From 0c47c4d02d55eb8b7c0f467dbf2971e7a1d870e0 Mon Sep 17 00:00:00 2001
From: Edwin Beasant <edwin_beasant@virtensys.com>
Date: Fri, 4 Jun 2010 20:32:12 +0000
Subject: [PATCH] This patch fixes the option rom code that was buggy when it
 switched segment registers before restoring register values. This was
 breaking the Geode VSA, and probably would have hurt other option roms as
 well.

Signed-off-by: Edwin Beasant <edwin_beasant@virtensys.com>
Acked-by: Patrick Georgi <patrick.georgi@coresystems.de>
Signed-off-by: Stefan Reinauer <stepan@coresystems.de>
Acked-by: Nils Jacobs <njacobs8@hetnet.nl>


git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5612 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1
---
 src/devices/oprom/x86_asm.S | 36 +++++++++++++++++++++---------------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/src/devices/oprom/x86_asm.S b/src/devices/oprom/x86_asm.S
index bbae4b1bce..e355da8fb9 100644
--- a/src/devices/oprom/x86_asm.S
+++ b/src/devices/oprom/x86_asm.S
@@ -141,20 +141,23 @@ __realmode_call = RELOCATED(.)
 	mov	%ax, %ds
 	lidt	__realmode_idt
 
-	/* Set all segments to 0x0000, ds to 0x0040 */
-	mov	%ax, %es
-	mov	%ax, %fs
-	mov	%ax, %gs
-	mov	$0x40, %ax
-	mov	%ax, %ds
-
 	/* initialize registers for option rom lcall */
 	movl	__registers +  0, %eax
 	movl	__registers +  4, %ebx
 	movl	__registers +  8, %ecx
 	movl	__registers + 12, %edx
 	movl	__registers + 16, %esi
-	movl	__registers + 20, %edi
+	movl	__registers + 20, %edi	
+
+	/* Set all segments to 0x0000, ds to 0x0040 */
+	push	%ax
+	xor	%ax, %ax
+	mov	%ax, %es
+	mov	%ax, %fs
+	mov	%ax, %gs
+	mov	$0x40, %ax
+	mov	%ax, %ds
+	pop	%ax
 
 	/* ************************************ */
 __lcall_instr = RELOCATED(.)
@@ -262,12 +265,6 @@ __realmode_interrupt = RELOCATED(.)
 	mov	%ax, %ds
 	lidt	__realmode_idt
 
-	/* Set all segments to 0x0000 */
-	mov	%ax, %ds
-	mov	%ax, %es
-	mov	%ax, %fs
-	mov	%ax, %gs
-
 	/* initialize registers for intXX call */
 	movl	__registers +  0, %eax
 	movl	__registers +  4, %ebx
@@ -276,6 +273,15 @@ __realmode_interrupt = RELOCATED(.)
 	movl	__registers + 16, %esi
 	movl	__registers + 20, %edi
 
+	/* Set all segments to 0x0000 */
+	push	%ax
+	xor	%ax, %ax
+	mov	%ax, %ds
+	mov	%ax, %es
+	mov	%ax, %fs
+	mov	%ax, %gs
+	pop	%ax
+
 __intXX_instr = RELOCATED(.)
 	.byte 0xcd, 0x00 /* This becomes intXX */
 
@@ -376,7 +382,7 @@ __interrupt_handler_16bit = RELOCATED(.)
 	mov	%ax, %ds
 	lidt	__realmode_idt
 
-	/* Set up segment registers to segment 0x0000 */
+	/* Set up segment registers to segment 0x0000 and ds to 0x040 */
 	mov	%ax, %es
 	mov	%ax, %fs
 	mov	%ax, %gs