bufp);
+
+    return ERTS_PORT_REDS_CMD_OUTPUT;
+}
+
+ErtsPortOpResult
+erts_port_output(Process *c_p,
+		 int flags,
+		 Port *prt,
+		 Eterm from,
+		 Eterm list,
+		 Eterm *refp)
+{
+    ErtsPortOpResult res;
+    ErtsProc2PortSigData *sigdp;
+    erts_driver_t *drv = prt->drv_ptr;
+    size_t size;
+    int try_call;
+    erts_aint32_t sched_flags, busy_flag, invalid_flags;
+    int task_flags;
+    ErtsProc2PortSigCallback port_sig_callback;
+    ErlDrvBinary *cbin = NULL;
+    ErlIOVec *evp = NULL;
+    char *buf = NULL;
+
+    ASSERT((flags & ~(ERTS_PORT_SIG_FLG_BANG_OP
+		      | ERTS_PORT_SIG_FLG_NOSUSPEND
+		      | ERTS_PORT_SIG_FLG_FORCE)) == 0);
+
+    busy_flag = ((flags & ERTS_PORT_SIG_FLG_FORCE)
+		 ? ((erts_aint32_t) 0)
+		 : ERTS_PTS_FLG_BUSY);
+    invalid_flags = busy_flag;
+    if (!refp)
+	invalid_flags |= ERTS_PTS_FLG_PARALLELISM;
+
+    /*
+     * Assumes caller have checked that port is valid...
+     */
+
+    sched_flags = erts_smp_atomic32_read_nob(&prt->sched.flags);
+    if (sched_flags & (busy_flag|ERTS_PTS_FLG_EXIT))
+	return ((sched_flags & busy_flag)
+		? ERTS_PORT_OP_BUSY
+		: ERTS_PORT_OP_DROPPED);
+
+    try_call = !(sched_flags & (invalid_flags|ERTS_PTS_FLGS_FORCE_SCHEDULE_OP));
+
+#ifdef USE_VM_PROBES
+    if(DTRACE_ENABLED(port_command)) {
+	DTRACE_FORMAT_COMMON_PID_AND_PORT(c_p->common.id, prt);
+	DTRACE4(port_command, process_str, port_str, prt->name, "command");
+    }
+#endif
+
+    if (drv->outputv) {
+	ErlIOVec ev;
 	SysIOVec iv[SMALL_WRITE_VEC];
 	ErlDrvBinary* bv[SMALL_WRITE_VEC];
 	SysIOVec* ivp;
 	ErlDrvBinary**  bvp;
-	ErlDrvBinary* cbin;
-	ErlIOVec ev;
+	int vsize;
+	Uint csize;
+	Uint pvsize;
+	Uint pcsize;
+	Uint blimit;
+	size_t iov_offset, binv_offset, alloc_size;
 
-	if (io_list_vec_len(list, &vsize, &csize,
-			    &pvsize, &pcsize, &size)) {
+	if (io_list_vec_len(list, &vsize, &csize, &pvsize, &pcsize, &size))
 	    goto bad_value;
+
+	iov_offset = ERTS_ALC_DATA_ALIGN_SIZE(sizeof(ErlIOVec));
+	binv_offset = iov_offset;
+	binv_offset += ERTS_ALC_DATA_ALIGN_SIZE((vsize+1)*sizeof(SysIOVec));
+	alloc_size = binv_offset;
+	alloc_size += (vsize+1)*sizeof(ErlDrvBinary *);
+
+	if (try_call && vsize < SMALL_WRITE_VEC) {
+	    ivp = ev.iov = iv;
+	    bvp = ev.binv = bv;
+	    evp = &ev;
 	}
+	else {
+	    char *ptr = erts_alloc((try_call
+				    ? ERTS_ALC_T_TMP
+				    : ERTS_ALC_T_DRV_CMD_DATA), alloc_size);
+
+	    evp = (ErlIOVec *) ptr;
+	    ivp = evp->iov = (SysIOVec *) (ptr + iov_offset);
+	    bvp = evp->binv = (ErlDrvBinary **) (ptr + binv_offset);
+	}
+
 	/* To pack or not to pack (small binaries) ...? */
-	vsize++;
-	if (vsize <= SMALL_WRITE_VEC) {
+	if (vsize < SMALL_WRITE_VEC) {
 	    /* Do NOT pack */
 	    blimit = 0;
-	} else {
+	}
+	else {
 	    /* Do pack */
 	    vsize = pvsize + 1;
 	    csize = pcsize;
 	    blimit = ERL_SMALL_IO_BIN_LIMIT;
 	}
 	/* Use vsize and csize from now on */
-	if (vsize <= SMALL_WRITE_VEC) {
-	    ivp = iv;
-	    bvp = bv;
-	} else {
-	    ivp = (SysIOVec *) erts_alloc(ERTS_ALC_T_TMP,
-					  vsize * sizeof(SysIOVec));
-	    bvp = (ErlDrvBinary**) erts_alloc(ERTS_ALC_T_TMP,
-					      vsize * sizeof(ErlDrvBinary*));
-	}
+
 	cbin = driver_alloc_binary(csize);
 	if (!cbin)
 	    erts_alloc_enomem(ERTS_ALC_T_DRV_BINARY, ERTS_SIZEOF_Binary(csize));
@@ -1161,120 +1831,695 @@ int erts_write_to_port(Eterm caller_id, Port *p, Eterm list)
 	ivp[0].iov_base = NULL;
 	ivp[0].iov_len = 0;
 	bvp[0] = NULL;
-	ev.vsize = io_list_to_vec(list, ivp+1, bvp+1, cbin, blimit);
-	if (ev.vsize < 0) {
-	    if (ivp != iv) {
-		erts_free(ERTS_ALC_T_TMP, (void *) ivp);
-	    }
-	    if (bvp != bv) {
-		erts_free(ERTS_ALC_T_TMP, (void *) bvp);
-	    }
+	evp->vsize = io_list_to_vec(list, ivp+1, bvp+1, cbin, blimit);
+	if (evp->vsize < 0) {
+	    if (evp != &ev)
+		erts_free(try_call ? ERTS_ALC_T_TMP : ERTS_ALC_T_DRV_CMD_DATA,
+			  evp);
 	    driver_free_binary(cbin);
 	    goto bad_value;
 	}
-	ev.vsize++;
 #if 0
 	/* This assertion may say something useful, but it can
 	   be falsified during the emulator test suites. */
-	ASSERT(ev.vsize == vsize);
+	ASSERT(evp->vsize == vsize);
 #endif
-	ev.size = size;  /* total size */
-	ev.iov = ivp;
-	ev.binv = bvp;
-#ifdef USE_VM_PROBES
-        if (DTRACE_ENABLED(driver_outputv)) {
-            DTRACE_FORMAT_COMMON_PID_AND_PORT(caller_id, p)
-            DTRACE4(driver_outputv, process_str, port_str, p->name, size);
-        }
-#endif
-	fpe_was_unmasked = erts_block_fpe();
-	(*drv->outputv)((ErlDrvData)p->drv_data, &ev);
-	erts_unblock_fpe(fpe_was_unmasked);
-	if (ivp != iv) {
-	    erts_free(ERTS_ALC_T_TMP, (void *) ivp);
-	}
-	if (bvp != bv) {
-	    erts_free(ERTS_ALC_T_TMP, (void *) bvp);
+	evp->vsize++;
+	evp->size = size;  /* total size */
+
+	if (!try_call) {
+	    int i;
+	    /* Need to increase refc on all binaries */
+	    for (i = 1; i < evp->vsize; i++)
+		if (bvp[i])
+		    driver_binary_inc_refc(bvp[i]);
 	}
-	driver_free_binary(cbin);
-    } else {
-	int r;
-	
-	/* Try with an 8KB buffer first (will often be enough I guess). */
-	size = 8*1024;
-	/* See below why the extra byte is added. */
-	buf = erts_alloc(ERTS_ALC_T_TMP, size+1);
-	r = io_list_to_buf(list, buf, size);
+	else {
+	    int i;
+	    ErlIOVec *new_evp;
+	    ErtsTryImmDrvCallResult try_call_res;
+	    ErtsTryImmDrvCallState try_call_state
+		= ERTS_INIT_TRY_IMM_DRV_CALL_STATE(
+		    c_p,
+		    prt,
+		    ERTS_PORT_SFLGS_INVALID_LOOKUP,
+		    invalid_flags,
+		    !refp,
+		    am_command);
+	    try_call_state.pre_chk_sched_flags = 0; /* already checked */
+	    try_call_res = try_imm_drv_call(&try_call_state);
+	    switch (try_call_res) {
+	    case ERTS_TRY_IMM_DRV_CALL_OK:
+		call_driver_outputv(flags & ERTS_PORT_SIG_FLG_BANG_OP,
+				    c_p->common.id,
+				    from,
+				    prt,
+				    drv,
+				    evp);
+		finalize_imm_drv_call(&try_call_state);
+		/* Fall through... */
+	    case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+		driver_free_binary(cbin);
+		if (evp != &ev)
+		    erts_free(ERTS_ALC_T_TMP, evp);
+		if (try_call_res == ERTS_TRY_IMM_DRV_CALL_OK)
+		    return ERTS_PORT_OP_DONE;
+		else
+		    return ERTS_PORT_OP_DROPPED;
+	    case ERTS_TRY_IMM_DRV_CALL_INVALID_SCHED_FLAGS:
+		sched_flags = try_call_state.sched_flags;
+	    case ERTS_TRY_IMM_DRV_CALL_BUSY_LOCK:
+		/* Schedule outputv() call instead... */
+		break;
+	    }
 
-#ifdef USE_VM_PROBES
-	if(DTRACE_ENABLED(port_command)) {
-            DTRACE_FORMAT_COMMON_PID_AND_PORT(caller_id, p)
-	    DTRACE4(port_command, process_str, port_str, p->name, "command");
-	}
+	    /* Need to increase refc on all binaries */
+	    for (i = 1; i < evp->vsize; i++)
+		if (bvp[i])
+		    driver_binary_inc_refc(bvp[i]);
+
+	    new_evp = erts_alloc(ERTS_ALC_T_DRV_CMD_DATA, alloc_size);
+
+	    if (evp != &ev) {
+		sys_memcpy((void *) new_evp, (void *) evp, alloc_size);
+		new_evp->iov = (SysIOVec *) (((char *) new_evp)
+					     + iov_offset);
+		bvp = new_evp->binv = (ErlDrvBinary **) (((char *) new_evp)
+							 + binv_offset);
+
+#ifdef DEBUG
+		ASSERT(new_evp->vsize == evp->vsize);
+		ASSERT(new_evp->size == evp->size);
+		for (i = 0; i < evp->vsize; i++) {
+		    ASSERT(new_evp->iov[i].iov_len == evp->iov[i].iov_len);
+		    ASSERT(new_evp->iov[i].iov_base == evp->iov[i].iov_base);
+		    ASSERT(new_evp->binv[i] == evp->binv[i]);
+		}
 #endif
 
