Index: arch/arm/at91/at91dbgu.c
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/at91/at91dbgu.c,v
retrieving revision 1.8
diff -u -u -r1.8 at91dbgu.c
--- arch/arm/at91/at91dbgu.c	2 Feb 2012 19:42:57 -0000	1.8
+++ arch/arm/at91/at91dbgu.c	11 Aug 2012 08:22:45 -0000
@@ -134,6 +134,7 @@
 
 static int	at91dbgu_param(struct tty *, struct termios *);
 static void	at91dbgu_start(struct tty *);
+static void	at91dbgu_flush(struct tty *);
 static int	at91dbgu_hwiflow(struct tty *, int);
 
 #if 0
@@ -245,6 +246,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = at91dbgu_start;
+	tp->t_flush = at91dbgu_flush;
 	tp->t_param = at91dbgu_param;
 	tp->t_hwiflow = at91dbgu_hwiflow;
 
@@ -385,6 +387,17 @@
 }
 
 static void
+at91dbgu_flush(struct tty *tp)
+{
+	struct at91dbgu_softc *sc
+		= device_lookup_private(&at91dbgu_cd, COMUNIT(tp->t_dev));
+	if (COM_ISALIVE(sc) == 0)
+		return;
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
+static void
 at91dbgu_start(struct tty *tp)
 {
 	struct at91dbgu_softc *sc
Index: arch/arm/at91/at91usart.c
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/at91/at91usart.c,v
retrieving revision 1.6
diff -u -u -r1.6 at91usart.c
--- arch/arm/at91/at91usart.c	2 Feb 2012 19:42:57 -0000	1.6
+++ arch/arm/at91/at91usart.c	11 Aug 2012 08:22:49 -0000
@@ -126,6 +126,7 @@
 
 static int	at91usart_param(struct tty *, struct termios *);
 static void	at91usart_start(struct tty *);
+static void	at91usart_flush(struct tty *);
 static int	at91usart_hwiflow(struct tty *, int);
 
 #if 0
@@ -279,6 +280,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = at91usart_start;
+	tp->t_flush = at91usart_flush;
 	tp->t_param = at91usart_param;
 	tp->t_hwiflow = at91usart_hwiflow;
 
@@ -469,6 +471,18 @@
 }
 
 static void
+at91usart_flush(struct tty *tp)
+{
+	struct at91usart_softc *sc
+		= device_lookup_private(&at91usart_cd, COMUNIT(tp->t_dev));
+
+	if (COM_ISALIVE(sc) == 0)
+		return;
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
+static void
 at91usart_start(struct tty *tp)
 {
 	struct at91usart_softc *sc
Index: arch/arm/ep93xx/epcom.c
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/ep93xx/epcom.c,v
retrieving revision 1.22
diff -u -u -r1.22 epcom.c
--- arch/arm/ep93xx/epcom.c	2 Feb 2012 19:42:57 -0000	1.22
+++ arch/arm/ep93xx/epcom.c	11 Aug 2012 08:22:50 -0000
@@ -122,6 +122,7 @@
 
 static int	epcomparam(struct tty *, struct termios *);
 static void	epcomstart(struct tty *);
+static void	epcomflush(struct tty *);
 static int	epcomhwiflow(struct tty *, int);
 
 static u_int	cflag2lcrhi(tcflag_t);
@@ -203,6 +204,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = epcomstart;
+	tp->t_flush = epcomflush;
 	tp->t_param = epcomparam;
 	tp->t_hwiflow = epcomhwiflow;
 
@@ -346,6 +348,17 @@
 }
 
 static void
+epcomflush(struct tty *tp)
+{
+	struct epcom_softc *sc
+		= device_lookup_private(&epcom_cd, COMUNIT(tp->t_dev));
+	if (COM_ISALIVE(sc) == 0)
+		return;
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
+static void
 epcomstart(struct tty *tp)
 {
 	struct epcom_softc *sc
Index: arch/arm/imx/imxuart.c
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/imx/imxuart.c,v
retrieving revision 1.9
diff -u -u -r1.9 imxuart.c
--- arch/arm/imx/imxuart.c	2 Feb 2012 19:42:58 -0000	1.9
+++ arch/arm/imx/imxuart.c	11 Aug 2012 08:22:52 -0000
@@ -277,6 +277,7 @@
 int	imxuspeed(long, struct imxuart_baudrate_ratio *);
 int	imxuparam(struct tty *, struct termios *);
 void	imxustart(struct tty *);
+void	imxuflush(struct tty *);
 int	imxuhwiflow(struct tty *, int);
 
 void	imxuart_shutdown(struct imxuart_softc *);
@@ -435,6 +436,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = imxustart;
+	tp->t_flush = imxuflush;
 	tp->t_param = imxuparam;
 	tp->t_hwiflow = imxuhwiflow;
 
