xref: /dports/emulators/qemu42/qemu-4.2.1/roms/edk2/IntelFrameworkModulePkg/Universal/Acpi/AcpiSupportDxe/AcpiSupportAcpiSupportProtocol.c

/** @file
  ACPI Support Protocol implementation

Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>

SPDX-License-Identifier: BSD-2-Clause-Patent

**/

//
// Includes
//
#include "AcpiSupport.h"
//
// The maximum number of tables that pre-allocated.
//
UINTN         mEfiAcpiMaxNumTables = EFI_ACPI_MAX_NUM_TABLES;
/**
  This function adds an ACPI table to the table list.  It will detect FACS and
  allocate the correct type of memory and properly align the table.

  @param  AcpiSupportInstance       Instance of the protocol.
  @param  Table                     Table to add.
  @param  Checksum                  Does the table require checksumming.
  @param  Version                   The version of the list to add the table to.
  @param  Handle                    Pointer for returning the handle.

  @return EFI_SUCCESS               The function completed successfully.
  @return EFI_OUT_OF_RESOURCES      Could not allocate a required resource.
  @return EFI_ABORTED               The table is a duplicate of a table that is required
                                    to be unique.
**/
EFI_STATUS
AddTableToList (
  IN EFI_ACPI_SUPPORT_INSTANCE            *AcpiSupportInstance,
  IN VOID                                 *Table,
  IN BOOLEAN                              Checksum,
  IN EFI_ACPI_TABLE_VERSION               Version,
  OUT UINTN                               *Handle
  );
/**
  This function finds and removes the table specified by the handle.

  @param  AcpiSupportInstance  Instance of the protocol.
  @param  Version              Bitmask of which versions to remove.
  @param  Handle               Table to remove.

  @return EFI_SUCCESS    The function completed successfully.
  @return EFI_ABORTED    An error occurred.
  @return EFI_NOT_FOUND  Handle not found in table list.
**/
EFI_STATUS
RemoveTableFromList (
  IN EFI_ACPI_SUPPORT_INSTANCE            *AcpiSupportInstance,
  IN EFI_ACPI_TABLE_VERSION               Version,
  IN UINTN                                Handle
  );
/**
  This function calculates and updates an UINT8 checksum.

  @param  Buffer          Pointer to buffer to checksum
  @param  Size            Number of bytes to checksum
  @param  ChecksumOffset  Offset to place the checksum result in

  @return EFI_SUCCESS             The function completed successfully.
**/
EFI_STATUS
AcpiPlatformChecksum (
  IN VOID       *Buffer,
  IN UINTN      Size,
  IN UINTN      ChecksumOffset
  );
/**
  Checksum all versions of the common tables, RSDP, RSDT, XSDT.

  @param  AcpiSupportInstance  Protocol instance private data.

  @return EFI_SUCCESS        The function completed successfully.

**/
EFI_STATUS
ChecksumCommonTables (
  IN OUT EFI_ACPI_SUPPORT_INSTANCE        *AcpiSupportInstance
  );

/**
  This function returns a table specified by an index if it exists.

  The function returns a buffer containing the table that the caller must free.
  The function also returns a handle used to identify the table for update or
  deletion using the SetAcpiTable function.

  @param This        Instance of the protocol.
  @param Index       Zero-based index of the table to retrieve.
  @param Table       Returned pointer to the table.
  @param Version     Versions that the table is currently used in.
  @param Handle      Handle of the table, used in updating tables.

  @retval EFI_SUCCESS             The function completed successfully.
  @retval EFI_NOT_FOUND           The requested table does not exist.

**/
EFI_STATUS
EFIAPI
GetAcpiTable (
  IN EFI_ACPI_SUPPORT_PROTOCOL            *This,
  IN INTN                                 Index,
  OUT VOID                                **Table,
  OUT EFI_ACPI_TABLE_VERSION              *Version,
  OUT UINTN                               *Handle
  )

{
  EFI_ACPI_SUPPORT_INSTANCE *AcpiSupportInstance;
  INTN                  TempIndex;
  LIST_ENTRY            *CurrentLink;
  LIST_ENTRY            *StartLink;
  EFI_ACPI_TABLE_LIST       *CurrentTable;

  //
  // Check for invalid input parameters
  //
  ASSERT (This);
  ASSERT (Table);
  ASSERT (Handle);

  //
  // Get the instance of the protocol
  //
  AcpiSupportInstance = EFI_ACPI_SUPPORT_INSTANCE_FROM_ACPI_SUPPORT_THIS (This);

  //
  // Find the table
  //
  CurrentLink = AcpiSupportInstance->TableList.ForwardLink;
  StartLink   = &AcpiSupportInstance->TableList;
  for (TempIndex = 0; (TempIndex < Index) && (CurrentLink != StartLink) && (CurrentLink != NULL); TempIndex++) {
    CurrentLink = CurrentLink->ForwardLink;
  }

  if (TempIndex != Index || CurrentLink == StartLink) {
    return EFI_NOT_FOUND;
  }
  //
  // Get handle and version
  //
  CurrentTable  = EFI_ACPI_TABLE_LIST_FROM_LINK (CurrentLink);
  *Handle       = CurrentTable->Handle;
  *Version      = CurrentTable->Version;

  //
  // Copy the table
  //
  *Table = AllocateCopyPool (CurrentTable->Table->Length, CurrentTable->Table);
  ASSERT (*Table);

  return EFI_SUCCESS;
}
/**
  This function adds, removes, or updates ACPI tables.  If the address is not
  null and the handle value is null, the table is added.  If both the address and
  handle are not null, the table at handle is updated with the table at address.
  If the address is null and the handle is not, the table at handle is deleted.

  @param  This                 Pointer of the protocol.
  @param  Table                Pointer to a table.
  @param  Checksum             Boolean indicating if the checksum should be calculated.
  @param  Version              Version(s) to set.
  @param  Handle               Handle of the table.

  @return EFI_SUCCESS             The function completed successfully.
  @return EFI_INVALID_PARAMETER   Both the Table and *Handle were NULL.
  @return EFI_ABORTED             Could not complete the desired request.

