From: Keir Fraser <keir.fraser@citrix.com>
Date: Mon, 31 Mar 2008 15:40:34 +0000 (+0100)
Subject: x86_64: Initialise upper half of 32-bit parameter registers when
X-Git-Tag: 3.2.1-rc3~9
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=00d2a35ea05024ead4c5c4d9ec4c696d7020c892;p=people%2Fvhanquez%2Fxen.git

x86_64: Initialise upper half of 32-bit parameter registers when
making Target Mode BIOS call. Fixes boot problems with some buggy
BIOSes.
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
xen-unstable changeset:   17325:ffcc213f87112a9bcae2524dc9dd08bc13911d8c
xen-unstable date:        Mon Mar 31 16:32:33 2008 +0100
---

diff --git a/xen/arch/x86/boot/trampoline.S b/xen/arch/x86/boot/trampoline.S
index 143612c91..af4de553a 100644
--- a/xen/arch/x86/boot/trampoline.S
+++ b/xen/arch/x86/boot/trampoline.S
@@ -156,9 +156,12 @@ trampoline_boot_cpu_entry:
         sti
 
 #if defined(__x86_64__)
-        /* Declare that our target operating mode is long mode. */
-        movw    $0xec00,%ax      # declare target operating mode
-        movw    $0x0002,%bx      # long mode
+        /*
+         * Declare that our target operating mode is long mode.
+         * Initialise 32-bit registers since some buggy BIOSes depend on it.
+         */
+        movl    $0xec00,%eax      # declare target operating mode
+        movl    $0x0002,%ebx      # long mode
         int     $0x15
 #endif