GC the cn_dbctl_t hook for consoles, it is unused.

This used to make syscons switch to vty0 when we entered DDB but this
was lost in the KDB shuffle.  We may want to bring it back down the road
but it should be done by calling cn_init_t/cn_term_t instead, possibly
with a flag argument saying "Debugger!"

sys/dev/syscons/syscons.c

@@ -222,11 +222,10 @@ static cn_init_t	sccninit;
 static cn_getc_t	sccngetc;
 static cn_checkc_t	sccncheckc;
 static cn_putc_t	sccnputc;
-static cn_dbctl_t	sccndbctl;
 static cn_term_t	sccnterm;
 
 CONS_DRIVER(sc, sccnprobe, sccninit, sccnterm, sccngetc, sccncheckc, sccnputc,
-	    sccndbctl);
+	    NULL);
 
 static	d_open_t	scopen;
 static	d_close_t	scclose;
@@ -1511,37 +1510,6 @@ sccncheckc(struct consdev *cd)
     return sccngetch(SCGETC_NONBLOCK);
 }
 
-static void
-sccndbctl(struct consdev *cd, int on)
-{
-    /* assert(sc_console_unit >= 0) */
-    /* try to switch to the kernel console screen */
-    if (on && debugger == 0) {
-	/*
-	 * TRY to make sure the screen saver is stopped, 
-	 * and the screen is updated before switching to 
-	 * the vty0.
-	 */
-	scrn_timer(NULL);
-	if (!cold
-	    && sc_console->sc->cur_scp->smode.mode == VT_AUTO
-	    && sc_console->smode.mode == VT_AUTO) {
-	    sc_console->sc->cur_scp->status |= MOUSE_HIDDEN;
-	    ++debugger;		/* XXX */
-#ifdef DDB
-	    /* unlock vty switching */
-	    sc_console->sc->flags &= ~SC_SCRN_VTYLOCK;
-#endif
-	    sc_switch_scr(sc_console->sc, sc_console->index);
-	    --debugger;		/* XXX */
-	}
-    }
-    if (on)
-	++debugger;
-    else
-	--debugger;
-}
-
 static int
 sccngetch(int flags)
 {

sys/dev/zs/zs.c

@@ -131,7 +131,6 @@ static cn_term_t zs_cnterm;
 static cn_getc_t zs_cngetc;
 static cn_checkc_t zs_cncheckc;
 static cn_putc_t zs_cnputc;
-static cn_dbctl_t zs_cndbctl;
 
 static int zstty_cngetc(struct zstty_softc *sc);
 static int zstty_cncheckc(struct zstty_softc *sc);
@@ -157,7 +156,7 @@ static struct cdevsw zstty_cdevsw = {
 static struct zstty_softc *zstty_cons;
 
 CONS_DRIVER(zs, zs_cnprobe, zs_cninit, zs_cnterm, zs_cngetc, zs_cncheckc,
-    zs_cnputc, zs_cndbctl);
+    zs_cnputc, NULL);
 
 int
 zs_probe(device_t dev)
@@ -859,11 +858,6 @@ zs_cnputc(struct consdev *cn, int c)
 	zstty_cnputc(sc, c);
 }
 
-static void
-zs_cndbctl(struct consdev *cn, int c)
-{
-}
-
 static void
 zstty_cnopen(struct zstty_softc *sc)
 {

sys/kern/tty_cons.c

@@ -635,25 +635,6 @@ cnputc(int c)
 	}
 }
 
-void
-cndbctl(int on)
-{
-	struct cn_device *cnd;
-	struct consdev *cn;
-	static int refcount;
-
-	if (!on)
-		refcount--;
-	if (refcount == 0)
-		STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
-			cn = cnd->cnd_cn;
-			if (cn->cn_dbctl != NULL)
-				cn->cn_dbctl(cn, on);
-		}
-	if (on)
-		refcount++;
-}
-
 static int consmsgbuf_size = 8192;
 SYSCTL_INT(_kern, OID_AUTO, consmsgbuf_size, CTLFLAG_RW, &consmsgbuf_size, 0,
     "");

sys/sys/cons.h

@@ -45,7 +45,6 @@ typedef	void	cn_term_t(struct consdev *);
 typedef	int	cn_getc_t(struct consdev *);
 typedef	int	cn_checkc_t(struct consdev *);
 typedef	void	cn_putc_t(struct consdev *, int);
-typedef	void	cn_dbctl_t(struct consdev *, int);
 
 struct consdev {
 	cn_probe_t	*cn_probe;
@@ -60,8 +59,6 @@ struct consdev {
 				/* kernel "return char if available" interface */
 	cn_putc_t	*cn_putc;
 				/* kernel putchar interface */
-	cn_dbctl_t	*cn_dbctl;
-				/* debugger control interface */
 	struct	tty *cn_tp;	/* tty structure for console device */
 	short	cn_pri;		/* pecking order; the higher the better */
 	void	*cn_arg;	/* drivers method argument */
@@ -85,7 +82,7 @@ struct consdev {
 
 #define CONS_DRIVER(name, probe, init, term, getc, checkc, putc, dbctl)	\
 	static struct consdev name##_consdev = {			\
-		probe, init, term, getc, checkc, putc, dbctl		\
+		probe, init, term, getc, checkc, putc			\
 	};								\
 	DATA_SET(cons_set, name##_consdev)
 
@@ -98,7 +95,6 @@ void	cnremove(struct consdev *);
 void	cnselect(struct consdev *);
 int	cncheckc(void);
 int	cngetc(void);
-void	cndbctl(int);
 void	cnputc(int);
 int	cnunavailable(void);