**/
EFI_STATUS
EFIAPI
SetAcpiTable (
  IN EFI_ACPI_SUPPORT_PROTOCOL            *This,
  IN VOID                                 *Table OPTIONAL,
  IN BOOLEAN                              Checksum,
  IN EFI_ACPI_TABLE_VERSION               Version,
  IN OUT UINTN                            *Handle
  )
{
  EFI_ACPI_SUPPORT_INSTANCE *AcpiSupportInstance;
  UINTN                     SavedHandle;
  EFI_STATUS                Status;

  //
  // Check for invalid input parameters
  //
  ASSERT (This);
  ASSERT (Handle != NULL);

  //
  // Get the instance of the protocol
  //
  AcpiSupportInstance = EFI_ACPI_SUPPORT_INSTANCE_FROM_ACPI_SUPPORT_THIS (This);

  //
  // Initialize locals
  //
  //
  // Determine desired action
  //
  if (*Handle == 0) {
    if (Table == NULL) {
      //
      // Invalid parameter combination
      //
      return EFI_INVALID_PARAMETER;
    } else {
      //
      // Add table
      //
      Status = AddTableToList (AcpiSupportInstance, Table, Checksum, Version, Handle);
    }
  } else {
    if (Table != NULL) {
      //
      // Update table
      //
      //
      // Delete the table list entry
      //
      Status = RemoveTableFromList (AcpiSupportInstance, Version, *Handle);
      if (EFI_ERROR (Status)) {
        //
        // Should not get an error here ever, but abort if we do.
        //
        return EFI_ABORTED;
      }
      //
      // Set the handle to replace the table at the same handle
      //
      SavedHandle                         = AcpiSupportInstance->CurrentHandle;
      AcpiSupportInstance->CurrentHandle  = *Handle;

      //
      // Add the table
      //
      Status = AddTableToList (AcpiSupportInstance, Table, Checksum, Version, Handle);

      //
      // Restore the saved current handle
      //
      AcpiSupportInstance->CurrentHandle = SavedHandle;
    } else {
      //
      // Delete table
      //
      Status = RemoveTableFromList (AcpiSupportInstance, Version, *Handle);
    }
  }

  if (EFI_ERROR (Status)) {
    //
    // Should not get an error here ever, but abort if we do.
    //
    return EFI_ABORTED;
  }
  //
  // Done
  //
  return EFI_SUCCESS;
}
/**
  This function publishes the specified versions of the ACPI tables by
  installing EFI configuration table entries for them.  Any combination of
  table versions can be published.

  @param  This                 Pointer of the protocol.
  @param  Version              Version(s) to publish.

  @return EFI_SUCCESS  The function completed successfully.
  @return EFI_ABORTED  The function could not complete successfully.

**/
EFI_STATUS
EFIAPI
PublishTables (
  IN EFI_ACPI_SUPPORT_PROTOCOL            *This,
  IN EFI_ACPI_TABLE_VERSION               Version
  )
{
  EFI_ACPI_SUPPORT_INSTANCE *AcpiSupportInstance;
  EFI_STATUS                Status;
  UINT32                    *CurrentRsdtEntry;
  VOID                      *CurrentXsdtEntry;
  UINT64                    Buffer64;

  //
  // Get the instance of the protocol
  //
  AcpiSupportInstance = EFI_ACPI_SUPPORT_INSTANCE_FROM_ACPI_SUPPORT_THIS (This);

  //
  // Reorder tables as some operating systems don't seem to find the
  // FADT correctly if it is not in the first few entries
  //

  //
  // Add FADT as the first entry
  //
  if ((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0) {
    CurrentRsdtEntry  = (UINT32 *) ((UINT8 *) AcpiSupportInstance->Rsdt1 + sizeof (EFI_ACPI_DESCRIPTION_HEADER));
    *CurrentRsdtEntry = (UINT32) (UINTN) AcpiSupportInstance->Fadt1;
  }
  if ((Version & EFI_ACPI_TABLE_VERSION_2_0) != 0 || (Version & EFI_ACPI_TABLE_VERSION_3_0) != 0) {
    CurrentRsdtEntry  = (UINT32 *) ((UINT8 *) AcpiSupportInstance->Rsdt3 + sizeof (EFI_ACPI_DESCRIPTION_HEADER));
    *CurrentRsdtEntry = (UINT32) (UINTN) AcpiSupportInstance->Fadt3;
    CurrentXsdtEntry  = (VOID *) ((UINT8 *) AcpiSupportInstance->Xsdt + sizeof (EFI_ACPI_DESCRIPTION_HEADER));
    //
    // Add entry to XSDT, XSDT expects 64 bit pointers, but
    // the table pointers in XSDT are not aligned on 8 byte boundary.
    //
    Buffer64 = (UINT64) (UINTN) AcpiSupportInstance->Fadt3;
    CopyMem (
      CurrentXsdtEntry,
      &Buffer64,
      sizeof (UINT64)
      );
  }

  //
  // Do checksum again because Dsdt/Xsdt is updated.
  //
  ChecksumCommonTables (AcpiSupportInstance);

  //
  // Add the RSD_PTR to the system table and store that we have installed the
  // tables.
  //
  if ((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0 && !AcpiSupportInstance->TablesInstalled1) {
    Status = gBS->InstallConfigurationTable (&gEfiAcpi10TableGuid, AcpiSupportInstance->Rsdp1);
    if (EFI_ERROR (Status)) {
      return EFI_ABORTED;
    }

    AcpiSupportInstance->TablesInstalled1 = TRUE;
  }

  if (((Version & EFI_ACPI_TABLE_VERSION_2_0) != 0 || (Version & EFI_ACPI_TABLE_VERSION_3_0) != 0) &&
      !AcpiSupportInstance->TablesInstalled3) {
    Status = gBS->InstallConfigurationTable (&gEfiAcpiTableGuid, AcpiSupportInstance->Rsdp3);
    if (EFI_ERROR (Status)) {
      return EFI_ABORTED;
    }

    AcpiSupportInstance->TablesInstalled3= TRUE;
  }

  return EFI_SUCCESS;
}
/**
  Installs an ACPI table into the RSDT/XSDT.
  Note that the ACPI table should be checksumed before installing it.
  Otherwise it will assert.

  @param  This                 Protocol instance pointer.
  @param  AcpiTableBuffer      A pointer to a buffer containing the ACPI table to be installed.
  @param  AcpiTableBufferSize  Specifies the size, in bytes, of the AcpiTableBuffer buffer.
  @param  TableKey             Reurns a key to refer to the ACPI table.

  @return EFI_SUCCESS            The table was successfully inserted.
  @return EFI_INVALID_PARAMETER  Either AcpiTableBuffer is NULL, TableKey is NULL, or AcpiTableBufferSize
                                 and the size field embedded in the ACPI table pointed to by AcpiTableBuffer
                                 are not in sync.
  @return EFI_OUT_OF_RESOURCES   Insufficient resources exist to complete the request.
  @retval EFI_ACCESS_DENIED      The table signature matches a table already
                                 present in the system and platform policy
                                 does not allow duplicate tables of this type.