@@ -1515,6 +1517,17 @@
 #endif
 }
 
+void
+imxuflush(struct tty *tp)
+{
+	struct imxuart_softc *sc =
+	    device_lookup_private(&imxuart_cd, IMXUART_UNIT(tp->t_dev));
+
+	if (IMXUART_ISALIVE(sc) == 0)
+		return;
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
 
 void
 imxustart(struct tty *tp)
Index: arch/arm/include/cpufunc.h
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/include/cpufunc.h,v
retrieving revision 1.57
diff -u -u -r1.57 cpufunc.h
--- arch/arm/include/cpufunc.h	21 Jul 2012 12:19:15 -0000	1.57
+++ arch/arm/include/cpufunc.h	11 Aug 2012 08:22:52 -0000
@@ -156,7 +156,7 @@
 extern struct cpu_functions cpufuncs;
 extern u_int cputype;
 
-#define cpu_id()		cpufuncs.cf_id()
+#define cpu_idnum()		cpufuncs.cf_id()
 
 #define cpu_control(c, e)	cpufuncs.cf_control(c, e)
 #define cpu_domains(d)		cpufuncs.cf_domains(d)
Index: arch/arm/ixp12x0/ixp12x0_com.c
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/ixp12x0/ixp12x0_com.c,v
retrieving revision 1.40
diff -u -u -r1.40 ixp12x0_com.c
--- arch/arm/ixp12x0/ixp12x0_com.c	2 Feb 2012 19:42:58 -0000	1.40
+++ arch/arm/ixp12x0/ixp12x0_com.c	11 Aug 2012 08:22:54 -0000
@@ -105,6 +105,7 @@
 
 static int	ixpcomparam(struct tty *, struct termios *);
 static void	ixpcomstart(struct tty *);
+static void	ixpcomflush(struct tty *);
 static int	ixpcomhwiflow(struct tty *, int);
 
 static u_int	cflag2cr(tcflag_t);
@@ -202,6 +203,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = ixpcomstart;
+	tp->t_flush = ixpcomflush;
 	tp->t_param = ixpcomparam;
 	tp->t_hwiflow = ixpcomhwiflow;
 
@@ -363,6 +365,17 @@
 }
 
 static void
+ixpcomflush(struct tty *tp)
+{
+	struct ixpcom_softc *sc
+		= device_lookup_private(&ixpcom_cd, COMUNIT(tp->t_dev));
+	if (COM_ISALIVE(sc) == 0)
+		return;
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
+static void
 ixpcomstart(struct tty *tp)
 {
 	struct ixpcom_softc *sc
Index: arch/arm/s3c2xx0/sscom.c
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/s3c2xx0/sscom.c,v
retrieving revision 1.37
diff -u -u -r1.37 sscom.c
--- arch/arm/s3c2xx0/sscom.c	7 Feb 2012 09:06:05 -0000	1.37
+++ arch/arm/s3c2xx0/sscom.c	11 Aug 2012 08:22:56 -0000
@@ -470,6 +470,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = sscomstart;
+	tp->t_flush = sscomflush;
 	tp->t_param = sscomparam;
 	tp->t_hwiflow = sscomhwiflow;
 
@@ -1267,6 +1268,17 @@
 
 
 void
+sscomflush(struct tty *tp)
+{
+	struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(tp->t_dev));
+
+	if (SSCOM_ISALIVE(sc) == 0)
+		return;
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
+void
 sscomstart(struct tty *tp)
 {
 	struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(tp->t_dev));
Index: arch/arm/s3c2xx0/sscom_var.h
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/s3c2xx0/sscom_var.h,v
retrieving revision 1.11
diff -u -u -r1.11 sscom_var.h
--- arch/arm/s3c2xx0/sscom_var.h	2 Feb 2012 19:42:58 -0000	1.11
+++ arch/arm/s3c2xx0/sscom_var.h	11 Aug 2012 08:22:56 -0000
@@ -281,6 +281,7 @@
 void	sscom_shutdown(struct sscom_softc *);
 void	sscomdiag		(void *);
 void	sscomstart(struct tty *);
+void	sscomflush(struct tty *);
 int	sscomparam(struct tty *, struct termios *);
 int	sscomread(dev_t, struct uio *, int);
 void	sscom_config(struct sscom_softc *);
Index: arch/arm/sa11x0/sa11x0_com.c
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/sa11x0/sa11x0_com.c,v
retrieving revision 1.50
diff -u -u -r1.50 sa11x0_com.c
--- arch/arm/sa11x0/sa11x0_com.c	2 Feb 2012 19:42:58 -0000	1.50
+++ arch/arm/sa11x0/sa11x0_com.c	11 Aug 2012 08:22:58 -0000
@@ -135,6 +135,7 @@
 static	u_int	cflag2cr0(tcflag_t);
 int		sacomparam(struct tty *, struct termios *);
 void		sacomstart(struct tty *);
+void		sacomflush(struct tty *);
 int		sacomhwiflow(struct tty *, int);
 
 void		sacom_loadchannelregs(struct sacom_softc *);
@@ -298,6 +299,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = sacomstart;
+	tp->t_flush = sacomflush;
 	tp->t_param = sacomparam;
 	tp->t_hwiflow = sacomhwiflow;
 
