Update video card preference policy, together with some memory leaks in Generic BDS Library.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@2234 6f19259b-4bc3-4df7-8a09-765794883524

6 files changed, 374 insertions, 140 deletions

diff --git a/EdkNt32Pkg/Include/Library/EdkGenericBdsLib.h b/EdkNt32Pkg/Include/Library/EdkGenericBdsLib.h
index ed52085..7ec0222 100644
--- a/EdkNt32Pkg/Include/Library/EdkGenericBdsLib.h
+++ b/EdkNt32Pkg/Include/Library/EdkGenericBdsLib.h
@@ -246,6 +246,17 @@ BdsLibUnpackDevicePath (
   IN EFI_DEVICE_PATH_PROTOCOL  *DevPath

   );

 

+VOID

+BdsLibSafeFreePool (

+  IN  VOID             *Buffer

+  );

+

+EFI_DEVICE_PATH_PROTOCOL *

+BdsLibDelPartMatchInstance (

+  IN     EFI_DEVICE_PATH_PROTOCOL  *Multi,

+  IN     EFI_DEVICE_PATH_PROTOCOL  *Single

+  );

+

 BOOLEAN

 BdsLibMatchDevicePaths (

   IN  EFI_DEVICE_PATH_PROTOCOL  *Multi,

diff --git a/EdkNt32Pkg/Library/EdkGenericBdsLib/BdsConsole.c b/EdkNt32Pkg/Library/EdkGenericBdsLib/BdsConsole.c
index 721d743..6c9097f 100644
--- a/EdkNt32Pkg/Library/EdkGenericBdsLib/BdsConsole.c
+++ b/EdkNt32Pkg/Library/EdkGenericBdsLib/BdsConsole.c
@@ -19,6 +19,30 @@ Abstract:
 

 --*/

 

+BOOLEAN

+IsNvNeed (

+  IN CHAR16 *ConVarName

+  )

+{

+  CHAR16 *Ptr;

+  

+  Ptr = ConVarName;

+  

+  //

+  // If the variable includes "Dev" at last, we consider

+  // it does not support NV attribute.

+  //

+  while (*Ptr) {

+    Ptr++;

+  }

+  

+  if ((*(Ptr - 3) == 'D') && (*(Ptr - 2) == 'e') && (*(Ptr - 1) == 'v')) {

+    return FALSE;

+  } else {

+    return TRUE;

+  }

+}

+

 EFI_STATUS

 BdsLibUpdateConsoleVariable (

   IN  CHAR16                    *ConVarName,

@@ -56,12 +80,12 @@ Returns:
   EFI_STATUS                Status;

   EFI_DEVICE_PATH_PROTOCOL  *VarConsole;

   UINTN                     DevicePathSize;

-  EFI_DEVICE_PATH_PROTOCOL  *Instance;

   EFI_DEVICE_PATH_PROTOCOL  *NewDevicePath;

+  EFI_DEVICE_PATH_PROTOCOL  *TempNewDevicePath;

+  UINT32                    Attributes;

 

   VarConsole      = NULL;

   DevicePathSize  = 0;

-  NewDevicePath   = NULL;

   Status          = EFI_UNSUPPORTED;

 

   //

@@ -79,73 +103,70 @@ Returns:
                 &gEfiGlobalVariableGuid,

                 &DevicePathSize

                 );

-

+                

+  //

+  // Initialize NewDevicePath

+  //

+  NewDevicePath  = VarConsole;

+  

+  //

+  // If ExclusiveDevicePath is even the part of the instance in VarConsole, delete it.

+  // In the end, NewDevicePath is the final device path.

+  //

   if (ExclusiveDevicePath != NULL && VarConsole != NULL) {

-    if (BdsLibMatchDevicePaths (VarConsole, ExclusiveDevicePath)) {

-

-      Instance = GetNextDevicePathInstance (&VarConsole, &DevicePathSize);

-

-      while (VarConsole != NULL) {

-        if (CompareMem (

-              Instance,

-              ExclusiveDevicePath,

-              DevicePathSize - sizeof (EFI_DEVICE_PATH_PROTOCOL)

-              ) == 0) {

-          //

-          // Remove the match part

-          //

-          NewDevicePath = AppendDevicePathInstance (NewDevicePath, VarConsole);

-          break;

