1) Use FeatureFlag PcdPciBusHotplugDeviceSupport to merge LightPciLib.c with PcdLib.c.

2) Correct some minor bugs: when invoking gRT->GetVariable the Attributes field can be optianal.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@2090 6f19259b-4bc3-4df7-8a09-765794883524

EdkModulePkg/Bus/Pci/IdeBus/Dxe/DriverConfiguration.c

@@ -161,7 +161,6 @@ IDEBusDriverConfigurationSetOptions (
   UINT8       NewValue;
   UINTN       DataSize;
   UINTN       Index;
-  UINT32      Attributes;
 
   if (ChildHandle != NULL) {
     return EFI_UNSUPPORTED;
@@ -173,7 +172,7 @@ IDEBusDriverConfigurationSetOptions (
   Status = gRT->GetVariable (
                   L"Configuration",
                   &gEfiCallerIdGuid,
-                  &Attributes,
+                  NULL,
                   &DataSize,
                   &Value
                   );
@@ -255,7 +254,6 @@ IDEBusDriverConfigurationOptionsValid (
   EFI_STATUS  Status;
   UINT8       Value;
   UINTN       DataSize;
-  UINT32      Attributes;
 
   if (ChildHandle != NULL) {
     return EFI_UNSUPPORTED;
@@ -265,7 +263,7 @@ IDEBusDriverConfigurationOptionsValid (
   Status = gRT->GetVariable (
                   L"Configuration",
                   &gEfiCallerIdGuid,
-                  &Attributes,
+                  NULL,
                   &DataSize,
                   &Value
                   );

EdkModulePkg/Bus/Pci/IdeBus/Dxe/idebus.c

@@ -181,7 +181,6 @@ IDEBusDriverBindingStart (
   UINT16                            CommandBlockBaseAddr;
   UINT16                            ControlBlockBaseAddr;
   UINTN                             DataSize;
-  UINT32                            Attributes;
   IDE_BUS_DRIVER_PRIVATE_DATA       *IdeBusDriverPrivateData;
 
   //
@@ -316,7 +315,7 @@ IDEBusDriverBindingStart (
   Status = gRT->GetVariable (
                   (CHAR16 *) L"Configuration",
                   &gEfiCallerIdGuid,
-                  &Attributes,
+                  NULL,
                   &DataSize,
                   &ConfigurationOptions
                   );

EdkModulePkg/Bus/Pci/PciBus/Dxe/PciBus.msa

@@ -7,11 +7,8 @@
     <Version>1.0</Version>
     <Abstract>Component description file for PciBus module.</Abstract>
     <Description>PCI bus driver. This module will probe all PCI devices and allocate MMIO and IO
-       space for these devices.
+       space for these devices. Please use PCD feature flag PcdPciBusHotplugDeviceSupport to enable
-       LightPcdLib.c tagged with "ToolCode="DUMMY"" is light weight verison for PCI library
+       support hot plug.</Description>
-       function. This version provide simple implementation and do not support hot plug. Only one
-       between PcdLib.c and LightPcdLib.c can be choosed. 
-    </Description>
     <Copyright>Copyright (c) 2006, Intel Corporation</Copyright>
     <License>All rights reserved. This program and the accompanying materials
       are licensed and made available under the terms and conditions of the BSD License
@@ -93,7 +90,6 @@
     <Filename>pcibus.c</Filename>
     <Filename>PciIo.c</Filename>
     <Filename>PciLib.c</Filename>
-    <Filename ToolCode="DUMMY">LightPciLib.c</Filename>
   </SourceFiles>
   <PackageDependencies>
     <Package PackageGuid="5e0e9358-46b6-4ae2-8218-4ab8b9bbdcec"/>
@@ -178,5 +174,11 @@
       <TokenSpaceGuidCName>gEfiGenericPlatformTokenSpaceGuid</TokenSpaceGuidCName>
       <HelpText>Whether VGA decoding is enabled on this platform so we should avoid those aliased resources</HelpText>
     </PcdEntry>
+    <PcdEntry PcdItemType="FEATURE_FLAG" Usage="ALWAYS_CONSUMED">
+      <C_Name>PcdPciBusHotplugDeviceSupport</C_Name>
+      <TokenSpaceGuidCName>gEfiGenericPlatformTokenSpaceGuid</TokenSpaceGuidCName>
+      <DefaultValue>TRUE</DefaultValue>
+      <HelpText>If TRUE, the PCI bus driver will support hot plug device. If not hot plug device is supported, this feature flag can be set to FALSE to save size.</HelpText>
+    </PcdEntry>
   </PcdCoded>
 </ModuleSurfaceArea>

