Add new boot flag to i386 boot: -p.

This flag adds a pausing utility. When ran with -p, during the kernel
probing phase, the kernel will pause after each line of output.
This pausing can be ended with the '.' key, and is automatically
suspended when entering ddb.

This flag comes in handy at systems without a serial port that either hang
during booting or reser.
Reviewed by:	(partly by jlemon)
MFC after:	1 week

sbin/reboot/boot_i386.8

@@ -223,6 +223,8 @@ probe the keyboard.  If no keyboard is found, the
 and
 .Fl h
 options are automatically set.
+.It Fl p
+pause after each attached device during the device probing phase.
 .It Fl r
 use the statically configured default for the device containing the
 root file system

sys/amd64/amd64/autoconf.c

@@ -176,7 +176,7 @@ configure_final(dummy)
 {
 	int i;
 
-/*	cninit_finish(); */
+	cninit_finish(); 
 
 	if (bootverbose) {
 

sys/boot/i386/libi386/bootinfo.c

@@ -100,6 +100,9 @@ bi_getboothowto(char *kargs)
 		case 'h':
 		    howto |= RB_SERIAL;
 		    break;
+		case 'p':
+		    howto |= RB_PAUSE;
+		    break;
 		case 'r':
 		    howto |= RB_DFLTROOT;
 		    break;

sys/boot/i386/libi386/bootinfo32.c

@@ -100,6 +100,9 @@ bi_getboothowto(char *kargs)
 		case 'h':
 		    howto |= RB_SERIAL;
 		    break;
+		case 'p':
+		    howto |= RB_PAUSE;
+		    break;
 		case 'r':
 		    howto |= RB_DFLTROOT;
 		    break;

sys/boot/i386/libi386/bootinfo64.c

@@ -100,6 +100,9 @@ bi_getboothowto(char *kargs)
 		case 'h':
 		    howto |= RB_SERIAL;
 		    break;
+		case 'p':
+		    howto |= RB_PAUSE;
+		    break;
 		case 'r':
 		    howto |= RB_DFLTROOT;
 		    break;

sys/i386/i386/autoconf.c

@@ -176,7 +176,7 @@ configure_final(dummy)
 {
 	int i;
 
-/*	cninit_finish(); */
+	cninit_finish(); 
 
 	if (bootverbose) {
 

sys/kern/tty_cons.c

@@ -55,6 +55,8 @@
 #include <sys/uio.h>
 #include <sys/vnode.h>
 
+#include <ddb/ddb.h>
+
 #include <machine/cpu.h>
 
 static	d_open_t	cnopen;
@@ -112,6 +114,9 @@ static int cn_mute;
 static int openflag;			/* how /dev/console was opened */
 static int cn_is_open;
 static dev_t cn_devfsdev;		/* represents the device private info */
+static u_char console_pausing;		/* pause after each line during probe */
+static char *console_pausestr=
+"<pause; press any key to proceed to next line or '.' to end pause mode>";
 
 void	cndebug(char *);
 
@@ -162,12 +167,20 @@ cninit(void)
 		cnadd(best_cn);
 		best_cn->cn_init(best_cn);
 	}
+	if (boothowto & RB_PAUSE)
+		console_pausing = 1;
 	/*
 	 * Make the best console the preferred console.
 	 */
 	cnselect(best_cn);
 }
 
+void
+cninit_finish()
+{
+	console_pausing = 0;
+} 
+
 /* add a new physical console to back the virtual console */
 int
 cnadd(struct consdev *cn)
@@ -526,6 +539,7 @@ cnputc(int c)
 {
 	struct cn_device *cnd;
 	struct consdev *cn;
+	char *cp;
 
 	if (cn_mute || c == '\0')
 		return;
@@ -535,6 +549,16 @@ cnputc(int c)
 			cn->cn_putc(cn->cn_dev, '\r');
 		cn->cn_putc(cn->cn_dev, c);
 	}
+	if (console_pausing && !db_active && (c == '\n')) {
+		for (cp = console_pausestr; *cp != '\0'; cp++)
+			cnputc(*cp);
+		if (cngetc() == '.')
+			console_pausing = 0;
+		cnputc('\r');
+		for (cp = console_pausestr; *cp != '\0'; cp++)
+			cnputc(' ');
+		cnputc('\r');
+	}
 }
 
 void

sys/sys/cons.h

@@ -88,6 +88,7 @@ extern int cons_unavail;
 
 /* Other kernel entry points. */
 void	cninit(void);
+void	cninit_finish(void);
 int	cnadd(struct consdev *);
 void	cnremove(struct consdev *);
 void	cnselect(struct consdev *);

sys/sys/reboot.h

@@ -61,6 +61,7 @@
 #define	RB_GDB		0x8000	/* use GDB remote debugger instead of DDB */
 #define	RB_MUTE		0x10000	/* Come up with the console muted */
 #define	RB_SELFTEST	0x20000	/* don't boot to normal operation, do selftest */
+#define	RB_PAUSE	0x40000 /* pause after each output line during probe */
 #define	RB_MULTIPLE	0x20000000	/* Use multiple consoles */
 
 #define	RB_BOOTINFO	0x80000000	/* have `struct bootinfo *' arg */