diff --git a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c
index 7308523ad8..d2224a20aa 100644
--- a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c
+++ b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c
@@ -1732,6 +1732,98 @@ CheckKeyboardConnect (
   }
 }
 
+/**
+   Disable NULL pointer detection
+*/
+VOID
+DisableNullDetection (
+  VOID
+  )
+{
+  EFI_STATUS                            Status;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR       Desc;
+
+  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0) {
+    return;
+  }
+
+  //
+  // Check current capabilities and attributes
+  //
+  Status = gDS->GetMemorySpaceDescriptor (0, &Desc);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Try to add EFI_MEMORY_RP support if necessary
+  //
+  if ((Desc.Capabilities & EFI_MEMORY_RP) == 0) {
+    Desc.Capabilities |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceCapabilities (0, EFI_PAGES_TO_SIZE(1),
+                                              Desc.Capabilities);
+    ASSERT_EFI_ERROR (Status);
+    if (EFI_ERROR (Status)) {
+      return;
+    }
+  }
+
+  //
+  // Don't bother if EFI_MEMORY_RP is already cleared.
+  //
+  if ((Desc.Attributes & EFI_MEMORY_RP) != 0) {
+    Desc.Attributes &= ~EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceAttributes (0, EFI_PAGES_TO_SIZE(1),
+                                            Desc.Attributes);
+    ASSERT_EFI_ERROR (Status);
+  } else {
+    DEBUG ((DEBUG_WARN, "!!! Page 0 is supposed to be disabled !!!\r\n"));
+  }
+}
+
+/**
+   Enable NULL pointer detection
+*/
+VOID
+EnableNullDetection (
+  VOID
+  )
+{
+  EFI_STATUS                            Status;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR       Desc;
+
+  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0) {
+    return;
+  }
+
+  //
+  // Check current capabilities and attributes
+  //
+  Status = gDS->GetMemorySpaceDescriptor (0, &Desc);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Try to add EFI_MEMORY_RP support if necessary
+  //
+  if ((Desc.Capabilities & EFI_MEMORY_RP) == 0) {
+    Desc.Capabilities |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceCapabilities (0, EFI_PAGES_TO_SIZE(1),
+                                              Desc.Capabilities);
+    ASSERT_EFI_ERROR (Status);
+    if (EFI_ERROR (Status)) {
+      return;
+    }
+  }
+
+  //
+  // Don't bother if EFI_MEMORY_RP is already set.
+  //
+  if ((Desc.Attributes & EFI_MEMORY_RP) == 0) {
+    Desc.Attributes |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceAttributes (0, EFI_PAGES_TO_SIZE(1),
+                                            Desc.Attributes);
+    ASSERT_EFI_ERROR (Status);
+  }
+}
+
 /**
   Timer event handler: read a series of key stroke from 8042
   and put them into memory key buffer. 
@@ -1839,6 +1931,11 @@ BiosKeyboardTimerHandler (
   //   0 Right Shift pressed
 
 
+  //
+  // Disable NULL pointer detection temporarily
+  //
+  DisableNullDetection ();
+
   //
   // Clear the CTRL and ALT BDA flag
   //
@@ -1916,6 +2013,10 @@ BiosKeyboardTimerHandler (
   KbFlag1 &= ~0x0C;                      
   *((UINT8 *) (UINTN) 0x417) = KbFlag1; 
 
+  //
+  // Restore NULL pointer detection
+  //
+  EnableNullDetection ();
   
   //
   // Output EFI input key and shift/toggle state
diff --git a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.h b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.h
index 0bf28ea140..c64ec0095e 100644
--- a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.h
+++ b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.h
@@ -18,6 +18,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 
 
