From 9fec701806f4a61705e75fcee03d590f58562126 Mon Sep 17 00:00:00 2001
From: Keir Fraser <keir@xensource.com>
Date: Thu, 25 Oct 2007 09:43:42 +0100
Subject: [PATCH] x86: GDTR must be reset after using real-mode BIOS services.
 Some BIOSes clobber GDTR. While we're here reset IDTR too, although it's not
 really necessary. Signed-off-by: John Byrne <john.l.byrne@hp.com>
 Sigend-off-by: Keir Fraser <keir@xensource.com>

---
 xen/arch/x86/boot/trampoline.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/xen/arch/x86/boot/trampoline.S b/xen/arch/x86/boot/trampoline.S
index 95a9d013de..6ffaa811ef 100644
--- a/xen/arch/x86/boot/trampoline.S
+++ b/xen/arch/x86/boot/trampoline.S
@@ -168,6 +168,10 @@ trampoline_boot_cpu_entry:
         /* Disable irqs before returning to protected mode. */
         cli
 
+        /* Reset GDT and IDT. Some BIOSes clobber GDTR. */
+        lidt    bootsym(idt_48)
+        lgdt    bootsym(gdt_48)
+
         /* Enter protected mode, and flush insn queue. */
         xor     %ax,%ax
         inc     %ax
-- 
2.30.2