-        } else {

-          //

-          // Continue the next instance

-          //

-          NewDevicePath = AppendDevicePathInstance (NewDevicePath, Instance);

-        }

-

-        Instance = GetNextDevicePathInstance (&VarConsole, &DevicePathSize);

-      }

-      //

-      // Reset the console variable with new device path

-      //

-      gRT->SetVariable (

-            ConVarName,

-            &gEfiGlobalVariableGuid,

-            EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,

-            GetDevicePathSize (NewDevicePath),

-            NewDevicePath

-            );

-    }

+      NewDevicePath = BdsLibDelPartMatchInstance (VarConsole, ExclusiveDevicePath);

   }

   //

-  // Try to append customized device path

+  // Try to append customized device path to NewDevicePath.

   //

-  VarConsole = BdsLibGetVariableAndSize (

-                ConVarName,

-                &gEfiGlobalVariableGuid,

-                &DevicePathSize

-                );

-

   if (CustomizedConDevicePath != NULL) {

-    if (!BdsLibMatchDevicePaths (VarConsole, CustomizedConDevicePath)) {

+    if (!BdsLibMatchDevicePaths (NewDevicePath, CustomizedConDevicePath)) {

       //

-      // In the first check, the default console variable will be null,

-      // just append current customized device path

+      // Check if there is part of CustomizedConDevicePath in NewDevicePath, delete it.

       //

-      VarConsole = AppendDevicePathInstance (VarConsole, CustomizedConDevicePath);

-

+      NewDevicePath = BdsLibDelPartMatchInstance (NewDevicePath, CustomizedConDevicePath);

       //

-      // Update the variable of the default console

+      // In the first check, the default console variable will be null,

+      // just append current customized device path

       //

-      gRT->SetVariable (

-            ConVarName,

-            &gEfiGlobalVariableGuid,

-            EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,

-            GetDevicePathSize (VarConsole),

-            VarConsole

-            );

+      TempNewDevicePath = NewDevicePath;

+      NewDevicePath = AppendDevicePathInstance (NewDevicePath, CustomizedConDevicePath);

+      BdsLibSafeFreePool(TempNewDevicePath);

     }

   }

+  

+  //

+  // The attribute for ConInDev, ConOutDev and ErrOutDev does not include NV.

+  //

+  if (IsNvNeed(ConVarName)) {

+    //

+    // ConVarName has NV attribute.

+    //

+    Attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE;

+  } else {

+    //

+    // ConVarName does not have NV attribute.

+    //

+    Attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS;

+  }

+  

+  //

+  // Finally, Update the variable of the default console by NewDevicePath

+  //

+  gRT->SetVariable (

+        ConVarName,

+        &gEfiGlobalVariableGuid,

+        Attributes,

+        GetDevicePathSize (NewDevicePath),

+        NewDevicePath

+        );

+

+  if (VarConsole == NewDevicePath) {

+    BdsLibSafeFreePool(VarConsole);

+  } else {

+    BdsLibSafeFreePool(VarConsole);

+    BdsLibSafeFreePool(NewDevicePath);

+  }

 

   return EFI_SUCCESS;

 

@@ -201,7 +222,7 @@ Returns:
     return EFI_UNSUPPORTED;

   }

 

-  CopyOfDevicePath = DuplicateDevicePath (StartDevicePath);

+  CopyOfDevicePath = StartDevicePath;

   do {

     //

     // Check every instance of the console variable

@@ -226,7 +247,7 @@ Returns:
     } else {

       DeviceExist = TRUE;

     }

-

+    BdsLibSafeFreePool(Instance);

   } while (CopyOfDevicePath != NULL);

 

   gBS->FreePool (StartDevicePath);

@@ -289,6 +310,8 @@ Returns:
     BdsLibUpdateConsoleVariable (L"ConIn", ConDevicePath, NULL);

   }

 

+  BdsLibSafeFreePool(HandleBuffer);

+

   Status = gBS->LocateHandleBuffer (

                   ByProtocol,

                   &gEfiSimpleTextOutProtocolGuid,

@@ -305,6 +328,9 @@ Returns:
     BdsLibUpdateConsoleVariable (L"ConOut", ConDevicePath, NULL);

     BdsLibUpdateConsoleVariable (L"ErrOut", ConDevicePath, NULL);

   }

+

+  BdsLibSafeFreePool(HandleBuffer);

+

   //

   // Connect all console variables

   //

@@ -337,8 +363,6 @@ Returns:
 --*/

 {

   EFI_STATUS                Status;

-  EFI_DEVICE_PATH_PROTOCOL  *VarErrout;

-  UINTN                     DevicePathSize;

 

   //

   // Connect all default console variables

@@ -356,14 +380,7 @@ Returns:
   // Special treat the err out device, becaues the null

   // err out var is legal.

