]> git.proxmox.com Git - mirror_edk2.git/blobdiff - MdeModulePkg/Universal/PlatformDriOverrideDxe/PlatDriOverrideLib.c
Merge application PlatOverMngr and library DxePlatDriOverLib into driver PlatDriOverr...
[mirror_edk2.git] / MdeModulePkg / Universal / PlatformDriOverrideDxe / PlatDriOverrideLib.c
diff --git a/MdeModulePkg/Universal/PlatformDriOverrideDxe/PlatDriOverrideLib.c b/MdeModulePkg/Universal/PlatformDriOverrideDxe/PlatDriOverrideLib.c
new file mode 100644 (file)
index 0000000..48beba0
--- /dev/null
@@ -0,0 +1,1898 @@
+/** @file\r
+  Implementation of the shared functions to do the platform driver vverride mapping.\r
+\r
+  Copyright (c) 2007 - 2009, Intel Corporation\r
+  All rights reserved. This program and the accompanying materials\r
+  are licensed and made available under the terms and conditions of the BSD License\r
+  which accompanies this distribution.  The full text of the license may be found at\r
+  http://opensource.org/licenses/bsd-license.php\r
+\r
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
+\r
+**/\r
+\r
+#include "InternalPlatDriOverrideDxe.h"\r
+\r
+#define PLATFORM_OVERRIDE_ITEM_SIGNATURE      SIGNATURE_32('p','d','o','i')\r
+ typedef struct _PLATFORM_OVERRIDE_ITEM {\r
+  UINTN                                 Signature;\r
+  LIST_ENTRY                            Link;\r
+  UINT32                                DriverInfoNum;\r
+  EFI_DEVICE_PATH_PROTOCOL              *ControllerDevicePath;\r
+  ///\r
+  /// List of DRIVER_IMAGE_INFO\r
+  ///\r
+  LIST_ENTRY                            DriverInfoList;\r
+  EFI_HANDLE                            LastReturnedImageHandle;\r
+} PLATFORM_OVERRIDE_ITEM;\r
+\r
+#define DRIVER_IMAGE_INFO_SIGNATURE           SIGNATURE_32('p','d','i','i')\r
+typedef struct _DRIVER_IMAGE_INFO {\r
+  UINTN                                 Signature;\r
+  LIST_ENTRY                            Link;\r
+  EFI_HANDLE                            ImageHandle;\r
+  EFI_DEVICE_PATH_PROTOCOL              *DriverImagePath;\r
+  BOOLEAN                               UnLoadable;\r
+  BOOLEAN                               UnStartable;\r
+} DRIVER_IMAGE_INFO;\r
+\r
+#define DEVICE_PATH_STACK_ITEM_SIGNATURE      SIGNATURE_32('d','p','s','i')\r
+typedef struct _DEVICE_PATH_STACK_ITEM{\r
+  UINTN                                 Signature;\r
+  LIST_ENTRY                            Link;\r
+  EFI_DEVICE_PATH_PROTOCOL              *DevicePath;\r
+} DEVICE_PATH_STACK_ITEM;\r
+\r
+\r
+LIST_ENTRY   mDevicePathStack = INITIALIZE_LIST_HEAD_VARIABLE (mDevicePathStack);\r
+\r
+/**\r
+  Push a controller device path into a globle device path list.\r
+\r
+  @param  DevicePath     The controller device path to push into stack\r
+\r
+  @retval EFI_SUCCESS    Device path successfully pushed into the stack.\r
+\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+PushDevPathStack (\r
+  IN  EFI_DEVICE_PATH_PROTOCOL    *DevicePath\r
+  )\r
+{\r
+  DEVICE_PATH_STACK_ITEM  *DevicePathStackItem;\r
+\r
+  DevicePathStackItem = AllocateZeroPool (sizeof (DEVICE_PATH_STACK_ITEM));\r
+  ASSERT (DevicePathStackItem != NULL);\r
+  DevicePathStackItem->Signature = DEVICE_PATH_STACK_ITEM_SIGNATURE;\r
+  DevicePathStackItem->DevicePath = DuplicateDevicePath (DevicePath);\r
+  InsertTailList (&mDevicePathStack, &DevicePathStackItem->Link);\r
+  return EFI_SUCCESS;\r
+}\r
+\r
+\r
+/**\r
+  Pop a controller device path from a globle device path list\r
+\r
+  @param  DevicePath     The controller device path popped from stack\r
+\r
+  @retval EFI_SUCCESS    Controller device path successfully popped.\r
+  @retval EFI_NOT_FOUND  Stack is empty.\r
+\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+PopDevPathStack (\r
+  OUT  EFI_DEVICE_PATH_PROTOCOL    **DevicePath\r
+  )\r
+{\r
+  DEVICE_PATH_STACK_ITEM  *DevicePathStackItem;\r
+  LIST_ENTRY              *ItemListIndex;\r
+\r
+  ItemListIndex = mDevicePathStack.BackLink;\r
+  //\r
+  // Check if the stack is empty\r
+  //\r
+  if (ItemListIndex != &mDevicePathStack){\r
+    DevicePathStackItem = CR(ItemListIndex, DEVICE_PATH_STACK_ITEM, Link, DEVICE_PATH_STACK_ITEM_SIGNATURE);\r
+    if (DevicePath != NULL) {\r
+      *DevicePath = DuplicateDevicePath (DevicePathStackItem->DevicePath);\r
+    }\r
+    FreePool (DevicePathStackItem->DevicePath);\r
+    RemoveEntryList (&DevicePathStackItem->Link);\r
+    FreePool (DevicePathStackItem);\r
+    return EFI_SUCCESS;\r
+  }\r
+  return EFI_NOT_FOUND;\r
+}\r
+\r
+\r
+/**\r
+  Check whether a controller device path is in a globle device path list\r
+\r
+  @param  DevicePath     The controller device path to check\r
+\r
+  @retval TRUE           DevicePath exists in the stack.\r
+  @retval FALSE          DevicePath does not exist in the stack.\r
+\r
+**/\r
+BOOLEAN\r
+EFIAPI\r
+CheckExistInStack (\r
+  IN  EFI_DEVICE_PATH_PROTOCOL    *DevicePath\r
+  )\r
+{\r
+  DEVICE_PATH_STACK_ITEM  *DevicePathStackItem;\r
+  LIST_ENTRY              *ItemListIndex;\r
+  UINTN                   DevicePathSize;\r
+\r
+  ItemListIndex = mDevicePathStack.BackLink;\r
+  while (ItemListIndex != &mDevicePathStack){\r
+    DevicePathStackItem = CR(ItemListIndex, DEVICE_PATH_STACK_ITEM, Link, DEVICE_PATH_STACK_ITEM_SIGNATURE);\r
+    DevicePathSize = GetDevicePathSize (DevicePath);\r
+    if (DevicePathSize == GetDevicePathSize (DevicePathStackItem->DevicePath)) {\r
+      if (CompareMem (DevicePath, DevicePathStackItem->DevicePath, DevicePathSize) == 0) {\r
+        return TRUE;\r
+      }\r
+    }\r
+    ItemListIndex = ItemListIndex->BackLink;\r
+  }\r
+\r
+  return FALSE;\r
+}\r
+\r
+/**\r
+  Update the FV file device path if it is not valid.\r
+\r
+  According to a file GUID, check a Fv file device path is valid. If it is invalid,\r
+  try to return the valid device path.\r
+  FV address maybe changes for memory layout adjust from time to time, use this funciton\r
+  could promise the Fv file device path is right.\r
+\r
+  @param  DevicePath               On input, the FV file device path to check\r
+                                   On output, the updated valid FV file device path\r
+  @param  FileGuid                 The FV file GUID\r
+  @param  CallerImageHandle        Image handle of the caller\r
+\r
+  @retval EFI_INVALID_PARAMETER    the input DevicePath or FileGuid is invalid\r
+                                   parameter\r
+  @retval EFI_UNSUPPORTED          the input DevicePath does not contain FV file\r
+                                   GUID at all\r
+  @retval EFI_ALREADY_STARTED      the input DevicePath has pointed to FV file, it\r
+                                   is valid\r
+  @retval EFI_SUCCESS              Successfully updated the invalid DevicePath,\r
+                                   and return the updated device path in DevicePath\r
+\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+UpdateFvFileDevicePath (\r
+  IN  OUT EFI_DEVICE_PATH_PROTOCOL      **DevicePath,\r
+  IN  EFI_GUID                          *FileGuid,\r
+  IN  EFI_HANDLE                        CallerImageHandle\r
+  )\r
+{\r
+  EFI_DEVICE_PATH_PROTOCOL      *TempDevicePath;\r
+  EFI_DEVICE_PATH_PROTOCOL      *LastDeviceNode;\r
+  EFI_STATUS                    Status;\r
+  EFI_GUID                      *GuidPoint;\r
+  UINTN                         Index;\r
+  UINTN                         FvHandleCount;\r
+  EFI_HANDLE                    *FvHandleBuffer;\r
+  EFI_FV_FILETYPE               Type;\r
+  UINTN                         Size;\r
+  EFI_FV_FILE_ATTRIBUTES        Attributes;\r
+  UINT32                        AuthenticationStatus;\r
+  BOOLEAN                       FindFvFile;\r
+  EFI_LOADED_IMAGE_PROTOCOL     *LoadedImage;\r
+  EFI_FIRMWARE_VOLUME2_PROTOCOL *Fv;\r
+  MEDIA_FW_VOL_FILEPATH_DEVICE_PATH FvFileNode;\r
+  EFI_HANDLE                    FoundFvHandle;\r
+  EFI_DEVICE_PATH_PROTOCOL      *NewDevicePath;\r
+  BOOLEAN                       HasFvNode;\r
+\r
+  if (DevicePath == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+\r
+  if (*DevicePath == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+\r
+  //\r
+  // Check whether the device path points to the default the input FV file\r
+  //\r
+  TempDevicePath = *DevicePath;\r
+  LastDeviceNode = TempDevicePath;\r
+  while (!IsDevicePathEnd (TempDevicePath)) {\r
+     LastDeviceNode = TempDevicePath;\r
+     TempDevicePath = NextDevicePathNode (TempDevicePath);\r
+  }\r
+  GuidPoint = EfiGetNameGuidFromFwVolDevicePathNode ((MEDIA_FW_VOL_FILEPATH_DEVICE_PATH *) LastDeviceNode);\r
+  if (GuidPoint == NULL) {\r
+    //\r
+    // If this option does not point to a FV file, just return EFI_UNSUPPORTED.\r
+    //\r
+    return EFI_UNSUPPORTED;\r
+  }\r
+\r
+  if (FileGuid != NULL) {\r
+    if (!CompareGuid (GuidPoint, FileGuid)) {\r
+      //\r
+      // If the FV file is not the input file GUID, just return EFI_UNSUPPORTED\r
+      //\r
+      return EFI_UNSUPPORTED;\r
+    }\r
+  } else {\r
+    FileGuid = GuidPoint;\r
+  }\r
+\r
+  //\r
+  // Check to see if the device path contains memory map node\r
+  //\r
+  TempDevicePath = *DevicePath;\r
+  HasFvNode = FALSE;\r
+  while (!IsDevicePathEnd (TempDevicePath)) {\r
+    //\r