-	if (r >= 0) {
-	    size -= r;
-#ifdef USE_VM_PROBES
-            if (DTRACE_ENABLED(driver_output)) {
-                DTRACE_FORMAT_COMMON_PID_AND_PORT(caller_id, p)
-                DTRACE4(driver_output, process_str, port_str, p->name, size);
-            }
+		erts_free(ERTS_ALC_T_TMP, evp);
+	    }
+	    else { /* from stack allocated structure; offsets may differ */
+
+		sys_memcpy((void *) new_evp, (void *) evp, sizeof(ErlIOVec));
+		new_evp->iov = (SysIOVec *) (((char *) new_evp)
+					     + iov_offset);
+		sys_memcpy((void *) new_evp->iov,
+			   (void *) evp->iov,
+			   evp->vsize * sizeof(SysIOVec));
+		new_evp->binv = (ErlDrvBinary **) (((char *) new_evp)
+						   + binv_offset);
+		sys_memcpy((void *) new_evp->binv,
+			   (void *) evp->binv,
+			   evp->vsize * sizeof(ErlDrvBinary *));
+
+#ifdef DEBUG
+		ASSERT(new_evp->vsize == evp->vsize);
+		ASSERT(new_evp->size == evp->size);
+		for (i = 0; i < evp->vsize; i++) {
+		    ASSERT(new_evp->iov[i].iov_len == evp->iov[i].iov_len);
+		    ASSERT(new_evp->iov[i].iov_base == evp->iov[i].iov_base);
+		    ASSERT(new_evp->binv[i] == evp->binv[i]);
+		}
 #endif
-	    fpe_was_unmasked = erts_block_fpe();
-	    (*drv->output)((ErlDrvData)p->drv_data, buf, size);
-	    erts_unblock_fpe(fpe_was_unmasked);
-	    erts_free(ERTS_ALC_T_TMP, buf);
+
+	    }
+
+	    evp = new_evp;
 	}
-	else if (r == -2) {
-	    erts_free(ERTS_ALC_T_TMP, buf);
-	    goto bad_value;
+
+	sigdp = erts_port_task_alloc_p2p_sig_data();
+	sigdp->u.outputv.from = from;
+	sigdp->u.outputv.evp = evp;
+	sigdp->u.outputv.cbinp = cbin;
+	port_sig_callback = port_sig_outputv;
+    }
+    else {
+	ErlDrvSizeT r;
+
+	/*
+	 * Apperently there exist code that write 1 byte to
+	 * much in buffer. Where it resides I don't know, but
+	 * we can live with one byte extra allocated...
+	 */
+
+	if (!try_call) {
+	    if (erts_iolist_size(list, &size))
+		goto bad_value;
+
+	    buf = erts_alloc(ERTS_ALC_T_DRV_CMD_DATA, size + 1);
+
+	    r = erts_iolist_to_buf(list, buf, size);
+	    ASSERT(ERTS_IOLIST_TO_BUF_SUCCEEDED(r));
 	}
 	else {
-	    ASSERT(r == -1); /* Overflow */
-	    erts_free(ERTS_ALC_T_TMP, buf);
-	    if (erts_iolist_size(list, &size)) {
-		goto bad_value;
+	    char *new_buf;
+	    ErtsTryImmDrvCallResult try_call_res;
+	    ErtsTryImmDrvCallState try_call_state
+		= ERTS_INIT_TRY_IMM_DRV_CALL_STATE(
+		    c_p,
+		    prt,
+		    ERTS_PORT_SFLGS_INVALID_LOOKUP,
+		    invalid_flags,
+		    !refp,
+		    am_command);
+
+	    /* Try with an 8KB buffer first (will often be enough I guess). */
+	    size = 8*1024;
+
+	    buf = erts_alloc(ERTS_ALC_T_TMP, size + 1);
+	    r = erts_iolist_to_buf(list, buf, size);
+
+	    if (ERTS_IOLIST_TO_BUF_SUCCEEDED(r)) {
+		ASSERT(r <= size);
+		size -= r;
+	    }
+	    else {
+		erts_free(ERTS_ALC_T_TMP, buf);
+		if (r == ERTS_IOLIST_TO_BUF_TYPE_ERROR)
+		    goto bad_value;
+		ASSERT(r == ERTS_IOLIST_TO_BUF_OVERFLOW);
+		if (erts_iolist_size(list, &size))
+		    goto bad_value;
+		buf = erts_alloc(ERTS_ALC_T_TMP, size + 1); 
+		r = erts_iolist_to_buf(list, buf, size);
+		ASSERT(ERTS_IOLIST_TO_BUF_SUCCEEDED(r));
+	    }
+	    try_call_state.pre_chk_sched_flags = 0; /* already checked */
+	    try_call_res = try_imm_drv_call(&try_call_state);
+	    switch (try_call_res) {
+	    case ERTS_TRY_IMM_DRV_CALL_OK:
+		call_driver_output(flags & ERTS_PORT_SIG_FLG_BANG_OP,
+				   c_p->common.id,
+				   from,
+				   prt,
+				   drv,
+				   buf,
+				   size);
+		finalize_imm_drv_call(&try_call_state);
+		/* Fall through... */
+	    case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+		erts_free(ERTS_ALC_T_TMP, buf);
+		if (try_call_res == ERTS_TRY_IMM_DRV_CALL_OK)
+		    return ERTS_PORT_OP_DONE;
+		else
+		    return ERTS_PORT_OP_DROPPED;
+	    case ERTS_TRY_IMM_DRV_CALL_INVALID_SCHED_FLAGS:
+		sched_flags = try_call_state.sched_flags;
+	    case ERTS_TRY_IMM_DRV_CALL_BUSY_LOCK:
+		/* Schedule outputv() call instead... */
+		break;
 	    }
 
-	    /*
-	     * I know drivers that pad space with '\0' this is clearly
-	     * incorrect but I don't feel like fixing them now, insted
-	     * add ONE extra byte.
-	     */
-	    buf = erts_alloc(ERTS_ALC_T_TMP, size+1); 
-	    r = io_list_to_buf(list, buf, size);
+	    new_buf = erts_alloc(ERTS_ALC_T_DRV_CMD_DATA, size + 1);
+	    sys_memcpy(new_buf, buf, size);
+	    erts_free(ERTS_ALC_T_TMP, buf);
+	    buf = new_buf;
+	}
+
+	sigdp = erts_port_task_alloc_p2p_sig_data();
+	sigdp->u.output.from = from;
+	sigdp->u.output.bufp = buf;
+	sigdp->u.output.size = size;
+	port_sig_callback = port_sig_output;
+    }
+
+    task_flags = ERTS_PT_FLG_WAIT_BUSY;
+    sigdp->flags = flags;
+    if (flags & (ERTS_P2P_SIG_DATA_FLG_FORCE|ERTS_P2P_SIG_DATA_FLG_NOSUSPEND)) {
+	task_flags = 0;
+	if (flags & ERTS_P2P_SIG_DATA_FLG_FORCE)
+	    sigdp->flags &= ~ERTS_P2P_SIG_DATA_FLG_NOSUSPEND;
+	else if (flags & ERTS_P2P_SIG_DATA_FLG_NOSUSPEND)
+	    task_flags = ERTS_PT_FLG_NOSUSPEND;
+    }
+
+    res = erts_schedule_proc2port_signal(c_p,
+					 prt,
+					 c_p->common.id,
+					 refp,
+					 sigdp,
+					 task_flags,
+					 port_sig_callback);
+
+    if (res != ERTS_PORT_OP_SCHEDULED) {
+	if (drv->outputv)
+	    cleanup_scheduled_outputv(evp, cbin);
+	else
+	    cleanup_scheduled_output(buf);
+	return res;
+    }
+
+    if ((sched_flags & (busy_flag|ERTS_PTS_FLG_EXIT)) == ERTS_PTS_FLG_BUSY)
+	return ERTS_PORT_OP_BUSY_SCHEDULED;
+
+    return res;
+
+bad_value:
+
+    flags |= ERTS_PORT_SIG_FLG_BAD_OUTPUT;
+    return bad_port_signal(c_p, flags, prt, from, refp, am_command);
+}
+
+static ERTS_INLINE ErtsPortOpResult
+call_deliver_port_exit(int bang_op,
+		       Eterm from,
+		       Port *prt,
+		       erts_aint32_t state,
+		       Eterm reason,
+		       int broken_link)
+{
+    /*
+     * if (bang_op)
+     *   we are part of a "Prt ! {From, close}" operation
+     * else
+     *   we are part of a call to port_close(Port)
+     * behave accordingly...
+     */
+
+    if (state & ERTS_PORT_SFLGS_INVALID_LOOKUP)
+	return ERTS_PORT_OP_DROPPED;
+
+    if (bang_op && from != ERTS_PORT_GET_CONNECTED(prt)) {
+	send_badsig(prt);
+	return ERTS_PORT_OP_DROPPED;
+    }
+
+    if (broken_link) {
+	ErtsLink *lnk = erts_remove_link(&ERTS_P_LINKS(prt), from);
+	if (lnk)
+	    erts_destroy_link(lnk);
+	else
+	    return ERTS_PORT_OP_DROPPED;
+    }
+
+    if (!erts_deliver_port_exit(prt, from, reason, bang_op))
+	return ERTS_PORT_OP_DROPPED;
+
 #ifdef USE_VM_PROBES
-            if (DTRACE_ENABLED(driver_output)) {
-                DTRACE_FORMAT_COMMON_PID_AND_PORT(caller_id, p)
-                DTRACE4(driver_output, process_str, port_str, p->name, size);
-            }
+    if(DTRACE_ENABLED(port_command) && bang_op) {
+	DTRACE_FORMAT_COMMON_PID_AND_PORT(from, prt);
+	DTRACE4(port_command, process_str, port_str, prt->name, "close");
+    }
 #endif
-	    fpe_was_unmasked = erts_block_fpe();
-	    (*drv->output)((ErlDrvData)p->drv_data, buf, size);
-	    erts_unblock_fpe(fpe_was_unmasked);
-	    erts_free(ERTS_ALC_T_TMP, buf);
+
+    return ERTS_PORT_OP_DONE;
+}
+
+static int
+port_sig_exit(Port *prt,
+	      erts_aint32_t state,
+	      int op,
+	      ErtsProc2PortSigData *sigdp)
+{
+    Eterm msg = am_badarg;
+    if (op == ERTS_PROC2PORT_SIG_EXEC) {
+	ErtsPortOpResult res;
+	int bang_op = sigdp->flags & ERTS_P2P_SIG_DATA_FLG_BANG_OP;
+	int broken_link = sigdp->flags & ERTS_P2P_SIG_DATA_FLG_BROKEN_LINK;
+	res = call_deliver_port_exit(bang_op,
+				     sigdp->u.exit.from,
+				     prt,
+				     state,
+				     sigdp->u.exit.reason,
+				     broken_link);
+
+	if (res == ERTS_PORT_OP_DONE)
+	    msg = am_true;
+    }
+    if (sigdp->u.exit.bp)
+	free_message_buffer(sigdp->u.exit.bp);
+    if (sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY)
+	port_sched_op_reply(sigdp->caller, sigdp->ref, msg);
+
+    return ERTS_PORT_REDS_EXIT;
+}
+
+ErtsPortOpResult
+erts_port_exit(Process *c_p,
+	       int flags,
+	       Port *prt,
+	       Eterm from,
+	       Eterm reason,
+	       Eterm *refp)
+{
+    ErtsPortOpResult res;
+    ErtsProc2PortSigData *sigdp;
+    ErlHeapFragment *bp = NULL;
+
+    ASSERT((flags & ~(ERTS_PORT_SIG_FLG_BANG_OP
+		      | ERTS_PORT_SIG_FLG_BROKEN_LINK
+		      | ERTS_PORT_SIG_FLG_FORCE_SCHED)) == 0);
+
+    if (!(flags & ERTS_PORT_SIG_FLG_FORCE_SCHED)) {
+	ErtsTryImmDrvCallState try_call_state
+	    = ERTS_INIT_TRY_IMM_DRV_CALL_STATE(c_p,
+					       prt,
+					       ERTS_PORT_SFLGS_INVALID_LOOKUP,
+					       0,
+					       !refp,
+					       am_exit);
+
+
+	switch (try_imm_drv_call(&try_call_state)) {
+	case ERTS_TRY_IMM_DRV_CALL_OK: {
+	    res = call_deliver_port_exit(flags & ERTS_PORT_SIG_FLG_BANG_OP,
+					 from,
+					 prt,
+					 try_call_state.state,
+					 reason,
+					 flags & ERTS_PORT_SIG_FLG_BROKEN_LINK);
+	    finalize_imm_drv_call(&try_call_state);
+	    return res;
+	}
+	case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+	    return ERTS_PORT_OP_DROPPED;
+	default:
+	    /* Schedule call instead... */
+	    break;
 	}
     }
-    p->bytes_out += size;
-    erts_smp_atomic_add_nob(&erts_bytes_out, size);
 
-#ifdef ERTS_SMP
-    if (p->xports)
-	erts_smp_xports_unlock(p);
-    ASSERT(!p->xports);
+    sigdp = erts_port_task_alloc_p2p_sig_data();
+    sigdp->flags = flags;
+    sigdp->u.exit.from = from;
+
+    if (is_immed(reason)) {
+	sigdp->u.exit.reason = reason;
+	sigdp->u.exit.bp = NULL;
+    }
+    else {
+	Eterm *hp;
+	Uint hsz = size_object(reason);
+	bp = new_message_buffer(hsz);
+	sigdp->u.exit.bp = bp;
+	hp = bp->mem;
+	sigdp->u.exit.reason = copy_struct(reason,
+					   hsz,
+					   &hp,
+					   &bp->off_heap);
+    }
+
+    res = erts_schedule_proc2port_signal(c_p,
+					 prt,
+					 c_p ? c_p->common.id : from,
+					 refp,
+					 sigdp,
+					 0,
+					 port_sig_exit);
+
+    if (res == ERTS_PORT_OP_DROPPED) {
+	if (bp)
+	    free_message_buffer(bp);
+    }
+
+    return res;
+}
+
+static ErtsPortOpResult
+set_port_connected(int bang_op,
+		   Eterm from,
+		   Port *prt,
+		   erts_aint32_t state,
+		   Eterm connect)
+{
+    /*
+     * if (bang_op)
+     *   we are part of a "Prt ! {From, {connect, Connect}}" operation
+     * else
+     *   we are part of a call to port_connect(Port, Connect)
+     * behave accordingly...
+     */
+
+    if (state & ERTS_PORT_SFLGS_INVALID_LOOKUP)
+	return ERTS_PORT_OP_DROPPED;
+
+    if (bang_op) { /* Bang operation */
+	if (is_not_internal_pid(connect) || ERTS_PORT_GET_CONNECTED(prt) != from) {
+	    send_badsig(prt);
+	    return ERTS_PORT_OP_DROPPED;
+	}
+
+	ERTS_PORT_SET_CONNECTED(prt, connect);
+	deliver_result(prt->common.id, from, am_connected);
+
+#ifdef USE_VM_PROBES
+	if(DTRACE_ENABLED(port_command)) {
+	    DTRACE_FORMAT_COMMON_PID_AND_PORT(from, prt);
+	    DTRACE4(port_command, process_str, port_str, prt->name, "connect");
+	}
 #endif
-    p->caller = NIL;
-    return 0;
+    }
+    else { /* Port BIF operation */
+	Process *rp = erts_proc_lookup_raw(connect);
+	if (!rp)
+	    return ERTS_PORT_OP_DROPPED;
+	erts_smp_proc_lock(rp, ERTS_PROC_LOCK_LINK);
+	if (ERTS_PROC_IS_EXITING(rp)) {
+	    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
+	    return ERTS_PORT_OP_DROPPED;
+	}
 