 #include <FrameworkDxe.h>
+#include <Pi/PiDxeCis.h>
 
 #include <Guid/StatusCodeDataTypeId.h>
 #include <Protocol/SimpleTextIn.h>
@@ -33,6 +34,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #include <Library/ReportStatusCodeLib.h>
 #include <Library/UefiDriverEntryPoint.h>
 #include <Library/UefiBootServicesTableLib.h>
+#include <Library/DxeServicesTableLib.h>
 #include <Library/MemoryAllocationLib.h>
 #include <Library/BaseLib.h>
 #include <Library/PcdLib.h>
diff --git a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf
index 4d4536466c..596f4ced44 100644
--- a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf
+++ b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf
@@ -60,6 +60,7 @@
   DebugLib
   BaseLib
   PcdLib
+  DxeServicesTableLib
 
 [Protocols]
   gEfiIsaIoProtocolGuid                         ## TO_START
@@ -73,6 +74,7 @@
 
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdFastPS2Detection                  ## SOMETIMES_CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask  ## CONSUMES
 
 [UserExtensions.TianoCore."ExtraFiles"]
   KeyboardDxeExtra.uni
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBda.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBda.c
index c45d5d4c3e..c6670febee 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBda.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBda.c
@@ -34,6 +34,8 @@ LegacyBiosInitBda (
   BDA_STRUC *Bda;
   UINT8     *Ebda;
 
+  DisableNullDetection ();
+
   Bda   = (BDA_STRUC *) ((UINTN) 0x400);
   Ebda  = (UINT8 *) ((UINTN) 0x9fc00);
 
@@ -62,5 +64,7 @@ LegacyBiosInitBda (
 
   *Ebda               = 0x01;
 
+  EnableNullDetection ();
+
   return EFI_SUCCESS;
 }
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBios.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBios.c
index 3ead2d9828..3176a989f6 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBios.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBios.c
@@ -40,6 +40,7 @@ VOID                  *mRuntimeSmbiosEntryPoint = NULL;
 EFI_PHYSICAL_ADDRESS  mReserveSmbiosEntryPoint = 0;
 EFI_PHYSICAL_ADDRESS  mStructureTableAddress   = 0;
 UINTN                 mStructureTablePages     = 0;
+BOOLEAN               mEndOfDxe                = FALSE;
 
 /**
   Do an AllocatePages () of type AllocateMaxAddress for EfiBootServicesCode
@@ -765,6 +766,135 @@ InstallSmbiosEventCallback (
   }
 }
 
+/**
+  Callback function to toggle EndOfDxe status. NULL pointer detection needs
+  this status to decide if it's necessary to change attributes of page 0.
+
+  @param  Event            Event whose notification function is being invoked.
+  @param  Context          The pointer to the notification function's context,
+                           which is implementation-dependent.
+
+**/
+VOID
+EFIAPI
+ToggleEndOfDxeStatus (
+  IN EFI_EVENT                Event,
+  IN VOID                     *Context
+  )
+{
+  mEndOfDxe = TRUE;
+  return;
+}
+
+//
+// Legacy BIOS needs to access memory between 0-4095, which will cause page
+// fault exception if NULL pointer detection mechanism is enabled. Following
+// functions can be used to disable/enable NULL pointer detection before/after
+// accessing those memory.
+//
+
+/**
+   Enable NULL pointer detection
+*/
+VOID
+EnableNullDetection (
+  VOID
+  )
+{
+  EFI_STATUS                            Status;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR       Desc;
+
+  if (((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0)
+      ||
+      ((mEndOfDxe == TRUE)  &&
+       ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT7|BIT0))
+        == (BIT7|BIT0)))
+     ) {
+    return;
+  }
+
+  //
+  // Check current capabilities and attributes
+  //
+  Status = gDS->GetMemorySpaceDescriptor (0, &Desc);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Try to add EFI_MEMORY_RP support if necessary
+  //
+  if ((Desc.Capabilities & EFI_MEMORY_RP) == 0) {
+    Desc.Capabilities |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceCapabilities (0, EFI_PAGES_TO_SIZE(1),
+                                              Desc.Capabilities);
+    ASSERT_EFI_ERROR (Status);
+    if (EFI_ERROR (Status)) {
+      return;
+    }
+  }
+
+  //
+  // Don't bother if EFI_MEMORY_RP is already set.
+  //
+  if ((Desc.Attributes & EFI_MEMORY_RP) == 0) {
+    Desc.Attributes |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceAttributes (0, EFI_PAGES_TO_SIZE(1),
+                                            Desc.Attributes);
+    ASSERT_EFI_ERROR (Status);
+  }
+}
+
+/**
+   Disable NULL pointer detection
+*/
+VOID
+DisableNullDetection (
+  VOID
+  )
+{
+  EFI_STATUS                            Status;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR       Desc;
+
+  if (((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0)
+      ||
+      ((mEndOfDxe == TRUE)  &&
+       ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT7|BIT0))
+        == (BIT7|BIT0)))
+     ) {
+    return;
+  }
+
+  //
+  // Check current capabilities and attributes
+  //
+  Status = gDS->GetMemorySpaceDescriptor (0, &Desc);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Try to add EFI_MEMORY_RP support if necessary
+  //
+  if ((Desc.Capabilities & EFI_MEMORY_RP) == 0) {
+    Desc.Capabilities |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceCapabilities (0, EFI_PAGES_TO_SIZE(1),
+                                              Desc.Capabilities);
+    ASSERT_EFI_ERROR (Status);
+    if (EFI_ERROR (Status)) {
+      return;
+    }
+  }
+
+  //
+  // Don't bother if EFI_MEMORY_RP is already cleared.
+  //
+  if ((Desc.Attributes & EFI_MEMORY_RP) != 0) {
+    Desc.Attributes &= ~EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceAttributes (0, EFI_PAGES_TO_SIZE(1),
+                                            Desc.Attributes);
+    ASSERT_EFI_ERROR (Status);
+  } else {
+    DEBUG ((DEBUG_WARN, "!!! Page 0 is supposed to be disabled !!!\r\n"));
+  }
+}
+
 /**
   Install Driver to produce Legacy BIOS protocol.
 
