Add a new mechanism, cndbctl(), to tell the console driver that

ddb is entered.  Don't refer to `in_Debugger' to see if we
are in the debugger.  (The variable used to be static in Debugger()
and wasn't updated if ddb is entered via traps and panic anyway.)

- Don't refer to `in_Debugger'.
- Add `db_active' to i386/i386/db_interface.d (as in
  alpha/alpha/db_interface.c).
- Remove cnpollc() stub from ddb/db_input.c.
- Add the dbctl function to syscons, pcvt, and sio. (The function for
  pcvt and sio is noop at the moment.)

Jointly developed by: bde and me

(The final version was tweaked by me and not reviewed by bde.  Thus,
if there is any error in this commit, that is entirely of mine, not
his.)

Some changes were obtained from: NetBSD

sys/alpha/alpha/db_interface.c

@@ -1,4 +1,5 @@
 /* $NetBSD: db_interface.c,v 1.2 1997/09/16 19:07:19 thorpej Exp $ */
+/* $FreeBSD$ */
 
 /* 
  * Mach Operating System
@@ -83,7 +84,7 @@ extern char *trap_type[];
 extern int trap_types;
 #endif
 
-int	db_active = 0;
+int	db_active;
 
 void	ddbprinttrap __P((unsigned long, unsigned long, unsigned long,
 	    unsigned long));
@@ -188,14 +189,14 @@ kdb_trap(a0, a1, a2, entry, regs)
 	s = splhigh();
 
 	db_active++;
-	cnpollc(TRUE);		/* Set polling mode, unblank video */
 
-	if (ddb_mode)
+	if (ddb_mode) {
+	    cndbctl(TRUE);	/* DDB active, unblank video */
 	    db_trap(entry, a0);	/* Where the work happens */
-	else
+	    cndbctl(FALSE);	/* DDB inactive */
+	} else
 	    gdb_handle_exception(&ddb_regs, entry, a0);
 
-	cnpollc(FALSE);		/* Resume interrupt mode */
 	db_active--;
 
 	splx(s);

sys/amd64/amd64/db_interface.c

@@ -52,6 +52,7 @@ extern jmp_buf	db_jmpbuf;
 
 extern void	gdb_handle_exception __P((db_regs_t *, int, int));
 
+int	db_active;
 db_regs_t ddb_regs;
 
 static jmp_buf	db_global_jmpbuf;
@@ -132,8 +133,6 @@ kdb_trap(type, code, regs)
 	    ddb_regs.tf_ss = rss();
 	}
 
-	cnpollc(TRUE);
-
 #ifdef SMP
 #ifdef CPUSTOP_ON_DDBBREAK
 
@@ -153,10 +152,14 @@ kdb_trap(type, code, regs)
 
 	(void) setjmp(db_global_jmpbuf);
 	db_global_jmpbuf_valid = TRUE;
-	if (ddb_mode)
+	db_active++;
+	if (ddb_mode) {
+	    cndbctl(TRUE);
 	    db_trap(type, code);
-	else
+	    cndbctl(FALSE);
+	} else
 	    gdb_handle_exception(&ddb_regs, type, code);
+	db_active--;
 	db_global_jmpbuf_valid = FALSE;
 
 #ifdef SMP
@@ -181,8 +184,6 @@ kdb_trap(type, code, regs)
 #endif /* CPUSTOP_ON_DDBBREAK */
 #endif /* SMP */
 
-	cnpollc(FALSE);
-
 	regs->tf_eip    = ddb_regs.tf_eip;
 	regs->tf_eflags = ddb_regs.tf_eflags;
 	regs->tf_eax    = ddb_regs.tf_eax;
@@ -296,12 +297,11 @@ db_write_bytes(addr, size, data)
  * Move this to machdep.c and allow it to be called if any debugger is
  * installed.
  */
-volatile int in_Debugger = 0;
-
 void
 Debugger(msg)
 	const char *msg;
 {
+	static volatile u_char in_Debugger;
 