@@ -1040,6 +1042,17 @@
 
 
 void
+sacomflush(struct tty *tp)
+{
+	struct sacom_softc *sc =
+		device_lookup_private(&sacom_cd, COMUNIT(tp->t_dev));
+	if (COM_ISALIVE(sc) == 0)
+		return;
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
+void
 sacomstart(struct tty *tp)
 {
 	struct sacom_softc *sc =
Index: arch/atari/dev/ser.c
===================================================================
RCS file: /cvsroot/src/sys/arch/atari/dev/ser.c,v
retrieving revision 1.52
diff -u -u -r1.52 ser.c
--- arch/atari/dev/ser.c	24 Apr 2011 16:26:55 -0000	1.52
+++ arch/atari/dev/ser.c	11 Aug 2012 08:22:59 -0000
@@ -225,6 +225,7 @@
 static int	sertrintr(void *);
 static int	serparam(struct tty *, struct termios *);
 static void	serstart(struct tty *);
+static void	serflush(struct tty *);
 
 struct consdev;
 void	sercnprobe(struct consdev *);
@@ -402,6 +403,7 @@
 
 		/* Add some entry points needed by the tty layer. */
 		tp->t_oproc = serstart;
+		tp->t_flush = serflush;
 		tp->t_param = serparam;
 		tp->t_hwiflow = serhwiflow;
 		tp->t_dev = dev;
@@ -916,6 +918,16 @@
 }
 
 void
+serflush(struct tty *tp)
+{
+	struct ser_softc *sc =
+	    device_lookup_private(&ser_cd, SERUNIT(tp->t_dev));
+
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
+void
 serstart(struct tty *tp)
 {
 	struct ser_softc *sc =
Index: arch/atari/dev/zs.c
===================================================================
RCS file: /cvsroot/src/sys/arch/atari/dev/zs.c,v
retrieving revision 1.74
diff -u -u -r1.74 zs.c
--- arch/atari/dev/zs.c	30 Jun 2011 20:09:21 -0000	1.74
+++ arch/atari/dev/zs.c	11 Aug 2012 08:23:00 -0000
@@ -251,6 +251,7 @@
 
 /* Routines called from other code. */
 static void	zsstart(struct tty *);
+static void	zsflush(struct tty *);
 
 /* Routines purely local to this driver. */
 static void	zsoverrun(int, long *, const char *);
@@ -409,6 +410,7 @@
 		tty_attach(tp);
 		tp->t_dev   = dev;
 		tp->t_oproc = zsstart;
+		tp->t_flush = zsflush;
 		tp->t_param = zsparam;
 	}
 
@@ -961,6 +963,17 @@
 	return 0;
 }
 
+static void
+zsflush(struct tty *tp)
+{
+	int unit = ZS_UNIT(tp->t_dev);
+	struct zs_softc *sc = device_lookup_private(&zs_cd, unit >> 1);
+	struct zs_chanstate *cs = sc->sc_cs[unit & 1];
+
+	cs->cs_tba = tp->t_outq.c_cf;
+	cs->cs_tbc = ndqb(&tp->t_outq, 0);
+}
+
 /*
  * Start or restart transmission.
  */
Index: arch/evbarm/dev/plcom.c
===================================================================
RCS file: /cvsroot/src/sys/arch/evbarm/dev/plcom.c,v
retrieving revision 1.40
diff -u -u -r1.40 plcom.c
--- arch/evbarm/dev/plcom.c	25 Jul 2012 07:26:17 -0000	1.40
+++ arch/evbarm/dev/plcom.c	11 Aug 2012 08:23:06 -0000
@@ -153,6 +153,7 @@
 static	u_char	cflag2lcr (tcflag_t);
 int	plcomparam	(struct tty *, struct termios *);
 void	plcomstart	(struct tty *);
+void	plcomflush	(struct tty *);
 int	plcomhwiflow	(struct tty *, int);
 
 void	plcom_loadchannelregs (struct plcom_softc *);
@@ -505,6 +506,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = plcomstart;
+	tp->t_flush = plcomflush;
 	tp->t_param = plcomparam;
 	tp->t_hwiflow = plcomhwiflow;
 
@@ -1625,6 +1627,18 @@
 
 
 void
+plcomflush(struct tty *tp)
+{
+	struct plcom_softc *sc =
+		device_lookup_private(&plcom_cd, PLCOMUNIT(tp->t_dev));
+
+	if (PLCOM_ISALIVE(sc) == 0)
+		return;
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
+void
 plcomstart(struct tty *tp)
 {
 	struct plcom_softc *sc =
Index: arch/evbppc/virtex/dev/xlcom.c
===================================================================
RCS file: /cvsroot/src/sys/arch/evbppc/virtex/dev/xlcom.c,v
retrieving revision 1.9
diff -u -u -r1.9 xlcom.c
--- arch/evbppc/virtex/dev/xlcom.c	18 Jun 2011 06:44:27 -0000	1.9
+++ arch/evbppc/virtex/dev/xlcom.c	11 Aug 2012 08:23:08 -0000
@@ -147,6 +147,7 @@
 /* Terminal line. */
 static int 	xlcom_param(struct tty *, struct termios *);
 static void 	xlcom_start(struct tty *);
+static void 	xlcom_flush(struct tty *);
 