   //

-  VarErrout = BdsLibGetVariableAndSize (

-                L"ErrOut",

-                &gEfiGlobalVariableGuid,

-                &DevicePathSize

-                );

-  if (VarErrout != NULL) {

-    BdsLibConnectConsoleVariable (L"ErrOut");

-  }

+  BdsLibConnectConsoleVariable (L"ErrOut");

 

   return EFI_SUCCESS;

 

diff --git a/EdkNt32Pkg/Library/EdkGenericBdsLib/BdsMisc.c b/EdkNt32Pkg/Library/EdkGenericBdsLib/BdsMisc.c
index 908bc30..e7add07 100644
--- a/EdkNt32Pkg/Library/EdkGenericBdsLib/BdsMisc.c
+++ b/EdkNt32Pkg/Library/EdkGenericBdsLib/BdsMisc.c
@@ -651,6 +651,95 @@ Returns:
   return Buffer;

 }

 

+VOID

+BdsLibSafeFreePool (

+  IN  VOID             *Buffer

+  )

+/*++

+

+Routine Description:

+

+  Free pool safely.

+

+Arguments:

+  

+  Buffer          - The allocated pool entry to free

+

+Returns:

+

+  Pointer of the buffer allocated.

+

+--*/

+{

+  if (Buffer != NULL) {

+    gBS->FreePool (Buffer);

+    Buffer = NULL;

+  }

+}

+

+EFI_DEVICE_PATH_PROTOCOL *

+BdsLibDelPartMatchInstance (

+  IN     EFI_DEVICE_PATH_PROTOCOL  *Multi,

+  IN     EFI_DEVICE_PATH_PROTOCOL  *Single

+  )

+/*++

+

+Routine Description:

+

+  Delete the instance in Multi which matches partly with Single instance

+

+Arguments:

+

+  Multi        - A pointer to a multi-instance device path data structure.

+

+  Single       - A pointer to a single-instance device path data structure.

+

+Returns:

+

+  This function will remove the device path instances in Multi which partly 

+  match with the Single, and return the result device path. If there is no

+  remaining device path as a result, this function will return NULL.

+

+--*/

+{

+  EFI_DEVICE_PATH_PROTOCOL  *Instance;

+  EFI_DEVICE_PATH_PROTOCOL  *NewDevicePath;

+  EFI_DEVICE_PATH_PROTOCOL  *TempNewDevicePath;

+  UINTN                     InstanceSize;

+  UINTN                     SingleDpSize;  

+  UINTN                     Size; 

+  

+  NewDevicePath     = NULL;

+  TempNewDevicePath = NULL;

+

+  if (Multi == NULL || Single == NULL) {

+    return Multi;

+  }

+  

+  Instance        =  GetNextDevicePathInstance (&Multi, &InstanceSize);

+  SingleDpSize    =  GetDevicePathSize (Single) - END_DEVICE_PATH_LENGTH;

+  InstanceSize    -= END_DEVICE_PATH_LENGTH;

+

+  while (Instance != NULL) {

+

+    Size = (SingleDpSize < InstanceSize) ? SingleDpSize : InstanceSize;    

+        

+    if ((CompareMem (Instance, Single, Size) != 0)) {

+      //

+      // Append the device path instance which does not match with Single

+      //

+      TempNewDevicePath = NewDevicePath;

+      NewDevicePath = AppendDevicePathInstance (NewDevicePath, Instance);

+      BdsLibSafeFreePool(TempNewDevicePath);

+    }

+    BdsLibSafeFreePool(Instance);

+    Instance = GetNextDevicePathInstance (&Multi, &InstanceSize);

+    InstanceSize  -= END_DEVICE_PATH_LENGTH;

+  }

+  

+  return NewDevicePath;