 	/*
 	 * XXX

sys/amd64/amd64/trap.c

@@ -90,9 +90,7 @@
 
 #include <machine/vm86.h>
 
-#ifdef DDB
-	extern int in_Debugger, debugger_on_panic;
-#endif
+#include <ddb/ddb.h>
 
 #include "isa.h"
 #include "npx.h"
@@ -900,7 +898,7 @@ trap_fatal(frame, eva)
 		return;
 #endif
 #ifdef DDB
-	if ((debugger_on_panic || in_Debugger) && kdb_trap(type, 0, frame))
+	if ((debugger_on_panic || db_active) && kdb_trap(type, 0, frame))
 		return;
 #endif
 	printf("trap number		= %d\n", type);

sys/ddb/db_input.c

@@ -361,10 +361,3 @@ db_check_interrupt()
 		break;
 	}
 }
-
-/* called from kdb_trap in db_interface.c */
-void
-cnpollc (flag)
-	int flag;
-{
-}

sys/ddb/ddb.h

@@ -67,9 +67,11 @@ func_name(addr, have_addr, count, modif)			\
 
 extern char *esym;
 extern db_expr_t db_maxoff;
+extern int db_active;
 extern int db_indent;
 extern int db_inst_count;
 extern int db_load_count;
+extern int debugger_on_panic;
 extern int db_store_count;
 extern db_expr_t db_radix;
 extern db_expr_t db_max_width;
@@ -77,7 +79,6 @@ extern db_expr_t db_tab_stop_width;
 
 struct vm_map;
 
-void		cnpollc __P((int));
 void		db_check_interrupt __P((void));
 void		db_clear_watchpoints __P((void));
 db_addr_t	db_disasm __P((db_addr_t loc, boolean_t altfmt));

sys/dev/sio/sio.c

@@ -2682,8 +2682,8 @@ static cn_getc_t siocngetc;
 static cn_putc_t siocnputc;
 
 #ifdef __i386__
-CONS_DRIVER(sio, siocnprobe, siocninit, NULL, siocngetc, siocncheckc, siocnputc);
-
+CONS_DRIVER(sio, siocnprobe, siocninit, NULL, siocngetc, siocncheckc,
+	    siocnputc, NULL);
 #endif
 
 /* To get the GDB related variables */

sys/dev/syscons/syscons.c

@@ -124,15 +124,7 @@ SYSCTL_INT(_machdep, OID_AUTO, enable_panic_key, CTLFLAG_RW, &enable_panic_key,
 
 #define VIRTUAL_TTY(sc, x) (SC_DEV((sc), (x))->si_tty)
 
-#define debugger	FALSE
-
-#ifdef __i386__
-#ifdef DDB
-extern int		in_Debugger;
-#undef debugger
-#define debugger	in_Debugger
-#endif /* DDB */
-#endif /* __i386__ */
+static	int		debugger;
 
 /* prototypes */
 static int scvidprobe(int unit, int flags, int cons);
@@ -199,13 +191,15 @@ 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;
 
 #if __alpha__
 void sccnattach(void);
 #endif
 
-CONS_DRIVER(sc, sccnprobe, sccninit, sccnterm, sccngetc, sccncheckc, sccnputc);
+CONS_DRIVER(sc, sccnprobe, sccninit, sccnterm, sccngetc, sccncheckc, sccnputc,
+	    sccndbctl);
 
 static	d_open_t	scopen;
 static	d_close_t	scclose;
@@ -1474,6 +1468,28 @@ sccncheckc(dev_t dev)
     return sccngetch(SCGETC_NONBLOCK);
 }
 
+static void
+sccndbctl(dev_t dev, int on)
+{
+    /* 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)
+	    switch_scr(sc_console->sc, sc_console->index);
+    }
+    if (on)
+	++debugger;
+    else
+	--debugger;
+}
+
 static int
 sccngetch(int flags)
 {
@@ -1553,7 +1569,7 @@ sccnupdate(scr_stat *scp)
     if (scp->sc->font_loading_in_progress || scp->sc->videoio_in_progress)
 	return;
 