 /* Generic device. */
 static void 	xlcom_attach(device_t, device_t, void *);
@@ -222,6 +223,7 @@
 	tp = tty_alloc();
 	tp->t_dev = dev;
 	tp->t_oproc = xlcom_start;
+	tp->t_flush = xlcom_flush;
 	tp->t_param = xlcom_param;
 	tp->t_hwiflow = NULL; 				/* No HW flow control */
 	tty_attach(tp);
@@ -585,6 +587,17 @@
 }
 
 static void
+xlcom_flush(struct tty *tp)
+{
+	struct xlcom_softc 	*sc;
+	sc = device_lookup_private(&xlcom_cd, UNIT(tp->t_dev));
+	if (sc == NULL)
+		return;
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
+static void
 xlcom_start(struct tty *tp)
 {
 	struct xlcom_softc 	*sc;
Index: arch/hpcmips/tx/txcom.c
===================================================================
RCS file: /cvsroot/src/sys/arch/hpcmips/tx/txcom.c,v
retrieving revision 1.45
diff -u -u -r1.45 txcom.c
--- arch/hpcmips/tx/txcom.c	24 Apr 2011 16:26:56 -0000	1.45
+++ arch/hpcmips/tx/txcom.c	11 Aug 2012 08:23:13 -0000
@@ -135,6 +135,7 @@
 void	txcom_break(struct txcom_softc *, int);
 void	txcom_modem(struct txcom_softc *, int);
 void	txcomstart(struct tty *);
+void	txcomflush(struct tty *);
 int	txcomparam(struct tty *, struct termios *);
 
 void	txcom_reset	(struct txcom_chip *);
@@ -232,6 +233,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = txcomstart;
+	tp->t_flush = txcomflush;
 	tp->t_param = txcomparam;
 	tp->t_hwiflow = NULL;
 	sc->sc_tty = tp;
@@ -1017,6 +1019,15 @@
 }
 
 void
+txcomflush(struct tty *tp)
+{
+	struct txcom_softc *sc;
+	sc = device_lookup_private(&txcom_cd, minor(tp->t_dev));
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
+void
 txcomstart(struct tty *tp)
 {
 	struct txcom_softc *sc;
Index: arch/mips/sibyte/dev/sbjcn.c
===================================================================
RCS file: /cvsroot/src/sys/arch/mips/sibyte/dev/sbjcn.c,v
retrieving revision 1.28
diff -u -u -r1.28 sbjcn.c
--- arch/mips/sibyte/dev/sbjcn.c	10 Jul 2011 23:32:03 -0000	1.28
+++ arch/mips/sibyte/dev/sbjcn.c	11 Aug 2012 08:23:20 -0000
@@ -148,6 +148,7 @@
 static int cflag2modes(tcflag_t, u_char *, u_char *);
 int	sbjcn_param(struct tty *, struct termios *);
 void	sbjcn_start(struct tty *);
+void	sbjcn_flush(struct tty *);
 int	sbjcn_hwiflow(struct tty *, int);
 
 void	sbjcn_loadchannelregs(struct sbjcn_channel *);
@@ -308,6 +309,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = sbjcn_start;
+	tp->t_flush = sbjcn_flush;
 	tp->t_param = sbjcn_param;
 	tp->t_hwiflow = sbjcn_hwiflow;
 
@@ -1109,6 +1111,15 @@
 }
 
 void
+sbjcn_flush(struct tty *tp)
+{
+	struct sbjcn_softc *sc = device_lookup_private(&sbjcn_cd, SBJCN_UNIT(tp->t_dev));
+	struct sbjcn_channel *ch = &sc->sc_channels[SBJCN_CHAN(tp->t_dev)];
+	ch->ch_tba = tp->t_outq.c_cf;
+	ch->ch_tbc = ndqb(&tp->t_outq, 0);
+}
+
+void
 sbjcn_start(struct tty *tp)
 {
 	struct sbjcn_softc *sc = device_lookup_private(&sbjcn_cd, SBJCN_UNIT(tp->t_dev));
Index: arch/mips/sibyte/dev/sbscn.c
===================================================================
RCS file: /cvsroot/src/sys/arch/mips/sibyte/dev/sbscn.c,v
retrieving revision 1.37
diff -u -u -r1.37 sbscn.c
--- arch/mips/sibyte/dev/sbscn.c	2 Feb 2012 19:43:00 -0000	1.37
+++ arch/mips/sibyte/dev/sbscn.c	11 Aug 2012 08:23:23 -0000
@@ -157,6 +157,7 @@
 static int cflag2modes(tcflag_t, u_char *, u_char *);
 int	sbscn_param(struct tty *, struct termios *);
 void	sbscn_start(struct tty *);
+void	sbscn_flush(struct tty *);
 int	sbscn_hwiflow(struct tty *, int);
 
 void	sbscn_loadchannelregs(struct sbscn_channel *);
@@ -337,6 +338,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = sbscn_start;
+	tp->t_flush = sbscn_flush;
 	tp->t_param = sbscn_param;
 	tp->t_hwiflow = sbscn_hwiflow;
 