@@ -802,6 +932,7 @@ LegacyBiosInstall (
   UINT64                             Length;
   UINT8                              *SecureBoot;
   EFI_EVENT                          InstallSmbiosEvent;
+  EFI_EVENT                          EndOfDxeEvent;
 
   //
   // Load this driver's image to memory
@@ -964,8 +1095,10 @@ LegacyBiosInstall (
   // Initialize region from 0x0000 to 4k. This initializes interrupt vector
   // range.
   //
+  DisableNullDetection ();
   gBS->SetMem ((VOID *) ClearPtr, 0x400, INITIAL_VALUE_BELOW_1K);
   ZeroMem ((VOID *) ((UINTN)ClearPtr + 0x400), 0xC00);
+  EnableNullDetection ();
 
   //
   // Allocate pages for OPROM usage
@@ -1104,12 +1237,17 @@ LegacyBiosInstall (
   //
   // Save Unexpected interrupt vector so can restore it just prior to boot
   //
+  DisableNullDetection ();
+
   BaseVectorMaster = (UINT32 *) (sizeof (UINT32) * PROTECTED_MODE_BASE_VECTOR_MASTER);
   Private->BiosUnexpectedInt = BaseVectorMaster[0];
   IntRedirCode = (UINT32) (UINTN) Private->IntThunk->InterruptRedirectionCode;
   for (Index = 0; Index < 8; Index++) {
     BaseVectorMaster[Index] = (EFI_SEGMENT (IntRedirCode + Index * 4) << 16) | EFI_OFFSET (IntRedirCode + Index * 4);
   }
+
+  EnableNullDetection ();
+
   //
   // Save EFI value
   //
@@ -1133,6 +1271,20 @@ LegacyBiosInstall (
                   );
   ASSERT_EFI_ERROR (Status);  
 
