Index: sys/boot/i386/boot2/boot2.c
===================================================================
--- sys/boot/i386/boot2/boot2.c	(revision 241434)
+++ sys/boot/i386/boot2/boot2.c	(working copy)
@@ -415,8 +415,10 @@ parse()
 	    }
 	    ioctrl = OPT_CHECK(RBX_DUAL) ? (IO_SERIAL|IO_KEYBOARD) :
 		     OPT_CHECK(RBX_SERIAL) ? IO_SERIAL : IO_KEYBOARD;
-	    if (ioctrl & IO_SERIAL)
-	        sio_init(115200 / comspeed);
+	    if (ioctrl & IO_SERIAL) {
+		if (sio_init(115200 / comspeed))
+			ioctrl &= ~IO_SERIAL;
+	    }
 	} else {
 	    for (q = arg--; *q && *q != '('; q++);
 	    if (*q) {
Index: sys/boot/i386/boot2/lib.h
===================================================================
--- sys/boot/i386/boot2/lib.h	(revision 241434)
+++ sys/boot/i386/boot2/lib.h	(working copy)
@@ -17,7 +17,7 @@
  * $FreeBSD$
  */
 
-void sio_init(int) __attribute__((regparm (3)));
+int sio_init(int) __attribute__((regparm (3)));
 void sio_flush(void);
 void sio_putc(int) __attribute__((regparm (3)));
 int sio_getc(void);
Index: sys/boot/i386/boot2/sio.S
===================================================================
--- sys/boot/i386/boot2/sio.S	(revision 241434)
+++ sys/boot/i386/boot2/sio.S	(working copy)
@@ -24,12 +24,15 @@
 		.globl sio_getc
 		.globl sio_ischar
 
-/* void sio_init(int div) */
+/* int sio_init(int div) */
 
 sio_init:	pushl %eax
 		movw $SIO_PRT+0x3,%dx		# Data format reg
 		movb $SIO_FMT|0x80,%al		# Set format
 		outb %al,(%dx)			#  and DLAB
+		inb (%dx),%al
+		cmpb $SIO_FMT|0x80,%al
+		jnz sio_init.1
 		subb $0x3,%dl			# Divisor latch reg
 		popl %eax
 		outw %ax,(%dx)			#  BPS
@@ -41,8 +44,13 @@ sio_init:	pushl %eax
 		outb %al,(%dx)			#  DTR
 		incl %edx			# Line status reg
 		call sio_flush
+		xor %eax,%eax
 		ret
+sio_init.1:	popl %eax
+		movb $0x1,%al
+		ret
 
+
 /* void sio_flush(void) */
 
 sio_flush.0:	call sio_getc.1 		# Get character
Index: sys/boot/i386/libi386/comconsole.c
===================================================================
--- sys/boot/i386/libi386/comconsole.c	(revision 241434)
+++ sys/boot/i386/libi386/comconsole.c	(working copy)
@@ -33,7 +33,7 @@ __FBSDID("$FreeBSD$");
 #include "libi386.h"
 
 #define COMC_FMT	0x3		/* 8N1 */
-#define COMC_TXWAIT	0x40000		/* transmit timeout */
+#define COMC_TXWAIT	0x80		/* transmit timeout */
 #define COMC_BPS(x)	(115200 / (x))	/* speed to DLAB divisor */
 #define COMC_DIV2BPS(x)	(115200 / (x))	/* DLAB divisor to speed */
 
@@ -57,6 +57,7 @@ static int	comc_speed_set(struct env_var *ev, int
 
 static int	comc_started;
 static int	comc_curspeed;
+static int	comc_disabled;
 
 struct console comconsole = {
     "comconsole",
@@ -76,9 +77,12 @@ comc_probe(struct console *cp)
     char *cons, *speedenv;
     int speed;
 
-    /* XXX check the BIOS equipment list? */
-    cp->c_flags |= (C_PRESENTIN | C_PRESENTOUT);
+    u_char	dlbh;
+    u_char	dlbl;
+    u_char	cfcr;
 
+    comc_disabled = 0;
+
     if (comc_curspeed == 0) {
 	comc_curspeed = COMSPEED;
 	/*
@@ -102,6 +106,22 @@ comc_probe(struct console *cp)
 	env_setenv("comconsole_speed", EV_VOLATILE, speedbuf, comc_speed_set,
 	    env_nounset);
     }
+
+    cfcr = inb(COMPORT + com_cfcr);
+    outb(COMPORT + com_cfcr, CFCR_DLAB | cfcr);
+
+    dlbl = inb(COMPORT + com_dlbl);
+    dlbh = inb(COMPORT + com_dlbh);
+
+    outb(COMPORT + com_cfcr, cfcr);
+
+    if (dlbl == 0xff && dlbh == 0xff && cfcr == 0xff) {
+	cp->c_flags &= ~(C_PRESENTIN | C_PRESENTOUT);
+	comc_disabled = 1;
+	return;
+    }
+
+    cp->c_flags |= (C_PRESENTIN | C_PRESENTOUT);
 }
 
 static int
@@ -121,6 +141,9 @@ comc_putchar(int c)
 {
     int wait;
 
+    if (comc_disabled)
+        return;
+
     for (wait = COMC_TXWAIT; wait > 0; wait--)
         if (inb(COMPORT + com_lsr) & LSR_TXRDY) {
 	    outb(COMPORT + com_data, (u_char)c);
@@ -131,6 +154,10 @@ comc_putchar(int c)
 static int
 comc_getchar(void)
 {
+
+    if (comc_disabled)
+        return -1;
+
     return(comc_ischar() ? inb(COMPORT + com_data) : -1);
 }
 
@@ -161,6 +188,7 @@ comc_speed_set(struct env_var *ev, int flags, cons
 static void
 comc_setup(int speed)
 {
+    int retry = 0x80;
 
     comc_curspeed = speed;
 
@@ -172,7 +200,7 @@ comc_setup(int speed)
 
     do
         inb(COMPORT + com_data);
-    while (inb(COMPORT + com_lsr) & LSR_RXRDY);
+    while (inb(COMPORT + com_lsr) & LSR_RXRDY && (--retry > 0));
 }
 
 static int