From 26a74a36c155e74463267e187b77b5c404dcd9cf Mon Sep 17 00:00:00 2001
From: li-elvin <li-elvin@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Wed, 19 Oct 2011 00:45:13 +0000
Subject: [PATCH] Use a local variable and assign 0 to it, then use it as
 legacy interrupt table base address.

Signed-off-by: li-elvin
Reviewed-by: mdkinney, ydong10

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12547 6f19259b-4bc3-4df7-8a09-765794883524
---
 IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
index 9a62499f05..16c873d8f5 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
@@ -57,6 +57,8 @@ LegacyBiosInt86 (
   IN  EFI_IA32_REGISTER_SET         *Regs
   )
 {
+  UINT32  *VectorBase;
+
   Regs->X.Flags.Reserved1 = 1;
   Regs->X.Flags.Reserved2 = 0;
   Regs->X.Flags.Reserved3 = 0;
@@ -66,11 +68,16 @@ LegacyBiosInt86 (
   Regs->X.Flags.IF        = 0;
   Regs->X.Flags.TF        = 0;
   Regs->X.Flags.CF        = 0;
-
+  //
+  // The base address of legacy interrupt vector table is 0.
+  // We use this base address to get the legacy interrupt handler.
+  //
+  VectorBase              = 0;
+  
   return InternalLegacyBiosFarCall (
            This,
-           (UINT16) (((UINT32 *)NULL)[BiosInt] >> 16),
-           (UINT16) ((UINT32 *)NULL)[BiosInt],
+           (UINT16) ((VectorBase)[BiosInt] >> 16),
+           (UINT16) (VectorBase)[BiosInt],
            Regs,
            &Regs->X.Flags,
            sizeof (Regs->X.Flags)
-- 
2.39.2