+  //
+  // Create callback to update status of EndOfDxe, which is needed by NULL
+  // pointer detection
+  //
+  Status = gBS->CreateEventEx (
+                  EVT_NOTIFY_SIGNAL,
+                  TPL_NOTIFY,
+                  ToggleEndOfDxeStatus,
+                  NULL,
+                  &gEfiEndOfDxeEventGroupGuid,
+                  &EndOfDxeEvent
+                  );
+  ASSERT_EFI_ERROR (Status);
+
   //
   // Make a new handle and install the protocol
   //
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosDxe.inf b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosDxe.inf
index 48473a0713..6efc7f36ae 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosDxe.inf
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosDxe.inf
@@ -108,6 +108,7 @@
   gEfiDiskInfoIdeInterfaceGuid                  ## SOMETIMES_CONSUMES ##GUID #Used in LegacyBiosBuildIdeData() to assure device is a disk
   gEfiSmbiosTableGuid                           ## SOMETIMES_CONSUMES ##SystemTable
   gEfiLegacyBiosGuid                            ## SOMETIMES_CONSUMES ##GUID #Used in LegacyBiosInstallVgaRom() to locate handle buffer
+  gEfiEndOfDxeEventGroupGuid                    ## CONSUMES
 
 [Guids.IA32]
   gEfiAcpi20TableGuid                           ## SOMETIMES_CONSUMES ##SystemTable
@@ -147,6 +148,7 @@
   gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdHighPmmMemorySize            ## CONSUMES
   gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdOpromReservedMemoryBase      ## CONSUMES
   gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdOpromReservedMemorySize      ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask        ## CONSUMES
 
 [Depex]
   gEfiLegacyRegion2ProtocolGuid AND gEfiLegacyInterruptProtocolGuid AND gEfiLegacyBiosPlatformProtocolGuid AND gEfiLegacy8259ProtocolGuid AND gEfiGenericMemTestProtocolGuid AND gEfiCpuArchProtocolGuid AND gEfiTimerArchProtocolGuid AND gEfiVariableWriteArchProtocolGuid
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosInterface.h b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosInterface.h
index fe9dd7463a..20dfef3fec 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosInterface.h
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosInterface.h
@@ -509,6 +509,8 @@ extern BBS_TABLE           *mBbsTable;
 
 extern EFI_GENERIC_MEMORY_TEST_PROTOCOL *gGenMemoryTest;
 
+extern BOOLEAN mEndOfDxe;
+
 #define PORT_70 0x70
 #define PORT_71 0x71
 
@@ -1542,4 +1544,20 @@ LegacyBiosInstallVgaRom (
   IN  LEGACY_BIOS_INSTANCE            *Private
   );
 
+/**
+   Enable NULL pointer detection
+*/
+VOID
+EnableNullDetection (
+  VOID
+  );
+
+/**
+   Disable NULL pointer detection
+*/
+VOID
+DisableNullDetection (
+  VOID
+  );
+
 #endif
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBootSupport.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBootSupport.c
index 1e098b3726..c2ac69ce69 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBootSupport.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBootSupport.c
@@ -1073,8 +1073,10 @@ GenericLegacyBoot (
   // Use 182/10 to avoid floating point math.
   //
   LocalTime = (LocalTime * 182) / 10;
+  DisableNullDetection ();
   BdaPtr    = (UINT32 *) (UINTN)0x46C;
   *BdaPtr   = LocalTime;
+  EnableNullDetection ();
 
   //
   // Shadow PCI ROMs. We must do this near the end since this will kick
@@ -1320,6 +1322,7 @@ GenericLegacyBoot (
     //          set of TIANO vectors) or takes it over.
     //
     //
+    DisableNullDetection ();
     BaseVectorMaster = (UINT32 *) (sizeof (UINT32) * PROTECTED_MODE_BASE_VECTOR_MASTER);
     for (Index = 0; Index < 8; Index++) {
       Private->ThunkSavedInt[Index] = BaseVectorMaster[Index];
@@ -1327,6 +1330,7 @@ GenericLegacyBoot (
         BaseVectorMaster[Index] = (UINT32) (Private->BiosUnexpectedInt);
       }
     }
+    EnableNullDetection ();
 
     ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));
     Regs.X.AX = Legacy16Boot;
@@ -1340,10 +1344,12 @@ GenericLegacyBoot (
       0
       );
 