+    // Use old Device Path\r
+    //\r
+    if (DevicePathType (TempDevicePath) == HARDWARE_DEVICE_PATH &&\r
+        DevicePathSubType (TempDevicePath) == HW_MEMMAP_DP) {\r
+      HasFvNode = TRUE;\r
+      break;\r
+    }\r
+    TempDevicePath = NextDevicePathNode (TempDevicePath);\r
+  }\r
+\r
+  if (!HasFvNode) {\r
+    return EFI_UNSUPPORTED;\r
+  }\r
+\r
+  //\r
+  // Check whether the input Fv file device path is valid\r
+  //\r
+  TempDevicePath = *DevicePath;\r
+  FoundFvHandle = NULL;\r
+  Status = gBS->LocateDevicePath (\r
+                  &gEfiFirmwareVolume2ProtocolGuid,\r
+                  &TempDevicePath,\r
+                  &FoundFvHandle\r
+                  );\r
+  if (!EFI_ERROR (Status)) {\r
+    Status = gBS->HandleProtocol (\r
+                    FoundFvHandle,\r
+                    &gEfiFirmwareVolume2ProtocolGuid,\r
+                    (VOID **) &Fv\r
+                    );\r
+    if (!EFI_ERROR (Status)) {\r
+      //\r
+      // Set FV ReadFile Buffer as NULL, only need to check whether input Fv file exist there\r
+      //\r
+      Status = Fv->ReadFile (\r
+                     Fv,\r
+                     FileGuid,\r
+                     NULL,\r
+                     &Size,\r
+                     &Type,\r
+                     &Attributes,\r
+                     &AuthenticationStatus\r
+                     );\r
+      if (!EFI_ERROR (Status)) {\r
+        return EFI_ALREADY_STARTED;\r
+      }\r
+    }\r
+  }\r
+\r
+  //\r
+  // Look for the input wanted FV file in current FV\r
+  // First, try to look for in Caller own FV. Caller and input wanted FV file usually are in the same FV\r
+  //\r
+  FindFvFile = FALSE;\r
+  FoundFvHandle = NULL;\r
+  Status = gBS->HandleProtocol (\r
+                  CallerImageHandle,\r
+                  &gEfiLoadedImageProtocolGuid,\r
+                  (VOID **) &LoadedImage\r
+                  );\r
+  if (!EFI_ERROR (Status)) {\r
+    Status = gBS->HandleProtocol (\r
+                    LoadedImage->DeviceHandle,\r
+                    &gEfiFirmwareVolume2ProtocolGuid,\r
+                    (VOID **) &Fv\r
+                    );\r
+    if (!EFI_ERROR (Status)) {\r
+      Status = Fv->ReadFile (\r
+                     Fv,\r
+                     FileGuid,\r
+                     NULL,\r
+                     &Size,\r
+                     &Type,\r
+                     &Attributes,\r
+                     &AuthenticationStatus\r
+                     );\r
+      if (!EFI_ERROR (Status)) {\r
+        FindFvFile = TRUE;\r
+        FoundFvHandle = LoadedImage->DeviceHandle;\r
+      }\r
+    }\r
+  }\r
+  //\r
+  // Second, if fail to find, try to enumerate all FV\r
+  //\r
+  if (!FindFvFile) {\r
+    gBS->LocateHandleBuffer (\r
+           ByProtocol,\r
+           &gEfiFirmwareVolume2ProtocolGuid,\r
+           NULL,\r
+           &FvHandleCount,\r
+           &FvHandleBuffer\r
+           );\r
+    for (Index = 0; Index < FvHandleCount; Index++) {\r
+      gBS->HandleProtocol (\r
+             FvHandleBuffer[Index],\r
+             &gEfiFirmwareVolume2ProtocolGuid,\r
+             (VOID **) &Fv\r
+             );\r
+\r
+      Status = Fv->ReadFile (\r
+                     Fv,\r
+                     FileGuid,\r
+                     NULL,\r
+                     &Size,\r
+                     &Type,\r
+                     &Attributes,\r
+                     &AuthenticationStatus\r
+                     );\r
+      if (EFI_ERROR (Status)) {\r
+        //\r
+        // Skip if input Fv file not in the FV\r
+        //\r
+        continue;\r
+      }\r
+      FindFvFile = TRUE;\r
+      FoundFvHandle = FvHandleBuffer[Index];\r
+      break;\r
+    }\r
+  }\r
+\r
+  if (FindFvFile) {\r
+    //\r
+    // Build the shell device path\r
+    //\r
+    NewDevicePath = DevicePathFromHandle (FoundFvHandle);\r
+    EfiInitializeFwVolDevicepathNode (&FvFileNode, FileGuid);\r
+    NewDevicePath = AppendDevicePathNode (NewDevicePath, (EFI_DEVICE_PATH_PROTOCOL *) &FvFileNode);\r
+    *DevicePath = NewDevicePath;\r
+    return EFI_SUCCESS;\r
+  }\r
+  return EFI_NOT_FOUND;\r
+}\r
+\r
+/**\r
+  Gets the data and size of a variable.\r
+\r
+  Read the EFI variable (VendorGuid/Name) and return a dynamically allocated\r
+  buffer, and the size of the buffer. If failure return NULL.\r
+\r
+  @param  Name                     String part of EFI variable name\r
+  @param  VendorGuid               GUID part of EFI variable name\r
+  @param  VariableSize             Returns the size of the EFI variable that was\r
+                                   read\r
+\r
+  @return Dynamically allocated memory that contains a copy of the EFI variable.\r
+          Caller is responsible freeing the buffer.\r
+  @retval NULL                     Variable was not read\r
+\r
+**/\r
+VOID *\r
+EFIAPI\r
+GetVariableAndSize (\r
+  IN  CHAR16              *Name,\r
+  IN  EFI_GUID            *VendorGuid,\r
+  OUT UINTN               *VariableSize\r
+  )\r
+{\r
+  EFI_STATUS  Status;\r
+  UINTN       BufferSize;\r
+  VOID        *Buffer;\r
+\r
+  Buffer = NULL;\r
+\r
+  //\r
+  // Pass in a zero size buffer to find the required buffer size.\r
+  //\r
+  BufferSize  = 0;\r
+  Status      = gRT->GetVariable (Name, VendorGuid, NULL, &BufferSize, Buffer);\r
+  if (Status == EFI_BUFFER_TOO_SMALL) {\r
+    //\r
+    // Allocate the buffer to return\r
+    //\r
+    Buffer = AllocateZeroPool (BufferSize);\r
+    if (Buffer == NULL) {\r
+      return NULL;\r
+    }\r
+    //\r
+    // Read variable into the allocated buffer.\r
+    //\r
+    Status = gRT->GetVariable (Name, VendorGuid, NULL, &BufferSize, Buffer);\r
+    if (EFI_ERROR (Status)) {\r
+      BufferSize = 0;\r
+    }\r
+  }\r
+\r
+  *VariableSize = BufferSize;\r
+  return Buffer;\r
+}\r
+\r
+/**\r
+  Connect to the handle to a device on the device path.\r
+\r
+  This function will create all handles associate with every device\r
+  path node. If the handle associate with one device path node can not\r
+  be created success, then still give one chance to do the dispatch,\r
+  which load the missing drivers if possible.\r
+\r
+  @param  DevicePathToConnect      The device path which will be connected, it can\r
+                                   be a multi-instance device path\r
+\r
+  @retval EFI_SUCCESS              All handles associate with every device path\r
+                                   node have been created\r
+  @retval EFI_OUT_OF_RESOURCES     There is no resource to create new handles\r
+  @retval EFI_NOT_FOUND            Create the handle associate with one device\r
+                                   path node failed\r
+\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+ConnectDevicePath (\r
+  IN EFI_DEVICE_PATH_PROTOCOL  *DevicePathToConnect\r
+  )\r
+{\r
+  EFI_STATUS                Status;\r
+  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;\r
+  EFI_DEVICE_PATH_PROTOCOL  *CopyOfDevicePath;\r
+  EFI_DEVICE_PATH_PROTOCOL  *Instance;\r
+  EFI_DEVICE_PATH_PROTOCOL  *RemainingDevicePath;\r
+  EFI_DEVICE_PATH_PROTOCOL  *Next;\r
+  EFI_HANDLE                Handle;\r
+  EFI_HANDLE                PreviousHandle;\r
+  UINTN                     Size;\r
+\r
+  if (DevicePathToConnect == NULL) {\r
+    return EFI_SUCCESS;\r
+  }\r
+\r
+  DevicePath        = DuplicateDevicePath (DevicePathToConnect);\r
+  CopyOfDevicePath  = DevicePath;\r
+  if (DevicePath == NULL) {\r
+    return EFI_OUT_OF_RESOURCES;\r
+  }\r
+\r
+  do {\r
+    //\r
+    // The outer loop handles multi instance device paths.\r
+    // Only console variables contain multiple instance device paths.\r
+    //\r
+    // After this call DevicePath points to the next Instance\r
+    //\r
+    Instance  = GetNextDevicePathInstance (&DevicePath, &Size);\r
+    ASSERT (Instance != NULL);\r
+\r
+    Next      = Instance;\r
+    while (!IsDevicePathEndType (Next)) {\r
+      Next = NextDevicePathNode (Next);\r
+    }\r
+\r
+    SetDevicePathEndNode (Next);\r
+\r
+    //\r
+    // Start the real work of connect with RemainingDevicePath\r
+    //\r
+    PreviousHandle = NULL;\r
+    do {\r
+      //\r
+      // Find the handle that best matches the Device Path. If it is only a\r
+      // partial match the remaining part of the device path is returned in\r
+      // RemainingDevicePath.\r
+      //\r
+      RemainingDevicePath = Instance;\r
+      Status              = gBS->LocateDevicePath (&gEfiDevicePathProtocolGuid, &RemainingDevicePath, &Handle);\r
+\r
+      if (!EFI_ERROR (Status)) {\r
+        if (Handle == PreviousHandle) {\r
+          //\r
+          // If no forward progress is made try invoking the Dispatcher.\r
+          // A new FV may have been added to the system an new drivers\r
+          // may now be found.\r
+          // Status == EFI_SUCCESS means a driver was dispatched\r
+          // Status == EFI_NOT_FOUND means no new drivers were dispatched\r
+          //\r
+          Status = gDS->Dispatch ();\r
+        }\r
+\r
+        if (!EFI_ERROR (Status)) {\r
+          PreviousHandle = Handle;\r
+          //\r
+          // Connect all drivers that apply to Handle and RemainingDevicePath,\r
