Index: boot/i386/cdboot/cdboot.S
===================================================================
RCS file: /home/source/dragonfly/cvs/src/sys/boot/i386/cdboot/cdboot.S,v
retrieving revision 1.7
diff -u -p -r1.7 cdboot.S
--- boot/i386/cdboot/cdboot.S	13 Jan 2006 19:41:50 -0000	1.7
+++ boot/i386/cdboot/cdboot.S	27 Feb 2007 23:57:54 -0000
@@ -461,10 +461,17 @@ twiddle:	push %ax			# Save
 		ret
 
 		/*
-		 * Enable A20
+		 * Enable A20. Put upper limit on amount of time we wait for the
+		 * keyboard controller to get ready (65K x ISA access time). If
+		 * we wait more than that amount it's likely that the hardware
+		 * is legacy-free and simply doesn't have keyboard controller
+		 * and don't need enabling A20 at all.
 		 */
 seta20: 	cli				# Disable interrupts
-seta20.1:	in $0x64,%al			# Get status
+		xor %cx,%cx			# Clear
+seta20.1:	inc %cx				# Increment, overflow?
+		jz seta20.3			# Yes
+		in $0x64,%al			# Get status
 		test $0x2,%al			# Busy?
 		jnz seta20.1			# Yes
 		mov $0xd1,%al			# Command: Write
@@ -474,7 +481,7 @@ seta20.2:	in $0x64,%al			# Get status
 		jnz seta20.2			# Yes
 		mov $0xdf,%al			# Enable
 		out %al,$0x60			#  A20
-		sti				# Enable interrupts
+seta20.3:	sti				# Enable interrupts
 		ret				# To caller
 
 		/*
Index: boot/i386/pxeldr/pxeldr.S
===================================================================
RCS file: /home/source/dragonfly/cvs/src/sys/boot/i386/pxeldr/pxeldr.S,v
retrieving revision 1.4
diff -u -p -r1.4 pxeldr.S
--- boot/i386/pxeldr/pxeldr.S	18 Jul 2004 23:40:09 -0000	1.4
+++ boot/i386/pxeldr/pxeldr.S	28 Feb 2007 14:26:15 -0000
@@ -234,10 +234,17 @@ putc:		movw $0x7,%bx			# attribute for o
 		jmp putstr			# keep looping
 
 		/*
-		 * Enable A20
+		 * Enable A20. Put upper limit on amount of time we wait for the
+		 * keyboard controller to get ready (65K x ISA access time). If
+		 * we wait more than that amount it's likely that the hardware
+		 * is legacy-free and simply doesn't have keyboard controller
+		 * and don't need enabling A20 at all.
 		 */
 seta20: 	cli				# Disable interrupts
-seta20.1:	inb $0x64,%al			# Get status
+		xor %cx,%cx			# Clear
+seta20.1:	inc %cx				# Increment, overflow?
+		jz seta20.3			# Yes
+		inb $0x64,%al			# Get status
 		testb $0x2,%al			# Busy?
 		jnz seta20.1			# Yes
 		movb $0xd1,%al			# Command: Write
@@ -247,7 +254,7 @@ seta20.2:	inb $0x64,%al			# Get status
 		jnz seta20.2			# Yes
 		movb $0xdf,%al			# Enable
 		outb %al,$0x60			#  A20
-		sti				# Enable interrupts
+seta20.3:	sti				# Enable interrupts
 		retw				# To caller
 
 		/*
Index: dev/misc/atkbdc_layer/atkbdc_isa.c
===================================================================
RCS file: /home/source/dragonfly/cvs/src/sys/dev/misc/atkbdc_layer/atkbdc_isa.c,v
retrieving revision 1.7
diff -u -p -r1.7 atkbdc_isa.c
--- dev/misc/atkbdc_layer/atkbdc_isa.c	22 Dec 2006 23:26:17 -0000	1.7
+++ dev/misc/atkbdc_layer/atkbdc_isa.c	28 Feb 2007 12:30:00 -0000
@@ -101,6 +101,12 @@ atkbdc_probe(device_t dev)
 	struct resource	*port1;
 	int		error;
 	int		rid;
+#if defined(__i386__)
+	bus_space_tag_t	tag;
+	bus_space_handle_t ioh1;
+	volatile int	i;
+	register_t	flags;
+#endif
 
 	/* check PnP IDs */
 	if (ISA_PNP_PROBE(device_get_parent(dev), dev, atkbdc_ids) == ENXIO)
@@ -126,6 +132,30 @@ atkbdc_probe(device_t dev)
 		return ENXIO;
 	}
 
+#if defined(__i386__)
+	/*
+	 * Check if we really have AT keyboard controller. Poll status
+	 * register until we get "all clear" indication. If no such
+	 * indication comes, it probably means that there is no AT
+	 * keyboard controller present. Give up in such case. Check relies
+	 * on the fact that reading from non-existing in/out port returns
+	 * 0xff on i386. May or may not be true on other platforms.
+	 */
+	tag = rman_get_bustag(port0);
+	ioh1 = rman_get_bushandle(port1);
+	flags = intr_disable();
+	for (i = 0; i != 65535; i++) {
+		if ((bus_space_read_1(tag, ioh1, 0) & 0x2) == 0)
+			break;
+	}
+	intr_restore(flags);
+	if (i == 65535) {
+		bus_release_resource(dev, SYS_RES_IOPORT, 0, port0);
+		bus_release_resource(dev, SYS_RES_IOPORT, 1, port1);
+		return ENXIO;
+	}
+#endif
+
 	error = atkbdc_probe_unit(device_get_unit(dev), port0, port1);
 
 	bus_release_resource(dev, SYS_RES_IOPORT, 0, port0);
Index: cpu/i386/include/cpufunc.h
===================================================================
RCS file: /home/source/dragonfly/cvs/src/sys/cpu/i386/include/cpufunc.h,v
retrieving revision 1.19
diff -u -p -r1.19 cpufunc.h
--- cpu/i386/include/cpufunc.h	7 Jan 2007 00:43:22 -0000	1.19
+++ cpu/i386/include/cpufunc.h	28 Feb 2007 12:27:12 -0000
@@ -677,6 +677,22 @@ load_dr7(u_int sel)
 	__asm __volatile("movl %0,%%dr7" : : "r" (sel));
 }
 
+static __inline register_t
+intr_disable(void)
+{
+	register_t eflags;
+
+	eflags = read_eflags();
+	cpu_disable_intr();
+	return (eflags);
+}
+
+static __inline void
+intr_restore(register_t eflags)
+{
+	write_eflags(eflags);
+}
+
 #else /* !__GNUC__ */
 
 int	breakpoint	(void);