**/
EFI_STATUS
EFIAPI
InstallAcpiTable (
  IN   EFI_ACPI_TABLE_PROTOCOL                    *This,
  IN   VOID                                       *AcpiTableBuffer,
  IN   UINTN                                      AcpiTableBufferSize,
  OUT  UINTN                                      *TableKey
  )
{
  EFI_ACPI_SUPPORT_INSTANCE *AcpiSupportInstance;
  EFI_ACPI_SUPPORT_PROTOCOL *AcpiSupport;
  EFI_STATUS                Status;
  VOID                      *AcpiTableBufferConst;

  //
  // Check for invalid input parameters
  //
  if ((AcpiTableBuffer == NULL) || (TableKey == NULL)
     || (((EFI_ACPI_DESCRIPTION_HEADER *) AcpiTableBuffer)->Length != AcpiTableBufferSize)) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Get the instance of the ACPI support protocol
  //
  AcpiSupportInstance = EFI_ACPI_TABLE_INSTANCE_FROM_ACPI_SUPPORT_THIS (This);
  AcpiSupport = &AcpiSupportInstance->AcpiSupport;

  //
  // Install the ACPI table by using ACPI support protocol
  //
  AcpiTableBufferConst = AllocateCopyPool (AcpiTableBufferSize, AcpiTableBuffer);
  *TableKey = 0;
  Status = AddTableToList (
             AcpiSupportInstance,
             AcpiTableBufferConst,
             TRUE,
             EFI_ACPI_TABLE_VERSION_1_0B | EFI_ACPI_TABLE_VERSION_2_0 | EFI_ACPI_TABLE_VERSION_3_0,
             TableKey
             );
  if (!EFI_ERROR (Status)) {
    Status = AcpiSupport->PublishTables (
                            AcpiSupport,
                            EFI_ACPI_TABLE_VERSION_1_0B | EFI_ACPI_TABLE_VERSION_2_0 | EFI_ACPI_TABLE_VERSION_3_0
                            );
  }
  FreePool (AcpiTableBufferConst);

  return Status;
}
/**
  Removes an ACPI table from the RSDT/XSDT.

  @param  This      Protocol instance pointer.
  @param  TableKey  Specifies the table to uninstall.  The key was returned from InstallAcpiTable().

  @return EFI_SUCCESS    The table was successfully uninstalled.
  @return EFI_NOT_FOUND  TableKey does not refer to a valid key for a table entry.

**/
EFI_STATUS
EFIAPI
UninstallAcpiTable (
  IN  EFI_ACPI_TABLE_PROTOCOL                    *This,
  IN  UINTN                                      TableKey
  )
{
  EFI_ACPI_SUPPORT_INSTANCE *AcpiSupportInstance;
  EFI_ACPI_SUPPORT_PROTOCOL *AcpiSupport;
  EFI_STATUS                Status;

  //
  // Get the instance of the ACPI support protocol
  //
  AcpiSupportInstance = EFI_ACPI_TABLE_INSTANCE_FROM_ACPI_SUPPORT_THIS (This);
  AcpiSupport = &AcpiSupportInstance->AcpiSupport;

  //
  // Uninstall the ACPI table by using ACPI support protocol
  //
  Status = RemoveTableFromList (
             AcpiSupportInstance,
             EFI_ACPI_TABLE_VERSION_1_0B | EFI_ACPI_TABLE_VERSION_2_0 | EFI_ACPI_TABLE_VERSION_3_0,
             TableKey
             );
  if (!EFI_ERROR (Status)) {
    Status = AcpiSupport->PublishTables (
                            AcpiSupport,
                            EFI_ACPI_TABLE_VERSION_1_0B | EFI_ACPI_TABLE_VERSION_2_0 | EFI_ACPI_TABLE_VERSION_3_0
                            );
  }

  if (EFI_ERROR (Status)) {
    return EFI_NOT_FOUND;
  } else {
    return EFI_SUCCESS;
  }
}
/**
  If the number of APCI tables exceeds the preallocated max table number, enlarge the table buffer.

  @param  AcpiSupportInstance       ACPI support protocol instance data structure

  @return EFI_SUCCESS             reallocate the table beffer successfully.
  @return EFI_OUT_OF_RESOURCES    Unable to allocate required resources.

**/
EFI_STATUS
ReallocateAcpiTableBuffer (
  IN EFI_ACPI_SUPPORT_INSTANCE            *AcpiSupportInstance
  )
{
  UINTN                      NewMaxTableNumber;
  UINTN                      TotalSize;
  UINT8                      *Pointer;
  EFI_PHYSICAL_ADDRESS       PageAddress;
  EFI_ACPI_SUPPORT_INSTANCE  TempPrivateData;
  EFI_STATUS                 Status;
  UINT64                     CurrentData;

  CopyMem (&TempPrivateData, AcpiSupportInstance, sizeof (EFI_ACPI_SUPPORT_INSTANCE));
  //
  // Enlarge the max table number from mEfiAcpiMaxNumTables to mEfiAcpiMaxNumTables + EFI_ACPI_MAX_NUM_TABLES
  //
  NewMaxTableNumber = mEfiAcpiMaxNumTables + EFI_ACPI_MAX_NUM_TABLES;
  //
  // Create RSDT, XSDT structures and allocate buffers.
  //
  TotalSize = sizeof (EFI_ACPI_DESCRIPTION_HEADER) +         // for ACPI 1.0 RSDT
              NewMaxTableNumber * sizeof (UINT32) +
              sizeof (EFI_ACPI_DESCRIPTION_HEADER) +         // for ACPI 2.0/3.0 RSDT
              NewMaxTableNumber * sizeof (UINT32) +
              sizeof (EFI_ACPI_DESCRIPTION_HEADER) +         // for ACPI 2.0/3.0 XSDT
              NewMaxTableNumber * sizeof (UINT64);

  //
  // Allocate memory in the lower 32 bit of address range for
  // compatibility with ACPI 1.0 OS.
  //
  // This is done because ACPI 1.0 pointers are 32 bit values.
  // ACPI 2.0 OS and all 64 bit OS must use the 64 bit ACPI table addresses.
  // There is no architectural reason these should be below 4GB, it is purely
  // for convenience of implementation that we force memory below 4GB.
  //
  PageAddress = 0xFFFFFFFF;
  Status = gBS->AllocatePages (
                  AllocateMaxAddress,
                  EfiACPIReclaimMemory,
                  EFI_SIZE_TO_PAGES (TotalSize),
                  &PageAddress
                  );

  if (EFI_ERROR (Status)) {
    return EFI_OUT_OF_RESOURCES;
  }

  Pointer = (UINT8 *) (UINTN) PageAddress;
  ZeroMem (Pointer, TotalSize);

