From d0652aa8ac8d82e077acf8e781557f4c4367dcf5 Mon Sep 17 00:00:00 2001
From: Avi Kivity <avi@redhat.com>
Date: Thu, 24 Dec 2009 15:38:50 +0200
Subject: [PATCH] linuxboot: fix gdt address calculation

The gdt address calculation in linuxboot.bin is broken in two ways: first
it loads %cs into %eax, but that instruction leaves the high bits of %eax
undefined and we did not clear them.  Secondly, we completely ignore the
incorrect %eax, and use the undefined %ebx instead.

With these issues fixed, linuxboot works again.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
 pc-bios/optionrom/linuxboot.S | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pc-bios/optionrom/linuxboot.S b/pc-bios/optionrom/linuxboot.S
index c4c9109b67..8aebe51ee5 100644
--- a/pc-bios/optionrom/linuxboot.S
+++ b/pc-bios/optionrom/linuxboot.S
@@ -86,9 +86,10 @@ copy_kernel:
 	/* Now create the GDT descriptor */
 	movw		$((3 * 8) - 1), -16(%bp)
 	mov		%cs, %eax
+	movzwl		%ax, %eax
 	shl		$4, %eax
-	addl		$gdt, %ebx
-	movl		%ebx, -14(%bp)
+	addl		$gdt, %eax
+	movl		%eax, -14(%bp)
 
 	/* And load the GDT */
 	data32 lgdt	-16(%bp)