EdkModulePkg/Bus/Pci/PciBus/Dxe/PciLib.c

@@ -25,7 +25,7 @@ Revision History
 
 #include "pcibus.h"
 
-EFI_PCI_HOTPLUG_REQUEST_PROTOCOL gPciHotPlugRequest = {
+GLOBAL_REMOVE_IF_UNREFERENCED EFI_PCI_HOTPLUG_REQUEST_PROTOCOL gPciHotPlugRequest = {
   PciHotPlugRequestNotify
 };
 
@@ -49,6 +49,10 @@ Returns:
 {
   EFI_HANDLE  Handle;
 
+  if (!FeaturePcdGet (PcdPciBusHotplugDeviceSupport)) {
+    return;
+  }
+
   Handle = NULL;
   *Status = gBS->InstallProtocolInterface (
                   &Handle,
@@ -78,6 +82,10 @@ Returns:
 {
   EFI_STATUS  Status;
 
+  if (!FeaturePcdGet (PcdPciBusHotplugDeviceSupport)) {
+    return;
+  }
+
   if (IS_CARDBUS_BRIDGE (&PciIoDevice->Parent->Pci)) {
 
     Status = gBS->InstallProtocolInterface (
@@ -109,6 +117,10 @@ Returns:
 {
   EFI_STATUS  Status;
 
+  if (!FeaturePcdGet (PcdPciBusHotplugDeviceSupport)) {
+    return;
+  }
+
   Status = gBS->OpenProtocol (
                   PciIoDevice->Handle,
                   &gEfiPciHotplugDeviceGuid,
@@ -152,6 +164,10 @@ Returns:
 {
   UINT32  Address;
 
+  if (!FeaturePcdGet (PcdPciBusHotplugDeviceSupport)) {
+    return;
+  }
+
   //
   // Read PciBar information from the bar register
   //
@@ -239,6 +255,10 @@ Returns:
   LIST_ENTRY      *CurrentLink;
   LIST_ENTRY      *LastLink;
 
+  if (!FeaturePcdGet (PcdPciBusHotplugDeviceSupport)) {
+    return EFI_SUCCESS;
+  }
+
   CurrentLink = Bridge->ChildList.ForwardLink;
 