  AcpiSupportInstance->Rsdt1 = (EFI_ACPI_DESCRIPTION_HEADER *) Pointer;
  Pointer += (sizeof (EFI_ACPI_DESCRIPTION_HEADER) + NewMaxTableNumber * sizeof (UINT32));
  AcpiSupportInstance->Rsdt3 = (EFI_ACPI_DESCRIPTION_HEADER *) Pointer;
  Pointer += (sizeof (EFI_ACPI_DESCRIPTION_HEADER) + NewMaxTableNumber * sizeof (UINT32));
  AcpiSupportInstance->Xsdt = (EFI_ACPI_DESCRIPTION_HEADER *) Pointer;

  //
  // Update RSDP to point to the new Rsdt and Xsdt address.
  //
  AcpiSupportInstance->Rsdp1->RsdtAddress = (UINT32) (UINTN) AcpiSupportInstance->Rsdt1;
  AcpiSupportInstance->Rsdp3->RsdtAddress = (UINT32) (UINTN) AcpiSupportInstance->Rsdt3;
  CurrentData = (UINT64) (UINTN) AcpiSupportInstance->Xsdt;
  CopyMem (&AcpiSupportInstance->Rsdp3->XsdtAddress, &CurrentData, sizeof (UINT64));

  //
  // copy the original Rsdt1, Rsdt3 and Xsdt structure to new buffer
  //
  CopyMem (AcpiSupportInstance->Rsdt1, TempPrivateData.Rsdt1, (sizeof (EFI_ACPI_DESCRIPTION_HEADER) + mEfiAcpiMaxNumTables * sizeof (UINT32)));
  CopyMem (AcpiSupportInstance->Rsdt3, TempPrivateData.Rsdt3, (sizeof (EFI_ACPI_DESCRIPTION_HEADER) + mEfiAcpiMaxNumTables * sizeof (UINT32)));
  CopyMem (AcpiSupportInstance->Xsdt, TempPrivateData.Xsdt, (sizeof (EFI_ACPI_DESCRIPTION_HEADER) + mEfiAcpiMaxNumTables * sizeof (UINT64)));

  //
  // Calculate orignal ACPI table buffer size
  //
  TotalSize = sizeof (EFI_ACPI_DESCRIPTION_HEADER) +         // for ACPI 1.0 RSDT
              mEfiAcpiMaxNumTables * sizeof (UINT32) +
              sizeof (EFI_ACPI_DESCRIPTION_HEADER) +         // for ACPI 2.0/3.0 RSDT
              mEfiAcpiMaxNumTables * sizeof (UINT32) +
              sizeof (EFI_ACPI_DESCRIPTION_HEADER) +         // for ACPI 2.0/3.0 XSDT
              mEfiAcpiMaxNumTables * sizeof (UINT64);
  gBS->FreePages ((EFI_PHYSICAL_ADDRESS)(UINTN)TempPrivateData.Rsdt1, EFI_SIZE_TO_PAGES (TotalSize));

  //
  // Update the Max ACPI table number
  //
  mEfiAcpiMaxNumTables = NewMaxTableNumber;
  return EFI_SUCCESS;
}
/**
  This function adds an ACPI table to the table list.  It will detect FACS and
  allocate the correct type of memory and properly align the table.

  @param  AcpiSupportInstance       Instance of the protocol.
  @param  Table                     Table to add.
  @param  Checksum                  Does the table require checksumming.
  @param  Version                   The version of the list to add the table to.
  @param  Handle                    Pointer for returning the handle.

  @return EFI_SUCCESS               The function completed successfully.
  @return EFI_OUT_OF_RESOURCES      Could not allocate a required resource.
  @retval EFI_ACCESS_DENIED         The table signature matches a table already
                                    present in the system and platform policy
                                    does not allow duplicate tables of this type.
**/
EFI_STATUS
AddTableToList (
  IN EFI_ACPI_SUPPORT_INSTANCE            *AcpiSupportInstance,
  IN VOID                                 *Table,
  IN BOOLEAN                              Checksum,
  IN EFI_ACPI_TABLE_VERSION               Version,
  OUT UINTN                               *Handle
  )
{
  EFI_STATUS          Status;
  EFI_ACPI_TABLE_LIST *CurrentTableList;
  UINT32              CurrentTableSignature;
  UINT32              CurrentTableSize;
  UINT32              *CurrentRsdtEntry;
  VOID                *CurrentXsdtEntry;
  UINT64              Buffer64;
  BOOLEAN             AddToRsdt;

  //
  // Check for invalid input parameters
  //
  ASSERT (AcpiSupportInstance);
  ASSERT (Table);
  ASSERT (Handle);

  //
  // Init locals
  //
  AddToRsdt = TRUE;

  //
  // Create a new list entry
  //
  CurrentTableList = AllocatePool (sizeof (EFI_ACPI_TABLE_LIST));
  ASSERT (CurrentTableList);

  //
  // Determine table type and size
  //
  CurrentTableSignature = ((EFI_ACPI_COMMON_HEADER *) Table)->Signature;
  CurrentTableSize      = ((EFI_ACPI_COMMON_HEADER *) Table)->Length;

  //
  // Allocate a buffer for the table.  All tables are allocated in the lower 32 bits of address space
  // for backwards compatibility with ACPI 1.0 OS.
  //
  // This is done because ACPI 1.0 pointers are 32 bit values.
  // ACPI 2.0 OS and all 64 bit OS must use the 64 bit ACPI table addresses.
  // There is no architectural reason these should be below 4GB, it is purely
  // for convenience of implementation that we force memory below 4GB.
  //
  CurrentTableList->PageAddress   = 0xFFFFFFFF;
  CurrentTableList->NumberOfPages = EFI_SIZE_TO_PAGES (CurrentTableSize);