- bad_value: 
-    p->caller = NIL;
-    {
-	erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
-	erts_dsprintf(dsbufp, "Bad value on output port '%s'\n", p->name);
-	erts_send_error_to_logger_nogl(dsbufp);
-	return 1;
+	erts_add_link(&ERTS_P_LINKS(rp), LINK_PID, prt->common.id);
+	erts_add_link(&ERTS_P_LINKS(prt), LINK_PID, connect);
+
+	ERTS_PORT_SET_CONNECTED(prt, connect);
+
+	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
+
+#ifdef USE_VM_PROBES
+	if (DTRACE_ENABLED(port_connect)) {
+	    DTRACE_CHARBUF(process_str, DTRACE_TERM_BUF_SIZE);
+	    DTRACE_CHARBUF(port_str, DTRACE_TERM_BUF_SIZE);
+	    DTRACE_CHARBUF(newprocess_str, DTRACE_TERM_BUF_SIZE);
+
+	    dtrace_pid_str(connect, process_str);
+	    erts_snprintf(port_str, sizeof(port_str), "%T", prt->common.id);
+	    dtrace_proc_str(rp, newprocess_str);
+	    DTRACE4(port_connect, process_str, port_str, prt->name, newprocess_str);
+	}
+#endif
+    }
+
+    return ERTS_PORT_OP_DONE;
+}
+
+static int
+port_sig_connect(Port *prt, erts_aint32_t state, int op, ErtsProc2PortSigData *sigdp)
+{
+    Eterm msg = am_badarg;
+    if (op == ERTS_PROC2PORT_SIG_EXEC) {
+	ErtsPortOpResult res;
+	res = set_port_connected(sigdp->flags & ERTS_P2P_SIG_DATA_FLG_BANG_OP,
+				 sigdp->u.connect.from,
+				 prt,
+				 state,
+				 sigdp->u.connect.connected);
+	if (res == ERTS_PORT_OP_DONE)
+	    msg = am_true;
+    }
+    if (sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY)
+	port_sched_op_reply(sigdp->caller, sigdp->ref, msg);
+    return ERTS_PORT_REDS_CONNECT;
+}
+
+ErtsPortOpResult
+erts_port_connect(Process *c_p,
+		  int flags,
+		  Port *prt,
+		  Eterm from,
+		  Eterm connect,
+		  Eterm *refp)
+{
+    ErtsProc2PortSigData *sigdp;
+    Eterm connect_id;
+    ErtsTryImmDrvCallState try_call_state
+	= ERTS_INIT_TRY_IMM_DRV_CALL_STATE(c_p,
+					   prt,
+					   ERTS_PORT_SFLGS_INVALID_LOOKUP,
+					   0,
+					   !refp,
+					   am_connect);
+
+    ASSERT((flags & ~ERTS_PORT_SIG_FLG_BANG_OP) == 0);
+
+    if (is_not_internal_pid(connect))
+	connect_id = NIL; /* Fail in op (for signal order) */
+    else
+	connect_id = connect;
+
+    switch (try_imm_drv_call(&try_call_state)) {
+    case ERTS_TRY_IMM_DRV_CALL_OK: {
+	ErtsPortOpResult res;
+	res = set_port_connected(flags & ERTS_PORT_SIG_FLG_BANG_OP,
+				 from,
+				 prt,
+				 try_call_state.state,
+				 connect_id);
+	finalize_imm_drv_call(&try_call_state);
+	return res;
+    }
+    case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+	return ERTS_PORT_OP_DROPPED;
+    default:
+	/* Schedule call instead... */
+	break;
     }
+
+    sigdp = erts_port_task_alloc_p2p_sig_data();
+    sigdp->flags = flags;
+
+    sigdp->u.connect.from = from;
+    sigdp->u.connect.connected = connect_id;
+    
+    return erts_schedule_proc2port_signal(c_p,
+					  prt,
+					  c_p->common.id,
+					  refp,
+					  sigdp,
+					  0,
+					  port_sig_connect);
+}
+
+static void
+port_unlink(Port *prt, Eterm from)
+{
+    ErtsLink *lnk = erts_remove_link(&ERTS_P_LINKS(prt), from);
+    if (lnk)
+	erts_destroy_link(lnk);
+}
+
+static int
+port_sig_unlink(Port *prt, erts_aint32_t state, int op, ErtsProc2PortSigData *sigdp)
+{
+    if (op == ERTS_PROC2PORT_SIG_EXEC)
+	port_unlink(prt, sigdp->u.unlink.from);
+    if (sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY)
+	port_sched_op_reply(sigdp->caller, sigdp->ref, am_true);
+    return ERTS_PORT_REDS_UNLINK;
+}
+
+ErtsPortOpResult
+erts_port_unlink(Process *c_p, Port *prt, Eterm from, Eterm *refp)
+{
+    ErtsProc2PortSigData *sigdp;
+    ErtsTryImmDrvCallState try_call_state
+	= ERTS_INIT_TRY_IMM_DRV_CALL_STATE(c_p,
+					   prt,
+					   ERTS_PORT_SFLGS_DEAD,
+					   0,
+					   !refp,
+					   am_unlink);
+
+    switch (try_imm_drv_call(&try_call_state)) {
+    case ERTS_TRY_IMM_DRV_CALL_OK:
+	port_unlink(prt, from);
+	finalize_imm_drv_call(&try_call_state);
+	return ERTS_PORT_OP_DONE;
+    case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+	return ERTS_PORT_OP_DROPPED;
+    default:
+	/* Schedule call instead... */
+	break;
+    }
+
+    sigdp = erts_port_task_alloc_p2p_sig_data();
+    sigdp->flags = 0;
+    sigdp->u.unlink.from = from;
+    
+    return erts_schedule_proc2port_signal(c_p,
+					  prt,
+					  c_p ? c_p->common.id : from,
+					  refp,
+					  sigdp,
+					  0,
+					  port_sig_unlink);
+}
+
+static void
+port_link_failure(Eterm port_id, Eterm linker)
+{
+    Process *rp;
+    ErtsProcLocks rp_locks = ERTS_PROC_LOCK_LINK|ERTS_PROC_LOCKS_XSIG_SEND;
+    ASSERT(is_internal_pid(linker));
+    rp = erts_pid2proc(NULL, 0, linker, rp_locks);
+    if (rp) {
+	ErtsLink *rlnk = erts_remove_link(&ERTS_P_LINKS(rp), port_id);
+	if (rlnk) {
+	    int xres = erts_send_exit_signal(NULL,
+					     port_id,
+					     rp,
+					     &rp_locks, 
+					     am_noproc,
+					     NIL,
+					     NULL,
+					     0);
+	    if (xres >= 0 && IS_TRACED_FL(rp, F_TRACE_PROCS)) {
+		/* We didn't exit the process and it is traced */
+		if (IS_TRACED_FL(rp, F_TRACE_PROCS))
+		    trace_proc(NULL, rp, am_getting_unlinked, port_id);
+	    }
+	}
+    }
+}
+
+static void
+port_link(Port *prt, erts_aint32_t state, Eterm to)
+{
+    if (!(state & ERTS_PORT_SFLGS_INVALID_LOOKUP))
+	erts_add_link(&ERTS_P_LINKS(prt), LINK_PID, to);
+    else
+	port_link_failure(prt->common.id, to);
+}
+
+static int
+port_sig_link(Port *prt, erts_aint32_t state, int op, ErtsProc2PortSigData *sigdp)
+{
+    if (op == ERTS_PROC2PORT_SIG_EXEC)
+	port_link(prt, state, sigdp->u.link.to);
+    else
+	port_link_failure(sigdp->u.link.port, sigdp->u.link.to);
+    if (sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY)
+	port_sched_op_reply(sigdp->caller, sigdp->ref, am_true);
+    return ERTS_PORT_REDS_LINK;
+}
+
+ErtsPortOpResult
+erts_port_link(Process *c_p, Port *prt, Eterm to, Eterm *refp)
+{
+    ErtsProc2PortSigData *sigdp;
+    ErtsTryImmDrvCallState try_call_state
+	= ERTS_INIT_TRY_IMM_DRV_CALL_STATE(c_p,
+					   prt,
+					   ERTS_PORT_SFLGS_INVALID_LOOKUP,
+					   0,
+					   !refp,
+					   am_link);
+
+    switch (try_imm_drv_call(&try_call_state)) {
+    case ERTS_TRY_IMM_DRV_CALL_OK:
+	port_link(prt, try_call_state.state, to);
+	finalize_imm_drv_call(&try_call_state);
+	return ERTS_PORT_OP_DONE;
+    case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+	return ERTS_PORT_OP_BADARG;
+    default:
+	/* Schedule call instead... */
+	break;
+    }
+
+    sigdp = erts_port_task_alloc_p2p_sig_data();
+    sigdp->flags = 0;
+    sigdp->u.link.port = prt->common.id;
+    sigdp->u.link.to = to;
+    
+    return erts_schedule_proc2port_signal(c_p,
+					  prt,
+					  c_p ? c_p->common.id : to,
+					  refp,
+					  sigdp,
+					  0,
+					  port_sig_link);
 }
 
 void erts_init_io(int port_tab_size,
@@ -1526,16 +2771,19 @@ deliver_result(Eterm sender, Eterm pid, Eterm res)
 	ErlOffHeap *ohp;
 	Eterm* hp;
 	Uint sz_res;
-	    sz_res = size_object(res);
-	    hp = erts_alloc_message_heap(sz_res + 3, &bp, &ohp, rp, &rp_locks);
-	    res = copy_struct(res, sz_res, &hp, ohp);
-	    tuple = TUPLE2(hp, sender, res);
+
+	sz_res = size_object(res);
+	hp = erts_alloc_message_heap(sz_res + 3, &bp, &ohp, rp, &rp_locks);
+	res = copy_struct(res, sz_res, &hp, ohp);
+	tuple = TUPLE2(hp, sender, res);
 	erts_queue_message(rp, &rp_locks, bp, tuple, NIL
 #ifdef USE_VM_PROBES
 			   , NIL
 #endif
 			   );
-	erts_smp_proc_unlock(rp, rp_locks);
+
+	if (rp_locks)
+	    erts_smp_proc_unlock(rp, rp_locks);
 	if (!scheduler)
 	    erts_smp_proc_dec_refc(rp);
 
@@ -2064,8 +3312,9 @@ static void sweep_one_link(ErtsLink *lnk, void *vpsc)
  * that is to kill a port till reason kill. Then the port is stopped.
  * 
  */
-void
-erts_do_exit_port(Port *p, Eterm from, Eterm reason)
+
+int
+erts_deliver_port_exit(Port *p, Eterm from, Eterm reason, int send_closed)
 {
    ErtsLink *lnk;
    Eterm rreason;
@@ -2090,11 +3339,17 @@ erts_do_exit_port(Port *p, Eterm from, Eterm reason)
 #endif
 
    state = erts_atomic32_read_nob(&p->state);
-   if ((state & (ERTS_PORT_SFLGS_DEAD|ERTS_PORT_SFLG_EXITING))
-       || ((reason == am_normal) &&
-	   ((from != ERTS_PORT_GET_CONNECTED(p)) && (from != p->common.id)))) {
-      return;
-   }
+   if (state & (ERTS_PORT_SFLGS_DEAD
+		| ERTS_PORT_SFLG_EXITING
+		| ERTS_PORT_SFLG_CLOSING))
+       return 0;
+
+   if (reason == am_normal && from != ERTS_PORT_GET_CONNECTED(p) && from != p->common.id)
+       return 0;
+
+   if (send_closed)
+       erts_atomic32_read_bor_relb(&p->state,
+				   ERTS_PORT_SFLG_SEND_CLOSED);
 
    if (IS_TRACED_FL(p, F_TRACE_PORTS)) {
    	trace_port(p, am_closed, reason);
@@ -2146,11 +3401,13 @@ erts_do_exit_port(Port *p, Eterm from, Eterm reason)
    else {
        terminate_port(p);
    }
+
+   return 1;
 }
 