   while (CurrentLink && CurrentLink != &Bridge->ChildList) {
@@ -286,6 +306,396 @@ EFI_STATUS
 PciHostBridgeResourceAllocator (
   IN EFI_PCI_HOST_BRIDGE_RESOURCE_ALLOCATION_PROTOCOL *PciResAlloc
   )
+{
+  if (FeaturePcdGet (PcdPciBusHotplugDeviceSupport)) {
+    return PciHostBridgeResourceAllocator_WithHotPlugDeviceSupport (
+             PciResAlloc
+             );
+  } else {
+    return PciHostBridgeResourceAllocator_WithoutHotPlugDeviceSupport (
+             PciResAlloc
+             );
+  }  
+}
+
+
+EFI_STATUS
+PciHostBridgeResourceAllocator_WithoutHotPlugDeviceSupport (
+  IN EFI_PCI_HOST_BRIDGE_RESOURCE_ALLOCATION_PROTOCOL *PciResAlloc
+  )
+/*++
+
+Routine Description:
+
+Arguments:
+
+Returns:
+
+  None
+
+--*/
+// TODO:    PciResAlloc - add argument and description to function comment
+// TODO:    EFI_NOT_FOUND - add return value to function comment
+// TODO:    EFI_OUT_OF_RESOURCES - add return value to function comment
+// TODO:    EFI_NOT_FOUND - add return value to function comment
+// TODO:    EFI_SUCCESS - add return value to function comment
+{
+  PCI_IO_DEVICE                   *RootBridgeDev;
+  EFI_HANDLE                      RootBridgeHandle;
+  VOID                            *AcpiConfig;
+  EFI_STATUS                      Status;
+  UINT64                          IoBase;
+  UINT64                          Mem32Base;
+  UINT64                          PMem32Base;
+  UINT64                          Mem64Base;
+  UINT64                          PMem64Base;
+  UINT64                          MaxOptionRomSize;
+  PCI_RESOURCE_NODE               *IoBridge;
+  PCI_RESOURCE_NODE               *Mem32Bridge;
+  PCI_RESOURCE_NODE               *PMem32Bridge;
+  PCI_RESOURCE_NODE               *Mem64Bridge;
+  PCI_RESOURCE_NODE               *PMem64Bridge;
+  PCI_RESOURCE_NODE               IoPool;
+  PCI_RESOURCE_NODE               Mem32Pool;
+  PCI_RESOURCE_NODE               PMem32Pool;
+  PCI_RESOURCE_NODE               Mem64Pool;
+  PCI_RESOURCE_NODE               PMem64Pool;
+  REPORT_STATUS_CODE_LIBRARY_DEVICE_HANDLE_EXTENDED_DATA  ExtendedData;
+
+  //
+  // Initialize resource pool
+  //
+  
+  InitializeResourcePool (&IoPool, PciBarTypeIo16);
+  InitializeResourcePool (&Mem32Pool, PciBarTypeMem32);
+  InitializeResourcePool (&PMem32Pool, PciBarTypePMem32);
+  InitializeResourcePool (&Mem64Pool, PciBarTypeMem64);
+  InitializeResourcePool (&PMem64Pool, PciBarTypePMem64);
+
+  RootBridgeDev     = NULL;
+  RootBridgeHandle  = 0;
+
+  while (PciResAlloc->GetNextRootBridge (PciResAlloc, &RootBridgeHandle) == EFI_SUCCESS) {
+    //
+    // Get RootBridg Device by handle
+    //
+    RootBridgeDev = GetRootBridgeByHandle (RootBridgeHandle);
+
+    if (RootBridgeDev == NULL) {
+      return EFI_NOT_FOUND;
+    }
+
+    //
+    // Get host bridge handle for status report
+    //
+    ExtendedData.Handle = RootBridgeDev->PciRootBridgeIo->ParentHandle;
+
+    //
+    // Create the entire system resource map from the information collected by
+    // enumerator. Several resource tree was created
+    //
+
+    IoBridge = CreateResourceNode (
+                RootBridgeDev,
+                0,
+                0xFFF,
+                0,
+                PciBarTypeIo16,
+                PciResUsageTypical
+                );
+
+    Mem32Bridge = CreateResourceNode (
+                    RootBridgeDev,
+                    0,
+                    0xFFFFF,
+                    0,
+                    PciBarTypeMem32,