  //
  // Allocation memory type depends on the type of the table
  //
  if ((CurrentTableSignature == EFI_ACPI_2_0_FIRMWARE_ACPI_CONTROL_STRUCTURE_SIGNATURE) ||
      (CurrentTableSignature == EFI_ACPI_4_0_UEFI_ACPI_DATA_TABLE_SIGNATURE)) {
    //
    // Allocate memory for the FACS.  This structure must be aligned
    // on a 64 byte boundary and must be ACPI NVS memory.
    // Using AllocatePages should ensure that it is always aligned.
    // Do not change signature for new ACPI version because they are same.
    //
    // UEFI table also need to be in ACPI NVS memory, because some data field
    // could be updated by OS present agent. For example, BufferPtrAddress in
    // SMM communication ACPI table.
    //
    ASSERT ((EFI_PAGE_SIZE % 64) == 0);
    Status = gBS->AllocatePages (
                    AllocateMaxAddress,
                    EfiACPIMemoryNVS,
                    CurrentTableList->NumberOfPages,
                    &CurrentTableList->PageAddress
                    );
  } else {
    //
    // All other tables are ACPI reclaim memory, no alignment requirements.
    //
    Status = gBS->AllocatePages (
                    AllocateMaxAddress,
                    EfiACPIReclaimMemory,
                    CurrentTableList->NumberOfPages,
                    &CurrentTableList->PageAddress
                    );
  }
  //
  // Check return value from memory alloc.
  //
  if (EFI_ERROR (Status)) {
    gBS->FreePool (CurrentTableList);
    return EFI_OUT_OF_RESOURCES;
  }
  //
  // Update the table pointer with the allocated memory start
  //
  CurrentTableList->Table = (EFI_ACPI_COMMON_HEADER *) (UINTN) CurrentTableList->PageAddress;

  //
  // Initialize the table contents
  //
  CurrentTableList->Signature = EFI_ACPI_TABLE_LIST_SIGNATURE;
  CopyMem (CurrentTableList->Table, Table, CurrentTableSize);
  CurrentTableList->Handle  = AcpiSupportInstance->CurrentHandle++;
  *Handle                   = CurrentTableList->Handle;
  CurrentTableList->Version = Version;

  //
  // Update internal pointers if this is a required table.  If it is a required
  // table and a table of that type already exists, return an error.
  //
  // Calculate the checksum if the table is not FACS.
  //
  switch (CurrentTableSignature) {

  case EFI_ACPI_1_0_FIXED_ACPI_DESCRIPTION_TABLE_SIGNATURE:
    //
    // We don't add the FADT in the standard way because some
    // OS expect the FADT to be early in the table list.
    // So we always add it as the first element in the list.
    //
    AddToRsdt = FALSE;

    //
    // Check that the table has not been previously added.
    //
   if (((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0 && AcpiSupportInstance->Fadt1 != NULL) ||
        ((Version & EFI_ACPI_TABLE_VERSION_2_0)  != 0 && AcpiSupportInstance->Fadt3 != NULL) ||
        ((Version & EFI_ACPI_TABLE_VERSION_3_0)  != 0 && AcpiSupportInstance->Fadt3 != NULL)
        ) {
      gBS->FreePages (CurrentTableList->PageAddress, CurrentTableList->NumberOfPages);
      gBS->FreePool (CurrentTableList);
      return EFI_ACCESS_DENIED;
    }
    //
    // Add the table to the appropriate table version
    //
    if ((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0) {
      //
      // Save a pointer to the table
      //
      AcpiSupportInstance->Fadt1 = (EFI_ACPI_1_0_FIXED_ACPI_DESCRIPTION_TABLE *) CurrentTableList->Table;

      //
      // Update pointers in FADT.  If tables don't exist this will put NULL pointers there.
      //
      AcpiSupportInstance->Fadt1->FirmwareCtrl  = (UINT32) (UINTN) AcpiSupportInstance->Facs1;
      AcpiSupportInstance->Fadt1->Dsdt          = (UINT32) (UINTN) AcpiSupportInstance->Dsdt1;

      //
      // RSDP OEM information is updated to match the FADT OEM information
      //
      CopyMem (
        &AcpiSupportInstance->Rsdp1->OemId,
        &AcpiSupportInstance->Fadt1->Header.OemId,
        6
        );

      //
      // RSDT OEM information is updated to match the FADT OEM information.
      //
      CopyMem (
        &AcpiSupportInstance->Rsdt1->OemId,
        &AcpiSupportInstance->Fadt1->Header.OemId,
        6
        );

      CopyMem (
        &AcpiSupportInstance->Rsdt1->OemTableId,
        &AcpiSupportInstance->Fadt1->Header.OemTableId,
        sizeof (UINT64)
        );
      AcpiSupportInstance->Rsdt1->OemRevision = AcpiSupportInstance->Fadt1->Header.OemRevision;
    }

    if ((Version & EFI_ACPI_TABLE_VERSION_2_0) != 0 ||
        (Version & EFI_ACPI_TABLE_VERSION_3_0) != 0) {
      //
      // Save a pointer to the table
      //
      AcpiSupportInstance->Fadt3 = (EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE *) CurrentTableList->Table;

      //
      // Update pointers in FADT.  If tables don't exist this will put NULL pointers there.
      // Note: If the FIRMWARE_CTRL is non-zero, then X_FIRMWARE_CTRL must be zero, and
      // vice-versa.
      //
      if ((UINT64)(UINTN)AcpiSupportInstance->Facs3 < BASE_4GB) {
        AcpiSupportInstance->Fadt3->FirmwareCtrl = (UINT32) (UINTN) AcpiSupportInstance->Facs3;
        ZeroMem (
          &AcpiSupportInstance->Fadt3->XFirmwareCtrl,
          sizeof (UINT64)
          );
      } else {
        AcpiSupportInstance->Fadt3->FirmwareCtrl = 0;
        Buffer64 = (UINT64) (UINTN) AcpiSupportInstance->Facs3;
        CopyMem (
          &AcpiSupportInstance->Fadt3->XFirmwareCtrl,
          &Buffer64,
          sizeof (UINT64)
          );
      }
      AcpiSupportInstance->Fadt3->Dsdt  = (UINT32) (UINTN) AcpiSupportInstance->Dsdt3;
      Buffer64                          = (UINT64) (UINTN) AcpiSupportInstance->Dsdt3;
      CopyMem (
        &AcpiSupportInstance->Fadt3->XDsdt,
        &Buffer64,
        sizeof (UINT64)
        );

      //
      // RSDP OEM information is updated to match the FADT OEM information
      //
      CopyMem (
        &AcpiSupportInstance->Rsdp3->OemId,
        &AcpiSupportInstance->Fadt3->Header.OemId,
        6
        );