@@ -1216,6 +1218,15 @@
 }
 
 void
+sbscn_flush(struct tty *tp)
+{
+	struct sbscn_softc *sc = device_lookup_private(&sbscn_cd, SBSCN_UNIT(tp->t_dev));
+	struct sbscn_channel *ch = &sc->sc_channels[SBSCN_CHAN(tp->t_dev)];
+	ch->ch_tba = tp->t_outq.c_cf;
+	ch->ch_tbc = ndqb(&tp->t_outq, 0);
+}
+
+void
 sbscn_start(struct tty *tp)
 {
 	struct sbscn_softc *sc = device_lookup_private(&sbscn_cd, SBSCN_UNIT(tp->t_dev));
Index: arch/sh3/dev/sci.c
===================================================================
RCS file: /cvsroot/src/sys/arch/sh3/dev/sci.c,v
retrieving revision 1.54
diff -u -u -r1.54 sci.c
--- arch/sh3/dev/sci.c	2 Feb 2012 19:43:00 -0000	1.54
+++ arch/sh3/dev/sci.c	11 Aug 2012 08:23:28 -0000
@@ -120,6 +120,7 @@
 #include <sh3/exception.h>
 
 static void	scistart(struct tty *);
+static void	sciflush(struct tty *);
 static int	sciparam(struct tty *, struct termios *);
 
 void scicnprobe(struct consdev *);
@@ -404,6 +405,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = scistart;
+	tp->t_flush = sciflush;
 	tp->t_param = sciparam;
 	tp->t_hwiflow = NULL;
 
@@ -419,6 +421,14 @@
 	tty_attach(tp);
 }
 
+static void
+sciflush(struct tty *tp)
+{
+	struct sci_softc *sc = device_lookup_private(&sci_cd,SCIUNIT(tp->t_dev));
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
 /*
  * Start or restart transmission.
  */
Index: arch/sh3/dev/scif.c
===================================================================
RCS file: /cvsroot/src/sys/arch/sh3/dev/scif.c,v
retrieving revision 1.61
diff -u -u -r1.61 scif.c
--- arch/sh3/dev/scif.c	2 Feb 2012 19:43:00 -0000	1.61
+++ arch/sh3/dev/scif.c	11 Aug 2012 08:23:30 -0000
@@ -219,6 +219,7 @@
 
 /* struct tty */
 static void scifstart(struct tty *);
+static void scifflush(struct tty *);
 static int scifparam(struct tty *, struct termios *);
 
 
@@ -482,6 +483,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = scifstart;
+	tp->t_flush = scifflush;
 	tp->t_param = scifparam;
 	tp->t_hwiflow = NULL;
 
@@ -500,6 +502,17 @@
 		aprint_error_dev(self, "unable to establish power handler\n");
 }
 
+static void
+scifflush(struct tty *tp)
+{
+	struct scif_softc *sc;
+
+	sc = device_lookup_private(&scif_cd, SCIFUNIT(tp->t_dev));
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+
+}
+
 /*
  * Start or restart transmission.
  */
Index: arch/sparc64/dev/sab.c
===================================================================
RCS file: /cvsroot/src/sys/arch/sparc64/dev/sab.c,v
retrieving revision 1.48
diff -u -u -r1.48 sab.c
--- arch/sparc64/dev/sab.c	2 Jun 2011 00:24:23 -0000	1.48
+++ arch/sparc64/dev/sab.c	11 Aug 2012 08:23:31 -0000
@@ -141,6 +141,7 @@
 int sabtty_match(device_t, cfdata_t, void *);
 void sabtty_attach(device_t, device_t, void *);
 void sabtty_start(struct tty *);
+void sabtty_flush(struct tty *);
 int sabtty_param(struct tty *, struct termios *);
 int sabtty_intr(struct sabtty_softc *, int *);
 void sabtty_softintr(struct sabtty_softc *);
@@ -393,6 +394,7 @@
 		}
 		tty_attach(sc->sc_tty);
 		sc->sc_tty->t_oproc = sabtty_start;
+		sc->sc_tty->t_flush = sabtty_flush;
 		sc->sc_tty->t_param = sabtty_param;
 	}
 