+                    PciResUsageTypical
+                    );
+
+    PMem32Bridge = CreateResourceNode (
+                    RootBridgeDev,
+                    0,
+                    0xFFFFF,
+                    0,
+                    PciBarTypePMem32,
+                    PciResUsageTypical
+                    );
+
+    Mem64Bridge = CreateResourceNode (
+                    RootBridgeDev,
+                    0,
+                    0xFFFFF,
+                    0,
+                    PciBarTypeMem64,
+                    PciResUsageTypical
+                    );
+
+    PMem64Bridge = CreateResourceNode (
+                    RootBridgeDev,
+                    0,
+                    0xFFFFF,
+                    0,
+                    PciBarTypePMem64,
+                    PciResUsageTypical
+                    );
+
+    //
+    // Create resourcemap by going through all the devices subject to this root bridge
+    //
+    Status = CreateResourceMap (
+              RootBridgeDev,
+              IoBridge,
+              Mem32Bridge,
+              PMem32Bridge,
+              Mem64Bridge,
+              PMem64Bridge
+              );
+
+    //
+    // Get the max ROM size that the root bridge can process
+    //
+    RootBridgeDev->RomSize = Mem32Bridge->Length;
+
+    //
+    // Get Max Option Rom size for current root bridge
+    //
+    MaxOptionRomSize = GetMaxOptionRomSize (RootBridgeDev);
+
+    //
+    // Enlarger the mem32 resource to accomdate the option rom
+    // if the mem32 resource is not enough to hold the rom
+    //
+    if (MaxOptionRomSize > Mem32Bridge->Length) {
+
+      Mem32Bridge->Length     = MaxOptionRomSize;
+      RootBridgeDev->RomSize  = MaxOptionRomSize;
+
+      //
+      // Alignment should be adjusted as well
+      //
+      if (Mem32Bridge->Alignment < MaxOptionRomSize - 1) {
+        Mem32Bridge->Alignment = MaxOptionRomSize - 1;
+      }
+    }
+    
+    //
+    // Based on the all the resource tree, contruct ACPI resource node to
+    // submit the resource aperture to pci host bridge protocol
+    //
+    Status = ConstructAcpiResourceRequestor (
+              RootBridgeDev,
+              IoBridge,
+              Mem32Bridge,
+              PMem32Bridge,
+              Mem64Bridge,
+              PMem64Bridge,
+              &AcpiConfig
+              );
+
+    //
+    // Insert these resource nodes into the database
+    //
+    InsertResourceNode (&IoPool, IoBridge);
+    InsertResourceNode (&Mem32Pool, Mem32Bridge);
+    InsertResourceNode (&PMem32Pool, PMem32Bridge);
+    InsertResourceNode (&Mem64Pool, Mem64Bridge);
+    InsertResourceNode (&PMem64Pool, PMem64Bridge);
+
+    if (Status == EFI_SUCCESS) {
+      //
+      // Submit the resource requirement
+      //
+      Status = PciResAlloc->SubmitResources (
+                              PciResAlloc,
+                              RootBridgeDev->Handle,
+                              AcpiConfig
+                              );
+    }
+    //
+    // Free acpi resource node
+    //
+    if (AcpiConfig) {
+      gBS->FreePool (AcpiConfig);
+    }
+
+    if (EFI_ERROR (Status)) {
+      //
+      // Destroy all the resource tree
+      //
+      DestroyResourceTree (&IoPool);
+      DestroyResourceTree (&Mem32Pool);
+      DestroyResourceTree (&PMem32Pool);
+      DestroyResourceTree (&Mem64Pool);
+      DestroyResourceTree (&PMem64Pool);
+      return Status;
+    }
+  }
+  //
+  // End while
+  //
+
+  //
+  // Notify pci bus driver starts to program the resource