+          // the Recursive flag is FALSE so only one level will be expanded.\r
+          //\r
+          // Do not check the connect status here, if the connect controller fail,\r
+          // then still give the chance to do dispatch, because partial\r
+          // RemainingDevicepath may be in the new FV\r
+          //\r
+          // 1. If the connect fails, RemainingDevicepath and handle will not\r
+          //    change, so next time will do the dispatch, then dispatch's status\r
+          //    will take effect\r
+          // 2. If the connect succeeds, the RemainingDevicepath and handle will\r
+          //    change, then avoid the dispatch, we have chance to continue the\r
+          //    next connection\r
+          //\r
+          gBS->ConnectController (Handle, NULL, RemainingDevicePath, FALSE);\r
+        }\r
+      }\r
+      //\r
+      // Loop until RemainingDevicePath is an empty device path\r
+      //\r
+    } while (!EFI_ERROR (Status) && !IsDevicePathEnd (RemainingDevicePath));\r
+\r
+  } while (DevicePath != NULL);\r
+\r
+  if (CopyOfDevicePath != NULL) {\r
+    FreePool (CopyOfDevicePath);\r
+  }\r
+  //\r
+  // All handle with DevicePath exists in the handle database\r
+  //\r
+  return Status;\r
+}\r
+\r
+/**\r
+  Free all the mapping database memory resource and initialize the mapping list entry.\r
+\r
+  @param  MappingDataBase          Mapping database list entry pointer\r
+\r
+  @retval EFI_SUCCESS              Mapping database successfully freed\r
+  @retval EFI_INVALID_PARAMETER    MappingDataBase is NULL\r
+\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+FreeMappingDatabase (\r
+  IN  OUT  LIST_ENTRY            *MappingDataBase\r
+  )\r
+{\r
+  LIST_ENTRY                  *OverrideItemListIndex;\r
+  LIST_ENTRY                  *ImageInfoListIndex;\r
+  PLATFORM_OVERRIDE_ITEM      *OverrideItem;\r
+  DRIVER_IMAGE_INFO           *DriverImageInfo;\r
+\r
+  if (MappingDataBase == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+\r
+  OverrideItemListIndex = GetFirstNode (MappingDataBase);\r
+  while (!IsNull (MappingDataBase, OverrideItemListIndex)) {\r
+    OverrideItem = CR(OverrideItemListIndex, PLATFORM_OVERRIDE_ITEM, Link, PLATFORM_OVERRIDE_ITEM_SIGNATURE);\r
+    //\r
+    // Free PLATFORM_OVERRIDE_ITEM.ControllerDevicePath[]\r
+    //\r
+    if (OverrideItem->ControllerDevicePath != NULL){\r
+      FreePool (OverrideItem->ControllerDevicePath);\r
+    }\r
+\r
+    ImageInfoListIndex = GetFirstNode (&OverrideItem->DriverInfoList);\r
+    while (!IsNull (&OverrideItem->DriverInfoList, ImageInfoListIndex)) {\r
+      //\r
+      // Free DRIVER_IMAGE_INFO.DriverImagePath[]\r
+      //\r
+      DriverImageInfo = CR(ImageInfoListIndex, DRIVER_IMAGE_INFO, Link, DRIVER_IMAGE_INFO_SIGNATURE);\r
+      if (DriverImageInfo->DriverImagePath != NULL) {\r
+        FreePool(DriverImageInfo->DriverImagePath);\r
+      }\r
+      //\r
+      // Free DRIVER_IMAGE_INFO itself\r
+      //\r
+      ImageInfoListIndex = GetNextNode (&OverrideItem->DriverInfoList, ImageInfoListIndex);\r
+      RemoveEntryList (&DriverImageInfo->Link);\r
+      FreePool (DriverImageInfo);\r
+    }\r
+    //\r
+    // Free PLATFORM_OVERRIDE_ITEM itself\r
+    //\r
+    OverrideItemListIndex = GetNextNode (MappingDataBase, OverrideItemListIndex);\r
+    RemoveEntryList (&OverrideItem->Link);\r
+    FreePool (OverrideItem);\r
+  }\r
+\r
+  InitializeListHead (MappingDataBase);\r
+  return EFI_SUCCESS;\r
+}\r
+\r
+\r
+/**\r
+  Create the mapping database according to variable.\r
+\r
+  Read the environment variable(s) that contain the override mappings from Controller Device Path to\r
+  a set of Driver Device Paths, and create the mapping database in memory with those variable info.\r
+  VariableLayout{\r
+  //\r
+  // NotEnd indicate whether the variable is the last one, and has no subsequent variable need to load.\r
+  // Each variable has MaximumVariableSize limitation, so we maybe need multiple variables to store\r
+  // large mapping infos.\r
+  // The variable(s) name rule is PlatDriOver, PlatDriOver1, PlatDriOver2, ....\r
+  //\r
+  UINT32                         NotEnd;               //Zero is the last one.\r
+  //\r
+  // The entry which contains the mapping that Controller Device Path to a set of Driver Device Paths\r
+  // There are often multi mapping entries in a variable.\r
+  //\r
+  UINT32                         SIGNATURE;            //SIGNATURE_32('p','d','o','i')\r
+  UINT32                         DriverNum;\r
+  EFI_DEVICE_PATH_PROTOCOL       ControllerDevicePath[];\r
+  EFI_DEVICE_PATH_PROTOCOL       DriverDevicePath[];\r
+  EFI_DEVICE_PATH_PROTOCOL       DriverDevicePath[];\r
+  EFI_DEVICE_PATH_PROTOCOL       DriverDevicePath[];\r
+  ......\r
+  UINT32                         NotEnd;                //Zero is the last one.\r
+  UINT32                         SIGNATURE;\r
+  UINT32                         DriverNum;\r
+  EFI_DEVICE_PATH_PROTOCOL       ControllerDevicePath[];\r
+  EFI_DEVICE_PATH_PROTOCOL       DriverDevicePath[];\r
+  EFI_DEVICE_PATH_PROTOCOL       DriverDevicePath[];\r
+  EFI_DEVICE_PATH_PROTOCOL       DriverDevicePath[];\r
+  ......\r
+  }\r
+\r
+  @param  MappingDataBase          Mapping database list entry pointer\r
+\r
+  @retval EFI_SUCCESS              Create the mapping database in memory successfully\r
+  @retval EFI_INVALID_PARAMETER    MappingDataBase pointer is null\r
+  @retval EFI_NOT_FOUND            Cannot find the 'PlatDriOver' NV variable\r
+  @retval EFI_VOLUME_CORRUPTED     The found NV variable is corrupted\r
+\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+InitOverridesMapping (\r
+  OUT  LIST_ENTRY            *MappingDataBase\r
+  )\r
+{\r
+  UINTN                       BufferSize;\r
+  VOID                        *VariableBuffer;\r
+  UINT8                       *VariableIndex;\r
+  UINTN                       VariableNum;\r
+  CHAR16                      OverrideVariableName[40];\r
+  UINT32                      NotEnd;\r
+  UINT32                      DriverNumber;\r
+  PLATFORM_OVERRIDE_ITEM      *OverrideItem;\r
+  DRIVER_IMAGE_INFO           *DriverImageInfo;\r
+  BOOLEAN                     Corrupted;\r
+  UINT32                      Signature;\r
+  EFI_DEVICE_PATH_PROTOCOL    *ControllerDevicePath;\r
+  EFI_DEVICE_PATH_PROTOCOL    *DriverDevicePath;\r
+  UINTN                       Index;\r
+\r
+  if (MappingDataBase == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+\r
+  //\r
+  // Check the environment variable(s) that contain the override mappings .\r
+  //\r
+  VariableBuffer = GetVariableAndSize (L"PlatDriOver", &gEfiCallerIdGuid, &BufferSize);\r
+  ASSERT ((UINTN) VariableBuffer % sizeof(UINTN) == 0);\r
+  if (VariableBuffer == NULL) {\r
+    return EFI_NOT_FOUND;\r
+  }\r
+\r
+  //\r
+  // Traverse all variables.\r
+  //\r
+  VariableNum = 1;\r
+  Corrupted = FALSE;\r
+  do {\r
+    VariableIndex = VariableBuffer;\r
+    //\r
+    // End flag\r
+    //\r
+    NotEnd = *(UINT32*) VariableIndex;\r
+    //\r
+    // Traverse the entries containing the mapping that Controller Device Path\r
+    // to a set of Driver Device Paths within this variable.\r
+    //\r
+    VariableIndex = VariableIndex + sizeof (UINT32);\r
+    while (VariableIndex < ((UINT8 *)VariableBuffer + BufferSize)) {\r
+      //\r
+      // Check signature of this entry\r
+      //\r
+      Signature = *(UINT32 *) VariableIndex;\r
+      if (Signature != PLATFORM_OVERRIDE_ITEM_SIGNATURE) {\r
+        Corrupted = TRUE;\r
+        break;\r
+      }\r
+      //\r
+      // Create PLATFORM_OVERRIDE_ITEM for this mapping\r
+      //\r
+      OverrideItem = AllocateZeroPool (sizeof (PLATFORM_OVERRIDE_ITEM));\r
+      ASSERT (OverrideItem != NULL);\r
+      OverrideItem->Signature = PLATFORM_OVERRIDE_ITEM_SIGNATURE;\r
+      InitializeListHead (&OverrideItem->DriverInfoList);\r
+      VariableIndex = VariableIndex + sizeof (UINT32);\r
+      //\r
+      // Get DriverNum\r
+      //\r
+      DriverNumber = *(UINT32*) VariableIndex;\r
+      OverrideItem->DriverInfoNum = DriverNumber;\r
+      VariableIndex = VariableIndex + sizeof (UINT32);\r
+      //\r
+      // Get ControllerDevicePath[]\r
+      //\r
+      ControllerDevicePath = (EFI_DEVICE_PATH_PROTOCOL *) VariableIndex;\r
+      OverrideItem->ControllerDevicePath = DuplicateDevicePath (ControllerDevicePath);\r
+      VariableIndex = VariableIndex + GetDevicePathSize (ControllerDevicePath);\r
+      //\r
+      // Align the VariableIndex since the controller device path may not be aligned, refer to the SaveOverridesMapping()\r
+      //\r
+      VariableIndex += ((sizeof(UINT32) - ((UINTN) (VariableIndex))) & (sizeof(UINT32) - 1));\r
+\r
+      //\r
+      // Get all DriverImageDevicePath[]\r
+      //\r
+      for (Index = 0; Index < DriverNumber; Index++) {\r
+        //\r
+        // Create DRIVER_IMAGE_INFO for this DriverDevicePath[]\r
+        //\r
+        DriverImageInfo = AllocateZeroPool (sizeof (DRIVER_IMAGE_INFO));\r
+        ASSERT (DriverImageInfo != NULL);\r
+        DriverImageInfo->Signature = DRIVER_IMAGE_INFO_SIGNATURE;\r
+\r
