Index: pxeldr.S
===================================================================
RCS file: /usr/cvs/src/sys/boot/i386/pxeldr/pxeldr.S,v
retrieving revision 1.13
diff -u -r1.13 pxeldr.S
--- pxeldr.S	14 May 2004 20:29:30 -0000	1.13
+++ pxeldr.S	11 Apr 2006 17:41:56 -0000
@@ -227,10 +227,17 @@
 		jmp putstr			# keep looping
 
 /*
- * Enable A20
+ * Enable A20. Put an upper limit on the amount of time we wait for the
+ * keyboard controller to get ready (65K x ISA access time). If
+ * we wait more than that amount, the hardware is probably
+ * legacy-free and simply doesn't have a keyboard controller.
+ * Thus, the A20 line is already enabled.
  */
 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
@@ -240,7 +247,7 @@
 		jnz seta20.2			# Yes
 		movb $0xdf,%al			# Enable
 		outb %al,$0x60			#  A20
-		sti				# Enable interrupts
+seta20.3:	sti				# Enable interrupts
 		retw				# To caller
 
 /*