From ec73ba31eccce73750a0a22f0e5e382d6feb53d3 Mon Sep 17 00:00:00 2001
From: kato <kato@FreeBSD.org>
Date: Sat, 16 May 1998 14:44:11 +0000
Subject: Some of newer PC-98 may cause "Windows Protection Fault" when booting
 Windows 95 after rebooting FreeBSD without power off.  In PC-98 system,
 reboot mode is set via I/O port 0x37 in cpu_reset(), and accessing of this
 port is the reason of the problem.  To avnoid the fault, current status of
 reboot mode should be checked before accessing the I/O port.

---
 sys/amd64/amd64/vm_machdep.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

(limited to 'sys/amd64/amd64/vm_machdep.c')

diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
index b157bb6..78f16ae 100644
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -38,7 +38,7 @@
  *
  *	from: @(#)vm_machdep.c	7.3 (Berkeley) 5/13/91
  *	Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
- *	$Id: vm_machdep.c,v 1.104 1998/03/17 09:10:05 kato Exp $
+ *	$Id: vm_machdep.c,v 1.105 1998/03/23 19:52:42 jlemon Exp $
  */
 
 #include "npx.h"
@@ -847,8 +847,10 @@ cpu_reset()
 	 * Attempt to do a CPU reset via CPU reset port.
 	 */
 	disable_intr();
-	outb(0x37, 0x0f);		/* SHUT0 = 0. */
-	outb(0x37, 0x0b);		/* SHUT1 = 0. */
+	if ((inb(0x35) & 0xa0) != 0xa0) {
+		outb(0x37, 0x0f);		/* SHUT0 = 0. */
+		outb(0x37, 0x0b);		/* SHUT1 = 0. */
+	}
 	outb(0xf0, 0x00);		/* Reset. */
 #else
 	/*
-- 
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