      //
      // RSDT OEM information is updated to match FADT OEM information.
      //
      CopyMem (
        &AcpiSupportInstance->Rsdt3->OemId,
        &AcpiSupportInstance->Fadt3->Header.OemId,
        6
        );
      CopyMem (
        &AcpiSupportInstance->Rsdt3->OemTableId,
        &AcpiSupportInstance->Fadt3->Header.OemTableId,
        sizeof (UINT64)
        );
      AcpiSupportInstance->Rsdt3->OemRevision = AcpiSupportInstance->Fadt3->Header.OemRevision;

      //
      // XSDT OEM information is updated to match FADT OEM information.
      //
      CopyMem (
        &AcpiSupportInstance->Xsdt->OemId,
        &AcpiSupportInstance->Fadt3->Header.OemId,
        6
        );
      CopyMem (
        &AcpiSupportInstance->Xsdt->OemTableId,
        &AcpiSupportInstance->Fadt3->Header.OemTableId,
        sizeof (UINT64)
        );
      AcpiSupportInstance->Xsdt->OemRevision = AcpiSupportInstance->Fadt3->Header.OemRevision;
    }

    //
    // Checksum the table
    //
    if (Checksum) {
      AcpiPlatformChecksum (
        CurrentTableList->Table,
        CurrentTableList->Table->Length,
        OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
        Checksum)
        );
    }
    break;

  case EFI_ACPI_1_0_FIRMWARE_ACPI_CONTROL_STRUCTURE_SIGNATURE:
    //
    // Check that the table has not been previously added.
    //
   if (((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0 && AcpiSupportInstance->Facs1 != NULL) ||
        ((Version & EFI_ACPI_TABLE_VERSION_2_0)  != 0 && AcpiSupportInstance->Facs3 != NULL) ||
        ((Version & EFI_ACPI_TABLE_VERSION_3_0)  != 0 && AcpiSupportInstance->Facs3 != NULL)
        ) {
      gBS->FreePages (CurrentTableList->PageAddress, CurrentTableList->NumberOfPages);
      gBS->FreePool (CurrentTableList);
      return EFI_ACCESS_DENIED;
    }
    //
    // FACS is referenced by FADT and is not part of RSDT
    //
    AddToRsdt = FALSE;

    //
    // Add the table to the appropriate table version
    //
    if ((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0) {
      //
      // Save a pointer to the table
      //
      AcpiSupportInstance->Facs1 = (EFI_ACPI_1_0_FIRMWARE_ACPI_CONTROL_STRUCTURE *) CurrentTableList->Table;

      //
      // If FADT already exists, update table pointers.
      //
      if (AcpiSupportInstance->Fadt1 != NULL) {
        AcpiSupportInstance->Fadt1->FirmwareCtrl = (UINT32) (UINTN) AcpiSupportInstance->Facs1;

        //
        // Checksum FADT table
        //
        AcpiPlatformChecksum (
          AcpiSupportInstance->Fadt1,
          AcpiSupportInstance->Fadt1->Header.Length,
          OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
          Checksum)
          );
      }
    }

    if ((Version & EFI_ACPI_TABLE_VERSION_2_0) != 0 ||
        (Version & EFI_ACPI_TABLE_VERSION_3_0) != 0) {
      //
      // Save a pointer to the table
      //
      AcpiSupportInstance->Facs3 = (EFI_ACPI_3_0_FIRMWARE_ACPI_CONTROL_STRUCTURE *) CurrentTableList->Table;

      //
      // If FADT already exists, update table pointers.
      //
      if (AcpiSupportInstance->Fadt3 != NULL) {
        //
        // Note: If the FIRMWARE_CTRL is non-zero, then X_FIRMWARE_CTRL must be zero, and
        // vice-versa.
        //
        if ((UINT64)(UINTN)AcpiSupportInstance->Facs3 < BASE_4GB) {
          AcpiSupportInstance->Fadt3->FirmwareCtrl  = (UINT32) (UINTN) AcpiSupportInstance->Facs3;
        } else {
          Buffer64 = (UINT64) (UINTN) AcpiSupportInstance->Facs3;
          CopyMem (
            &AcpiSupportInstance->Fadt3->XFirmwareCtrl,
            &Buffer64,
            sizeof (UINT64)
            );
        }

        //
        // Checksum FADT table
        //
        AcpiPlatformChecksum (
          AcpiSupportInstance->Fadt3,
          AcpiSupportInstance->Fadt3->Header.Length,
          OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
          Checksum)
          );
      }
    }

    break;

  case EFI_ACPI_1_0_DIFFERENTIATED_SYSTEM_DESCRIPTION_TABLE_SIGNATURE:
    //
    // Check that the table has not been previously added.
    //
   if (((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0 && AcpiSupportInstance->Dsdt1 != NULL) ||
        ((Version & EFI_ACPI_TABLE_VERSION_2_0)  != 0 && AcpiSupportInstance->Dsdt3 != NULL) ||
        ((Version & EFI_ACPI_TABLE_VERSION_3_0)  != 0 && AcpiSupportInstance->Dsdt3 != NULL)
        ) {
      gBS->FreePages (CurrentTableList->PageAddress, CurrentTableList->NumberOfPages);
      gBS->FreePool (CurrentTableList);
      return EFI_ACCESS_DENIED;
    }
    //
    // DSDT is referenced by FADT and is not part of RSDT
    //
    AddToRsdt = FALSE;

    //
    // Add the table to the appropriate table version
    //
    if ((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0) {
      //
      // Save a pointer to the table
      //
      AcpiSupportInstance->Dsdt1 = (EFI_ACPI_DESCRIPTION_HEADER *) CurrentTableList->Table;

      //
      // If FADT already exists, update table pointers.
      //
      if (AcpiSupportInstance->Fadt1 != NULL) {
        AcpiSupportInstance->Fadt1->Dsdt = (UINT32) (UINTN) AcpiSupportInstance->Dsdt1;

        //
        // Checksum FADT table
        //
        AcpiPlatformChecksum (
          AcpiSupportInstance->Fadt1,
          AcpiSupportInstance->Fadt1->Header.Length,
          OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
          Checksum)
          );
      }
    }

     if ((Version & EFI_ACPI_TABLE_VERSION_2_0) != 0 ||
        (Version & EFI_ACPI_TABLE_VERSION_3_0) != 0) {
      //
      // Save a pointer to the table
      //
      AcpiSupportInstance->Dsdt3 = (EFI_ACPI_DESCRIPTION_HEADER *) CurrentTableList->Table;

