diff --git a/MdePkg/Library/PeiPalCallLib/PeiPalCallLib.inf b/MdePkg/Library/PeiPalCallLib/PeiPalCallLib.inf
index 046e80cda2..b3632564dd 100644
--- a/MdePkg/Library/PeiPalCallLib/PeiPalCallLib.inf
+++ b/MdePkg/Library/PeiPalCallLib/PeiPalCallLib.inf
@@ -22,7 +22,7 @@
   FILE_GUID                      = B53DC524-6B98-4584-940B-8F1363DEF09E
   MODULE_TYPE                    = PEIM
   VERSION_STRING                 = 1.0
-  LIBRARY_CLASS                  = PalCallLib 
+  LIBRARY_CLASS                  = PalCallLib|PEI_CORE PEIM SEC
   EDK_RELEASE_VERSION            = 0x00020000
   EFI_SPECIFICATION_VERSION      = 0x00020000
 
diff --git a/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.c b/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.c
index 83372e86d4..91d77f5fcb 100644
--- a/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.c
+++ b/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.c
@@ -77,7 +77,7 @@ GetDevicePathSize (
   //
   // Compute the size and add back in the size of the end device path structure
   //
-  return ((UINTN) DevicePath - (UINTN) Start) + sizeof (EFI_DEVICE_PATH_PROTOCOL);
+  return ((UINTN) DevicePath - (UINTN) Start) + EfiDevicePathNodeLength (DevicePath);
 }
 
 /**
@@ -99,7 +99,6 @@ DuplicateDevicePath (
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
   )
 {
-  EFI_DEVICE_PATH_PROTOCOL  *NewDevicePath;
   UINTN                     Size;
 
   //
@@ -113,9 +112,8 @@ DuplicateDevicePath (
   //
   // Allocate space for duplicate device path
   //
-  NewDevicePath = AllocateCopyPool (Size, DevicePath);
 
-  return NewDevicePath;
+  return AllocateCopyPool (Size, DevicePath);
 }
 
 /**
@@ -168,7 +166,7 @@ AppendDevicePath (
   //
   Size1         = GetDevicePathSize (FirstDevicePath);
   Size2         = GetDevicePathSize (SecondDevicePath);
-  Size          = Size1 + Size2 - sizeof (EFI_DEVICE_PATH_PROTOCOL);
+  Size          = Size1 + Size2 - EFI_END_DEVICE_PATH_LENGTH;
 
   NewDevicePath = AllocatePool (Size);
 
@@ -178,7 +176,7 @@ AppendDevicePath (
     // Over write FirstDevicePath EndNode and do the copy
     //
     DevicePath2 = (EFI_DEVICE_PATH_PROTOCOL *) ((CHAR8 *) NewDevicePath +
-                  (Size1 - sizeof (EFI_DEVICE_PATH_PROTOCOL)));
+                  (Size1 - EFI_END_DEVICE_PATH_LENGTH));
     CopyMem (DevicePath2, SecondDevicePath, Size2);
   }
 
@@ -226,7 +224,7 @@ AppendDevicePathNode (
   //
   NodeLength = DevicePathNodeLength (DevicePathNode);
 
-  TempDevicePath = AllocatePool (NodeLength + sizeof (EFI_DEVICE_PATH_PROTOCOL));
+  TempDevicePath = AllocatePool (NodeLength + EFI_END_DEVICE_PATH_LENGTH);
   if (TempDevicePath == NULL) {
     return NULL;
   }
@@ -398,7 +396,7 @@ GetNextDevicePathInstance (
   @param  NodeSubType                The device node sub-type for the new device node.
   @param  NodeLength                 The length of the new device node.
 
-  @return The new device path.
+  @return A pointer to the new create device path.
 
 **/
 EFI_DEVICE_PATH_PROTOCOL *
@@ -510,7 +508,7 @@ DevicePathFromHandle (
                                      may be NULL.
   @param  FileName                   A pointer to a Null-terminated Unicode string.
 
-  @return The allocated device path.
+  @return A pointer to the new created file device path.
 
 **/
 EFI_DEVICE_PATH_PROTOCOL *
diff --git a/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.inf b/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.inf
index f0cd5e2e34..2ec381d262 100644
--- a/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.inf
+++ b/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.inf
@@ -1,7 +1,7 @@
 #/** @file
-# Component description file for the entry point to a EFIDXE Drivers
+# Library instance implement the library class UefiDevicePathLib defined in Mde
+# library specification.
 #
-# Library to abstract Framework extensions that conflict with UEFI 2.0 Specification
 # Copyright (c) 2007, Intel Corporation
 #
 #  All rights reserved. This program and the accompanying materials
diff --git a/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c b/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c
index 607a701dd7..a1a8650f0d 100644
--- a/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c
+++ b/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c
@@ -1,5 +1,6 @@
 /** @file
-  UEFI Device Path Library.
+  Library instance that implement UEFI Device Path Library class based on protocol
+  gEfiDevicePathUtilitiesProtocolGuid.
 
   Copyright (c) 2006, Intel Corporation<BR>
   All rights reserved. This program and the accompanying materials
@@ -25,8 +26,6 @@
 #include <Library/BaseMemoryLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 
-#include "UefiDevicePathLibInternal.h"
-
 STATIC EFI_DEVICE_PATH_UTILITIES_PROTOCOL          *mDevicePathUtilities = NULL;
 
 /**
@@ -245,7 +244,7 @@ GetNextDevicePathInstance (
   @param  NodeSubType                The device node sub-type for the new device node.
   @param  NodeLength                 The length of the new device node.
 
-  @return The new device path.
+  @return A pointer to the new created file device path 
 
 **/
 EFI_DEVICE_PATH_PROTOCOL *
@@ -325,7 +324,7 @@ DevicePathFromHandle (
                                      may be NULL.
   @param  FileName                   A pointer to a Null-terminated Unicode string.
 
-  @return The allocated device path.
+  @return A pointer to the new created file device path 
 
 **/
 EFI_DEVICE_PATH_PROTOCOL *
diff --git a/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLibInternal.h b/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLibInternal.h
deleted file mode 100644
index 9587712e81..0000000000
--- a/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLibInternal.h
+++ /dev/null
@@ -1,38 +0,0 @@
-/** @file
-  Internal Header file for UEFI Device Path Library.
-
-  Copyright (c) 2006, Intel Corporation<BR>
-  All rights reserved. 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
-  http://opensource.org/licenses/bsd-license.php
-
-  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
-  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
-
-**/
-
-#ifndef _UEFI_DEVICEPATH_LIB_INTERNAL_H_
-#define _UEFI_DEVICEPATH_LIB_INTERNAL_H_
-
-
-/**
-  The constructor function caches the pointer to DevicePathUtilites protocol.
-  
-  The constructor function locates DevicePathUtilities protocol from protocol database.
-  It will ASSERT() if that operation fails and it will always return EFI_SUCCESS. 
-
-  @param  ImageHandle   The firmware allocated handle for the EFI image.
-  @param  SystemTable   A pointer to the EFI System Table.
-  
-  @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
-
-**/
-EFI_STATUS
-EFIAPI
-DevicePathLibConstructor (
-  IN      EFI_HANDLE                ImageHandle,
-  IN      EFI_SYSTEM_TABLE          *SystemTable
-  );
-
-#endif