+}

+

 BOOLEAN

 BdsLibMatchDevicePaths (

   IN  EFI_DEVICE_PATH_PROTOCOL  *Multi,

diff --git a/EdkUnixPkg/Include/Library/EdkGenericBdsLib.h b/EdkUnixPkg/Include/Library/EdkGenericBdsLib.h
index ed52085..7ec0222 100644
--- a/EdkUnixPkg/Include/Library/EdkGenericBdsLib.h
+++ b/EdkUnixPkg/Include/Library/EdkGenericBdsLib.h
@@ -246,6 +246,17 @@ BdsLibUnpackDevicePath (
   IN EFI_DEVICE_PATH_PROTOCOL  *DevPath

   );

 

+VOID

+BdsLibSafeFreePool (

+  IN  VOID             *Buffer

+  );

+

+EFI_DEVICE_PATH_PROTOCOL *

+BdsLibDelPartMatchInstance (

+  IN     EFI_DEVICE_PATH_PROTOCOL  *Multi,

+  IN     EFI_DEVICE_PATH_PROTOCOL  *Single

+  );

+

 BOOLEAN

 BdsLibMatchDevicePaths (

   IN  EFI_DEVICE_PATH_PROTOCOL  *Multi,

diff --git a/EdkUnixPkg/Library/EdkGenericBdsLib/BdsConsole.c b/EdkUnixPkg/Library/EdkGenericBdsLib/BdsConsole.c
index 721d743..6c9097f 100644
--- a/EdkUnixPkg/Library/EdkGenericBdsLib/BdsConsole.c
+++ b/EdkUnixPkg/Library/EdkGenericBdsLib/BdsConsole.c
@@ -19,6 +19,30 @@ Abstract:
 

 --*/

 

+BOOLEAN

+IsNvNeed (

+  IN CHAR16 *ConVarName

+  )

+{

+  CHAR16 *Ptr;

+  

+  Ptr = ConVarName;

+  

+  //

+  // If the variable includes "Dev" at last, we consider

+  // it does not support NV attribute.

+  //

+  while (*Ptr) {

+    Ptr++;

+  }

+  

+  if ((*(Ptr - 3) == 'D') && (*(Ptr - 2) == 'e') && (*(Ptr - 1) == 'v')) {

+    return FALSE;

+  } else {

+    return TRUE;

+  }

+}

+

 EFI_STATUS

 BdsLibUpdateConsoleVariable (

   IN  CHAR16                    *ConVarName,

@@ -56,12 +80,12 @@ Returns:
   EFI_STATUS                Status;

   EFI_DEVICE_PATH_PROTOCOL  *VarConsole;

   UINTN                     DevicePathSize;

-  EFI_DEVICE_PATH_PROTOCOL  *Instance;

   EFI_DEVICE_PATH_PROTOCOL  *NewDevicePath;

+  EFI_DEVICE_PATH_PROTOCOL  *TempNewDevicePath;

+  UINT32                    Attributes;

 

   VarConsole      = NULL;

   DevicePathSize  = 0;

-  NewDevicePath   = NULL;

   Status          = EFI_UNSUPPORTED;

 

   //

@@ -79,73 +103,70 @@ Returns:
                 &gEfiGlobalVariableGuid,

                 &DevicePathSize

                 );

-

+                

+  //

+  // Initialize NewDevicePath

+  //

+  NewDevicePath  = VarConsole;

+  

+  //

+  // If ExclusiveDevicePath is even the part of the instance in VarConsole, delete it.

+  // In the end, NewDevicePath is the final device path.

+  //

   if (ExclusiveDevicePath != NULL && VarConsole != NULL) {

-    if (BdsLibMatchDevicePaths (VarConsole, ExclusiveDevicePath)) {

-

-      Instance = GetNextDevicePathInstance (&VarConsole, &DevicePathSize);

-

-      while (VarConsole != NULL) {

-        if (CompareMem (

-              Instance,

-              ExclusiveDevicePath,

-              DevicePathSize - sizeof (EFI_DEVICE_PATH_PROTOCOL)

-              ) == 0) {

-          //

-          // Remove the match part

-          //

-          NewDevicePath = AppendDevicePathInstance (NewDevicePath, VarConsole);

-          break;

-        } else {

-          //

-          // Continue the next instance

-          //

-          NewDevicePath = AppendDevicePathInstance (NewDevicePath, Instance);

-        }

-

-        Instance = GetNextDevicePathInstance (&VarConsole, &DevicePathSize);

-      }

-      //

-      // Reset the console variable with new device path

-      //

-      gRT->SetVariable (

-            ConVarName,

-            &gEfiGlobalVariableGuid,

-            EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,

-            GetDevicePathSize (NewDevicePath),

-            NewDevicePath

-            );

-    }

+      NewDevicePath = BdsLibDelPartMatchInstance (VarConsole, ExclusiveDevicePath);

   }

   //

-  // Try to append customized device path

+  // Try to append customized device path to NewDevicePath.