      //
      // If FADT already exists, update table pointers.
      //
      if (AcpiSupportInstance->Fadt3 != NULL) {
        AcpiSupportInstance->Fadt3->Dsdt  = (UINT32) (UINTN) AcpiSupportInstance->Dsdt3;
        Buffer64                          = (UINT64) (UINTN) AcpiSupportInstance->Dsdt3;
        CopyMem (
          &AcpiSupportInstance->Fadt3->XDsdt,
          &Buffer64,
          sizeof (UINT64)
          );

        //
        // Checksum FADT table
        //
        AcpiPlatformChecksum (
          AcpiSupportInstance->Fadt3,
          AcpiSupportInstance->Fadt3->Header.Length,
          OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
          Checksum)
          );
      }
    }
    //
    // Checksum the table
    //
    if (Checksum) {
      AcpiPlatformChecksum (
        CurrentTableList->Table,
        CurrentTableList->Table->Length,
        OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
        Checksum)
        );
    }
    break;

  default:
    //
    // Checksum the table
    //
    if (Checksum) {
      AcpiPlatformChecksum (
        CurrentTableList->Table,
        CurrentTableList->Table->Length,
        OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
        Checksum)
        );
    }
    break;
  }
  //
  // Add the table to the current list of tables
  //
  InsertTailList (&AcpiSupportInstance->TableList, &CurrentTableList->Link);

  //
  // Add the table to RSDT and/or XSDT table entry lists.
  //
  //
  // Add to ACPI 1.0b table tree
  //
  if ((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0) {
    if (AddToRsdt) {
      //
      // If the table number exceed the gEfiAcpiMaxNumTables, enlarge the table buffer
      //
      if (AcpiSupportInstance->NumberOfTableEntries1 >= mEfiAcpiMaxNumTables) {
        Status = ReallocateAcpiTableBuffer (AcpiSupportInstance);
        ASSERT_EFI_ERROR (Status);
      }
      CurrentRsdtEntry = (UINT32 *)
        (
          (UINT8 *) AcpiSupportInstance->Rsdt1 +
          sizeof (EFI_ACPI_DESCRIPTION_HEADER) +
          AcpiSupportInstance->NumberOfTableEntries1 *
          sizeof (UINT32)
        );

      //
      // Add entry to the RSDT unless its the FACS or DSDT
      //
      *CurrentRsdtEntry = (UINT32) (UINTN) CurrentTableList->Table;

      //
      // Update RSDT length
      //
      AcpiSupportInstance->Rsdt1->Length = AcpiSupportInstance->Rsdt1->Length + sizeof (UINT32);

      AcpiSupportInstance->NumberOfTableEntries1++;
    }
  }
  //
  // Add to ACPI 2.0/3.0  table tree
  //
  if ((Version & EFI_ACPI_TABLE_VERSION_2_0) != 0 || (Version & EFI_ACPI_TABLE_VERSION_3_0) != 0) {
    if (AddToRsdt) {
       //
       // If the table number exceed the gEfiAcpiMaxNumTables, enlarge the table buffer
       //
       if (AcpiSupportInstance->NumberOfTableEntries3 >= mEfiAcpiMaxNumTables) {
         Status = ReallocateAcpiTableBuffer (AcpiSupportInstance);
         ASSERT_EFI_ERROR (Status);
       }
      //
      // At this time, it is assumed that RSDT and XSDT maintain parallel lists of tables.
      // If it becomes necessary to maintain separate table lists, changes will be required.
      //
      CurrentRsdtEntry = (UINT32 *)
        (
          (UINT8 *) AcpiSupportInstance->Rsdt3 +
          sizeof (EFI_ACPI_DESCRIPTION_HEADER) +
          AcpiSupportInstance->NumberOfTableEntries3 *
          sizeof (UINT32)
        );

      //
      // This pointer must not be directly dereferenced as the XSDT entries may not
      // be 64 bit aligned resulting in a possible fault.  Use CopyMem to update.
      //
      CurrentXsdtEntry = (VOID *)
        (
          (UINT8 *) AcpiSupportInstance->Xsdt +
          sizeof (EFI_ACPI_DESCRIPTION_HEADER) +
          AcpiSupportInstance->NumberOfTableEntries3 *
          sizeof (UINT64)
        );

      //
      // Add entry to the RSDT
      //
      *CurrentRsdtEntry = (UINT32) (UINTN) CurrentTableList->Table;

      //
      // Update RSDT length
      //
      AcpiSupportInstance->Rsdt3->Length = AcpiSupportInstance->Rsdt3->Length + sizeof (UINT32);

      //
      // Add entry to XSDT, XSDT expects 64 bit pointers, but
      // the table pointers in XSDT are not aligned on 8 byte boundary.
      //
      Buffer64 = (UINT64) (UINTN) CurrentTableList->Table;
      CopyMem (
        CurrentXsdtEntry,
        &Buffer64,
        sizeof (UINT64)
        );

      //
      // Update length
      //
      AcpiSupportInstance->Xsdt->Length = AcpiSupportInstance->Xsdt->Length + sizeof (UINT64);

      AcpiSupportInstance->NumberOfTableEntries3++;
    }
  }

  ChecksumCommonTables (AcpiSupportInstance);
  return EFI_SUCCESS;
}
/**
  This function finds the table specified by the handle and returns a pointer to it.
  If the handle is not found, EFI_NOT_FOUND is returned and the contents of Table are
  undefined.

  @param  Handle      Table to find.
  @param  TableList   Table list to search
  @param  Table       Pointer to table found.

  @return EFI_SUCCESS    The function completed successfully.
  @return EFI_NOT_FOUND  No table found matching the handle specified.

**/
EFI_STATUS
FindTableByHandle (
  IN UINTN                                Handle,
  IN LIST_ENTRY                       *TableList,
  OUT EFI_ACPI_TABLE_LIST                 **Table
  )
{
  LIST_ENTRY      *CurrentLink;
  EFI_ACPI_TABLE_LIST *CurrentTable;

  //
  // Check for invalid input parameters
  //
  ASSERT (Table);

  //
  // Find the table
  //
  CurrentLink = TableList->ForwardLink;

  while (CurrentLink != TableList) {
    CurrentTable = EFI_ACPI_TABLE_LIST_FROM_LINK (CurrentLink);
    if (CurrentTable->Handle == Handle) {
      //
      // Found handle, so return this table.
      //
      *Table = CurrentTable;
      return EFI_SUCCESS;
    }

    CurrentLink = CurrentLink->ForwardLink;
  }
  //
  // Table not found
  //
  return EFI_NOT_FOUND;
}
/**
  This function removes a basic table from the RSDT and/or XSDT.
  For Acpi 1.0 tables, pass in the Rsdt.
  For Acpi 2.0 tables, pass in both Rsdt and Xsdt.

