[Xen-changelog] [xen-3.2-testing] x86_64: Initialise upper half of 32-bit parameter registers when

["Xen patchbot-3.2-testing" <patchbot-3.2-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1206978034 -3600
# Node ID ca7bfc8f5ea5d39188309fed05afb4b55974df4a
# Parent  11efc5dc5d2c98010c47ac7689fd953815ed3cc5
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@xxxxxxxxxx>
xen-unstable changeset:   17325:ffcc213f87112a9bcae2524dc9dd08bc13911d8c
xen-unstable date:        Mon Mar 31 16:32:33 2008 +0100
---
 xen/arch/x86/boot/trampoline.S |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff -r 11efc5dc5d2c -r ca7bfc8f5ea5 xen/arch/x86/boot/trampoline.S
--- a/xen/arch/x86/boot/trampoline.S    Mon Mar 31 16:40:13 2008 +0100
+++ b/xen/arch/x86/boot/trampoline.S    Mon Mar 31 16:40:34 2008 +0100
@@ -156,9 +156,12 @@ 1:      mov     $(BOOT_TRAMPOLINE>>4),%a
         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
 

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