+        DriverDevicePath = (EFI_DEVICE_PATH_PROTOCOL *) VariableIndex;\r
+        DriverImageInfo->DriverImagePath = DuplicateDevicePath (DriverDevicePath);\r
+        VariableIndex = VariableIndex + GetDevicePathSize (DriverDevicePath);\r
+        //\r
+        // Align the VariableIndex since the driver image device path may not be aligned, refer to the SaveOverridesMapping()\r
+        //\r
+        VariableIndex += ((sizeof(UINT32) - ((UINTN) (VariableIndex))) & (sizeof(UINT32) - 1));\r
+\r
+        InsertTailList (&OverrideItem->DriverInfoList, &DriverImageInfo->Link);\r
+      }\r
+      InsertTailList (MappingDataBase, &OverrideItem->Link);\r
+    }\r
+\r
+    FreePool (VariableBuffer);\r
+    if (Corrupted) {\r
+      FreeMappingDatabase (MappingDataBase);\r
+      return EFI_VOLUME_CORRUPTED;\r
+    }\r
+\r
+    //\r
+    // If there are additional variables (PlatDriOver1, PlatDriOver2, PlatDriOver3.....), get them.\r
+    // NotEnd indicates whether current variable is the end variable.\r
+    //\r
+    if (NotEnd != 0) {\r
+      UnicodeSPrint (OverrideVariableName, sizeof (OverrideVariableName), L"PlatDriOver%d", VariableNum++);\r
+      VariableBuffer = GetVariableAndSize (OverrideVariableName, &gEfiCallerIdGuid, &BufferSize);\r
+      ASSERT ((UINTN) VariableBuffer % sizeof(UINTN) == 0);\r
+      if (VariableBuffer == NULL) {\r
+        FreeMappingDatabase (MappingDataBase);\r
+        return EFI_VOLUME_CORRUPTED;\r
+      }\r
+    }\r
+\r
+  } while (NotEnd != 0);\r
+\r
+  return EFI_SUCCESS;\r
+}\r
+\r
+\r
+/**\r
+  Calculate the needed size in NV variable for recording a specific PLATFORM_OVERRIDE_ITEM info.\r
+\r
+  @param  OverrideItemListIndex    Pointer to the list of a specific PLATFORM_OVERRIDE_ITEM\r
+\r
+  @return The needed size number\r
+\r
+**/\r
+UINTN\r
+EFIAPI\r
+GetOneItemNeededSize (\r
+  IN  LIST_ENTRY            *OverrideItemListIndex\r
+  )\r
+{\r
+  UINTN                       NeededSize;\r
+  PLATFORM_OVERRIDE_ITEM      *OverrideItem;\r
+  LIST_ENTRY                  *ImageInfoListIndex;\r
+  DRIVER_IMAGE_INFO           *DriverImageInfo;\r
+  UINTN                       DevicePathSize;\r
+\r
+  NeededSize = 0;\r
+  OverrideItem = CR(OverrideItemListIndex, PLATFORM_OVERRIDE_ITEM, Link, PLATFORM_OVERRIDE_ITEM_SIGNATURE);\r
+  NeededSize += sizeof (UINT32); //UINT32  SIGNATURE;\r
+  NeededSize += sizeof (UINT32); //UINT32  DriverNum;\r
+  DevicePathSize = GetDevicePathSize (OverrideItem->ControllerDevicePath);\r
+  NeededSize += DevicePathSize; // ControllerDevicePath\r
+  //\r
+  // Align the controller device path\r
+  //\r
+  NeededSize += ((sizeof(UINT32) - DevicePathSize) & (sizeof(UINT32) - 1));\r
+  //\r
+  // Traverse the Driver Info List of this Override Item\r
+  //\r
+  ImageInfoListIndex = GetFirstNode (&OverrideItem->DriverInfoList);\r
+  while (!IsNull (&OverrideItem->DriverInfoList, ImageInfoListIndex)) {\r
+    DriverImageInfo = CR(ImageInfoListIndex, DRIVER_IMAGE_INFO, Link, DRIVER_IMAGE_INFO_SIGNATURE);\r
+    DevicePathSize = GetDevicePathSize (DriverImageInfo->DriverImagePath);\r
+    NeededSize += DevicePathSize; //DriverDevicePath\r
+    //\r
+    // Align the driver image device path\r
+    //\r
+    NeededSize += ((sizeof(UINT32) - DevicePathSize) & (sizeof(UINT32) - 1));\r
+    ImageInfoListIndex = GetNextNode (&OverrideItem->DriverInfoList, ImageInfoListIndex);\r
+  }\r
+\r
+  return NeededSize;\r
+}\r
+\r
+/**\r
+  Deletes all environment variable(s) that contain the override mappings from Controller Device Path to\r
+  a set of Driver Device Paths.\r
+\r
+  @retval EFI_SUCCESS  Delete all variable(s) successfully.\r
+\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+DeleteOverridesVariables (\r
+  VOID\r
+  )\r
+{\r
+  EFI_STATUS                  Status;\r
+  VOID                        *VariableBuffer;\r
+  UINTN                       VariableNum;\r
+  UINTN                       BufferSize;\r
+  UINTN                       Index;\r
+  CHAR16                      OverrideVariableName[40];\r
+\r
+  //\r
+  // Get environment variable(s) number\r
+  //\r
+  VariableNum = 0;\r
+  VariableBuffer = GetVariableAndSize (L"PlatDriOver", &gEfiCallerIdGuid, &BufferSize);\r
+  VariableNum++;\r
+  if (VariableBuffer == NULL) {\r
+    return EFI_NOT_FOUND;\r
+  }\r
+  //\r
+  // Check NotEnd to get all PlatDriOverX variable(s)\r
+  //\r
+  while ((*(UINT32*)VariableBuffer) != 0) {\r
+    UnicodeSPrint (OverrideVariableName, sizeof (OverrideVariableName), L"PlatDriOver%d", VariableNum);\r
+    VariableBuffer = GetVariableAndSize (OverrideVariableName, &gEfiCallerIdGuid, &BufferSize);\r
+    VariableNum++;\r
+    ASSERT (VariableBuffer != NULL);\r
+  }\r
+\r
+  //\r
+  // Delete PlatDriOver and all additional variables, if exist.\r
+  //\r
+  Status = gRT->SetVariable (\r
+                  L"PlatDriOver",\r
+                  &gEfiCallerIdGuid,\r
+                  EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,\r
+                  0,\r
+                  NULL\r
+                  );\r
+  ASSERT (!EFI_ERROR (Status));\r
+  for (Index = 1; Index < VariableNum; Index++) {\r
+    UnicodeSPrint (OverrideVariableName, sizeof (OverrideVariableName), L"PlatDriOver%d", Index);\r
+    Status = gRT->SetVariable (\r
+                    OverrideVariableName,\r
+                    &gEfiCallerIdGuid,\r
+                    EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,\r
+                    0,\r
+                    NULL\r
+                    );\r
+    ASSERT (!EFI_ERROR (Status));\r
+  }\r
+  return EFI_SUCCESS;\r
+}\r
+\r
+\r
+/**\r
+  Save the memory mapping database into NV environment variable(s).\r
+\r
+  @param  MappingDataBase          Mapping database list entry pointer\r
+\r
+  @retval EFI_SUCCESS              Save memory mapping database successfully\r
+  @retval EFI_INVALID_PARAMETER    MappingDataBase pointer is null\r
+\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+SaveOverridesMapping (\r
+  IN  LIST_ENTRY              *MappingDataBase\r
+  )\r
+{\r
+  EFI_STATUS                  Status;\r
+  VOID                        *VariableBuffer;\r
+  UINT8                       *VariableIndex;\r
+  UINTN                       NumIndex;\r
+  CHAR16                      OverrideVariableName[40];\r
+  UINT32                      NotEnd;\r
+  PLATFORM_OVERRIDE_ITEM      *OverrideItem;\r
+  DRIVER_IMAGE_INFO           *DriverImageInfo;\r
+  LIST_ENTRY                  *OverrideItemListIndex;\r
+  LIST_ENTRY                  *ItemIndex;\r
+  LIST_ENTRY                  *ImageInfoListIndex;\r
+  UINTN                       VariableNeededSize;\r
+  UINT64                      MaximumVariableStorageSize;\r
+  UINT64                      RemainingVariableStorageSize;\r
+  UINT64                      MaximumVariableSize;\r
+  UINTN                       OneItemNeededSize;\r
+\r
+  if (MappingDataBase == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+\r
+  if (IsListEmpty (MappingDataBase)) {\r
+    Status = DeleteOverridesVariables ();\r
+    ASSERT_EFI_ERROR (Status);\r
+    return EFI_SUCCESS;\r
+  }\r
+\r
+  //\r
+  // Get the the maximum size of an individual EFI variable in current system\r
+  //\r
+  gRT->QueryVariableInfo (\r
+          EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,\r
+          &MaximumVariableStorageSize,\r
+          &RemainingVariableStorageSize,\r
+          &MaximumVariableSize\r
+          );\r
+\r
+  NumIndex = 0;\r
+  OverrideItemListIndex = GetFirstNode (MappingDataBase);\r
+  while (!IsNull (MappingDataBase, OverrideItemListIndex)) {\r
+    //\r
+    // Try to find the most proper variable size which <= MaximumVariableSize,\r
+    // but can contain mapping info as much as possible\r
+    //\r
+    VariableNeededSize = sizeof (UINT32); // NotEnd;\r
+    ItemIndex = OverrideItemListIndex;\r
+    NotEnd = FALSE;\r
+    //\r
+    // Traverse all PLATFORM_OVERRIDE_ITEMs and get the total size.\r
+    //\r
+    while (!IsNull (MappingDataBase, ItemIndex)) {\r
+      OneItemNeededSize = GetOneItemNeededSize (ItemIndex);\r
+      //\r
+      // If the total size exceeds the MaximumVariableSize, then we must use\r
+      // multiple variables.\r
+      //\r
+      if ((VariableNeededSize +\r
+           OneItemNeededSize +\r
+           sizeof (VARIABLE_HEADER) +\r
+           StrSize (L"PlatDriOver ")\r
+           ) >= MaximumVariableSize\r
+          ) {\r
+        NotEnd = TRUE;\r
+        break;\r
+      }\r
+\r
+      VariableNeededSize += OneItemNeededSize;\r
+      ItemIndex = GetNextNode (MappingDataBase, ItemIndex);\r
+    }\r
+\r
+    if (NotEnd != 0) {\r
+      if (VariableNeededSize == sizeof (UINT32)) {\r
+        //\r
+        // If an individual EFI variable cannot contain a single Item, return error\r
+        //\r
+        return EFI_OUT_OF_RESOURCES;\r
+      }\r
+    }\r
+\r
+    //\r
+    // VariableNeededSize is the most proper variable size, allocate variable buffer\r
+    // ItemIndex now points to the next PLATFORM_OVERRIDE_ITEM which is not covered by VariableNeededSize\r
+    //\r
+    VariableBuffer = AllocateZeroPool (VariableNeededSize);\r
+    ASSERT (VariableBuffer != NULL);\r