+    DisableNullDetection ();
     BaseVectorMaster = (UINT32 *) (sizeof (UINT32) * PROTECTED_MODE_BASE_VECTOR_MASTER);
     for (Index = 0; Index < 8; Index++) {
       BaseVectorMaster[Index] = Private->ThunkSavedInt[Index];
     }
+    EnableNullDetection ();
   }
   Private->LegacyBootEntered = TRUE;
   if ((mBootMode == BOOT_LEGACY_OS) || (mBootMode == BOOT_UNCONVENTIONAL_DEVICE)) {
@@ -1731,9 +1737,11 @@ LegacyBiosBuildE820 (
   //
   // First entry is 0 to (640k - EBDA)
   //
+  DisableNullDetection ();
   E820Table[0].BaseAddr  = 0;
   E820Table[0].Length    = (UINT64) ((*(UINT16 *) (UINTN)0x40E) << 4);
   E820Table[0].Type      = EfiAcpiAddressRangeMemory;
+  EnableNullDetection ();
 
   //
   // Second entry is (640k - EBDA) to 640k
@@ -1967,6 +1975,8 @@ LegacyBiosCompleteBdaBeforeBoot (
   UINT16                      MachineConfig;
   DEVICE_PRODUCER_DATA_HEADER *SioPtr;
 
+  DisableNullDetection ();
+
   Bda           = (BDA_STRUC *) ((UINTN) 0x400);
   MachineConfig = 0;
 
@@ -2025,6 +2035,8 @@ LegacyBiosCompleteBdaBeforeBoot (
   MachineConfig       = (UINT16) (MachineConfig + 0x00 + 0x02 + (SioPtr->MousePresent * 0x04));
   Bda->MachineConfig  = MachineConfig;
 
+  EnableNullDetection ();
+
   return EFI_SUCCESS;
 }
 
@@ -2049,15 +2061,20 @@ LegacyBiosUpdateKeyboardLedStatus (
   UINT8                 LocalLeds;
   EFI_IA32_REGISTER_SET Regs;
 
-  Bda                 = (BDA_STRUC *) ((UINTN) 0x400);
-
   Private             = LEGACY_BIOS_INSTANCE_FROM_THIS (This);
+
+  DisableNullDetection ();
+
+  Bda                 = (BDA_STRUC *) ((UINTN) 0x400);
   LocalLeds           = Leds;
   Bda->LedStatus      = (UINT8) ((Bda->LedStatus &~0x07) | LocalLeds);
   LocalLeds           = (UINT8) (LocalLeds << 4);
   Bda->ShiftStatus    = (UINT8) ((Bda->ShiftStatus &~0x70) | LocalLeds);
   LocalLeds           = (UINT8) (Leds & 0x20);
   Bda->KeyboardStatus = (UINT8) ((Bda->KeyboardStatus &~0x20) | LocalLeds);
+
+  EnableNullDetection ();
+
   //
   // Call into Legacy16 code to allow it to do any processing
   //
@@ -2102,7 +2119,9 @@ LegacyBiosCompleteStandardCmosBeforeBoot (
   //            to large capacity drives
   // CMOS 14 = BDA 40:10 plus bit 3(display enabled)
   //
+  DisableNullDetection ();
   Bda = (UINT8)(*((UINT8 *)((UINTN)0x410)) | BIT3);
+  EnableNullDetection ();
 
   //
   // Force display enabled
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
index 8ffdf0c1ff..d38cef3e33 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
@@ -2279,6 +2279,7 @@ LegacyBiosInstallRom (
   UINTN                 Function;
   EFI_IA32_REGISTER_SET Regs;
   UINT8                 VideoMode;
+  UINT8                 OldVideoMode;
   EFI_TIME              BootTime;
   UINT32                *BdaPtr;
   UINT32                LocalTime;
@@ -2299,6 +2300,7 @@ LegacyBiosInstallRom (
   Device          = 0;
   Function        = 0;
   VideoMode       = 0;
+  OldVideoMode    = 0;
   PhysicalAddress = 0;
   MaxRomAddr      = PcdGet32 (PcdEndOpromShadowAddress);
 