+  //
+  Status = NotifyPhase (PciResAlloc, EfiPciHostBridgeAllocateResources);
+
+  if (EFI_ERROR (Status)) {
+    //
+    // Allocation failed, then return
+    //
+    return EFI_OUT_OF_RESOURCES;
+  }
+  //
+  // Raise the EFI_IOB_PCI_RES_ALLOC status code
+  //
+  REPORT_STATUS_CODE_WITH_EXTENDED_DATA (
+        EFI_PROGRESS_CODE,
+        EFI_IO_BUS_PCI | EFI_IOB_PCI_PC_RES_ALLOC,
+        (VOID *) &ExtendedData,
+        sizeof (ExtendedData)
+        );
+
+  //
+  // Notify pci bus driver starts to program the resource
+  //
+  NotifyPhase (PciResAlloc, EfiPciHostBridgeSetResources);
+
+  RootBridgeDev     = NULL;
+
+  RootBridgeHandle  = 0;
+
+  while (PciResAlloc->GetNextRootBridge (PciResAlloc, &RootBridgeHandle) == EFI_SUCCESS) {
+    //
+    // Get RootBridg Device by handle
+    //
+    RootBridgeDev = GetRootBridgeByHandle (RootBridgeHandle);
+
+    if (RootBridgeDev == NULL) {
+      return EFI_NOT_FOUND;
+    }
+    
+    //
+    // Get acpi resource node for all the resource types
+    //
+    AcpiConfig = NULL;
+    Status = PciResAlloc->GetProposedResources (
+                            PciResAlloc,
+                            RootBridgeDev->Handle,
+                            &AcpiConfig
+                            );
+
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
+
+    //
+    // Get the resource base by interpreting acpi resource node
+    //
+    //
+    GetResourceBase (
+      AcpiConfig,
+      &IoBase,
+      &Mem32Base,
+      &PMem32Base,
+      &Mem64Base,
+      &PMem64Base
+      );
+
+    //
+    // Process option rom for this root bridge
+    //
+    Status = ProcessOptionRom (RootBridgeDev, Mem32Base, RootBridgeDev->RomSize);
+
+    //
+    // Create the entire system resource map from the information collected by
+    // enumerator. Several resource tree was created
+    //
+    Status = GetResourceMap (
+              RootBridgeDev,
+              &IoBridge,
+              &Mem32Bridge,
+              &PMem32Bridge,
+              &Mem64Bridge,
+              &PMem64Bridge,
+              &IoPool,
+              &Mem32Pool,
+              &PMem32Pool,
+              &Mem64Pool,
+              &PMem64Pool
+              );
+
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
+
+    //
+    // Program IO resources
+    //
+    ProgramResource (
+      IoBase,
+      IoBridge
+      );
+
+    //
+    // Program Mem32 resources
+    //
+    ProgramResource (
+      Mem32Base,
+      Mem32Bridge
+      );
+
+    //
+    // Program PMem32 resources
+    //
+    ProgramResource (
+      PMem32Base,
+      PMem32Bridge
+      );
+
+    //
+    // Program Mem64 resources
+    //
+    ProgramResource (
+      Mem64Base,
+      Mem64Bridge
+      );
+
+    //
+    // Program PMem64 resources
+    //
+    ProgramResource (
+      PMem64Base,
+      PMem64Bridge
+      );
+
+    if (AcpiConfig != NULL) {
+      gBS->FreePool (AcpiConfig);
+    }
+  }
+
+  //
+  // Destroy all the resource tree
+  //
+  DestroyResourceTree (&IoPool);
+  DestroyResourceTree (&Mem32Pool);
+  DestroyResourceTree (&PMem32Pool);
+  DestroyResourceTree (&Mem64Pool);
+  DestroyResourceTree (&PMem64Pool);
+
+  //
+  // Notify the resource allocation phase is to end
+  //
+  NotifyPhase (PciResAlloc, EfiPciHostBridgeEndResourceAllocation);
+
+  return EFI_SUCCESS;
+}
+
+
+EFI_STATUS
+PciHostBridgeResourceAllocator_WithHotPlugDeviceSupport (
+  IN EFI_PCI_HOST_BRIDGE_RESOURCE_ALLOCATION_PROTOCOL *PciResAlloc
+  )
 /*++
 