@@ -1077,6 +1079,14 @@
 }
 
 void
+sabtty_flush(struct tty *tp)
+{
+	struct sabtty_softc *sc = device_lookup_private(&sabtty_cd, SABUNIT(tp->t_dev));
+	sc->sc_txc = ndqb(&tp->t_outq, 0);
+	sc->sc_txp = tp->t_outq.c_cf;
+}
+
+void
 sabtty_start(struct tty *tp)
 {
 	struct sabtty_softc *sc = device_lookup_private(&sabtty_cd, SABUNIT(tp->t_dev));
Index: dev/ic/cd18xx.c
===================================================================
RCS file: /cvsroot/src/sys/dev/ic/cd18xx.c,v
retrieving revision 1.28
diff -u -u -r1.28 cd18xx.c
--- dev/ic/cd18xx.c	24 Apr 2011 16:26:59 -0000	1.28
+++ dev/ic/cd18xx.c	11 Aug 2012 08:23:41 -0000
@@ -151,6 +151,7 @@
 
 static void	cdtty_shutdown(struct cd18xx_softc *, struct cdtty_port *);
 static void	cdttystart(struct tty *);
+static void	cdttyflush(struct tty *);
 static int	cdttyparam(struct tty *, struct termios *);
 static void	cdtty_break(struct cd18xx_softc *, struct cdtty_port *, int);
 static void	cdtty_modem(struct cd18xx_softc *, struct cdtty_port *, int);
@@ -330,6 +331,7 @@
 	/* get a tty structure */
 	p->p_tty = tty_alloc();
 	p->p_tty->t_oproc = cdttystart;
+	p->p_tty->t_flush = cdttyflush;
 	p->p_tty->t_param = cdttyparam;
 	p->p_tty->t_hwiflow = cdttyhwiflow;
 
@@ -634,6 +636,15 @@
 	return (0);
 }
 
+static void
+cdttyflush(struct tty *tp)
+{
+	struct cd18xx_softc *sc = device_lookup_private(&clcd_cd, CD18XX_INSTANCE(tp->t_dev));
+	struct cdtty_port *p = &sc->sc_ports[CD18XX_CHANNEL(tp->t_dev)];
+	p->p_tba = tp->t_outq.c_cf;
+	p->p_tbc = ndqb(&tp->t_outq, 0);
+}
+
 /*
  * Start or restart transmission.
  */
Index: dev/ic/clmpcc.c
===================================================================
RCS file: /cvsroot/src/sys/dev/ic/clmpcc.c,v
retrieving revision 1.45
diff -u -u -r1.45 clmpcc.c
--- dev/ic/clmpcc.c	1 Oct 2011 15:59:01 -0000	1.45
+++ dev/ic/clmpcc.c	11 Aug 2012 08:23:42 -0000
@@ -73,6 +73,7 @@
 static int	clmpcc_param(struct tty *, struct termios *);
 static void	clmpcc_set_params(struct clmpcc_chan *);
 static void	clmpcc_start(struct tty *);
+static void	clmpcc_flush(struct tty *);
 static int 	clmpcc_modem_control(struct clmpcc_chan *, int, int);
 
 #define	CLMPCCUNIT(x)		(minor(x) & 0x7fffc)
@@ -290,6 +291,7 @@
 
 		tp = tty_alloc();
 		tp->t_oproc = clmpcc_start;
+		tp->t_flush = clmpcc_flush;
 		tp->t_param = clmpcc_param;
 
 		ch->ch_tty = tp;
@@ -978,10 +980,21 @@
 }
 
 static void
+clmpcc_flush(struct tty *tp)
+{
+	struct clmpcc_softc *sc =
+	    device_lookup_private(&clmpcc_cd, CLMPCCUNIT(tp->t_dev));
+	struct clmpcc_chan *ch = &sc->sc_chans[CLMPCCCHAN(tp->t_dev)];
+	ch->ch_obuf_addr = tp->t_outq.c_cf;
+	ch->ch_obuf_size = ndqb(&tp->t_outq, 0);
+}
+
+static void
 clmpcc_start(struct tty *tp)
 {
 	struct clmpcc_softc *sc =
 	    device_lookup_private(&clmpcc_cd, CLMPCCUNIT(tp->t_dev));
+
 	struct clmpcc_chan *ch = &sc->sc_chans[CLMPCCCHAN(tp->t_dev)];
 	u_int oldch;
 	int s;
Index: dev/ic/com.c
===================================================================
RCS file: /cvsroot/src/sys/dev/ic/com.c,v
retrieving revision 1.306
diff -u -u -r1.306 com.c
--- dev/ic/com.c	21 May 2012 20:51:46 -0000	1.306
+++ dev/ic/com.c	11 Aug 2012 08:23:43 -0000
@@ -162,6 +162,7 @@
 static	u_char	cflag2lcr(tcflag_t);
 int	comparam(struct tty *, struct termios *);
 void	comstart(struct tty *);
+void	comflush(struct tty *);
 int	comhwiflow(struct tty *, int);
 
 void	com_loadchannelregs(struct com_softc *);
@@ -504,6 +505,7 @@
 
 	tp = tty_alloc();
 	tp->t_oproc = comstart;
+	tp->t_flush = comflush;
 	tp->t_param = comparam;
 	tp->t_hwiflow = comhwiflow;
 
