From ee9202997be14184e0b781ed378388b25d16e998 Mon Sep 17 00:00:00 2001
From: okuji <okuji@localhost>
Date: Sat, 21 Dec 2002 00:34:33 +0000
Subject: [PATCH] 2002-12-21  Yoshinori K. Okuji  <okuji@enbug.org>

	* stage2/asm.S (gateA20): First, try a BIOS call (INT 15H,
	AX=2400/2401). Use the keyboard controller, only if that failed.
---
 ChangeLog    |  5 +++++
 stage2/asm.S | 30 ++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 7bb210ccf..1b526ce59 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2002-12-21  Yoshinori K. Okuji  <okuji@enbug.org>
+
+	* stage2/asm.S (gateA20): First, try a BIOS call (INT 15H,
+	AX=2400/2401). Use the keyboard controller, only if that failed.
+
 2002-12-11  Yoshinori K. Okuji  <okuji@enbug.org>
 
 	Add a workaround for buggy BIOSes which don't pass boot drive
diff --git a/stage2/asm.S b/stage2/asm.S
index d56e0f747..fd5e50b9b 100644
--- a/stage2/asm.S
+++ b/stage2/asm.S
@@ -1660,6 +1660,36 @@ ENTRY(set_vbe_mode)
  */
 
 ENTRY(gateA20)
+	/* first, try a BIOS call */
+	pushl	%ebp
+	movl	8(%esp), %edx
+	
+	call	EXT_C(prot_to_real)
+	
+	.code16
+	movw	$0x2400, %ax
+	testw	%dx, %dx
+	jz	1f
+	incw	%ax
+1:	stc
+	int	$0x15
+	jnc	2f
+
+	/* set non-zero if failed */
+	movb	$1, %ah
+
+	/* save the status */
+2:	movb	%ah, %dl
+
+	DATA32	call	EXT_C(real_to_prot)
+	.code32
+
+	popl	%ebp
+	testb	%dl, %dl
+	jnz	3f
+	ret
+
+3:	/* use keyboard controller */
 	pushl	%eax
 
 	call    gloop1