+    ASSERT ((UINTN) VariableBuffer % sizeof(UINTN) == 0);\r
+\r
+    //\r
+    // Fill the variable buffer according to MappingDataBase\r
+    //\r
+    VariableIndex = VariableBuffer;\r
+    *(UINT32 *) VariableIndex = NotEnd;\r
+    VariableIndex += sizeof (UINT32); // pass NotEnd\r
+    //\r
+    // ItemIndex points to the next PLATFORM_OVERRIDE_ITEM which is not covered by VariableNeededSize\r
+    //\r
+    while (OverrideItemListIndex != ItemIndex){\r
+      *(UINT32 *) VariableIndex = PLATFORM_OVERRIDE_ITEM_SIGNATURE;\r
+      VariableIndex += sizeof (UINT32); // pass SIGNATURE\r
+\r
+      OverrideItem = CR(OverrideItemListIndex, PLATFORM_OVERRIDE_ITEM, Link, PLATFORM_OVERRIDE_ITEM_SIGNATURE);\r
+      *(UINT32 *) VariableIndex = OverrideItem->DriverInfoNum;\r
+      VariableIndex += sizeof (UINT32); // pass DriverNum\r
+\r
+      CopyMem (VariableIndex, OverrideItem->ControllerDevicePath, GetDevicePathSize (OverrideItem->ControllerDevicePath));\r
+      VariableIndex += GetDevicePathSize (OverrideItem->ControllerDevicePath); // pass ControllerDevicePath\r
+\r
+      //\r
+      // Align the VariableIndex since the controller device path may not be aligned\r
+      //\r
+      VariableIndex += ((sizeof(UINT32) - ((UINTN) (VariableIndex))) & (sizeof(UINT32) - 1));\r
+      //\r
+      // Save the Driver Info List of this PLATFORM_OVERRIDE_ITEM\r
+      //\r
+      ImageInfoListIndex = GetFirstNode (&OverrideItem->DriverInfoList);\r
+      while (!IsNull (&OverrideItem->DriverInfoList, ImageInfoListIndex)) {\r
+        DriverImageInfo = CR(ImageInfoListIndex, DRIVER_IMAGE_INFO, Link, DRIVER_IMAGE_INFO_SIGNATURE);\r
+        CopyMem (VariableIndex, DriverImageInfo->DriverImagePath, GetDevicePathSize (DriverImageInfo->DriverImagePath));\r
+        VariableIndex += GetDevicePathSize (DriverImageInfo->DriverImagePath); // pass DriverImageDevicePath\r
+        //\r
+        // Align the VariableIndex since the driver image device path may not be aligned\r
+        //\r
+        VariableIndex += ((sizeof(UINT32) - ((UINTN) (VariableIndex))) & (sizeof(UINT32) - 1));\r
+        ImageInfoListIndex = GetNextNode (&OverrideItem->DriverInfoList, ImageInfoListIndex);\r
+      }\r
+\r
+      OverrideItemListIndex =  GetNextNode (MappingDataBase, OverrideItemListIndex);\r
+    }\r
+\r
+    ASSERT (((UINTN)VariableIndex - (UINTN)VariableBuffer) == VariableNeededSize);\r
+\r
+    if (NumIndex == 0) {\r
+      UnicodeSPrint (OverrideVariableName, sizeof (OverrideVariableName), L"PlatDriOver");\r
+    } else {\r
+      UnicodeSPrint (OverrideVariableName, sizeof (OverrideVariableName), L"PlatDriOver%d", NumIndex );\r
+    }\r
+\r
+    Status = gRT->SetVariable (\r
+                    OverrideVariableName,\r
+                    &gEfiCallerIdGuid,\r
+                    EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,\r
+                    VariableNeededSize,\r
+                    VariableBuffer\r
+                    );\r
+    ASSERT (!EFI_ERROR(Status));\r
+\r
+    NumIndex ++;\r
+    FreePool (VariableBuffer);\r
+  }\r
+\r
+  return EFI_SUCCESS;\r
+}\r
+\r
+/**\r
+  Get the first Binding protocol which has the specific image handle.\r
+\r
+  @param  ImageHandle          The Image handle\r
+  @param  BindingHandle        The BindingHandle of the found Driver Binding protocol.\r
+                               If Binding protocol is not found, it is set to NULL. \r
+\r
+  @return                      Pointer into the Binding Protocol interface\r
+  @retval NULL                 The paramter is not valid or the binding protocol is not found.\r
+\r
+**/\r
+EFI_DRIVER_BINDING_PROTOCOL *\r
+EFIAPI\r
+GetBindingProtocolFromImageHandle (\r
+  IN  EFI_HANDLE   ImageHandle,\r
+  OUT EFI_HANDLE   *BindingHandle\r
+  )\r
+{\r
+  EFI_STATUS                        Status;\r
+  UINTN                             Index;\r
+  UINTN                             DriverBindingHandleCount;\r
+  EFI_HANDLE                        *DriverBindingHandleBuffer;\r
+  EFI_DRIVER_BINDING_PROTOCOL       *DriverBindingInterface;\r
+\r
+  if (BindingHandle == NULL || ImageHandle == NULL) {\r
+    return NULL;\r
+  }\r
+  //\r
+  // Get all drivers which support driver binding protocol\r
+  //\r
+  DriverBindingHandleCount  = 0;\r
+  Status = gBS->LocateHandleBuffer (\r
+                  ByProtocol,\r
+                  &gEfiDriverBindingProtocolGuid,\r
+                  NULL,\r
+                  &DriverBindingHandleCount,\r
+                  &DriverBindingHandleBuffer\r
+                  );\r
+  if (EFI_ERROR (Status) || (DriverBindingHandleCount == 0)) {\r
+    return NULL;\r
+  }\r
+\r
+  for (Index = 0; Index < DriverBindingHandleCount; Index++) {\r
+    DriverBindingInterface = NULL;\r
+    Status = gBS->OpenProtocol (\r
+                    DriverBindingHandleBuffer[Index],\r
+                    &gEfiDriverBindingProtocolGuid,\r
+                    (VOID **) &DriverBindingInterface,\r
+                    NULL,\r
+                    NULL,\r
+                    EFI_OPEN_PROTOCOL_GET_PROTOCOL\r
+                    );\r
+    if (EFI_ERROR (Status)) {\r
+      continue;\r
+    }\r
+\r
+    if (DriverBindingInterface->ImageHandle == ImageHandle) {\r
+      *BindingHandle = DriverBindingHandleBuffer[Index];\r
+      FreePool (DriverBindingHandleBuffer);\r
+      return DriverBindingInterface;\r
+    }\r
+  }\r
+\r
+  //\r
+  // If no Driver Binding Protocol instance is found\r
+  //\r
+  FreePool (DriverBindingHandleBuffer);\r
+  *BindingHandle = NULL;\r
+  return NULL;\r
+}\r
+\r
+/**\r
+  Return the current TPL.\r
+\r
+  @return Current TPL\r
+\r
+**/\r
+EFI_TPL\r
+GetCurrentTpl (\r
+  VOID\r
+  )\r
+{\r
+  EFI_TPL                 Tpl;\r
+\r
+  Tpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
+  gBS->RestoreTPL (Tpl);\r
+\r
+  return Tpl;\r
+}\r
+\r
+\r
+/**\r
+  Retrieves the image handle of the platform override driver for a controller in\r
+  the system from the memory mapping database.\r
+\r
+  @param  ControllerHandle         The device handle of the controller to check if\r
+                                   a driver override exists.\r
+  @param  DriverImageHandle        On input, the previously returnd driver image handle.\r
+                                   On output, a pointer to the next driver handle.\r
+                                   Passing in a pointer to NULL, will return the\r
+                                   first driver handle for ControllerHandle.\r
+  @param  MappingDataBase          Mapping database list entry pointer\r
+  @param  CallerImageHandle        The caller driver's image handle, for\r
+                                   UpdateFvFileDevicePath use.\r
+\r
+  @retval EFI_INVALID_PARAMETER    The handle specified by ControllerHandle is not\r
+                                   a valid handle.  Or DriverImagePath is not a\r
+                                   device path that was returned on a previous call\r
+                                   to GetDriverPath().\r
+  @retval EFI_NOT_FOUND            A driver override for ControllerHandle was not\r
+                                   found.\r
+  @retval EFI_UNSUPPORTED          The operation is not supported.\r
+  @retval EFI_SUCCESS              The driver override for ControllerHandle was\r
+                                   returned in DriverImagePath.\r
+\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+GetDriverFromMapping (\r
+  IN     EFI_HANDLE                                     ControllerHandle,\r
+  IN OUT EFI_HANDLE                                     *DriverImageHandle,\r
+  IN     LIST_ENTRY                                     *MappingDataBase,\r
+  IN     EFI_HANDLE                                     CallerImageHandle\r
+  )\r
+{\r
+  EFI_STATUS                  Status;\r
+  EFI_DEVICE_PATH_PROTOCOL    *ControllerDevicePath;\r
+  BOOLEAN                     ControllerFound;\r
+  BOOLEAN                     ImageFound;\r
+  EFI_HANDLE                  *ImageHandleBuffer;\r
+  UINTN                       ImageHandleCount;\r
+  UINTN                       Index;\r
+  EFI_DRIVER_BINDING_PROTOCOL *DriverBinding;\r
+  EFI_HANDLE                  DriverBindingHandle;\r
+  BOOLEAN                     FoundLastReturned;\r
+  PLATFORM_OVERRIDE_ITEM      *OverrideItem;\r
+  DRIVER_IMAGE_INFO           *DriverImageInfo;\r
+  LIST_ENTRY                  *OverrideItemListIndex;\r
+  LIST_ENTRY                  *ImageInfoListIndex;\r
+  EFI_DEVICE_PATH_PROTOCOL    *TempDriverImagePath;\r
+  EFI_HANDLE                  ImageHandle;\r
+  EFI_HANDLE                  Handle;\r
+  EFI_DEVICE_PATH_PROTOCOL    *LoadedImageDevicePath;\r
+  EFI_BUS_SPECIFIC_DRIVER_OVERRIDE_PROTOCOL  *BusSpecificDriverOverride;\r
+  UINTN                       DevicePathSize;\r
+\r
+  //\r
+  // Check that ControllerHandle is a valid handle\r
+  //\r
+  if (ControllerHandle == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+  //\r
+  // Get the device path of ControllerHandle\r
+  //\r
+  Status = gBS->HandleProtocol (\r
+                  ControllerHandle,\r
+                  &gEfiDevicePathProtocolGuid,\r