 /* About the states ERTS_PORT_SFLG_EXITING and ERTS_PORT_SFLG_CLOSING used above.
 **
-** ERTS_PORT_SFLG_EXITING is a recursion protection for erts_do_exit_port().
+** ERTS_PORT_SFLG_EXITING is a recursion protection for erts_deliver_port_exit().
 ** It is unclear  whether this state is necessary or not, it might be possible
 ** to merge it with ERTS_PORT_SFLG_CLOSING. ERTS_PORT_SFLG_EXITING only persists
 ** over a section of sequential (but highly recursive) code.
@@ -2166,233 +3423,1108 @@ erts_do_exit_port(Port *p, Eterm from, Eterm reason)
 **   {PID, close}
 **   {PID, {command, io-list}}
 **   {PID, {connect, New_PID}}
-**
-**
 */
-void erts_port_command(Process *proc,
-		       Eterm caller_id,
-		       Port *port,
-		       Eterm command)
+ErtsPortOpResult
+erts_port_command(Process *c_p,
+		  int flags,
+		  Port *port,
+		  Eterm command,
+		  Eterm *refp)
 {
     Eterm *tp;
-    Eterm pid;
 
-    if (!port)
-	return;
+    ASSERT(port);
 
-    erts_smp_proc_unlock(proc, ERTS_PROC_LOCK_MAIN);
-    ERTS_SMP_CHK_NO_PROC_LOCKS;
-    ASSERT(!INVALID_PORT(port, port->common.id));
+    flags |= ERTS_PORT_SIG_FLG_BANG_OP;
 
     if (is_tuple_arity(command, 2)) {
+	Eterm cntd;
 	tp = tuple_val(command);
-	if ((pid = ERTS_PORT_GET_CONNECTED(port)) == tp[1]) {
-	    /* PID must be connected */
+	cntd = tp[1];
+	if (is_internal_pid(cntd)) {
 	    if (tp[2] == am_close) {
-		erts_atomic32_read_bor_relb(&port->state,
-					    ERTS_PORT_SFLG_SEND_CLOSED);
-		erts_do_exit_port(port, pid, am_normal);
-
-#ifdef USE_VM_PROBES
-		if(DTRACE_ENABLED(port_command)) {
-                    DTRACE_FORMAT_COMMON_PROC_AND_PORT(proc, port)
-		    DTRACE4(port_command, process_str, port_str, port->name, "close");
-		}
-#endif
-		goto done;
+		if (!erts_port_synchronous_ops)
+		    refp = NULL;
+		flags &= ~ERTS_PORT_SIG_FLG_NOSUSPEND;
+		return erts_port_exit(c_p, flags, port, cntd, am_normal, refp);
 	    } else if (is_tuple_arity(tp[2], 2)) {
 		tp = tuple_val(tp[2]);
 		if (tp[1] == am_command) {
-		    if (erts_write_to_port(caller_id, port, tp[2]) == 0)
-			goto done;
-		} else if ((tp[1] == am_connect) && is_internal_pid(tp[2])) {
-#ifdef USE_VM_PROBES
-		    if(DTRACE_ENABLED(port_command)) {
-                        DTRACE_FORMAT_COMMON_PROC_AND_PORT(proc, port)
-			DTRACE4(port_command, process_str, port_str, port->name, "connect");
-		    }
-#endif
-		    ERTS_PORT_SET_CONNECTED_RELB(port, tp[2]);
-		    deliver_result(port->common.id, pid, am_connected);
-		    goto done;
+		    if (!(flags & ERTS_PORT_SIG_FLG_NOSUSPEND)
+			&& !erts_port_synchronous_ops)
+			refp = NULL;
+		    return erts_port_output(c_p, flags, port, cntd, tp[2], refp);
+		}
+		else if (tp[1] == am_connect) {
+		    if (!erts_port_synchronous_ops)
+			refp = NULL;
+		    flags &= ~ERTS_PORT_SIG_FLG_NOSUSPEND;
+		    return erts_port_connect(c_p, flags, port, cntd, tp[2], refp);
 		}
 	    }
 	}
     }
 
-    {
-	ErtsProcLocks rp_locks = ERTS_PROC_LOCKS_XSIG_SEND;
-	Process* rp = erts_pid2proc(NULL, 0,
-				    ERTS_PORT_GET_CONNECTED(port), rp_locks);
-	if (rp) {
-	    (void) erts_send_exit_signal(NULL,
-					 port->common.id,
-					 rp,
-					 &rp_locks, 
-					 am_badsig,
-					 NIL,
-					 NULL,
-					 0);
-	    erts_smp_proc_unlock(rp, rp_locks);
-	}
+    /* badsig */
+    if (!erts_port_synchronous_ops)
+	refp = NULL;
+    flags &= ~ERTS_PORT_SIG_FLG_NOSUSPEND;
+    return bad_port_signal(c_p, flags, port, c_p->common.id, refp, am_command);
+}
+
+static ERTS_INLINE ErtsPortOpResult
+call_driver_control(Eterm caller,
+		    Port *prt,
+		    unsigned int command,
+		    char *bufp,
+		    ErlDrvSizeT size,
+		    char **resp_bufp,
+		    ErlDrvSizeT *from_size)
+{
+    ErlDrvSSizeT cres;
+
+    if (!prt->drv_ptr->control)
+	return ERTS_PORT_OP_BADARG;
 
+
+#ifdef USE_VM_PROBES
+    if (DTRACE_ENABLED(port_control) || DTRACE_ENABLED(driver_control)) {
+        DTRACE_FORMAT_COMMON_PID_AND_PORT(caller, prt);
+        DTRACE4(port_control, process_str, port_str, prt->name, command);
+        DTRACE5(driver_control, process_str, port_str, prt->name,
+                command, size);
     }
- done:
-    erts_smp_proc_lock(proc, ERTS_PROC_LOCK_MAIN);
+#endif
+
+    prt->caller = caller;
+    cres = prt->drv_ptr->control((ErlDrvData) prt->drv_data,
+				 command,
+				 bufp,
+				 size,
+				 resp_bufp,
+				 *from_size);
+    prt->caller = NIL;
+
+    if (cres < 0)
+	return ERTS_PORT_OP_BADARG;
+
+    *from_size = (ErlDrvSizeT) cres;
+
+    return ERTS_PORT_OP_DONE;
 }
 
-/*
- * Control a port synchronously. 
- * Returns either a list or a binary.
- */
-Eterm
-erts_port_control(Process* p, Port* prt, Uint command, Eterm iolist)
-{
-    byte* to_port = NULL;	/* Buffer to write to port. */
-				/* Initialization is for shutting up
-				   warning about use before set. */
-    Uint to_len = 0;		/* Length of buffer. */
-    int must_free = 0;		/* True if the buffer should be freed. */
-    char port_result[ERL_ONHEAP_BIN_LIMIT];  /* Default buffer for result from port. */
-    char* port_resp;		/* Pointer to result buffer. */
-    ErlDrvSSizeT n;
-    ErlDrvSSizeT (*control)
-	(ErlDrvData, unsigned, char*, ErlDrvSizeT, char**, ErlDrvSizeT);
-    int fpe_was_unmasked;
+static void
+cleanup_scheduled_control(Binary *binp, char *bufp)
+{
+    if (binp) {
+	if (erts_refc_dectest(&binp->refc, 0) == 0)
+	    erts_bin_free(binp);
+    }
+    else {
+	if (bufp)
+	    erts_free(ERTS_ALC_T_DRV_CTRL_DATA, bufp);
+    }
+}
 
-    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));
 
-    if ((control = prt->drv_ptr->control) == NULL) {
-	return THE_NON_VALUE;
+static ERTS_INLINE Uint
+port_control_result_size(int control_flags,
+			 char *resp_bufp,
+			 ErlDrvSizeT *resp_size,
+			 char *pre_alloc_buf)
+{
+    if (!resp_bufp)
+	return (Uint) 0;
+
+    if (control_flags & PORT_CONTROL_FLAG_BINARY) {
+	if (resp_bufp != pre_alloc_buf) {
+	    ErlDrvBinary *dbin = (ErlDrvBinary *) resp_bufp;
+	    *resp_size = dbin->orig_size;
+	    if (*resp_size > ERL_ONHEAP_BIN_LIMIT)
+		return PROC_BIN_SIZE;
+	}
+	ASSERT(*resp_size <= ERL_ONHEAP_BIN_LIMIT);
+	return (Uint) heap_bin_size((*resp_size));
     }
 
-    /*
-     * Convert the iolist to a buffer, pointed to by to_port,
-     * and with its length in to_len.
-     */
-    if (is_binary(iolist) && binary_bitoffset(iolist) == 0) {
+    return (Uint) 2*(*resp_size);
+}
+
+static ERTS_INLINE Eterm
+write_port_control_result(int control_flags,
+			  char *resp_bufp,
+			  ErlDrvSizeT resp_size,
+			  char *pre_alloc_buf,
+			  Eterm **hpp,
+			  ErlHeapFragment *bp,
+			  ErlOffHeap *ohp)
+{
+    Eterm res;
+    if (!resp_bufp)
+	return NIL;
+    if (control_flags & PORT_CONTROL_FLAG_BINARY) {
+	/* Binary result */
+	ErlDrvBinary *dbin;
+	ErlHeapBin *hbin;
+
+	if (resp_bufp == pre_alloc_buf)
+	    dbin = NULL;
+	else {
+	    dbin = (ErlDrvBinary *) resp_bufp;
+	    if (dbin->orig_size > ERL_ONHEAP_BIN_LIMIT) {
+		ProcBin* pb = (ProcBin *) *hpp;
+		*hpp += PROC_BIN_SIZE;
+		pb->thing_word = HEADER_PROC_BIN;
+		pb->size = dbin->orig_size;
+		pb->next = ohp->first;
+		ohp->first = (struct erl_off_heap_header *) pb;
+		pb->val = ErlDrvBinary2Binary(dbin);
+		pb->bytes = (byte*) dbin->orig_bytes;
+		pb->flags = 0;
+		OH_OVERHEAD(ohp, dbin->orig_size / sizeof(Eterm));
+		return make_binary(pb);
+	    }
+	    resp_bufp = dbin->orig_bytes;
+	    resp_size = dbin->orig_size;
+	}
+
+	hbin = (ErlHeapBin *) *hpp;
+	*hpp += heap_bin_size(resp_size);
+	ASSERT(resp_size <= ERL_ONHEAP_BIN_LIMIT);
+	hbin->thing_word = header_heap_bin(resp_size);
+	hbin->size = resp_size;
+	sys_memcpy(hbin->data, resp_bufp, resp_size);
+	if (dbin)
+	    driver_free_binary(dbin);
+	return make_binary(hbin);
+    }
+
+    /* List result */
+    res = buf_to_intlist(hpp, resp_bufp, resp_size, NIL);
+    if (resp_bufp != pre_alloc_buf)
+	driver_free(resp_bufp);
+    return res;
+}
+
+static int
+port_sig_control(Port *prt,
+		 erts_aint32_t state,
+		 int op,
+		 ErtsProc2PortSigData *sigdp)
+{
+    ASSERT(sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY);
+
+    if (op == ERTS_PROC2PORT_SIG_EXEC) {
+	char resp_buf[ERL_ONHEAP_BIN_LIMIT];
+	ErlDrvSizeT resp_size = sizeof(resp_buf);
+	char *resp_bufp = &resp_buf[0];
+	ErtsPortOpResult res;
+
+	res = call_driver_control(sigdp->caller,
+				  prt,
+				  sigdp->u.control.command,
+				  sigdp->u.control.bufp,
+				  sigdp->u.control.size,
+				  &resp_bufp,
+				  &resp_size);
+
+	if (res == ERTS_PORT_OP_DONE) {
+	    Eterm msg;
+	    Eterm *hp, *hp_start;
+	    ErlHeapFragment *bp;
+	    ErlOffHeap *ohp;
+	    Process *rp;
+	    ErtsProcLocks rp_locks = 0;
+	    Uint hsz;
+	    int control_flags;
+
+	    rp = erts_proc_lookup_raw(sigdp->caller);
+	    if (!rp)
+		goto done;
+
+	    control_flags = prt->control_flags;
+
+	    hsz = ERTS_QUEUE_PORT_SCHED_OP_REPLY_SIZE;
+	    hsz += port_control_result_size(control_flags,
+					    resp_bufp,
+					    &resp_size,
+					    &resp_buf[0]);
+
+	    hp_start = hp = erts_alloc_message_heap(hsz,
+						    &bp,
+						    &ohp,
+						    rp,
+						    &rp_locks);
+
+	    msg = write_port_control_result(control_flags,
+					    resp_bufp,
+					    resp_size,
+					    &resp_buf[0],
+					    &hp,
+					    bp,
+					    ohp);
+
+	    queue_port_sched_op_reply(rp,
+				      &rp_locks,
+				      hp_start,
+				      hp,
+				      hsz,
+				      bp,
+				      sigdp->ref,
+				      msg);
+
+	    if (rp_locks)
+		erts_smp_proc_unlock(rp, rp_locks);
+	    goto done;
+	}
+    }
+
+    /* failure */
+
+    port_sched_op_reply(sigdp->caller, sigdp->ref, am_badarg);
+
+done:
+
+    cleanup_scheduled_control(sigdp->u.control.binp,
+			      sigdp->u.control.bufp);
+
+    return ERTS_PORT_REDS_CONTROL;
+}
+
+
+ErtsPortOpResult
+erts_port_control(Process* c_p,
+		  Port *prt,
+		  unsigned int command,
+		  Eterm data,
+		  Eterm *retvalp)
+{
+    ErtsPortOpResult res;
+    char *bufp = NULL;
+    ErlDrvSizeT size = 0;
+    int try_call;
+    int tmp_alloced = 0;
+    erts_aint32_t sched_flags;
+    Binary *binp;
+    int copy;
+    ErtsProc2PortSigData *sigdp;
+
+    sched_flags = erts_smp_atomic32_read_nob(&prt->sched.flags);
+    if (sched_flags & ERTS_PTS_FLG_EXIT)
+	return ERTS_PORT_OP_BADARG;
+
+    try_call = !(sched_flags & ERTS_PTS_FLGS_FORCE_SCHEDULE_OP);
+
+    if (is_binary(data) && binary_bitoffset(data) == 0) {
+	byte *bytep;
 	ERTS_DECLARE_DUMMY(Uint bitoffs);
 	ERTS_DECLARE_DUMMY(Uint bitsize);
-	ERTS_GET_BINARY_BYTES(iolist, to_port, bitoffs, bitsize);
-	to_len = binary_size(iolist);
+	ERTS_GET_BINARY_BYTES(data, bytep, bitoffs, bitsize);
+	bufp = (char *) bytep;
+	size = binary_size(data);
     } else {
 	int r;
 