 Routine Description:
@@ -787,6 +1197,7 @@ Returns:
   return EFI_SUCCESS;
 }
 
+
 EFI_STATUS
 PciScanBus (
   IN PCI_IO_DEVICE                      *Bridge,
@@ -794,6 +1205,204 @@ PciScanBus (
   OUT UINT8                             *SubBusNumber,
   OUT UINT8                             *PaddedBusRange
   )
+{
+  if (FeaturePcdGet (PcdPciBusHotplugDeviceSupport)) {
+    return PciScanBus_WithHotPlugDeviceSupport (
+      Bridge, 
+      StartBusNumber, 
+      SubBusNumber, 
+      PaddedBusRange
+      );
+  } else {
+    return PciScanBus_WithoutHotPlugDeviceSupport (
+      Bridge, 
+      StartBusNumber, 
+      SubBusNumber, 
+      PaddedBusRange
+      );
+  }
+}
+
+
+EFI_STATUS
+PciScanBus_WithoutHotPlugDeviceSupport (
+  IN PCI_IO_DEVICE                      *Bridge,
+  IN UINT8                              StartBusNumber,
+  OUT UINT8                             *SubBusNumber,
+  OUT UINT8                             *PaddedBusRange
+  )
+/*++
+
+Routine Description:
+
+  This routine is used to assign bus number to the given PCI bus system
+
+Arguments:
+
+Returns:
+
+  None
+
+--*/
+// TODO:    Bridge - add argument and description to function comment
+// TODO:    StartBusNumber - add argument and description to function comment
+// TODO:    SubBusNumber - add argument and description to function comment
+// TODO:    PaddedBusRange - add argument and description to function comment
+// TODO:    EFI_DEVICE_ERROR - add return value to function comment
+// TODO:    EFI_SUCCESS - add return value to function comment
+{
+  EFI_STATUS                      Status;
+  PCI_TYPE00                      Pci;
+  UINT8                           Device;
+  UINT8                           Func;
+  UINT64                          Address;
+  UINTN                           SecondBus;
+  UINT16                          Register;
+  PCI_IO_DEVICE                   *PciDevice;
+  EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL *PciRootBridgeIo;
+
+  PciRootBridgeIo = Bridge->PciRootBridgeIo;
+  SecondBus       = 0;
+  Register        = 0;
+
+  ResetAllPpbBusReg (Bridge, StartBusNumber);
+
+  for (Device = 0; Device <= PCI_MAX_DEVICE; Device++) {
+    for (Func = 0; Func <= PCI_MAX_FUNC; Func++) {
+
+      //
+      // Check to see whether a pci device is present
+      //
+      Status = PciDevicePresent (
+                PciRootBridgeIo,
+                &Pci,
+                StartBusNumber,
+                Device,
+                Func
+                );
+
+      if (!EFI_ERROR (Status)   && 
+          (IS_PCI_BRIDGE (&Pci) ||
+          IS_CARDBUS_BRIDGE (&Pci))) {
+
+        //
+        // Get the bridge information
+        //
+        Status = PciSearchDevice (
+                  Bridge,
+                  &Pci,
+                  StartBusNumber,
+                  Device,
+                  Func,
+                  &PciDevice
+                  );
+
+        if (EFI_ERROR (Status)) {
+          return Status;
+        }
+
+        (*SubBusNumber)++;
+
+        SecondBus = (*SubBusNumber);
+
+        Register  = (UINT16) ((SecondBus << 8) | (UINT16) StartBusNumber);
+
+        Address   = EFI_PCI_ADDRESS (StartBusNumber, Device, Func, 0x18);
+
+        Status = PciRootBridgeIo->Pci.Write (
+                                        PciRootBridgeIo,
+                                        EfiPciWidthUint16,
+                                        Address,
+                                        1,
+                                        &Register
+                                        );
+
+        //
+        // Initialize SubBusNumber to SecondBus
+        //
+        Address = EFI_PCI_ADDRESS (StartBusNumber, Device, Func, 0x1A);
+        Status = PciRootBridgeIo->Pci.Write (
+                                        PciRootBridgeIo,
+                                        EfiPciWidthUint8,
+                                        Address,
+                                        1,
+                                        SubBusNumber
+                                        );
+        //
+        // If it is PPB, resursively search down this bridge
+        //
+        if (IS_PCI_BRIDGE (&Pci)) {
+          //
+          // Temporarily initialize SubBusNumber to maximum bus number to ensure the
+          // PCI configuration transaction to go through any PPB
+          //
+          Address   = EFI_PCI_ADDRESS (StartBusNumber, Device, Func, 0x1A);
+          Register  = 0xFF;
+          Status = PciRootBridgeIo->Pci.Write (
+                                          PciRootBridgeIo,
+                                          EfiPciWidthUint8,
+                                          Address,
+                                          1,
+                                          &Register
+                                          );
+
+          PreprocessController (
+            PciDevice,
+            PciDevice->BusNumber,
+            PciDevice->DeviceNumber,
+            PciDevice->FunctionNumber,
+            EfiPciBeforeChildBusEnumeration
+            );
+
+          Status = PciScanBus (
+                    PciDevice,
+                    (UINT8) (SecondBus),
+                    SubBusNumber,
+                    PaddedBusRange
+                    );
+
+          if (EFI_ERROR (Status)) {
+            return EFI_DEVICE_ERROR;
+          }
+        }
+
+        //
+        // Set the current maximum bus number under the PPB
+        //
+
+        Address = EFI_PCI_ADDRESS (StartBusNumber, Device, Func, 0x1A);
+
+        Status = PciRootBridgeIo->Pci.Write (
+                                        PciRootBridgeIo,
+                                        EfiPciWidthUint8,
+                                        Address,
+                                        1,
+                                        SubBusNumber
+                                        );
+
+      }
+
+      if (Func == 0 && !IS_PCI_MULTI_FUNC (&Pci)) {
+
+        //
+        // Skip sub functions, this is not a multi function device
+        //
+
+        Func = PCI_MAX_FUNC;
+      }
+    }
+  }
+
+  return EFI_SUCCESS;
+}
+
+EFI_STATUS
+PciScanBus_WithHotPlugDeviceSupport (
+  IN PCI_IO_DEVICE                      *Bridge,
+  IN UINT8                              StartBusNumber,
+  OUT UINT8                             *SubBusNumber,
+  OUT UINT8                             *PaddedBusRange
+  )
 /*++
 