@@ -1590,6 +1592,18 @@
 	CSR_WRITE_1(regsp, COM_REG_MCR, sc->sc_mcr_active);
 }
 
+void
+comflush(struct tty *tp)
+{
+	struct com_softc *sc =
+	    device_lookup_private(&com_cd, COMUNIT(tp->t_dev));
+
+	if (COM_ISALIVE(sc) == 0)
+		return;
+
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
 
 void
 comstart(struct tty *tp)
Index: dev/ic/z8530tty.c
===================================================================
RCS file: /cvsroot/src/sys/dev/ic/z8530tty.c,v
retrieving revision 1.128
diff -u -u -r1.128 z8530tty.c
--- dev/ic/z8530tty.c	24 Apr 2011 16:27:00 -0000	1.128
+++ dev/ic/z8530tty.c	11 Aug 2012 08:23:46 -0000
@@ -260,6 +260,7 @@
 
 static void zs_shutdown(struct zstty_softc *);
 static void	zsstart(struct tty *);
+static void	zsflush(struct tty *);
 static int	zsparam(struct tty *, struct termios *);
 static void zs_modem(struct zstty_softc *, int);
 static void tiocm_to_zs(struct zstty_softc *, u_long, int);
@@ -393,6 +394,7 @@
 	tp = tty_alloc();
 	tp->t_dev = dev;
 	tp->t_oproc = zsstart;
+	tp->t_flush = zsflush;
 	tp->t_param = zsparam;
 	tp->t_hwiflow = zshwiflow;
 	tty_attach(tp);
@@ -875,6 +877,15 @@
 	return (error);
 }
 
+static void
+zsflush(struct tty *tp)
+{
+	struct zstty_softc *zst =
+	    device_lookup_private(&zstty_cd, ZSUNIT(tp->t_dev));
+	zst->zst_tba = tp->t_outq.c_cf;
+	zst->zst_tbc = ndqb(&tp->t_outq, 0);
+}
+
 /*
  * Start or restart transmission.
  */
Index: dev/marvell/gtmpsc.c
===================================================================
RCS file: /cvsroot/src/sys/dev/marvell/gtmpsc.c,v
retrieving revision 1.43
diff -u -u -r1.43 gtmpsc.c
--- dev/marvell/gtmpsc.c	24 Apr 2011 16:27:00 -0000	1.43
+++ dev/marvell/gtmpsc.c	11 Aug 2012 08:23:47 -0000
@@ -116,6 +116,7 @@
 STATIC void gtmpsc_softintr(void *);
 
 STATIC void gtmpscstart(struct tty *);
+STATIC void gtmpscflush(struct tty *);
 STATIC int  gtmpscparam(struct tty *, struct termios *);
 
 STATIC void gtmpsc_shutdownhook(void *);
@@ -330,6 +331,7 @@
 
 	sc->sc_tty = tp = tty_alloc();
 	tp->t_oproc = gtmpscstart;
+	tp->t_flush = gtmpscflush;
 	tp->t_param = gtmpscparam;
 	tty_attach(tp);
 
@@ -749,6 +751,20 @@
 
 
 STATIC void
+gtmpscflush(struct tty *tp)
+{
+	struct gtmpsc_softc *sc;
+	unsigned int unit;
+
+	unit = GTMPSCUNIT(tp->t_dev);
+	sc = device_lookup_private(&gtmpsc_cd, unit);
+	if (sc == NULL)
+		return;
+	sc->sc_tba = tp->t_outq.c_cf;
+	sc->sc_tbc = ndqb(&tp->t_outq, 0);
+}
+
+STATIC void
 gtmpscstart(struct tty *tp)
 {
 	struct gtmpsc_softc *sc;
Index: dev/sbus/magma.c
===================================================================
RCS file: /cvsroot/src/sys/dev/sbus/magma.c,v
retrieving revision 1.55
diff -u -u -r1.55 magma.c
--- dev/sbus/magma.c	24 Apr 2011 16:27:01 -0000	1.55
+++ dev/sbus/magma.c	11 Aug 2012 08:23:53 -0000
@@ -811,6 +811,7 @@
  *	mttytty			return tty pointer for mtty
  *	mttystop		stop mtty device
  *	mtty_start		start mtty device
+ *	mtty_flush		reset output queue
  *	mtty_param		set mtty parameters
  *	mtty_modem_control	set modem control lines
  */
@@ -848,6 +849,7 @@
 		}
 		tty_attach(tp);
 		tp->t_oproc = mtty_start;
+		tp->t_flush = mtty_flush;
 		tp->t_param = mtty_param;
 
