From: Jeff Fan <jeff.fan@intel.com>
Date: Tue, 8 Dec 2015 05:19:34 +0000 (+0000)
Subject: UefiCpuPkg/MtrrLib: Add PCD PcdCpuNumberOfReservedVariableMtrrs
X-Git-Tag: edk2-stable201903~8354
X-Git-Url: https://git.proxmox.com/?p=mirror_edk2.git;a=commitdiff_plain;h=46309b1101b626c8d3528d85d48383ea156fedf0

UefiCpuPkg/MtrrLib: Add PCD PcdCpuNumberOfReservedVariableMtrrs

Current MtrrLib reserves 2 variable MTRRs for some legacy OS boot (CSM boots)
may require some MTRRs to be reserved for OS use. But UEFI OS boot will not use
MTRRs.

Per Scott's suggestion in
link: http://article.gmane.org/gmane.comp.bios.edk2.devel/4099
Add one PCD PcdCpuNumberOfReservedVariableMtrrs to specify the number of
variable MTRRs reserved for OS use. Setting its default value to 2 is for
back-compatibility.

Cc: Scott Duplichan <scott@notabs.org>
Cc: Feng Tian <feng.tian@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Suggested-by: Scott Duplichan <scott@notabs.org>
Reviewed-by: Feng Tian <feng.tian@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19151 6f19259b-4bc3-4df7-8a09-765794883524
---

diff --git a/UefiCpuPkg/Include/Library/MtrrLib.h b/UefiCpuPkg/Include/Library/MtrrLib.h
index e06fff7f01..f9002e7cbf 100644
--- a/UefiCpuPkg/Include/Library/MtrrLib.h
+++ b/UefiCpuPkg/Include/Library/MtrrLib.h
@@ -1,7 +1,7 @@
 /** @file
   MTRR setting library
 
-  Copyright (c) 2008 - 2011, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2008 - 2015, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -26,6 +26,7 @@
 #define  MTRR_NUMBER_OF_VARIABLE_MTRR  32
 //
 // Firmware need reserve 2 MTRR for OS
+// Note: It is replaced by PCD PcdCpuNumberOfReservedVariableMtrrs
 //
 #define  RESERVED_FIRMWARE_VARIABLE_MTRR_NUMBER  2
 
diff --git a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
index a65560542c..82223379e7 100644
--- a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
+++ b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
@@ -140,13 +140,15 @@ GetFirmwareVariableMtrrCount (
   )
 {
   UINT32  VariableMtrrCount;
+  UINT32  ReservedMtrrNumber;
 
   VariableMtrrCount = GetVariableMtrrCount ();
-  if (VariableMtrrCount < RESERVED_FIRMWARE_VARIABLE_MTRR_NUMBER) {
+  ReservedMtrrNumber = PcdGet32 (PcdCpuNumberOfReservedVariableMtrrs);
+  if (VariableMtrrCount < ReservedMtrrNumber) {
     return 0;
   }
 
-  return VariableMtrrCount - RESERVED_FIRMWARE_VARIABLE_MTRR_NUMBER;
+  return VariableMtrrCount - ReservedMtrrNumber;
 }
 
 /**
diff --git a/UefiCpuPkg/Library/MtrrLib/MtrrLib.inf b/UefiCpuPkg/Library/MtrrLib/MtrrLib.inf
index 64ec9bd0b0..01a4d84da0 100644
--- a/UefiCpuPkg/Library/MtrrLib/MtrrLib.inf
+++ b/UefiCpuPkg/Library/MtrrLib/MtrrLib.inf
@@ -1,7 +1,7 @@
 ## @file
 #  MTRR library provides APIs for MTRR operation.
 #
-#  Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
 #  This program and the accompanying materials
 #  are licensed and made available under the terms and conditions of the BSD License
 #  which accompanies this distribution.  The full text of the license may be found at
@@ -41,3 +41,6 @@
   CpuLib
   DebugLib
 
+[Pcd]
+  gUefiCpuPkgTokenSpaceGuid.PcdCpuNumberOfReservedVariableMtrrs   ## SOMETIMES_CONSUMES
+
diff --git a/UefiCpuPkg/UefiCpuPkg.dec b/UefiCpuPkg/UefiCpuPkg.dec
index e783a7b536..a694146689 100644
--- a/UefiCpuPkg/UefiCpuPkg.dec
+++ b/UefiCpuPkg/UefiCpuPkg.dec
@@ -167,6 +167,11 @@
   # @Prompt SMM CPU Synchronization Method.
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmSyncMode|0x00|UINT8|0x60000014
 
+  ## Specifies the number of variable MTRRs reserved for OS use. The default number of
+  #  MTRRs reserved for OS use is 2.
+  # @Prompt Number of reserved variable MTRRs.
+  gUefiCpuPkgTokenSpaceGuid.PcdCpuNumberOfReservedVariableMtrrs|0x2|UINT32|0x00000015
+
 [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx]
   ## Specifies timeout value in microseconds for the BSP to detect all APs for the first time.
   # @Prompt Timeout for the BSP to detect all APs for the first time.