 Routine Description:
@@ -1175,6 +1784,10 @@ Returns:
   PCI_IO_DEVICE *RootBridgeDev;
   EFI_STATUS    Status;
 
+  if (!FeaturePcdGet (PcdPciBusHotplugDeviceSupport)) {
+    return EFI_SUCCESS;
+  }
+
   RootBridgeHandle = NULL;
 
   while (PciResAlloc->GetNextRootBridge (PciResAlloc, &RootBridgeHandle) == EFI_SUCCESS) {
@@ -1271,6 +1884,8 @@ Returns:
     //
   }
 
+  if (FeaturePcdGet (PcdPciBusHotplugDeviceSupport)) {
+
     //                                                            
     // Notify the bus allocation phase is finished for the first time
     //                                                            
@@ -1325,6 +1940,12 @@ Returns:
       //
       NotifyPhase (PciResAlloc, EfiPciHostBridgeEndBusAllocation);
     }
+  } else {
+    //
+    // Notify the bus allocation phase is to end
+    //
+    NotifyPhase (PciResAlloc, EfiPciHostBridgeEndBusAllocation);
+  }
 
   //
   // Notify the resource allocation phase is to start

EdkModulePkg/Bus/Pci/PciBus/Dxe/PciLib.h

@@ -15,9 +15,9 @@ Module Name:
   
 Abstract:
 
-  PCI Bus Driver Lib header file
+  PCI Bus Driver Lib header file.
-  It abstracts some functions that can be different 
+  Please use PCD feature flag PcdPciBusHotplugDeviceSupport to enable
-  between light PCI bus driver and full PCI bus driver
+  support hot plug.
 
 Revision History
 
@@ -154,6 +154,18 @@ Returns:
 --*/
 ;
 
+EFI_STATUS
+PciHostBridgeResourceAllocator_WithoutHotPlugDeviceSupport (
+  IN EFI_PCI_HOST_BRIDGE_RESOURCE_ALLOCATION_PROTOCOL *PciResAlloc
+  )
+;
+
+EFI_STATUS
+PciHostBridgeResourceAllocator_WithHotPlugDeviceSupport (
+  IN EFI_PCI_HOST_BRIDGE_RESOURCE_ALLOCATION_PROTOCOL *PciResAlloc
+  )
+;
+
 EFI_STATUS
 PciScanBus (
   IN PCI_IO_DEVICE                      *Bridge,
@@ -181,6 +193,24 @@ Returns:
 --*/
 ;
 
+EFI_STATUS
+PciScanBus_WithHotPlugDeviceSupport (
+  IN PCI_IO_DEVICE                      *Bridge,
+  IN UINT8                              StartBusNumber,
+  OUT UINT8                             *SubBusNumber,
+  OUT UINT8                             *PaddedBusRange
+  )
+;
+
+EFI_STATUS
+PciScanBus_WithoutHotPlugDeviceSupport (
+  IN PCI_IO_DEVICE                      *Bridge,
+  IN UINT8                              StartBusNumber,
+  OUT UINT8                             *SubBusNumber,
+  OUT UINT8                             *PaddedBusRange
+  )
+;
+
 EFI_STATUS
 PciRootBridgeP2CProcess (
   IN PCI_IO_DEVICE *Bridge