-	/* Try with an 8KB buffer first (will often be enough I guess). */
-	to_len = 8*1024;
-	to_port = erts_alloc(ERTS_ALC_T_TMP, to_len);
-	must_free = 1;
+	if (!try_call) {
+	    if (erts_iolist_size(data, &size))
+		return ERTS_PORT_OP_BADARG;
+	    bufp = erts_alloc(ERTS_ALC_T_DRV_CTRL_DATA, size);
+	    r = erts_iolist_to_buf(data, bufp, size);
+	    ASSERT(r == 0);
+	}
+	else {
+	    /* Try with an 8KB buffer first (will often be enough I guess). */
+	    size = 8*1024;
+	    bufp = erts_alloc(ERTS_ALC_T_TMP, size);
+	    tmp_alloced = 1;
+
+	    r = erts_iolist_to_buf(data, bufp, size);
+	    if (ERTS_IOLIST_TO_BUF_SUCCEEDED(r)) {
+		size -= r;
+	    } else {
+		if (r == ERTS_IOLIST_TO_BUF_TYPE_ERROR) { /* Type error */
+		    erts_free(ERTS_ALC_T_TMP, bufp);
+		    return ERTS_PORT_OP_BADARG;
+		}
+		else {
+		    ASSERT(r == ERTS_IOLIST_TO_BUF_OVERFLOW); /* Overflow */
+		    erts_free(ERTS_ALC_T_TMP, bufp);
+		    if (erts_iolist_size(data, &size))
+			return ERTS_PORT_OP_BADARG; /* Type error */
+		}
+		bufp = erts_alloc(ERTS_ALC_T_TMP, size);
+		r = erts_iolist_to_buf(data, bufp, size);
+		ASSERT(r == 0);
+	    }
+	}
+    }
 
-	/*
-	 * In versions before R10B, we used to reserve random
-	 * amounts of extra memory. From R10B, we allocate the
-	 * exact amount.
-	 */
-	r = io_list_to_buf(iolist, (char*) to_port, to_len);
-	if (r >= 0) {
-	    to_len -= r;
-	} else if (r == -2) {	/* Type error */
-	    erts_free(ERTS_ALC_T_TMP, (void *) to_port);
-	    return THE_NON_VALUE;
-	} else {
-	    ASSERT(r == -1);	/* Overflow */
-	    erts_free(ERTS_ALC_T_TMP, (void *) to_port);
-	    if (erts_iolist_size(iolist, &to_len)) { /* Type error */
-		return THE_NON_VALUE;
+    if (try_call) {
+	char resp_buf[ERL_ONHEAP_BIN_LIMIT];
+	char* resp_bufp = &resp_buf[0];
+	ErlDrvSizeT resp_size = sizeof(resp_buf);
+	ErtsTryImmDrvCallResult try_call_res;
+	ErtsTryImmDrvCallState try_call_state
+	    = ERTS_INIT_TRY_IMM_DRV_CALL_STATE(
+		c_p,
+		prt,
+		ERTS_PORT_SFLGS_INVALID_LOOKUP,
+		0,
+		0,
+		am_control);
+
+	try_call_res = try_imm_drv_call(&try_call_state);
+	switch (try_call_res) {
+	case ERTS_TRY_IMM_DRV_CALL_OK: {
+	    Eterm *hp;
+	    Uint hsz;
+	    int control_flags;
+
+	    res = call_driver_control(c_p->common.id,
+				      prt,
+				      command,
+				      bufp,
+				      size,
+				      &resp_bufp,
+				      &resp_size);
+	    finalize_imm_drv_call(&try_call_state);
+	    if (tmp_alloced)
+		erts_free(ERTS_ALC_T_TMP, bufp);
+	    if (res == ERTS_PORT_OP_BADARG) {
+		return ERTS_PORT_OP_BADARG;
 	    }
-	    must_free = 1;
-	    to_port = erts_alloc(ERTS_ALC_T_TMP, to_len);
-	    r = io_list_to_buf(iolist, (char*) to_port, to_len);
-	    ASSERT(r == 0);
+
+	    control_flags = prt->control_flags;
+
+	    hsz = port_control_result_size(control_flags,
+					   resp_bufp,
+					   &resp_size,
+					   &resp_buf[0]);
+	    hp = HAlloc(c_p, hsz);
+	    *retvalp = write_port_control_result(control_flags,
+						 resp_bufp,
+						 resp_size,
+						 &resp_buf[0],
+						 &hp,
+						 NULL,
+						 &c_p->off_heap);
+	    return ERTS_PORT_OP_DONE;
+	}
+	case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+	    if (tmp_alloced)
+		erts_free(ERTS_ALC_T_TMP, bufp);
+	    return ERTS_PORT_OP_BADARG;
+	default:
+	    /* Schedule control() call instead... */
+	    break;
 	}
     }
 
-    prt->caller = p->common.id;	/* Internal pid */
+    /* Convert data into something that can be scheduled */
 
-    erts_smp_proc_unlock(p, ERTS_PROC_LOCK_MAIN);
-    ERTS_SMP_CHK_NO_PROC_LOCKS;
+    copy = tmp_alloced;
+
+    binp = NULL;
+
+    if (is_binary(data) && binary_bitoffset(data) == 0) {
+	Eterm *ebinp = binary_val_rel(data, NULL);
+	ASSERT(!tmp_alloced);
+	if (*ebinp == HEADER_SUB_BIN)
+	    ebinp = binary_val_rel(((ErlSubBin *) ebinp)->orig, NULL);
+	if (*ebinp != HEADER_PROC_BIN)
+	    copy = 1;
+	else {
+	    binp = ((ProcBin *) ebinp)->val;
+	    ASSERT(bufp < bufp + size);
+	    ASSERT(binp->orig_bytes <= bufp
+		   && bufp + size <= binp->orig_bytes + binp->orig_size);
+	    erts_refc_inc(&binp->refc, 1);
+	}
+    }
+
+    if (copy) {
+	char *old_bufp = bufp;
+	bufp = erts_alloc(ERTS_ALC_T_DRV_CTRL_DATA, size);
+	sys_memcpy(bufp, old_bufp, size);
+	if (tmp_alloced)
+	    erts_free(ERTS_ALC_T_TMP, old_bufp);
+    }
+
+    sigdp = erts_port_task_alloc_p2p_sig_data();
+    sigdp->flags = 0;
+    sigdp->u.control.binp = binp;
+    sigdp->u.control.command = command;
+    sigdp->u.control.bufp = bufp;
+    sigdp->u.control.size = size;
+    
+    res = erts_schedule_proc2port_signal(c_p,
+					 prt,
+					 c_p->common.id,
+					 retvalp,
+					 sigdp,
+					 0,
+					 port_sig_control);
+    if (res != ERTS_PORT_OP_SCHEDULED) {
+	cleanup_scheduled_control(binp, bufp);
+	return ERTS_PORT_OP_BADARG;
+    }
+    return res;
+}
+
+static ERTS_INLINE ErtsPortOpResult
+call_driver_call(Eterm caller,
+		 Port *prt,
+		 unsigned int command,
+		 char *bufp,
+		 ErlDrvSizeT size,
+		 char **resp_bufp,
+		 ErlDrvSizeT *from_size,
+		 unsigned *ret_flagsp)
+{
+    ErlDrvSSizeT cres;
+
+    if (!prt->drv_ptr->call)
+	return ERTS_PORT_OP_BADARG;
 
 #ifdef USE_VM_PROBES
-    if (DTRACE_ENABLED(port_control) || DTRACE_ENABLED(driver_control)) {
-        DTRACE_FORMAT_COMMON_PROC_AND_PORT(p, prt);
-        DTRACE4(port_control, process_str, port_str, prt->name, command);
-        DTRACE5(driver_control, process_str, port_str, prt->name,
-                command, to_len);
+    if (DTRACE_ENABLED(driver_call)) {
+        DTRACE_CHARBUF(process_str, DTRACE_TERM_BUF_SIZE);
+        DTRACE_CHARBUF(port_str, DTRACE_TERM_BUF_SIZE);
+
+        dtrace_pid_str(caller, process_str);
+        dtrace_port_str(prt, port_str);
+        DTRACE5(driver_call, process_str, port_str, prt->name, command, size);
     }
 #endif
 
-    /*
-     * Call the port's control routine.
-     */
+    prt->caller = caller;
+    cres = prt->drv_ptr->call((ErlDrvData) prt->drv_data,
+			      command,
+			      bufp,
+			      size,
+			      resp_bufp,
+			      *from_size,
+			      ret_flagsp);
+    prt->caller = NIL;
 
-    port_resp = port_result;
-    fpe_was_unmasked = erts_block_fpe();
-    n = control((ErlDrvData)prt->drv_data, command, (char*)to_port, to_len,
-		&port_resp, sizeof(port_result));
-    erts_unblock_fpe(fpe_was_unmasked);
-    if (must_free) {
-	erts_free(ERTS_ALC_T_TMP, (void *) to_port);
+    if (cres <= 0
+	|| ((byte) (*resp_bufp)[0]) != VERSION_MAGIC)
+	return ERTS_PORT_OP_BADARG;
+
+    *from_size = (ErlDrvSizeT) cres;
+
+    return ERTS_PORT_OP_DONE;
+}
+
+
+static
+void cleanup_scheduled_call(char *bufp)
+{
+    if (bufp)
+	erts_free(ERTS_ALC_T_DRV_CALL_DATA, bufp);
+}
+
+static int
+port_sig_call(Port *prt,
+	      erts_aint32_t state,
+	      int op,
+	      ErtsProc2PortSigData *sigdp)
+{
+    char resp_buf[256];
+    ErlDrvSizeT resp_size = sizeof(resp_buf);
+    char *resp_bufp = &resp_buf[0];
+    unsigned ret_flags = 0U;
+
+
+    ASSERT(sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY);
+
+    if (op == ERTS_PROC2PORT_SIG_EXEC) {
+	ErtsPortOpResult res;
+
+	res = call_driver_call(sigdp->caller,
+			       prt,
+			       sigdp->u.call.command,
+			       sigdp->u.call.bufp,
+			       sigdp->u.call.size,
+			       &resp_bufp,
+			       &resp_size,
+			       &ret_flags);
+
+	if (res == ERTS_PORT_OP_DONE) {
+	    Eterm msg;
+	    Eterm *hp;
+	    ErlHeapFragment *bp;
+	    ErlOffHeap *ohp;
+	    Process *rp;
+	    ErtsProcLocks rp_locks = 0;
+	    Uint hsz;
+
+	    rp = erts_proc_lookup_raw(sigdp->caller);
+	    if (!rp)
+		goto done;
+
+	    hsz = erts_decode_ext_size((byte *) resp_bufp, resp_size);
+	    if (hsz >= 0) {
+		Eterm *hp_start;
+		byte *endp;
+
+		hsz += 3; /* ok tuple */
+		hsz += ERTS_QUEUE_PORT_SCHED_OP_REPLY_SIZE;
+
+		hp_start = hp = erts_alloc_message_heap(hsz,
+							&bp,
+							&ohp,
+							rp,
+							&rp_locks);
+		endp = (byte *) resp_bufp;
+		msg = erts_decode_ext(&hp, ohp, &endp);
+		if (is_value(msg)) {
+		    msg = TUPLE2(hp, am_ok, msg);
+		    hp += 3;
+
+		    queue_port_sched_op_reply(rp,
+					      &rp_locks,
+					      hp_start,
+					      hp,
+					      hsz,
+					      bp,
+					      sigdp->ref,
+					      msg);
+
+		    if (rp_locks)
+			erts_smp_proc_unlock(rp, rp_locks);
+		    goto done;
+		}
+		if (bp)
+		    free_message_buffer(bp);
+		if (rp_locks)
+		    erts_smp_proc_unlock(rp, rp_locks);
+	    }
+	}
     }
-    prt->caller = NIL;
-#ifdef ERTS_SMP
-    if (prt->xports)
-	erts_smp_xports_unlock(prt);
-    ASSERT(!prt->xports);
-#endif
 
