From e47f0da4087bd00f1ee0697d0a9020ec4373e447 Mon Sep 17 00:00:00 2001
From: andrewfish <andrewfish@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Thu, 14 Jul 2011 02:31:02 +0000
Subject: [PATCH] MdeModulePkg: Add PcdDxeIplBuildPageTables for DxeIpl X64 to
 optionally not rebuild the page tables.

signed-off-by: andrewfish
reviewed-by: rsun3



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12016 6f19259b-4bc3-4df7-8a09-765794883524
---
 MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf        |  5 ++++-
 MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c | 16 ++++++++++------
 MdeModulePkg/MdeModulePkg.dec                  |  6 ++++++
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf b/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
index 5c5f7e82a5..784fdf18f6 100644
--- a/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
+++ b/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
@@ -45,7 +45,7 @@
 [Sources.X64]
   X64/VirtualMemory.h
   X64/VirtualMemory.c
-  X64/DxeLoadFunc.c
+  X64/DxeLoadFunc.c    
 
 [Sources.IPF]
   Ipf/DxeLoadFunc.c
@@ -90,6 +90,9 @@
 [FeaturePcd.IA32]
   gEfiMdeModulePkgTokenSpaceGuid.PcdDxeIplSwitchToLongMode
 
+[FeaturePcd.X64]
+  gEfiMdeModulePkgTokenSpaceGuid.PcdDxeIplBuildPageTables
+
 [FeaturePcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdDxeIplSupportUefiDecompress
 
diff --git a/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c b/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c
index 1b12801d67..729e1ee325 100644
--- a/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c
+++ b/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c
@@ -52,18 +52,22 @@ HandOffToDxeCore (
   TopOfStack = (VOID *) ((UINTN) BaseOfStack + EFI_SIZE_TO_PAGES (STACK_SIZE) * EFI_PAGE_SIZE - CPU_STACK_ALIGNMENT);
   TopOfStack = ALIGN_POINTER (TopOfStack, CPU_STACK_ALIGNMENT);
 
-  //
-  // Create page table and save PageMapLevel4 to CR3
-  //
-  PageTables = CreateIdentityMappingPageTables ();
-
+  if (FeaturePcdGet (PcdDxeIplBuildPageTables)) {
+    //
+    // Create page table and save PageMapLevel4 to CR3
+    //
+    PageTables = CreateIdentityMappingPageTables ();
+  }
+  
   //
   // End of PEI phase signal
   //
   Status = PeiServicesInstallPpi (&gEndOfPeiSignalPpi);
   ASSERT_EFI_ERROR (Status);
 
-  AsmWriteCr3 (PageTables);
+  if (FeaturePcdGet (PcdDxeIplBuildPageTables)) {
+    AsmWriteCr3 (PageTables);
+  }
 
   //
   // Update the contents of BSP stack HOB to reflect the real stack info passed to DxeCore.
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 92e56ded55..a86a0462c4 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -364,6 +364,12 @@
   #
   gEfiMdeModulePkgTokenSpaceGuid.PcdDxeIplSwitchToLongMode|TRUE|BOOLEAN|0x0001003b
 
+  ##
+  # This feature flag specifies whether DxeIpl should rebuild page tables. This flag only
+  # makes sense in the case where the DxeIpl and the DxeCore are both X64.
+  #
+  gEfiMdeModulePkgTokenSpaceGuid.PcdDxeIplBuildPageTables|TRUE|BOOLEAN|0x0001003c
+
 [PcdsFixedAtBuild]
   ## Dynamic type PCD can be registered callback function for Pcd setting action.
   #  PcdMaxPeiPcdCallBackNumberPerPcdEntry indicate maximum number of callback function
-- 
2.39.2