EdkModulePkg/EdkModulePkg.fpd

@@ -3698,6 +3698,14 @@
           <MaxDatumSize>1</MaxDatumSize>
           <Value>FALSE</Value>
         </PcdData>
+        <PcdData ItemType="FEATURE_FLAG">
+          <C_Name>PcdPciBusHotplugDeviceSupport</C_Name>
+          <Token>0x0001003d</Token>
+          <TokenSpaceGuidCName>gEfiGenericPlatformTokenSpaceGuid</TokenSpaceGuidCName>
+          <DatumType>BOOLEAN</DatumType>
+          <MaxDatumSize>1</MaxDatumSize>
+          <Value>TRUE</Value>
+        </PcdData>
       </PcdBuildDefinition>
       <ModuleSaBuildOptions>
         <FvBinding>NULL</FvBinding>
@@ -8991,6 +8999,14 @@
           <MaxDatumSize>1</MaxDatumSize>
           <Value>FALSE</Value>
         </PcdData>
+        <PcdData ItemType="FEATURE_FLAG">
+          <C_Name>PcdPciBusHotplugDeviceSupport</C_Name>
+          <Token>0x0001003d</Token>
+          <TokenSpaceGuidCName>gEfiGenericPlatformTokenSpaceGuid</TokenSpaceGuidCName>
+          <DatumType>BOOLEAN</DatumType>
+          <MaxDatumSize>1</MaxDatumSize>
+          <Value>TRUE</Value>
+        </PcdData>
       </PcdBuildDefinition>
       <ModuleSaBuildOptions>
         <FvBinding>NULL</FvBinding>
@@ -13262,6 +13278,14 @@
           <MaxDatumSize>1</MaxDatumSize>
           <Value>FALSE</Value>
         </PcdData>
+        <PcdData ItemType="FEATURE_FLAG">
+          <C_Name>PcdPciBusHotplugDeviceSupport</C_Name>
+          <Token>0x0001003d</Token>
+          <TokenSpaceGuidCName>gEfiGenericPlatformTokenSpaceGuid</TokenSpaceGuidCName>
+          <DatumType>BOOLEAN</DatumType>
+          <MaxDatumSize>1</MaxDatumSize>
+          <Value>TRUE</Value>
+        </PcdData>
       </PcdBuildDefinition>
       <ModuleSaBuildOptions>
         <FvBinding>NULL</FvBinding>
@@ -17180,6 +17204,14 @@
           <MaxDatumSize>1</MaxDatumSize>
           <Value>FALSE</Value>
         </PcdData>
+        <PcdData ItemType="FEATURE_FLAG">
+          <C_Name>PcdPciBusHotplugDeviceSupport</C_Name>
+          <Token>0x0001003d</Token>
+          <TokenSpaceGuidCName>gEfiGenericPlatformTokenSpaceGuid</TokenSpaceGuidCName>
+          <DatumType>BOOLEAN</DatumType>
+          <MaxDatumSize>1</MaxDatumSize>
+          <Value>TRUE</Value>
+        </PcdData>
       </PcdBuildDefinition>
       <ModuleSaBuildOptions>
         <FvBinding>NULL</FvBinding>

EdkModulePkg/EdkModulePkg.spd

@@ -1260,5 +1260,14 @@
       <DefaultValue>FALSE</DefaultValue>
       <HelpText>If this feature is enabled, DXE IPL will build a series of HOBs to share code with DXE Core.</HelpText>
     </PcdEntry>
+    <PcdEntry>
+      <C_Name>PcdPciBusHotplugDeviceSupport</C_Name>
+      <Token>0x0001003d</Token>
+      <TokenSpaceGuidCName>gEfiGenericPlatformTokenSpaceGuid</TokenSpaceGuidCName>
+      <DatumType>BOOLEAN</DatumType>
+      <ValidUsage>FEATURE_FLAG</ValidUsage>
+      <DefaultValue>TRUE</DefaultValue>
+      <HelpText>If TRUE, the PCI bus driver will support hot plug device. If not hot plug device is supported, this feature flag can be set to FALSE to save size.</HelpText>
+    </PcdEntry>
   </PcdDeclarations>
 </PackageSurfaceArea>

EdkModulePkg/Universal/PCD/Dxe/Service.c

@@ -767,7 +767,7 @@ SetHiiVariable (
   Status = gRT->GetVariable (
     (UINT16 *)VariableName,
     VariableGuid,
-    &Attribute,
+    NULL,
     &Size,
     NULL
     );

EdkNt32Pkg/Dxe/PlatformBds/Generic/MemoryTest.c

@@ -240,7 +240,6 @@ Returns:
   EFI_GRAPHICS_OUTPUT_BLT_PIXEL     Color;
   UINT8                             Value;
   UINTN                             DataSize;
-  UINT32                            Attributes;
 
   ReturnStatus = EFI_SUCCESS;
   ZeroMem (&Key, sizeof (EFI_INPUT_KEY));
@@ -412,7 +411,7 @@ Done:
   Status = gRT->GetVariable (
                   L"BootState",
                   &gEfiBootStateGuid,
-                  &Attributes,
+                  NULL,
                   &DataSize,
                   &Value
                   );