-    erts_smp_proc_lock(p, ERTS_PROC_LOCK_MAIN);
-    /*
-     * Handle the result.
-     */
+    port_sched_op_reply(sigdp->caller, sigdp->ref, am_badarg);
+
+done:
 
-    if (n < 0) {
-	return THE_NON_VALUE;
+    if (resp_bufp != &resp_buf[0] && !(ret_flags & DRIVER_CALL_KEEP_BUFFER))
+	driver_free(resp_bufp);
+
+    cleanup_scheduled_call(sigdp->u.call.bufp);
+
+    return ERTS_PORT_REDS_CALL;
+}
+
+
+ErtsPortOpResult
+erts_port_call(Process* c_p,
+	       Port *prt,
+	       unsigned int command,
+	       Eterm data,
+	       Eterm *retvalp)
+{
+    ErtsPortOpResult res;
+    char input_buf[256];
+    char *bufp;
+    byte *endp;
+    ErlDrvSizeT size;
+    int try_call;
+    erts_aint32_t sched_flags;
+    ErtsProc2PortSigData *sigdp;
+
+    sched_flags = erts_smp_atomic32_read_nob(&prt->sched.flags);
+    if (sched_flags & ERTS_PTS_FLG_EXIT) {
+	return ERTS_PORT_OP_BADARG;
     }
 
-    if ((prt->control_flags & PORT_CONTROL_FLAG_BINARY) == 0) {	/* List result */
-	Eterm ret;	
-	Eterm* hp = HAlloc(p, 2*n);
-	ret = buf_to_intlist(&hp, port_resp, n, NIL);
-	if (port_resp != port_result) {
-	    driver_free(port_resp);
+    try_call = !(sched_flags & ERTS_PTS_FLGS_FORCE_SCHEDULE_OP);
+
+    size = erts_encode_ext_size(data);
+
+    if (!try_call)
+	bufp = erts_alloc(ERTS_ALC_T_DRV_CALL_DATA, size);
+    else if (size <= sizeof(input_buf))
+	bufp = &input_buf[0];
+    else
+	bufp = erts_alloc(ERTS_ALC_T_TMP, size);
+
+    endp = (byte *) bufp;
+    erts_encode_ext(data, &endp);
+
+    if (endp - (byte *) bufp > size)
+	ERTS_INTERNAL_ERROR("erts_internal:port_call() - Buffer overflow");
+
+    size = endp - (byte *) bufp;
+
+    if (try_call) {
+	char resp_buf[255];
+	char* resp_bufp = &resp_buf[0];
+	ErlDrvSizeT resp_size = sizeof(resp_buf);
+	ErtsTryImmDrvCallResult try_call_res;
+	ErtsTryImmDrvCallState try_call_state
+	    = ERTS_INIT_TRY_IMM_DRV_CALL_STATE(
+		c_p,
+		prt,
+		ERTS_PORT_SFLGS_INVALID_LOOKUP,
+		0,
+		0,
+		am_call);
+
+	try_call_res = try_imm_drv_call(&try_call_state);
+	switch (try_call_res) {
+	case ERTS_TRY_IMM_DRV_CALL_OK: {
+	    Eterm *hp, *hp_end;
+	    Uint hsz;
+	    unsigned ret_flags = 0U;
+	    Eterm term;
+
+	    res = call_driver_call(c_p->common.id,
+				   prt,
+				   command,
+				   bufp,
+				   size,
+				   &resp_bufp,
+				   &resp_size,
+				   &ret_flags);
+
+	    finalize_imm_drv_call(&try_call_state);
+	    if (bufp != &input_buf[0])
+		erts_free(ERTS_ALC_T_TMP, bufp);
+	    if (res == ERTS_PORT_OP_BADARG)
+		return ERTS_PORT_OP_BADARG;
+	    hsz = erts_decode_ext_size((byte *) resp_bufp, resp_size);
+	    if (hsz < 0)
+		return ERTS_PORT_OP_BADARG;
+	    hsz += 3;
+	    hp = HAlloc(c_p, hsz);
+	    hp_end = hp + hsz;
+	    endp = (byte *) resp_bufp;
+	    term = erts_decode_ext(&hp, &MSO(c_p), &endp);
+	    if (term == THE_NON_VALUE)
+		return ERTS_PORT_OP_BADARG;
+	    *retvalp = TUPLE2(hp, am_ok, term);
+	    hp += 3;
+	    HRelease(c_p, hp_end, hp);
+	    if (resp_buf != &resp_buf[0]
+		&& !(ret_flags & DRIVER_CALL_KEEP_BUFFER))
+		driver_free(resp_buf);
+	    return ERTS_PORT_OP_DONE;
 	}
-	return ret;
-    } 
-    else if (port_resp == NULL) {
-	return NIL;
-    } 
-    else {                   /* Binary result */
-	ErlDrvBinary *dbin;
-	ErlHeapBin *hbin;
-	if (port_resp != port_result) {
-	    dbin = (ErlDrvBinary *) port_resp;
-	    if (dbin->orig_size > ERL_ONHEAP_BIN_LIMIT) {
-		ProcBin* pb = (ProcBin *) HAlloc(p, PROC_BIN_SIZE);
-		pb->thing_word = HEADER_PROC_BIN;
-		pb->size = dbin->orig_size;
-		pb->next = MSO(p).first;
-		MSO(p).first = (struct erl_off_heap_header*)pb;
-		pb->val = ErlDrvBinary2Binary(dbin);
-		pb->bytes = (byte*) dbin->orig_bytes;
-		pb->flags = 0;
-		OH_OVERHEAD(&(MSO(p)), dbin->orig_size / sizeof(Eterm));
-		return make_binary(pb);
-	    }
-	    port_resp = dbin->orig_bytes;
-	    n = dbin->orig_size;
-	} else {
-	    dbin = NULL;
+	case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+	    if (bufp != &input_buf[0])
+		erts_free(ERTS_ALC_T_TMP, bufp);
+	    return ERTS_PORT_OP_BADARG;
+	default:
+	    /* Schedule call() call instead... */
+	    break;
 	}
-	hbin = (ErlHeapBin*) HAlloc(p, heap_bin_size(n));
-	ASSERT(n <= ERL_ONHEAP_BIN_LIMIT);
-	hbin->thing_word = header_heap_bin(n);
-	hbin->size = n;
-	sys_memcpy(hbin->data, port_resp, n);
-	if (dbin != NULL) {
-	    driver_free_binary(dbin);
+    }
+
+    /* Convert data into something that can be scheduled */
+
+    if (bufp == &input_buf[0] || try_call) {
+	char *new_bufp = erts_alloc(ERTS_ALC_T_DRV_CALL_DATA, size);
+	sys_memcpy(new_bufp, bufp, size);
+	if (bufp != &input_buf[0])
+	    erts_free(ERTS_ALC_T_TMP, bufp);
+	bufp = new_bufp;
+    }
+
+    sigdp = erts_port_task_alloc_p2p_sig_data();
+    sigdp->flags = 0;
+    sigdp->u.call.command = command;
+    sigdp->u.call.bufp = bufp;
+    sigdp->u.call.size = size;
+    
+    res = erts_schedule_proc2port_signal(c_p,
+					 prt,
+					 c_p->common.id,
+					 retvalp,
+					 sigdp,
+					 0,
+					 port_sig_call);
+    if (res != ERTS_PORT_OP_SCHEDULED) {
+	cleanup_scheduled_call(bufp);
+	return ERTS_PORT_OP_BADARG;
+    }
+    return res;
+}
+
+static Eterm
+make_port_info_term(Eterm **hpp_start,
+		    Eterm **hpp,
+		    Uint *hszp,
+		    ErlHeapFragment **bpp,
+		    Port *prt,
+		    Eterm item)
+{
+    ErlOffHeap *ohp;
+
+    if (is_value(item)) {
+	if (erts_bld_port_info(NULL, NULL, hszp, prt, item) == am_false)
+	    return THE_NON_VALUE;
+	if (*hszp) {
+	    *bpp = new_message_buffer(*hszp);
+	    *hpp_start = *hpp = (*bpp)->mem;
+	    ohp = &(*bpp)->off_heap;
 	}
-	return make_binary(hbin);
+	else {
+	    *bpp = NULL;
+	    *hpp_start = *hpp = NULL;
+	    ohp = NULL;
+	}
+	return erts_bld_port_info(hpp, ohp, NULL, prt, item);
+    }
+    else {
+	int i;
+	int len;
+	int start;
+	static Eterm item[] = ERTS_PORT_INFO_1_ITEMS;
+	static Eterm value[sizeof(item)/sizeof(item[0])];
+
+	start = 0;
+	len = sizeof(item)/sizeof(item[0]);
+
+	for (i = start; i < sizeof(item)/sizeof(item[0]); i++) {
+	    ASSERT(is_atom(item[i]));
+	    value[i] = erts_bld_port_info(NULL, NULL, hszp, prt, item[i]);
+	}
+
+	if (value[0] == am_undefined) {
+	    start++;
+	    len--;
+	}
+
+	erts_bld_list(NULL, hszp, len, &value[start]);
+
+	*bpp = new_message_buffer(*hszp);
+	*hpp_start = *hpp = (*bpp)->mem;
+	ohp = &(*bpp)->off_heap;
+
+	for (i = start; i < sizeof(item)/sizeof(item[0]); i++)
+	    value[i] = erts_bld_port_info(hpp, ohp, NULL, prt, item[i]);
+
+	return erts_bld_list(hpp, NULL, len, &value[start]);
+    }
+}
+
+static int
+port_sig_info(Port *prt,
+	      erts_aint32_t state,
+	      int op,
+	      ErtsProc2PortSigData *sigdp)
+{
+    ASSERT(sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY);
+    if (op != ERTS_PROC2PORT_SIG_EXEC)
+	port_sched_op_reply(sigdp->caller, sigdp->ref, am_undefined);
+    else {
+	Eterm *hp, *hp_start;
+	Uint hsz;
+	ErlHeapFragment *bp;
+	Eterm value;
+	Process *rp;
+	ErtsProcLocks rp_locks = 0;
+
+	rp = erts_proc_lookup_raw(sigdp->caller);
+	if (!rp)
+	    return ERTS_PORT_REDS_INFO;
+
+	hsz = ERTS_QUEUE_PORT_SCHED_OP_REPLY_SIZE;
+	value = make_port_info_term(&hp_start,
+				    &hp,
+				    &hsz,
+				    &bp,
+				    prt,
+				    sigdp->u.info.item);
+	if (is_value(value)) {
+	    queue_port_sched_op_reply(rp,
+				      &rp_locks,
+				      hp_start,
+				      hp,
+				      hsz,
+				      bp,
+				      sigdp->ref,
+				      value);
+	}
+	if (rp_locks)
+	    erts_smp_proc_unlock(rp, rp_locks);
+    }
+    return ERTS_PORT_REDS_INFO;
+}
+
+ErtsPortOpResult
+erts_port_info(Process* c_p,
+	       Port *prt,
+	       Eterm item,
+	       Eterm *retvalp)
+{
+    ErtsProc2PortSigData *sigdp;
+    ErtsTryImmDrvCallResult try_call_res;
+    ErtsTryImmDrvCallState try_call_state
+	= ERTS_INIT_TRY_IMM_DRV_CALL_STATE(
+	    c_p,
+	    prt,
+	    ERTS_PORT_SFLGS_INVALID_LOOKUP,
+	    0,
+	    0,
+	    am_info);
+
+    try_call_res = try_imm_drv_call(&try_call_state);
+    switch (try_call_res) {
+    case ERTS_TRY_IMM_DRV_CALL_OK: {
+	Eterm *hp, *hp_start;
+	ErlHeapFragment *bp;
+	Uint hsz = 0;
+	Eterm value = make_port_info_term(&hp_start, &hp, &hsz, &bp, prt, item);
+	finalize_imm_drv_call(&try_call_state);
+	if (is_non_value(value))
+	    return ERTS_PORT_OP_BADARG;
+	else if (is_immed(value))
+	    *retvalp = value;
+	else {
+	    Uint used_h_size = hp - hp_start;
+	    hp = HAlloc(c_p, used_h_size);
+	    *retvalp = copy_struct(value, used_h_size, &hp, &MSO(c_p));
+	    free_message_buffer(bp);
+	}
+	return ERTS_PORT_OP_DONE;
     }
+    case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+	return ERTS_PORT_OP_DROPPED;
+    case ERTS_TRY_IMM_DRV_CALL_INVALID_SCHED_FLAGS:
+    case ERTS_TRY_IMM_DRV_CALL_BUSY_LOCK:
+	/* Schedule call instead... */
+	break;
+    }
+
+    sigdp = erts_port_task_alloc_p2p_sig_data();
+    sigdp->flags = 0;
+    sigdp->u.info.item = item;
+
+    return erts_schedule_proc2port_signal(c_p,
+					  prt,
+					  c_p->common.id,
+					  retvalp,
+					  sigdp,
+					  0,
+					  port_sig_info);
+}
+
+static int
+port_sig_set_data(Port *prt,
+		  erts_aint32_t state,
+		  int op,
+		  ErtsProc2PortSigData *sigdp)
+{
+    ASSERT(sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY);
+
+    if (op == ERTS_PROC2PORT_SIG_EXEC) {
+	if (prt->bp)
+	    free_message_buffer(prt->bp);
+	prt->bp = sigdp->u.set_data.bp;
+	prt->data = sigdp->u.set_data.data;
+	port_sched_op_reply(sigdp->caller, sigdp->ref, am_true);
+    }
+    else {
+	if (sigdp->u.set_data.bp)
+	    free_message_buffer(sigdp->u.set_data.bp);
+	port_sched_op_reply(sigdp->caller, sigdp->ref, am_badarg);
+    }
+    return ERTS_PORT_REDS_SET_DATA;
+}
+
+ErtsPortOpResult
+erts_port_set_data(Process* c_p,
+		   Port *prt,
+		   Eterm data,
+		   Eterm *refp)
+{
+    ErtsPortOpResult res;
+    Eterm set_data;
+    ErlHeapFragment *bp;
+    ErtsProc2PortSigData *sigdp;
+    ErtsTryImmDrvCallResult try_call_res;
+    ErtsTryImmDrvCallState try_call_state
+	= ERTS_INIT_TRY_IMM_DRV_CALL_STATE(
+	    c_p,
+	    prt,
+	    ERTS_PORT_SFLGS_INVALID_LOOKUP,
+	    0,
+	    !refp,
+	    am_set_data);
+
+    if (is_immed(data)) {
+	set_data = data;
+	bp = NULL;
+    }
+    else {
+	Eterm *hp;
+	Uint sz = size_object(data);
+	bp = new_message_buffer(sz);
+	hp = bp->mem;
+	set_data = copy_struct(data, sz, &hp, &bp->off_heap);
+    }
+
+    try_call_res = try_imm_drv_call(&try_call_state);
+    switch (try_call_res) {
+    case ERTS_TRY_IMM_DRV_CALL_OK:
+	if (prt->bp)
+	    free_message_buffer(prt->bp);
+	prt->bp = bp;
+	prt->data = set_data;
+	finalize_imm_drv_call(&try_call_state);
+	return ERTS_PORT_OP_DONE;
+    case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+	return ERTS_PORT_OP_DROPPED;
+    case ERTS_TRY_IMM_DRV_CALL_INVALID_SCHED_FLAGS:
+    case ERTS_TRY_IMM_DRV_CALL_BUSY_LOCK:
+	/* Schedule call instead... */
+	break;
+    }
+
+    sigdp = erts_port_task_alloc_p2p_sig_data();
+    sigdp->flags = 0;
+    sigdp->u.set_data.data = set_data;
+    sigdp->u.set_data.bp = bp;
+
+    res = erts_schedule_proc2port_signal(c_p,
+					 prt,
+					 c_p->common.id,
+					 refp,
+					 sigdp,
+					 0,
+					 port_sig_set_data);
+    if (res != ERTS_PORT_OP_SCHEDULED && bp)
+	free_message_buffer(bp);
+    return res;
+}
+
+static int
+port_sig_get_data(Port *prt,
+		  erts_aint32_t state,
+		  int op,
+		  ErtsProc2PortSigData *sigdp)
+{
+    ASSERT(sigdp->flags & ERTS_P2P_SIG_DATA_FLG_REPLY);
+    if (op != ERTS_PROC2PORT_SIG_EXEC)
+	port_sched_op_reply(sigdp->caller, sigdp->ref, am_badarg);
+    else {
+	Process *rp;
+	ErtsProcLocks rp_locks = 0;
+
+	rp = erts_proc_lookup_raw(sigdp->caller);
+	if (rp) {
+	    Uint hsz;
+	    Eterm *hp, *hp_start;
+	    Eterm data, msg;
+	    ErlHeapFragment *bp;
+	    ErlOffHeap *ohp;
+
+	    hsz = ERTS_QUEUE_PORT_SCHED_OP_REPLY_SIZE;
+	    hsz += 3;
+	    if (prt->bp)
+		hsz += prt->bp->used_size;
+
+	    hp_start = hp = erts_alloc_message_heap(hsz,
+						    &bp,
+						    &ohp,
+						    rp,
+						    &rp_locks);
+
+	    if (is_immed(prt->data))
+		data = prt->data;
+	    else
+		data = copy_struct(prt->data,
+				   prt->bp->used_size,
+				   &hp,
+				   &bp->off_heap);
+
+
+
+	    msg = TUPLE2(hp, am_ok, data);
+	    hp += 3;
+
+	    queue_port_sched_op_reply(rp,
+				      &rp_locks,
+				      hp_start,
+				      hp,
+				      hsz,
+				      bp,
+				      sigdp->ref,
+				      msg);
+	    if (rp_locks)
+		erts_smp_proc_unlock(rp, rp_locks);
+	}
+    }
+    return ERTS_PORT_REDS_GET_DATA;
+}
+
+ErtsPortOpResult
+erts_port_get_data(Process* c_p,
+		   Port *prt,
+		   Eterm *retvalp)
+{
+    ErtsProc2PortSigData *sigdp;
+    ErtsTryImmDrvCallResult try_call_res;
+    ErtsTryImmDrvCallState try_call_state
+	= ERTS_INIT_TRY_IMM_DRV_CALL_STATE(
+	    c_p,
+	    prt,
+	    ERTS_PORT_SFLGS_INVALID_LOOKUP,
+	    0,
+	    0,
+	    am_get_data);
+
+    try_call_res = try_imm_drv_call(&try_call_state);
+    switch (try_call_res) {
+    case ERTS_TRY_IMM_DRV_CALL_OK: {
+	Eterm *hp;
+	Eterm data;
+	ErlHeapFragment *bp;
+	Uint sz;
+	if (is_immed(prt->data)) {
+	    bp = NULL;
+	    data = prt->data;
+	}
+	else {
+	    bp = new_message_buffer(prt->bp->used_size);
+	    data = copy_struct(prt->data,
+			       prt->bp->used_size,
+			       &hp,
+			       &bp->off_heap);
+	}	    
+	finalize_imm_drv_call(&try_call_state);
+	if (is_immed(data))
+	    sz = 0;
+	else 
+	    sz = bp->used_size;
+
+	hp = HAlloc(c_p,  sz + 3);
+	if (is_not_immed(data)) {
+	    data = copy_struct(data, bp->used_size, &hp, &MSO(c_p));
+	    free_message_buffer(bp);
+	}
+	*retvalp = TUPLE2(hp, am_ok, data);
+	return ERTS_PORT_OP_DONE;
+    }
+    case ERTS_TRY_IMM_DRV_CALL_INVALID_PORT:
+	return ERTS_PORT_OP_DROPPED;
+    case ERTS_TRY_IMM_DRV_CALL_INVALID_SCHED_FLAGS:
+    case ERTS_TRY_IMM_DRV_CALL_BUSY_LOCK:
+	/* Schedule call instead... */
+	break;
+    }
+
+    sigdp = erts_port_task_alloc_p2p_sig_data();
+    sigdp->flags = 0;
+
+    return erts_schedule_proc2port_signal(c_p,
+					  prt,
+					  c_p->common.id,
+					  retvalp,
+					  sigdp,
+					  0,
+					  port_sig_get_data);
 }
 