@@ -2401,6 +2403,8 @@ LegacyBiosInstallRom (
   // 2. BBS compliants drives will not change 40:75 until boot time.
   // 3. Onboard IDE controllers will change 40:75
   //
+  DisableNullDetection ();
+
   LocalDiskStart = (UINT8) ((*(UINT8 *) ((UINTN) 0x475)) + 0x80);
   if ((Private->Disk4075 + 0x80) < LocalDiskStart) {
     //
@@ -2426,6 +2430,9 @@ LegacyBiosInstallRom (
     //
     VideoMode = *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE));
   }
+
+  EnableNullDetection ();
+
   //
   // Notify the platform that we are about to scan the ROM
   //
@@ -2466,9 +2473,11 @@ LegacyBiosInstallRom (
   // Multiply result by 18.2 for number of ticks since midnight.
   // Use 182/10 to avoid floating point math.
   //
+  DisableNullDetection ();
   LocalTime = (LocalTime * 182) / 10;
   BdaPtr    = (UINT32 *) ((UINTN) 0x46C);
   *BdaPtr   = LocalTime;
+  EnableNullDetection ();
   
   //
   // Pass in handoff data
@@ -2564,7 +2573,11 @@ LegacyBiosInstallRom (
     //
     // Set mode settings since PrepareToScanRom may change mode
     //
-    if (VideoMode != *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE))) {
+    DisableNullDetection ();
+    OldVideoMode = *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE));
+    EnableNullDetection ();
+
+    if (VideoMode != OldVideoMode) {
       //
       // The active video mode is changed, restore it to original mode.
       //
@@ -2604,7 +2617,9 @@ LegacyBiosInstallRom (
     }
   }
 
+  DisableNullDetection ();
   LocalDiskEnd = (UINT8) ((*(UINT8 *) ((UINTN) 0x475)) + 0x80);
+  EnableNullDetection ();
   
   //
   // Allow platform to perform any required actions after the
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
index 3d9a8b9649..f42c13cd89 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
@@ -57,7 +57,11 @@ LegacyBiosInt86 (
   IN  EFI_IA32_REGISTER_SET         *Regs
   )
 {
-  UINT32  *VectorBase;
+  UINT16                Segment;
+  UINT16                Offset;
+  LEGACY_BIOS_INSTANCE  *Private;
+
+  Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);
 
   Regs->X.Flags.Reserved1 = 1;
   Regs->X.Flags.Reserved2 = 0;
@@ -72,12 +76,15 @@ LegacyBiosInt86 (
   // The base address of legacy interrupt vector table is 0.
   // We use this base address to get the legacy interrupt handler.
   //
-  VectorBase              = 0;
+  DisableNullDetection ();
+  Segment               = (UINT16)(((UINT32 *)0)[BiosInt] >> 16);
+  Offset                = (UINT16)((UINT32 *)0)[BiosInt];
+  EnableNullDetection ();
   
   return InternalLegacyBiosFarCall (
            This,
-           (UINT16) ((VectorBase)[BiosInt] >> 16),
-           (UINT16) (VectorBase)[BiosInt],
+           Segment,
+           Offset,
            Regs,
            &Regs->X.Flags,
            sizeof (Regs->X.Flags)
@@ -293,9 +300,15 @@ InternalLegacyBiosFarCall (
       UINTN                 EbdaBaseAddress;
       UINTN                 ReservedEbdaBaseAddress;
 
-      EbdaBaseAddress = (*(UINT16 *) (UINTN) 0x40E) << 4;
-      ReservedEbdaBaseAddress = CONVENTIONAL_MEMORY_TOP - PcdGet32 (PcdEbdaReservedMemorySize);
-      ASSERT (ReservedEbdaBaseAddress <= EbdaBaseAddress);
+      //
+      // Skip this part of debug code if NULL pointer detection is enabled
+      //
+      if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0) {
+        EbdaBaseAddress = (*(UINT16 *) (UINTN) 0x40E) << 4;
+        ReservedEbdaBaseAddress = CONVENTIONAL_MEMORY_TOP
+                                  - PcdGet32 (PcdEbdaReservedMemorySize);
+        ASSERT (ReservedEbdaBaseAddress <= EbdaBaseAddress);
+      }
     }
   );