 		mp->mp_tty = tp;
@@ -1156,6 +1158,16 @@
 	splx(s);
 }
 
+void
+mtty_flush(struct tty *tp)
+{
+	struct mtty_softc *ms = device_lookup_private(&mtty_cd,
+						      MAGMA_CARD(tp->t_dev));
+	struct mtty_port *mp = &ms->ms_port[MAGMA_PORT(tp->t_dev)];
+	mp->mp_txc = ndqb(&tp->t_outq, 0);
+	mp->mp_txp = tp->t_outq.c_cf;
+}
+
 /*
  * Start output, after a stop.
  */
Index: dev/sbus/magmareg.h
===================================================================
RCS file: /cvsroot/src/sys/dev/sbus/magmareg.h,v
retrieving revision 1.16
diff -u -u -r1.16 magmareg.h
--- dev/sbus/magmareg.h	17 Sep 2009 16:28:12 -0000	1.16
+++ dev/sbus/magmareg.h	11 Aug 2012 08:23:54 -0000
@@ -212,6 +212,7 @@
 int mtty_modem_control(struct mtty_port *, int, int);
 int mtty_param(struct tty *, struct termios *);
 void mtty_start(struct tty *);
+void mtty_flush(struct tty *);
 
 int mbpp_match(device_t, cfdata_t, void *);
 void mbpp_attach(device_t, device_t, void *);
Index: dev/sbus/spif.c
===================================================================
RCS file: /cvsroot/src/sys/dev/sbus/spif.c,v
retrieving revision 1.28
diff -u -u -r1.28 spif.c
--- dev/sbus/spif.c	18 Jul 2011 00:58:52 -0000	1.28
+++ dev/sbus/spif.c	11 Aug 2012 08:23:55 -0000
@@ -294,6 +294,7 @@
 		tp = tty_alloc();
 
 		tp->t_oproc = stty_start;
+		tp->t_flush = stty_flush;
 		tp->t_param = stty_param;
 
 		sp->sp_tty = tp;
@@ -689,6 +690,16 @@
 }
 
 void
+stty_flush(struct tty *tp)
+{
+	struct stty_softc *stc = device_lookup_private(&stty_cd,
+						       SPIF_CARD(tp->t_dev));
+	struct stty_port *sp = &stc->sc_port[SPIF_PORT(tp->t_dev)];
+	sp->sp_txc = ndqb(&tp->t_outq, 0);
+	sp->sp_txp = tp->t_outq.c_cf;
+}
+
+void
 stty_start(struct tty *tp)
 {
 	struct stty_softc *stc = device_lookup_private(&stty_cd,
Index: dev/sbus/spifreg.h
===================================================================
RCS file: /cvsroot/src/sys/dev/sbus/spifreg.h,v
retrieving revision 1.4
diff -u -u -r1.4 spifreg.h
--- dev/sbus/spifreg.h	12 May 2009 14:43:59 -0000	1.4
+++ dev/sbus/spifreg.h	11 Aug 2012 08:23:55 -0000
@@ -408,6 +408,7 @@
 void	stty_write_ccr(struct spif_softc *, u_int8_t);
 int	stty_compute_baud(speed_t, int, u_int8_t *, u_int8_t *);
 void	stty_start(struct tty *);
+void	stty_flush(struct tty *);
 
 int	sbpp_match(device_t, cfdata_t, void *);
 void	sbpp_attach(device_t, device_t, void *);
Index: kern/tty.c
===================================================================
RCS file: /cvsroot/src/sys/kern/tty.c,v
retrieving revision 1.250
diff -u -u -r1.250 tty.c
--- kern/tty.c	12 Mar 2012 18:27:08 -0000	1.250
+++ kern/tty.c	11 Aug 2012 08:24:03 -0000
@@ -1349,8 +1349,11 @@
 		break;
 	case TIOCSQSIZE:
 		if ((error = tty_get_qsize(&s, *(int *)data)) == 0 &&
-		    s != tp->t_qsize)
+		    s != tp->t_qsize) {
 			tty_set_qsize(tp, s);
+			if (tp->t_flush)
+				(*tp->t_flush)(tp);
+		}
 		return error;
 	default:
 		/* We may have to load the compat module for this. */
Index: sys/tty.h
===================================================================
RCS file: /cvsroot/src/sys/sys/tty.h,v
retrieving revision 1.90
diff -u -u -r1.90 tty.h
--- sys/tty.h	24 Sep 2011 00:05:38 -0000	1.90
+++ sys/tty.h	11 Aug 2012 08:24:11 -0000
@@ -134,8 +134,8 @@
 	struct	termios t_termios;	/* Termios state. */
 	struct	winsize t_winsize;	/* Window size. */
 					/* Start output. */
-	void	(*t_oproc)(struct tty *);
-					/* Set hardware state. */
+	void	(*t_oproc)(struct tty *);/* Set hardware state. */
+	void	(*t_flush)(struct tty *);/* Reset output queue. */
 	int	(*t_param)(struct tty *, struct termios *);
 					/* Set hardware flow control. */
 	int	(*t_hwiflow)(struct tty *, int);