 typedef struct {
@@ -2459,7 +4591,7 @@ print_port_info(Port *p, int to, void *arg)
 }
 
 void
-set_busy_port(ErlDrvPort port_num, int on)
+set_busy_port(ErlDrvPort dprt, int on)
 {
     Port *prt;
     erts_aint32_t flags;
@@ -2470,34 +4602,38 @@ set_busy_port(ErlDrvPort port_num, int on)
 
     ERTS_SMP_CHK_NO_PROC_LOCKS;
 
-    prt = erts_drvport2port_raw(port_num);
+    prt = erts_drvport2port_raw(dprt);
     if (!prt)
 	return;
 
     if (on) {
-	flags = erts_smp_atomic32_read_bor_nob(&prt->sched.flags,
-					       ERTS_PTS_FLG_BUSY);
+	flags = erts_smp_atomic32_read_bor_acqb(&prt->sched.flags,
+						ERTS_PTS_FLG_BUSY);
 	if (flags & ERTS_PTS_FLG_BUSY)
 	    return; /* Already busy */
+
+	if (flags & ERTS_PTS_FLG_HAVE_NS_TASKS)
+	    erts_port_task_abort_nosuspend_tasks(prt);
+
 #ifdef USE_VM_PROBES
         if (DTRACE_ENABLED(port_busy)) {
             erts_snprintf(port_str, sizeof(port_str),
-                          "%T", prt->id);
+                          "%T", prt->common.id);
             DTRACE1(port_busy, port_str);
         }
 #endif
     } else {
         ErtsProcList *plp;
 
-	flags = erts_smp_atomic32_read_band_nob(&prt->sched.flags,
-						~ERTS_PTS_FLG_BUSY);
+	flags = erts_smp_atomic32_read_band_acqb(&prt->sched.flags,
+						 ~ERTS_PTS_FLG_BUSY);
 	if (!(flags & ERTS_PTS_FLG_BUSY))
 	    return; /* Already non-busy */
 
 #ifdef USE_VM_PROBES
         if (DTRACE_ENABLED(port_not_busy)) {
             erts_snprintf(port_str, sizeof(port_str),
-                          "%T", prt->id);
+                          "%T", prt->common.id);
             DTRACE1(port_not_busy, port_str);
         }
 #endif
@@ -2539,7 +4675,7 @@ set_busy_port(ErlDrvPort port_num, int on)
                 ErtsProcList* plp2 = plp;
 
                 erts_snprintf(port_str, sizeof(port_str),
-                             "%T", erts_port[port_num]);
+                             "%T", prt->common.id);
                 while (plp2 != NULL) {
                     erts_snprintf(pid_str, sizeof(pid_str), "%T", plp2->pid);
                     DTRACE2(process_port_unblocked, pid_str, port_str);
@@ -3748,8 +5884,7 @@ ErlDrvBinary* driver_realloc_binary(ErlDrvBinary* bin, ErlDrvSizeT size)
 }
 
 
-void driver_free_binary(dbin)
-ErlDrvBinary* dbin;
+void driver_free_binary(ErlDrvBinary* dbin)
 {
     Binary *bin;
     if (!dbin) {
@@ -4705,13 +6840,13 @@ driver_failure_term(ErlDrvPort ix, Eterm term, int eof)
     } else if (eof && (state & ERTS_PORT_SFLG_SOFT_EOF)) {
 	deliver_result(prt->common.id, ERTS_PORT_GET_CONNECTED(prt), am_eof);
     } else {
-	/* XXX UGLY WORK AROUND, Let do_exit_port terminate the port */
+	/* XXX UGLY WORK AROUND, Let erts_deliver_port_exit() terminate the port */
 	if (prt->port_data_lock)
 	    driver_pdl_lock(prt->port_data_lock);
 	prt->ioq.size = 0;
 	if (prt->port_data_lock)
 	    driver_pdl_unlock(prt->port_data_lock);
-	erts_do_exit_port(prt, prt->common.id, eof ? am_normal : term);
+	erts_deliver_port_exit(prt, prt->common.id, eof ? am_normal : term, 0);
     }
     return 0;
 }
diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index fd6f34e96e..9c3f9551c7 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -564,7 +564,7 @@ __decl_noreturn void __noreturn erl_exit(int n, char*, ...);
 #define ERTS_DUMP_EXIT	(INT_MIN + 2)	/* crash dump; then exit() */
 
 #define ERTS_INTERNAL_ERROR(What) \
-    erl_exit(ERTS_ABORT_EXIT, "%s:%d:%s(): Internal error: %s",	\
+    erl_exit(ERTS_ABORT_EXIT, "%s:%d:%s(): Internal error: %s\n", \
 	     __FILE__, __LINE__, __func__, What)
 