-    if (debugger || panicstr || shutdown_in_progress) {
+    if (debugger > 0 || panicstr || shutdown_in_progress) {
 	sc_touch_scrn_saver();
     } else if (scp != scp->sc->cur_scp) {
 	return;
@@ -1626,7 +1642,7 @@ scrn_timer(void *arg)
 
     /* should we stop the screen saver? */
     getmicrouptime(&tv);
-    if (debugger || panicstr || shutdown_in_progress)
+    if (debugger > 0 || panicstr || shutdown_in_progress)
 	sc_touch_scrn_saver();
     if (run_scrn_saver) {
 	if (tv.tv_sec > sc->scrn_time_stamp + scrn_blank_time)
@@ -3720,21 +3736,6 @@ scgetc(sc_softc_t *sc, u_int flags)
 	    case DBG:
 #ifndef SC_DISABLE_DDBKEY
 #ifdef DDB
-		if (debugger)
-		    break;
-		/* try to switch to the kernel console screen */
-		if (sc_console) {
-		    /*
-		     * 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)
-			switch_scr(sc_console->sc, sc_console->index);
-		}
 		Debugger("manual escape to debugger");
 #else
 		printf("No debugger in kernel\n");

sys/i386/i386/db_interface.c

@@ -52,6 +52,7 @@ extern jmp_buf	db_jmpbuf;
 
 extern void	gdb_handle_exception __P((db_regs_t *, int, int));
 
+int	db_active;
 db_regs_t ddb_regs;
 
 static jmp_buf	db_global_jmpbuf;
@@ -132,8 +133,6 @@ kdb_trap(type, code, regs)
 	    ddb_regs.tf_ss = rss();
 	}
 
-	cnpollc(TRUE);
-
 #ifdef SMP
 #ifdef CPUSTOP_ON_DDBBREAK
 
@@ -153,10 +152,14 @@ kdb_trap(type, code, regs)
 
 	(void) setjmp(db_global_jmpbuf);
 	db_global_jmpbuf_valid = TRUE;
-	if (ddb_mode)
+	db_active++;
+	if (ddb_mode) {
+	    cndbctl(TRUE);
 	    db_trap(type, code);
-	else
+	    cndbctl(FALSE);
+	} else
 	    gdb_handle_exception(&ddb_regs, type, code);
+	db_active--;
 	db_global_jmpbuf_valid = FALSE;
 
 #ifdef SMP
@@ -181,8 +184,6 @@ kdb_trap(type, code, regs)
 #endif /* CPUSTOP_ON_DDBBREAK */
 #endif /* SMP */
 
-	cnpollc(FALSE);
-
 	regs->tf_eip    = ddb_regs.tf_eip;
 	regs->tf_eflags = ddb_regs.tf_eflags;
 	regs->tf_eax    = ddb_regs.tf_eax;
@@ -296,12 +297,11 @@ db_write_bytes(addr, size, data)
  * Move this to machdep.c and allow it to be called if any debugger is
  * installed.
  */
-volatile int in_Debugger = 0;
-
 void
 Debugger(msg)
 	const char *msg;
 {
+	static volatile u_char in_Debugger;
 
 	/*
 	 * XXX

sys/i386/i386/trap.c

@@ -90,9 +90,7 @@
 
 #include <machine/vm86.h>
 
-#ifdef DDB
-	extern int in_Debugger, debugger_on_panic;
-#endif
+#include <ddb/ddb.h>
 
 #include "isa.h"
 #include "npx.h"
@@ -900,7 +898,7 @@ trap_fatal(frame, eva)
 		return;
 #endif
 #ifdef DDB
-	if ((debugger_on_panic || in_Debugger) && kdb_trap(type, 0, frame))
+	if ((debugger_on_panic || db_active) && kdb_trap(type, 0, frame))
 		return;
 #endif
 	printf("trap number		= %d\n", type);

sys/i386/isa/pcvt/pcvt_drv.c

@@ -92,7 +92,8 @@ static cn_getc_t	pccngetc;
 static cn_checkc_t	pccncheckc;
 static cn_putc_t	pccnputc;
 