+                  (VOID **) &ControllerDevicePath\r
+                  );\r
+  if (EFI_ERROR (Status) || ControllerDevicePath == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+\r
+  //\r
+  // Search ControllerDevicePath in MappingDataBase\r
+  //\r
+  OverrideItem = NULL;\r
+  ControllerFound = FALSE;\r
+  DevicePathSize = GetDevicePathSize (ControllerDevicePath);\r
+\r
+  OverrideItemListIndex = GetFirstNode (MappingDataBase);\r
+  while (!IsNull (MappingDataBase, OverrideItemListIndex)) {\r
+    OverrideItem = CR(OverrideItemListIndex, PLATFORM_OVERRIDE_ITEM, Link, PLATFORM_OVERRIDE_ITEM_SIGNATURE);\r
+    if (DevicePathSize == GetDevicePathSize (OverrideItem->ControllerDevicePath)) {\r
+      if (CompareMem (\r
+            ControllerDevicePath,\r
+            OverrideItem->ControllerDevicePath,\r
+            DevicePathSize\r
+            ) == 0\r
+          ) {\r
+        ControllerFound = TRUE;\r
+        break;\r
+      }\r
+    }\r
+    OverrideItemListIndex = GetNextNode (MappingDataBase, OverrideItemListIndex);\r
+  }\r
+\r
+  if (!ControllerFound) {\r
+    return EFI_NOT_FOUND;\r
+  }\r
+  //\r
+  // Passing in a pointer to NULL, will return the first driver device path for ControllerHandle.\r
+  // Check whether the driverImagePath is not a device path that was returned on a previous call to GetDriverPath().\r
+  //\r
+  if (*DriverImageHandle != NULL) {\r
+    if (*DriverImageHandle != OverrideItem->LastReturnedImageHandle) {\r
+      return EFI_INVALID_PARAMETER;\r
+    }\r
+  }\r
+  //\r
+  // The GetDriverPath() may be called recursively, because it use ConnectDevicePath() internally,\r
+  //  so should check whether there is a dead loop.\r
+  //  Here use a controller device path stack to record all processed controller device path during a GetDriverPath() call,\r
+  //  and check the controller device path whether appear again during the GetDriverPath() call.\r
+  //\r
+  if (CheckExistInStack (OverrideItem->ControllerDevicePath)) {\r
+    //\r
+    // There is a dependecy dead loop if the ControllerDevicePath appear in stack twice\r
+    //\r
+    return EFI_UNSUPPORTED;\r
+  }\r
+  PushDevPathStack (OverrideItem->ControllerDevicePath);\r
+\r
+  //\r
+  // Check every override driver, try to load and start them\r
+  //\r
+  ImageInfoListIndex = GetFirstNode (&OverrideItem->DriverInfoList);\r
+  while (!IsNull (&OverrideItem->DriverInfoList, ImageInfoListIndex)) {\r
+    DriverImageInfo = CR(ImageInfoListIndex, DRIVER_IMAGE_INFO, Link, DRIVER_IMAGE_INFO_SIGNATURE);\r
+    if (DriverImageInfo->ImageHandle == NULL) {\r
+      //\r
+      // Skip if the image is unloadable or unstartable\r
+      //\r
+      if ((!DriverImageInfo->UnLoadable) && ((!DriverImageInfo->UnStartable))) {\r
+        TempDriverImagePath = DriverImageInfo->DriverImagePath;\r
+        //\r
+        // If the image device path contains an FV node, check the FV file device path is valid.\r
+        // If it is invalid, try to return the valid device path.\r
+        // FV address maybe changes for memory layout adjust from time to time,\r
+        // use this funciton could promise the FV file device path is right.\r
+        //\r
+        Status = UpdateFvFileDevicePath (&TempDriverImagePath, NULL, CallerImageHandle);\r
+        if (!EFI_ERROR (Status)) {\r
+          FreePool (DriverImageInfo->DriverImagePath);\r
+          DriverImageInfo->DriverImagePath = TempDriverImagePath;\r
+        }\r
+        //\r
+        // Get all Loaded Image protocol to check whether the driver image has been loaded and started\r
+        //\r
+        ImageFound = FALSE;\r
+        ImageHandleCount  = 0;\r
+        Status = gBS->LocateHandleBuffer (\r
+                        ByProtocol,\r
+                        &gEfiLoadedImageProtocolGuid,\r
+                        NULL,\r
+                        &ImageHandleCount,\r
+                        &ImageHandleBuffer\r
+                        );\r
+        if (EFI_ERROR (Status) || (ImageHandleCount == 0)) {\r
+          return EFI_NOT_FOUND;\r
+        }\r
+\r
+        for(Index = 0; Index < ImageHandleCount; Index ++) {\r
+          //\r
+          // Get the EFI Loaded Image Device Path Protocol\r
+          //\r
+          LoadedImageDevicePath = NULL;\r
+          Status = gBS->HandleProtocol (\r
+                          ImageHandleBuffer[Index],\r
+                          &gEfiLoadedImageDevicePathProtocolGuid,\r
+                          (VOID **) &LoadedImageDevicePath\r
+                          );\r
+          if (EFI_ERROR (Status)) {\r
+            //\r
+            // Maybe not all EFI_LOADED_IMAGE_DEVICE_PATH_PROTOCOL existed.\r
+            //\r
+            continue;\r
+          }\r
+\r
+          DevicePathSize = GetDevicePathSize (DriverImageInfo->DriverImagePath);\r
+          if (DevicePathSize == GetDevicePathSize (LoadedImageDevicePath)) {\r
+            if (CompareMem (\r
+                  DriverImageInfo->DriverImagePath,\r
+                  LoadedImageDevicePath,\r
+                  GetDevicePathSize (LoadedImageDevicePath)\r
+                  ) == 0\r
+                ) {\r
+              ImageFound = TRUE;\r
+              break;\r
+            }\r
+          }\r
+        }\r
+\r
+        if (ImageFound) {\r
+          //\r
+          // Find its related driver binding protocol\r
+          // Driver binding handle may be different with its driver's Image Handle.\r
+          //\r
+          DriverBindingHandle = NULL;\r
+          DriverBinding = GetBindingProtocolFromImageHandle (\r
+                            ImageHandleBuffer[Index],\r
+                            &DriverBindingHandle\r
+                            );\r
+          ASSERT (DriverBinding != NULL);\r
+          DriverImageInfo->ImageHandle = ImageHandleBuffer[Index];\r
+        } else if (GetCurrentTpl() <= TPL_CALLBACK){\r
+          //\r
+          // The driver image has not been loaded and started. Try to load and start it now.\r
+          // Try to connect all device in the driver image path.\r
+          //\r
+          // Note: LoadImage() and  StartImage() should be called under CALLBACK TPL in theory, but\r
+          // since many device need to be connected in  CALLBACK level environment( e.g. Usb devices )\r
+          // and the Fat and Patition driver can endure executing in CALLBACK level in fact, so here permit\r
+          // to use LoadImage() and  StartImage() in CALLBACK TPL.\r
+          //\r
+          Status = ConnectDevicePath (DriverImageInfo->DriverImagePath);\r
+          //\r
+          // check whether it points to a PCI Option Rom image,\r
+          // and try to use bus override protocol to get its first option rom image driver\r
+          //\r
+          TempDriverImagePath = DriverImageInfo->DriverImagePath;\r
+          gBS->LocateDevicePath (&gEfiDevicePathProtocolGuid, &TempDriverImagePath, &Handle);\r
+          //\r
+          // Get the Bus Specific Driver Override Protocol instance on the Controller Handle\r
+          //\r
+          Status = gBS->HandleProtocol(\r
+                          Handle,\r
+                          &gEfiBusSpecificDriverOverrideProtocolGuid,\r
+                          (VOID **) &BusSpecificDriverOverride\r
+                          );\r
+          if (!EFI_ERROR (Status) && (BusSpecificDriverOverride != NULL)) {\r
+            ImageHandle = NULL;\r
+            Status = BusSpecificDriverOverride->GetDriver (\r
+                                                  BusSpecificDriverOverride,\r
+                                                  &ImageHandle\r
+                                                  );\r
+            if (!EFI_ERROR (Status)) {\r
+              //\r
+              // Find its related driver binding protocol\r
+              // Driver binding handle may be different with its driver's Image handle\r
+              //\r
+              DriverBindingHandle = NULL;\r
+              DriverBinding = GetBindingProtocolFromImageHandle (\r
+                                ImageHandle,\r
+                                &DriverBindingHandle\r
+                                );\r
+              ASSERT (DriverBinding != NULL);\r
+              DriverImageInfo->ImageHandle = ImageHandle;\r
+            }\r
+          }\r
+          //\r
+          // Skip if any device cannot be connected now, future passes through GetDriver() may be able to load that driver.\r
+          // Only file path media or FwVol Device Path Node remain if all device is connected\r
+          //\r
+          TempDriverImagePath = DriverImageInfo->DriverImagePath;\r
+          gBS->LocateDevicePath (&gEfiDevicePathProtocolGuid, &TempDriverImagePath, &Handle);\r
+          if (((DevicePathType (TempDriverImagePath) == MEDIA_DEVICE_PATH) &&\r
+               (DevicePathSubType (TempDriverImagePath) == MEDIA_FILEPATH_DP)) ||\r
+              (EfiGetNameGuidFromFwVolDevicePathNode ((MEDIA_FW_VOL_FILEPATH_DEVICE_PATH *) TempDriverImagePath) != NULL)\r
+             ) {\r
+            //\r
+            // Try to load the driver\r
+            //\r
+            TempDriverImagePath = DriverImageInfo->DriverImagePath;\r