 Eterm erts_check_io_info(void *p);
@@ -641,6 +641,7 @@ typedef struct _SysDriverOpts {
     char *wd;			/* Working directory. */
     unsigned spawn_type;        /* Bitfield of ERTS_SPAWN_DRIVER | 
 				   ERTS_SPAWN_EXTERNAL | both*/ 
+    int parallelism;            /* Optimize for parallelism */
 } SysDriverOpts;
 
 extern char *erts_default_arg0;
diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index fb203c6076..164bed51d1 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -3017,12 +3017,13 @@ buf_to_intlist(Eterm** hpp, char *buf, size_t len, Eterm tail)
 **        ;
 ** 
 ** Return remaining bytes in buffer on success
-**        -1 on overflow
-**        -2 on type error (including that result would not be a whole number of bytes)
+**        ERTS_IOLIST_TO_BUF_OVERFLOW on overflow
+**        ERTS_IOLIST_TO_BUF_TYPE_ERROR on type error (including that result would not be a whole number of bytes)
 */
 
-int io_list_to_buf(Eterm obj, char* buf, int len)
+ErlDrvSizeT erts_iolist_to_buf(Eterm obj, char* buf, ErlDrvSizeT alloced_len)
 {
+    ErlDrvSizeT len = (ErlDrvSizeT) alloced_len;
     Eterm* objp;
     DECLARE_ESTACK(s);
     goto L_again;
@@ -3115,20 +3116,20 @@ int io_list_to_buf(Eterm obj, char* buf, int len)
 
  L_type_error:
     DESTROY_ESTACK(s);
-    return -2;
+    return ERTS_IOLIST_TO_BUF_TYPE_ERROR;
 
  L_overflow:
     DESTROY_ESTACK(s);
-    return -1;
+    return ERTS_IOLIST_TO_BUF_OVERFLOW;
 }
 
 /*
  * Return 0 if successful, and non-zero if unsuccessful.
  */
-int erts_iolist_size(Eterm obj, Uint* sizep)
+int erts_iolist_size(Eterm obj, ErlDrvSizeT* sizep)
 {
     Eterm* objp;
-    Uint size = 0;
+    Uint size = 0; /* Intentionally Uint due to halfword heap */
     DECLARE_ESTACK(s);
     goto L_again;
 
@@ -3180,7 +3181,7 @@ int erts_iolist_size(Eterm obj, Uint* sizep)
 #undef SAFE_ADD
 
     DESTROY_ESTACK(s);
-    *sizep = size;
+    *sizep = (ErlDrvSizeT) size;
     return ERTS_IOLIST_OK;
 
  L_overflow_error:
diff --git a/erts/emulator/test/busy_port_SUITE.erl b/erts/emulator/test/busy_port_SUITE.erl
index 3a29fd4d68..32e907ca69 100644
--- a/erts/emulator/test/busy_port_SUITE.erl
+++ b/erts/emulator/test/busy_port_SUITE.erl
@@ -148,9 +148,9 @@ message_order(Config) when is_list(Config) ->
 
 send_to_busy_1(Parent) ->
     {Owner, Slave} = get_slave(),
-    Slave ! {Owner, {command, "set_me_busy"}},
-    Slave ! {Owner, {command, "hello"}},
-    Slave ! {Owner, {command, "hello again"}},
+    (catch port_command(Slave, "set_me_busy")),
+    (catch port_command(Slave, "hello")),
+    (catch port_command(Slave, "hello again")),
     receive
 	Message ->
 	    Parent ! {self(), Message}
@@ -193,10 +193,10 @@ system_monitor(Config) when is_list(Config) ->
     ?line Busy = 
 	spawn_link(
 	  fun() ->
-		  Slave ! {Owner,{command,"set busy"}},
+		  (catch port_command(Slave, "set busy")),
 		  receive {Parent,alpha} -> ok end,
-		  Slave ! {Owner,{command,"busy"}},
-		  Slave ! {Owner,{command,"free"}},
+		  (catch port_command(Slave, "busy")),
+		  (catch port_command(Slave, "free")),
 		  Parent ! {self(),alpha},
 		  command(lock),
 		  receive {Parent,beta} -> ok end,
@@ -212,7 +212,7 @@ system_monitor(Config) when is_list(Config) ->
     ?line Void = rec(Void),
     ?line Busy ! {self(), beta},
     ?line {monitor,Owner,busy_port,Slave} = rec(Void),
-    ?line Master ! {Owner, {command, "u"}},
+    ?line port_command(Master, "u"),
     ?line {Busy,beta} = rec(Void),
     ?line Void = rec(Void),
     ?line _NewMonitor = erlang:system_monitor(OldMonitor),
@@ -296,9 +296,9 @@ no_trap_exit_process(ResultTo, Link, Config) ->
 	      linked -> ok;
 	      unlink -> unlink(Slave)
 	  end,
-    ?line Slave ! {self(), {command, "lock port"}},
+    ?line (catch port_command(Slave, "lock port")),
     ?line ResultTo ! {self(), port_created, Slave},
-    ?line Slave ! {self(), {command, "suspend me"}},
+    ?line (catch port_command(Slave, "suspend me")),
     ok.
 
 %% Assuming the following scenario,
@@ -339,9 +339,9 @@ busy_port_exit_process(ResultTo, Config) ->
     ?line load_busy_driver(Config),
     ?line _Master = open_port({spawn, "busy_drv master"}, [eof]),
     ?line Slave = open_port({spawn, "busy_drv slave"}, [eof]),
-    ?line Slave ! {self(), {command, "lock port"}},
+    ?line (catch port_command(Slave, "lock port")),
     ?line ResultTo ! {self(), port_created, Slave},
-    ?line Slave ! {self(), {command, "suspend me"}},
+    ?line (catch port_command(Slave, "suspend me")),
     receive
 	{'EXIT', Slave, die} ->
 	    ResultTo ! {self(), ok};
@@ -383,8 +383,8 @@ multiple_writers(Config) when is_list(Config) ->
 
 quick_writer() ->
     {Owner, Port} = get_slave(),
-    Port ! {Owner, {command, "port to busy"}},
-    Port ! {Owner, {command, "lock me"}},
+    (catch port_command(Port, "port to busy")),
+    (catch port_command(Port, "lock me")),
     ok.
 
 hard_busy_driver(Config) when is_list(Config) ->
@@ -644,11 +644,11 @@ loop(Master, Slave) ->
 	    Pid ! {busy_drv_reply, {self(), Slave}},
 	    loop(Master, Slave);
 	{Pid, unlock} ->
-	    Master ! {self(), {command, "u"}},
+	    port_command(Master, "u"),
 	    Pid ! {busy_drv_reply, ok},
 	    loop(Master, Slave);
 	{Pid, lock} ->
-	    Master ! {self(), {command, "l"}},
+	    port_command(Master, "l"),
 	    Pid ! {busy_drv_reply, ok},
 	    loop(Master, Slave);
 	{Pid, {port_command,Data}} ->
diff --git a/erts/emulator/test/ddll_SUITE.erl b/erts/emulator/test/ddll_SUITE.erl
index 6e15c228cd..4675cab15c 100644
--- a/erts/emulator/test/ddll_SUITE.erl
+++ b/erts/emulator/test/ddll_SUITE.erl
@@ -136,8 +136,8 @@ delayed_unload_with_ports(Config) when is_list(Config) ->
     ?line {ok,pending_driver,Ref} = erl_ddll:try_unload(echo_drv,[{monitor, pending_driver}]),
     ?line ok = receive _ -> false after 0 -> ok end,
     ?line Port ! {self(), close},
-    ?line 1 = erl_ddll:info(echo_drv, port_count),
     ?line ok = receive {Port,closed} -> ok after 1000 -> false end,
+    ?line 1 = erl_ddll:info(echo_drv, port_count),
     ?line Port2 ! {self(), close},
     ?line ok = receive {Port2,closed} -> ok after 1000 -> false end,
     ?line ok = receive {'DOWN', Ref, driver, echo_drv, unloaded} -> ok after 1000 -> false end,
diff --git a/erts/emulator/test/port_SUITE.erl b/erts/emulator/test/port_SUITE.erl
index 0a1ef5a78f..b00e7f0b59 100644
--- a/erts/emulator/test/port_SUITE.erl
+++ b/erts/emulator/test/port_SUITE.erl
@@ -90,7 +90,7 @@
 	 mix_up_ports/1, otp_5112/1, otp_5119/1, otp_6224/1,
 	 exit_status_multi_scheduling_block/1, ports/1,
 	 spawn_driver/1, spawn_executable/1, close_deaf_port/1,
-	 unregister_name/1]).
+	 unregister_name/1, parallelism_option/1]).
 
 -export([]).
 
@@ -114,7 +114,8 @@ all() ->
      stderr_to_stdout, otp_3906, otp_4389, win_massive,
      mix_up_ports, otp_5112, otp_5119,
      exit_status_multi_scheduling_block, ports, spawn_driver,
-     spawn_executable, close_deaf_port, unregister_name].
+     spawn_executable, close_deaf_port, unregister_name,
+     parallelism_option].
 
 groups() -> 
     [{stream, [], [stream_small, stream_big]},
@@ -1364,6 +1365,43 @@ spawn_driver(Config) when is_list(Config) ->
     ?line test_server:timetrap_cancel(Dog),
     ok.
 
+parallelism_option(suite) ->
+    [];
+parallelism_option(doc) ->
+    ["Test parallelism option of open_port"];
+parallelism_option(Config) when is_list(Config) ->
+    ?line Dog = test_server:timetrap(test_server:seconds(10)),
+    ?line Path = ?config(data_dir, Config),
+    ?line ok = load_driver(Path, "echo_drv"),
+    ?line Port = erlang:open_port({spawn_driver, "echo_drv"},
+				  [{parallelism, true}]),
+    ?line {parallelism, true} = erlang:port_info(Port, parallelism),
+    ?line Port ! {self(), {command, "Hello port!"}},
+    ?line receive 
+	      {Port, {data, "Hello port!"}} = Msg1 -> 
+		  io:format("~p~n", [Msg1]),
+		  ok; 
+	      Other ->
+		  test_server:fail({unexpected, Other})
+	  end,
+    ?line Port ! {self(), close},
+    ?line receive {Port, closed} -> ok end,
+
+    ?line Port2 = erlang:open_port({spawn_driver, "echo_drv -Hello port?"}, 
+				   [{parallelism, false}]),
+    ?line {parallelism, false} = erlang:port_info(Port2, parallelism),
+    ?line receive 
+	      {Port2, {data, "Hello port?"}} = Msg2 -> 
+		  io:format("~p~n", [Msg2]),
+		  ok; 
+	      Other2 ->
+		  test_server:fail({unexpected2, Other2})
+	  end,
+    ?line Port2 ! {self(), close},
+    ?line receive {Port2, closed} -> ok end,
+    ?line test_server:timetrap_cancel(Dog),
+    ok.
+
 spawn_executable(suite) ->
     [];
 spawn_executable(doc) ->
@@ -1632,6 +1670,7 @@ otp_5112(Config) when is_list(Config) ->
     ?line ?t:format("Links1: ~p~n",[Links1]),
     ?line true = lists:member(Port, Links1),
     ?line Port ! {self(), {command, ""}},
+    ?line wait_until(fun () -> lists:member(Port, erlang:ports()) == false end),
     ?line {links, Links2} = process_info(self(),links),
     ?line ?t:format("Links2: ~p~n",[Links2]),
     ?line false = lists:member(Port, Links2), %% This used to fail
@@ -1703,38 +1742,8 @@ otp_5119_fill_empty_port_tab(Ports) ->
 		  ?line LastPort
 	  end.
 
--define(DEF_MAX_PORTS, 1024).
-
-max_ports_env() ->
-    ?line case os:getenv("ERL_MAX_PORTS") of
-	      EMP when is_list(EMP) ->
-		  case catch list_to_integer(EMP) of
-		      Int when is_integer(Int) -> ?line Int;
-		      _ -> ?line false
-		  end;
-	      _ -> ?line false
-	  end.
-
 max_ports() ->
-    ?line PreMaxPorts
-	= case max_ports_env() of
-	      Env when is_integer(Env) -> ?line Env;
-	      _ ->
-		  ?line case os:type() of
-			    {unix, _} ->
-				?line UlimStr = string:strip(os:cmd("ulimit -n")
-							     -- "\n"),
-				?line case catch list_to_integer(UlimStr) of
-					  Ulim when is_integer(Ulim) -> ?line Ulim;
-					  _ -> ?line ?DEF_MAX_PORTS
-				      end;
-			    _ -> ?line ?DEF_MAX_PORTS
-			end
-	  end,
-    ?line case PreMaxPorts > ?DEF_MAX_PORTS of
-	      true -> ?line PreMaxPorts;
-	      false -> ?line ?DEF_MAX_PORTS
-	  end.
+    erlang:system_info(port_limit).
 
 port_ix(Port) when is_port(Port) ->
     ?line ["#Port",_,PortIxStr] = string:tokens(erlang:port_to_list(Port),
@@ -2344,5 +2353,12 @@ close_deaf_port_1(N, Cmd) ->
     	_:eagain ->
 	    {comment, "Could not spawn more than " ++ integer_to_list(N) ++ " OS processes."}
     end.
-    
 
+wait_until(Fun) ->
+    case catch Fun() of
+	true ->
+	    ok;
+	_ ->
+	    receive after 100 -> ok end,
+	    wait_until(Fun)
+    end.