-CONS_DRIVER(pc, pccnprobe, pccninit, pccnterm, pccngetc, pccncheckc, pccnputc);
+CONS_DRIVER(pc, pccnprobe, pccninit, pccnterm, pccngetc, pccncheckc, pccnputc,
+	    NULL);
 
 static	d_open_t	pcopen;
 static	d_close_t	pcclose;

sys/isa/sio.c

@@ -2682,8 +2682,8 @@ static cn_getc_t siocngetc;
 static cn_putc_t siocnputc;
 
 #ifdef __i386__
-CONS_DRIVER(sio, siocnprobe, siocninit, NULL, siocngetc, siocncheckc, siocnputc);
-
+CONS_DRIVER(sio, siocnprobe, siocninit, NULL, siocngetc, siocncheckc,
+	    siocnputc, NULL);
 #endif
 
 /* To get the GDB related variables */

sys/kern/subr_trap.c

@@ -90,9 +90,7 @@
 
 #include <machine/vm86.h>
 
-#ifdef DDB
-	extern int in_Debugger, debugger_on_panic;
-#endif
+#include <ddb/ddb.h>
 
 #include "isa.h"
 #include "npx.h"
@@ -900,7 +898,7 @@ trap_fatal(frame, eva)
 		return;
 #endif
 #ifdef DDB
-	if ((debugger_on_panic || in_Debugger) && kdb_trap(type, 0, frame))
+	if ((debugger_on_panic || db_active) && kdb_trap(type, 0, frame))
 		return;
 #endif
 	printf("trap number		= %d\n", type);

sys/kern/tty_cons.c

@@ -97,7 +97,7 @@ static d_open_t *cn_phys_open;		/* physical device open function */
 struct consdev *cn_tab;			/* physical console device info */
 static dev_t condev_t;			/* represents the device private info */
 
-CONS_DRIVER(cons, NULL, NULL, NULL, NULL, NULL, NULL);
+CONS_DRIVER(cons, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
 
 void
 cninit()
@@ -423,6 +423,22 @@ cnputc(c)
 	}
 }
 
+void
+cndbctl(on)
+	int on;
+{
+	static int refcount;
+
+	if (cn_tab == NULL)
+		return;
+	if (!on)
+		refcount--;
+	if (refcount == 0 && cn_tab->cn_dbctl != NULL)
+		(*cn_tab->cn_dbctl)(cn_tab->cn_dev, on);
+	if (on)
+		refcount++;
+}
+
 static void
 cn_drvinit(void *unused)
 {

sys/sys/cons.h

@@ -49,6 +49,7 @@ typedef	void	cn_term_t __P((struct consdev *));
 typedef	int	cn_getc_t __P((dev_t));
 typedef	int	cn_checkc_t __P((dev_t));
 typedef	void	cn_putc_t __P((dev_t, int));
+typedef	void	cn_dbctl_t __P((dev_t, int));
 
 struct consdev {
 	cn_probe_t	*cn_probe;
@@ -63,6 +64,8 @@ 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 */
 	dev_t	cn_dev;		/* major/minor of device */
 	short	cn_pri;		/* pecking order; the higher the better */
@@ -79,9 +82,9 @@ extern	struct linker_set cons_set;
 extern	int cons_unavail;
 extern	struct consdev *cn_tab;
 
-#define CONS_DRIVER(name, probe, init, term, getc, checkc, putc)	\
+#define CONS_DRIVER(name, probe, init, term, getc, checkc, putc, dbctl)	\
 	static struct consdev name##_consdev = {			\
-		probe, init, term, getc, checkc, putc			\
+		probe, init, term, getc, checkc, putc, dbctl		\
 	};								\
 	DATA_SET(cons_set, name##_consdev)
 
@@ -90,6 +93,7 @@ int	cncheckc __P((void));
 int	cngetc __P((void));
 void	cninit __P((void));
 void	cninit_finish __P((void));
+void	cndbctl __P((int));
 void	cnputc __P((int));
 
 #endif /* _KERNEL */