+            Status = gBS->LoadImage (\r
+                            FALSE,\r
+                            CallerImageHandle,\r
+                            TempDriverImagePath,\r
+                            NULL,\r
+                            0,\r
+                            &ImageHandle\r
+                            );\r
+            if (!EFI_ERROR (Status)) {\r
+              //\r
+              // Try to start the driver\r
+              //\r
+              Status = gBS->StartImage (ImageHandle, NULL, NULL);\r
+              if (EFI_ERROR (Status)){\r
+                DriverImageInfo->UnStartable = TRUE;\r
+                DriverImageInfo->ImageHandle = NULL;\r
+              } else {\r
+                //\r
+                // Find its related driver binding protocol\r
+                // Driver binding handle may be different with its driver's Image handle\r
+                //\r
+                DriverBindingHandle = NULL;\r
+                DriverBinding = GetBindingProtocolFromImageHandle (\r
+                                   ImageHandle,\r
+                                   &DriverBindingHandle\r
+                                   );\r
+                ASSERT (DriverBinding != NULL);\r
+                DriverImageInfo->ImageHandle = ImageHandle;\r
+              }\r
+            } else {\r
+              DriverImageInfo->UnLoadable = TRUE;\r
+              DriverImageInfo->ImageHandle = NULL;\r
+            }\r
+          }\r
+        }\r
+        FreePool (ImageHandleBuffer);\r
+      }\r
+    }\r
+    ImageInfoListIndex = GetNextNode (&OverrideItem->DriverInfoList, ImageInfoListIndex);\r
+  }\r
+  //\r
+  // Finish try to load and start the override driver of a controller, popup the controller's device path\r
+  //\r
+  PopDevPathStack (NULL);\r
+\r
+  //\r
+  // return the DriverImageHandle for ControllerHandle\r
+  //\r
+  FoundLastReturned = FALSE;\r
+  ImageInfoListIndex = GetFirstNode (&OverrideItem->DriverInfoList);\r
+  while (!IsNull (&OverrideItem->DriverInfoList, ImageInfoListIndex)) {\r
+    DriverImageInfo = CR(ImageInfoListIndex, DRIVER_IMAGE_INFO, Link, DRIVER_IMAGE_INFO_SIGNATURE);\r
+    if (DriverImageInfo->ImageHandle != NULL) {\r
+      if ((*DriverImageHandle == NULL) || FoundLastReturned) {\r
+        //\r
+        // If DriverImageHandle is NULL, then we just need to return the first driver.\r
+        // If FoundLastReturned, this means we have just encountered the previously returned driver.\r
+        // For both cases, we just return the image handle of this driver.\r
+        //\r
+        OverrideItem->LastReturnedImageHandle = DriverImageInfo->ImageHandle;\r
+        *DriverImageHandle = DriverImageInfo->ImageHandle;\r
+        return EFI_SUCCESS;\r
+      } else if (*DriverImageHandle == DriverImageInfo->ImageHandle){\r
+        //\r
+        // We have found the previously returned driver.\r
+        //\r
+        FoundLastReturned = TRUE;\r
+      }\r
+    }\r
+    ImageInfoListIndex = GetNextNode (&OverrideItem->DriverInfoList, ImageInfoListIndex);\r
+  }\r
+\r
+  return EFI_NOT_FOUND;\r
+}\r
+\r
+\r
+/**\r
+  Check mapping database whether already has the mapping info which\r
+  records the input Controller to input DriverImage.\r
+\r
+  @param  ControllerDevicePath     The controller device path is to be check.\r
+  @param  DriverImageDevicePath    The driver image device path is to be check.\r
+  @param  MappingDataBase          Mapping database list entry pointer\r
+  @param  DriverInfoNum            the controller's total override driver number\r
+  @param  DriverImageNO            The driver order number for the input DriverImage.\r
+                                   If the DriverImageDevicePath is NULL, DriverImageNO is not set.\r
+\r
+  @retval EFI_INVALID_PARAMETER    ControllerDevicePath or MappingDataBase is NULL.\r
+  @retval EFI_NOT_FOUND            ControllerDevicePath is not found in MappingDataBase or\r
+                                   DriverImageDevicePath is not found in the found DriverImage Info list. \r
+  @retval EFI_SUCCESS              The controller's total override driver number and \r
+                                   input DriverImage's order number is correctly return.\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+CheckMapping (\r
+  IN     EFI_DEVICE_PATH_PROTOCOL                       *ControllerDevicePath,\r
+  IN     EFI_DEVICE_PATH_PROTOCOL                       *DriverImageDevicePath  OPTIONAL,\r
+  IN     LIST_ENTRY                                     *MappingDataBase,\r
+  OUT    UINT32                                         *DriverInfoNum  OPTIONAL,\r
+  OUT    UINT32                                         *DriverImageNO  OPTIONAL\r
+  )\r
+{\r
+  LIST_ENTRY                  *OverrideItemListIndex;\r
+  PLATFORM_OVERRIDE_ITEM      *OverrideItem;\r
+  LIST_ENTRY                  *ImageInfoListIndex;\r
+  DRIVER_IMAGE_INFO           *DriverImageInfo;\r
+  BOOLEAN                     Found;\r
+  UINT32                      ImageNO;\r
+  UINTN                       DevicePathSize;\r
+\r
+  if (ControllerDevicePath == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+  if (MappingDataBase == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+\r
+  //\r
+  // Search ControllerDevicePath in MappingDataBase\r
+  //\r
+  Found = FALSE;\r
+  OverrideItem = NULL;\r
+  OverrideItemListIndex = GetFirstNode (MappingDataBase);\r
+  while (!IsNull (MappingDataBase, OverrideItemListIndex)) {\r
+    OverrideItem = CR(OverrideItemListIndex, PLATFORM_OVERRIDE_ITEM, Link, PLATFORM_OVERRIDE_ITEM_SIGNATURE);\r
+    DevicePathSize = GetDevicePathSize (ControllerDevicePath);\r
+    if (DevicePathSize == GetDevicePathSize (OverrideItem->ControllerDevicePath)) {\r
+      if (CompareMem (\r
+            ControllerDevicePath,\r
+            OverrideItem->ControllerDevicePath,\r
+            DevicePathSize\r
+            ) == 0\r
+          ) {\r
+        Found = TRUE;\r
+        break;\r
+      }\r
+    }\r
+    OverrideItemListIndex = GetNextNode (MappingDataBase, OverrideItemListIndex);\r
+  }\r
+\r
+  if (!Found) {\r
+    //\r
+    // ControllerDevicePath is not in MappingDataBase\r
+    //\r
+    return EFI_NOT_FOUND;\r
+  }\r
+\r
+  ASSERT (OverrideItem->DriverInfoNum != 0);\r
+  if (DriverInfoNum != NULL) {\r
+    *DriverInfoNum = OverrideItem->DriverInfoNum;\r
+  }\r
+\r
+  //\r
+  // If DriverImageDevicePath is NULL, skip checking DriverImageDevicePath\r
+  // in the controller's Driver Image Info List\r
+  //\r
+  if (DriverImageDevicePath == NULL) {\r
+    return EFI_SUCCESS;\r
+  }\r
+  //\r
+  // return the DriverImageHandle for ControllerHandle\r
+  //\r
+  ImageNO = 0;\r
+  Found = FALSE;\r
+  ImageInfoListIndex = GetFirstNode (&OverrideItem->DriverInfoList);\r
+  while (!IsNull (&OverrideItem->DriverInfoList, ImageInfoListIndex)) {\r
+    DriverImageInfo = CR(ImageInfoListIndex, DRIVER_IMAGE_INFO, Link, DRIVER_IMAGE_INFO_SIGNATURE);\r
+    ImageNO++;\r
+    DevicePathSize = GetDevicePathSize (DriverImageDevicePath);\r
+    if (DevicePathSize == GetDevicePathSize (DriverImageInfo->DriverImagePath)) {\r
+      if (CompareMem (\r
+            DriverImageDevicePath,\r
+            DriverImageInfo->DriverImagePath,\r
+            GetDevicePathSize (DriverImageInfo->DriverImagePath)\r
+            ) == 0\r
+          ) {\r
+        Found = TRUE;\r
+        break;\r
+      }\r
+    }\r
+    ImageInfoListIndex = GetNextNode (&OverrideItem->DriverInfoList, ImageInfoListIndex);\r
+  }\r
+\r
+  if (!Found) {\r
+    //\r
+    // DriverImageDevicePath is not found in the controller's Driver Image Info List\r
+    //\r
+    return EFI_NOT_FOUND;\r
+  } else {\r
+    if (DriverImageNO != NULL) {\r
+      *DriverImageNO = ImageNO;\r
+    }\r
+    return EFI_SUCCESS;\r
+  }\r
+}\r
+\r
+\r
+/**\r
+  Insert a driver image as a controller's override driver into the mapping database.\r
+  The driver image's order number is indicated by DriverImageNO.\r
+\r
+  @param  ControllerDevicePath     The controller device path need to add a\r
+                                   override driver image item\r
+  @param  DriverImageDevicePath    The driver image device path need to be insert\r
+  @param  MappingDataBase          Mapping database list entry pointer\r
+  @param  DriverImageNO            The inserted order number. If this number is taken, \r
+                                   the larger available number will be used.\r
+\r
+  @retval EFI_INVALID_PARAMETER    ControllerDevicePath is NULL, or DriverImageDevicePath is NULL\r
+                                   or MappingDataBase is NULL\r
+  @retval EFI_ALREADY_STARTED      The input Controller to input DriverImage has been \r
+                                   recorded into the mapping database.\r
+  @retval EFI_SUCCESS              The Controller and DriverImage are inserted into \r
+                                   the mapping database successfully.\r
+\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+InsertDriverImage (\r
+  IN     EFI_DEVICE_PATH_PROTOCOL                       *ControllerDevicePath,\r