   //

-  VarConsole = BdsLibGetVariableAndSize (

-                ConVarName,

-                &gEfiGlobalVariableGuid,

-                &DevicePathSize

-                );

-

   if (CustomizedConDevicePath != NULL) {

-    if (!BdsLibMatchDevicePaths (VarConsole, CustomizedConDevicePath)) {

+    if (!BdsLibMatchDevicePaths (NewDevicePath, CustomizedConDevicePath)) {

       //

-      // In the first check, the default console variable will be null,

-      // just append current customized device path

+      // Check if there is part of CustomizedConDevicePath in NewDevicePath, delete it.

       //

-      VarConsole = AppendDevicePathInstance (VarConsole, CustomizedConDevicePath);

-

+      NewDevicePath = BdsLibDelPartMatchInstance (NewDevicePath, CustomizedConDevicePath);

       //

-      // Update the variable of the default console

+      // In the first check, the default console variable will be null,

+      // just append current customized device path

       //

-      gRT->SetVariable (

-            ConVarName,

-            &gEfiGlobalVariableGuid,

-            EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,

-            GetDevicePathSize (VarConsole),

-            VarConsole

-            );

+      TempNewDevicePath = NewDevicePath;

+      NewDevicePath = AppendDevicePathInstance (NewDevicePath, CustomizedConDevicePath);

+      BdsLibSafeFreePool(TempNewDevicePath);

     }

   }

+  

+  //

+  // The attribute for ConInDev, ConOutDev and ErrOutDev does not include NV.

+  //

+  if (IsNvNeed(ConVarName)) {

+    //

+    // ConVarName has NV attribute.

+    //

+    Attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE;

+  } else {

+    //

+    // ConVarName does not have NV attribute.

+    //

+    Attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS;

+  }

+  

+  //

+  // Finally, Update the variable of the default console by NewDevicePath

+  //

+  gRT->SetVariable (

+        ConVarName,

+        &gEfiGlobalVariableGuid,

+        Attributes,

+        GetDevicePathSize (NewDevicePath),

+        NewDevicePath

+        );

+

+  if (VarConsole == NewDevicePath) {

+    BdsLibSafeFreePool(VarConsole);

+  } else {

+    BdsLibSafeFreePool(VarConsole);

+    BdsLibSafeFreePool(NewDevicePath);

+  }

 

   return EFI_SUCCESS;

 

@@ -201,7 +222,7 @@ Returns:
     return EFI_UNSUPPORTED;

   }

 

-  CopyOfDevicePath = DuplicateDevicePath (StartDevicePath);

+  CopyOfDevicePath = StartDevicePath;

   do {

     //

     // Check every instance of the console variable

@@ -226,7 +247,7 @@ Returns:
     } else {

       DeviceExist = TRUE;

     }

-

+    BdsLibSafeFreePool(Instance);

   } while (CopyOfDevicePath != NULL);

 

   gBS->FreePool (StartDevicePath);

@@ -289,6 +310,8 @@ Returns:
     BdsLibUpdateConsoleVariable (L"ConIn", ConDevicePath, NULL);

   }

 

+  BdsLibSafeFreePool(HandleBuffer);

+

   Status = gBS->LocateHandleBuffer (

                   ByProtocol,

                   &gEfiSimpleTextOutProtocolGuid,

@@ -305,6 +328,9 @@ Returns:
     BdsLibUpdateConsoleVariable (L"ConOut", ConDevicePath, NULL);

     BdsLibUpdateConsoleVariable (L"ErrOut", ConDevicePath, NULL);

   }

+

+  BdsLibSafeFreePool(HandleBuffer);

+

   //

   // Connect all console variables

   //

@@ -337,8 +363,6 @@ Returns:
 --*/

 {

   EFI_STATUS                Status;

-  EFI_DEVICE_PATH_PROTOCOL  *VarErrout;

-  UINTN                     DevicePathSize;

 

   //

   // Connect all default console variables

@@ -356,14 +380,7 @@ Returns:
   // Special treat the err out device, becaues the null

   // err out var is legal.