+  IN     EFI_DEVICE_PATH_PROTOCOL                       *DriverImageDevicePath,\r
+  IN     LIST_ENTRY                                     *MappingDataBase,\r
+  IN     UINT32                                         DriverImageNO\r
+  )\r
+{\r
+  EFI_STATUS                  Status;\r
+  LIST_ENTRY                  *OverrideItemListIndex;\r
+  PLATFORM_OVERRIDE_ITEM      *OverrideItem;\r
+  LIST_ENTRY                  *ImageInfoListIndex;\r
+  DRIVER_IMAGE_INFO           *DriverImageInfo;\r
+  BOOLEAN                     Found;\r
+  UINT32                      ImageNO;\r
+  UINTN                       DevicePathSize;\r
+\r
+  if (ControllerDevicePath == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+  if (DriverImageDevicePath == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+  if (MappingDataBase == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+\r
+  //\r
+  // If the driver is already in the controller's Driver Image Info List,\r
+  // just return EFI_ALREADY_STARTED.\r
+  //\r
+  Status = CheckMapping (\r
+             ControllerDevicePath,\r
+             DriverImageDevicePath,\r
+             MappingDataBase,\r
+             NULL,\r
+             NULL\r
+             );\r
+  if (Status == EFI_SUCCESS) {\r
+    return EFI_ALREADY_STARTED;\r
+  }\r
+\r
+  //\r
+  // Search the input ControllerDevicePath in MappingDataBase\r
+  //\r
+  Found = FALSE;\r
+  OverrideItem = NULL;\r
+  OverrideItemListIndex = GetFirstNode (MappingDataBase);\r
+  while (!IsNull (MappingDataBase, OverrideItemListIndex)) {\r
+    OverrideItem = CR(OverrideItemListIndex, PLATFORM_OVERRIDE_ITEM, Link, PLATFORM_OVERRIDE_ITEM_SIGNATURE);\r
+    DevicePathSize = GetDevicePathSize (ControllerDevicePath);\r
+    if (DevicePathSize == GetDevicePathSize (OverrideItem->ControllerDevicePath)) {\r
+      if (CompareMem (\r
+            ControllerDevicePath,\r
+            OverrideItem->ControllerDevicePath,\r
+            DevicePathSize\r
+            ) == 0\r
+          ) {\r
+        Found = TRUE;\r
+        break;\r
+      }\r
+    }\r
+    OverrideItemListIndex = GetNextNode (MappingDataBase, OverrideItemListIndex);\r
+  }\r
+  //\r
+  // If cannot find, this is a new controller item\r
+  // Add the Controller related PLATFORM_OVERRIDE_ITEM structrue in mapping data base\r
+  //\r
+  if (!Found) {\r
+    OverrideItem = AllocateZeroPool (sizeof (PLATFORM_OVERRIDE_ITEM));\r
+    ASSERT (OverrideItem != NULL);\r
+    OverrideItem->Signature = PLATFORM_OVERRIDE_ITEM_SIGNATURE;\r
+    OverrideItem->ControllerDevicePath = DuplicateDevicePath (ControllerDevicePath);\r
+    InitializeListHead (&OverrideItem->DriverInfoList);\r
+    InsertTailList (MappingDataBase, &OverrideItem->Link);\r
+  }\r
+\r
+  //\r
+  // Prepare the driver image related DRIVER_IMAGE_INFO structure.\r
+  //\r
+  DriverImageInfo = AllocateZeroPool (sizeof (DRIVER_IMAGE_INFO));\r
+  ASSERT (DriverImageInfo != NULL);\r
+  DriverImageInfo->Signature = DRIVER_IMAGE_INFO_SIGNATURE;\r
+  DriverImageInfo->DriverImagePath = DuplicateDevicePath (DriverImageDevicePath);\r
+  //\r
+  // Find the driver image wanted order location\r
+  //\r
+  ImageNO = 0;\r
+  Found = FALSE;\r
+  ImageInfoListIndex = GetFirstNode (&OverrideItem->DriverInfoList);\r
+  while (!IsNull (&OverrideItem->DriverInfoList, ImageInfoListIndex)) {\r
+    if (ImageNO == (DriverImageNO - 1)) {\r
+      //\r
+      // find the wanted order location, insert it\r
+      //\r
+      InsertTailList (ImageInfoListIndex, &DriverImageInfo->Link);\r
+      OverrideItem->DriverInfoNum ++;\r
+      Found = TRUE;\r
+      break;\r
+    }\r
+    ImageNO++;\r
+    ImageInfoListIndex = GetNextNode (&OverrideItem->DriverInfoList, ImageInfoListIndex);\r
+  }\r
+\r
+  if (!Found) {\r
+    //\r
+    // if not find the wanted order location, add it as last item of the controller mapping item\r
+    //\r
+    InsertTailList (&OverrideItem->DriverInfoList, &DriverImageInfo->Link);\r
+    OverrideItem->DriverInfoNum ++;\r
+  }\r
+\r
+  return EFI_SUCCESS;\r
+}\r
+\r
+\r
+/**\r
+  Delete a controller's override driver from the mapping database.\r
+\r
+  @param  ControllerDevicePath     The controller device path will be deleted \r
+                                   when all drivers images on it are removed.\r
+  @param  DriverImageDevicePath    The driver image device path will be delete.\r
+                                   If NULL, all driver image will be delete.\r
+  @param  MappingDataBase          Mapping database list entry pointer\r
+\r
+  @retval EFI_INVALID_PARAMETER    ControllerDevicePath is NULL, or MappingDataBase is NULL\r
+  @retval EFI_NOT_FOUND            ControllerDevicePath is not found in MappingDataBase or\r
+                                   DriverImageDevicePath is not found in the found DriverImage Info list. \r
+  @retval EFI_SUCCESS              Delete the specified driver successfully.\r
+\r
+**/\r
+EFI_STATUS\r
+EFIAPI\r
+DeleteDriverImage (\r
+  IN     EFI_DEVICE_PATH_PROTOCOL                       *ControllerDevicePath,\r
+  IN     EFI_DEVICE_PATH_PROTOCOL                       *DriverImageDevicePath,\r
+  IN     LIST_ENTRY                                     *MappingDataBase\r
+  )\r
+{\r
+  EFI_STATUS                  Status;\r
+  LIST_ENTRY                  *OverrideItemListIndex;\r
+  PLATFORM_OVERRIDE_ITEM      *OverrideItem;\r
+  LIST_ENTRY                  *ImageInfoListIndex;\r
+  DRIVER_IMAGE_INFO           *DriverImageInfo;\r
+  BOOLEAN                     Found;\r
+  UINTN                       DevicePathSize;\r
+\r
+  if (ControllerDevicePath == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+\r
+  if (MappingDataBase == NULL) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+\r
+  //\r
+  // If ControllerDevicePath is not found in mapping database, return EFI_NOT_FOUND.\r
+  //\r
+  Status = CheckMapping (\r
+             ControllerDevicePath,\r
+             DriverImageDevicePath,\r
+             MappingDataBase,\r
+             NULL,\r
+             NULL\r
+             );\r
+  if (EFI_ERROR (Status)) {\r
+    return EFI_NOT_FOUND;\r
+  }\r
+\r
+  //\r
+  // Search ControllerDevicePath in MappingDataBase\r
+  //\r
+  Found = FALSE;\r
+  OverrideItem = NULL;\r
+  OverrideItemListIndex = GetFirstNode (MappingDataBase);\r
+  while (!IsNull (MappingDataBase, OverrideItemListIndex)) {\r
+    OverrideItem = CR(OverrideItemListIndex, PLATFORM_OVERRIDE_ITEM, Link, PLATFORM_OVERRIDE_ITEM_SIGNATURE);\r
+    DevicePathSize = GetDevicePathSize (ControllerDevicePath);\r
+    if (DevicePathSize == GetDevicePathSize (OverrideItem->ControllerDevicePath)) {\r
+      if (CompareMem (\r
+            ControllerDevicePath,\r
+            OverrideItem->ControllerDevicePath,\r
+            DevicePathSize\r
+            ) == 0\r
+          ) {\r
+        Found = TRUE;\r
+        break;\r
+      }\r
+    }\r
+    OverrideItemListIndex = GetNextNode (MappingDataBase, OverrideItemListIndex);\r
+  }\r
+\r
+  ASSERT (Found);\r
+  ASSERT (OverrideItem->DriverInfoNum != 0);\r
+\r
+  Found = FALSE;\r
+  ImageInfoListIndex = GetFirstNode (&OverrideItem->DriverInfoList);\r
+  while (!IsNull (&OverrideItem->DriverInfoList, ImageInfoListIndex)) {\r
+    DriverImageInfo = CR(ImageInfoListIndex, DRIVER_IMAGE_INFO, Link, DRIVER_IMAGE_INFO_SIGNATURE);\r
+    ImageInfoListIndex = GetNextNode (&OverrideItem->DriverInfoList, ImageInfoListIndex);\r
+    if (DriverImageDevicePath != NULL) {\r
+      //\r
+      // Search for the specified DriverImageDevicePath and remove it, then break.\r
+      //\r
+      DevicePathSize = GetDevicePathSize (DriverImageDevicePath);\r
+      if (DevicePathSize == GetDevicePathSize (DriverImageInfo->DriverImagePath)) {\r
+        if (CompareMem (\r
+              DriverImageDevicePath,\r
+              DriverImageInfo->DriverImagePath,\r
+              GetDevicePathSize (DriverImageInfo->DriverImagePath)\r
+              ) == 0\r
+            ) {\r
+          Found = TRUE;\r
+          FreePool(DriverImageInfo->DriverImagePath);\r
+          RemoveEntryList (&DriverImageInfo->Link);\r
+          OverrideItem->DriverInfoNum --;\r
+          break;\r
+        }\r
+      }\r
+    } else {\r
+      //\r
+      // Remove all existing driver image info entries, so no break here.\r
+      //\r
+      Found = TRUE;\r
+      FreePool(DriverImageInfo->DriverImagePath);\r
+      RemoveEntryList (&DriverImageInfo->Link);\r
+      OverrideItem->DriverInfoNum --;\r
+    }\r
+  }\r
+\r
+  //\r
+  // Confirm all driver image info entries have been removed,\r
+  // if DriverImageDevicePath is NULL.\r
+  //\r
+  if (DriverImageDevicePath == NULL) {\r
+    ASSERT (OverrideItem->DriverInfoNum == 0);\r
+  }\r
+  //\r
+  // If Override Item has no driver image info entry, then delete this item.\r
+  //\r
+  if (OverrideItem->DriverInfoNum == 0) {\r
+    FreePool(OverrideItem->ControllerDevicePath);\r
+    RemoveEntryList (&OverrideItem->Link);\r
+    FreePool (OverrideItem);\r
+  }\r
+\r
+  if (!Found) {\r
+    //\r
+    // DriverImageDevicePath is not NULL and cannot be found in the controller's\r
+    // driver image info list.\r
+    //\r
+    return EFI_NOT_FOUND;\r
+  }\r
+\r
+  return EFI_SUCCESS;\r
+}\r