   //

-  VarErrout = BdsLibGetVariableAndSize (

-                L"ErrOut",

-                &gEfiGlobalVariableGuid,

-                &DevicePathSize

-                );

-  if (VarErrout != NULL) {

-    BdsLibConnectConsoleVariable (L"ErrOut");

-  }

+  BdsLibConnectConsoleVariable (L"ErrOut");

 

   return EFI_SUCCESS;

 

diff --git a/EdkUnixPkg/Library/EdkGenericBdsLib/BdsMisc.c b/EdkUnixPkg/Library/EdkGenericBdsLib/BdsMisc.c
index 6b4d1aa..2662ba7 100644
--- a/EdkUnixPkg/Library/EdkGenericBdsLib/BdsMisc.c
+++ b/EdkUnixPkg/Library/EdkGenericBdsLib/BdsMisc.c
@@ -652,6 +652,95 @@ Returns:
   return Buffer;

 }

 

+VOID

+BdsLibSafeFreePool (

+  IN  VOID             *Buffer

+  )

+/*++

+

+Routine Description:

+

+  Free pool safely.

+

+Arguments:

+  

+  Buffer          - The allocated pool entry to free

+

+Returns:

+

+  Pointer of the buffer allocated.

+

+--*/

+{

+  if (Buffer != NULL) {

+    gBS->FreePool (Buffer);

+    Buffer = NULL;

+  }

+}

+

+EFI_DEVICE_PATH_PROTOCOL *

+BdsLibDelPartMatchInstance (

+  IN     EFI_DEVICE_PATH_PROTOCOL  *Multi,

+  IN     EFI_DEVICE_PATH_PROTOCOL  *Single

+  )

+/*++

+

+Routine Description:

+

+  Delete the instance in Multi which matches partly with Single instance

+

+Arguments:

+

+  Multi        - A pointer to a multi-instance device path data structure.

+

+  Single       - A pointer to a single-instance device path data structure.

+

+Returns:

+

+  This function will remove the device path instances in Multi which partly 

+  match with the Single, and return the result device path. If there is no

+  remaining device path as a result, this function will return NULL.

+

+--*/

+{

+  EFI_DEVICE_PATH_PROTOCOL  *Instance;

+  EFI_DEVICE_PATH_PROTOCOL  *NewDevicePath;

+  EFI_DEVICE_PATH_PROTOCOL  *TempNewDevicePath;

+  UINTN                     InstanceSize;

+  UINTN                     SingleDpSize;  

+  UINTN                     Size; 

+  

+  NewDevicePath     = NULL;

+  TempNewDevicePath = NULL;

+

+  if (Multi == NULL || Single == NULL) {

+    return Multi;

+  }

+  

+  Instance        =  GetNextDevicePathInstance (&Multi, &InstanceSize);

+  SingleDpSize    =  GetDevicePathSize (Single) - END_DEVICE_PATH_LENGTH;

+  InstanceSize    -= END_DEVICE_PATH_LENGTH;

+

+  while (Instance != NULL) {

+

+    Size = (SingleDpSize < InstanceSize) ? SingleDpSize : InstanceSize;    

+        

+    if ((CompareMem (Instance, Single, Size) != 0)) {

+      //

+      // Append the device path instance which does not match with Single

+      //

+      TempNewDevicePath = NewDevicePath;

+      NewDevicePath = AppendDevicePathInstance (NewDevicePath, Instance);

+      BdsLibSafeFreePool(TempNewDevicePath);

+    }

+    BdsLibSafeFreePool(Instance);

+    Instance = GetNextDevicePathInstance (&Multi, &InstanceSize);

+    InstanceSize  -= END_DEVICE_PATH_LENGTH;

+  }

+  

+  return NewDevicePath;

+}

+

 BOOLEAN

 BdsLibMatchDevicePaths (

   IN  EFI_DEVICE_PATH_PROTOCOL  *Multi,