  @param  Table                 Pointer to table found.
  @param  NumberOfTableEntries  Current number of table entries in the RSDT/XSDT
  @param  Rsdt                  Pointer to the RSDT to remove from
  @param  Xsdt                  Pointer to the Xsdt to remove from

  @return EFI_SUCCESS            The function completed successfully.
  @return EFI_INVALID_PARAMETER  The table was not found in both Rsdt and Xsdt.

**/
EFI_STATUS
RemoveTableFromRsdt (
  IN OUT EFI_ACPI_TABLE_LIST              * Table,
  IN OUT UINTN                            *NumberOfTableEntries,
  IN OUT EFI_ACPI_DESCRIPTION_HEADER      * Rsdt,
  IN OUT EFI_ACPI_DESCRIPTION_HEADER      * Xsdt OPTIONAL
  )
{
  UINT32  *CurrentRsdtEntry;
  VOID    *CurrentXsdtEntry;
  UINT64  CurrentTablePointer64;
  UINTN   TempIndex;

  //
  // Check for invalid input parameters
  //
  ASSERT (Table);
  ASSERT (NumberOfTableEntries);
  ASSERT (Rsdt);

  //
  // Find the table entry in the RSDT and XSDT
  //
  for (TempIndex = 0; TempIndex < *NumberOfTableEntries; TempIndex++) {
    //
    // At this time, it is assumed that RSDT and XSDT maintain parallel lists of tables.
    // If it becomes necessary to maintain separate table lists, changes will be required.
    //
    CurrentRsdtEntry = (UINT32 *) ((UINT8 *) Rsdt + sizeof (EFI_ACPI_DESCRIPTION_HEADER) + TempIndex * sizeof (UINT32));
    if (Xsdt != NULL) {
      //
      // This pointer must not be directly dereferenced as the XSDT entries may not
      // be 64 bit aligned resulting in a possible fault.  Use CopyMem to update.
      //
      CurrentXsdtEntry = (VOID *) ((UINT8 *) Xsdt + sizeof (EFI_ACPI_DESCRIPTION_HEADER) + TempIndex * sizeof (UINT64));

      //
      // Read the entry value out of the XSDT
      //
      CopyMem (&CurrentTablePointer64, CurrentXsdtEntry, sizeof (UINT64));
    } else {
      //
      // Initialize to NULL
      //
      CurrentXsdtEntry      = 0;
      CurrentTablePointer64 = 0;
    }
    //
    // Check if we have found the corresponding entry in both RSDT and XSDT
    //
    if (*CurrentRsdtEntry == (UINT32) (UINTN) Table->Table &&
        ((Xsdt == NULL) || CurrentTablePointer64 == (UINT64) (UINTN) Table->Table)
        ) {
      //
      // Found entry, so copy all following entries and shrink table
      // We actually copy all + 1 to copy the initialized value of memory over
      // the last entry.
      //
      CopyMem (CurrentRsdtEntry, CurrentRsdtEntry + 1, (*NumberOfTableEntries - TempIndex) * sizeof (UINT32));
      Rsdt->Length = Rsdt->Length - sizeof (UINT32);
      if (Xsdt != NULL) {
        CopyMem (CurrentXsdtEntry, ((UINT64 *) CurrentXsdtEntry) + 1, (*NumberOfTableEntries - TempIndex) * sizeof (UINT64));
        Xsdt->Length = Xsdt->Length - sizeof (UINT64);
      }
      break;
    } else if (TempIndex + 1 == *NumberOfTableEntries) {
      //
      // At the last entry, and table not found
      //
      return EFI_INVALID_PARAMETER;
    }
  }
  //
  // Checksum the tables
  //
  AcpiPlatformChecksum (
    Rsdt,
    Rsdt->Length,
    OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
    Checksum)
    );

  if (Xsdt != NULL) {
    AcpiPlatformChecksum (
      Xsdt,
      Xsdt->Length,
      OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
      Checksum)
      );
  }
  //
  // Decrement the number of tables
  //
  (*NumberOfTableEntries)--;

  return EFI_SUCCESS;
}
/**
  This function removes a table and frees any associated memory.

  @param  AcpiSupportInstance  Instance of the protocol.
  @param  Version            Version(s) to delete.
  @param  Table              Pointer to table found.

  @return EFI_SUCCESS  The function completed successfully.

**/
EFI_STATUS
DeleteTable (
  IN EFI_ACPI_SUPPORT_INSTANCE            *AcpiSupportInstance,
  IN EFI_ACPI_TABLE_VERSION               Version,
  IN OUT EFI_ACPI_TABLE_LIST              *Table
  )
{
  UINT32  CurrentTableSignature;
  BOOLEAN RemoveFromRsdt;

  //
  // Check for invalid input parameters
  //
  ASSERT (AcpiSupportInstance);
  ASSERT (Table);

  //
  // Init locals
  //
  RemoveFromRsdt        = TRUE;

  if (Table->Table != NULL) {
    CurrentTableSignature = ((EFI_ACPI_COMMON_HEADER *) Table->Table)->Signature;

    //
    // Basic tasks to accomplish delete are:
    //   Determine removal requirements (in RSDT/XSDT or not)
    //   Remove entry from RSDT/XSDT
    //   Remove any table references to the table
    //   If no one is using the table
    //      Free the table (removing pointers from private data and tables)
    //      Remove from list
    //      Free list structure
    //
    //
    // Determine if this table is in the RSDT or XSDT
    //
    if ((CurrentTableSignature == EFI_ACPI_1_0_FIRMWARE_ACPI_CONTROL_STRUCTURE_SIGNATURE) ||
        (CurrentTableSignature == EFI_ACPI_2_0_DIFFERENTIATED_SYSTEM_DESCRIPTION_TABLE_SIGNATURE) ||
        (CurrentTableSignature == EFI_ACPI_3_0_DIFFERENTIATED_SYSTEM_DESCRIPTION_TABLE_SIGNATURE)
        ) {
      RemoveFromRsdt = FALSE;
    }
    //
    // We don't remove the FADT in the standard way because some
    // OS expect the FADT to be early in the table list.
    // So we always put it as the first element in the list.
    //
    if (CurrentTableSignature == EFI_ACPI_1_0_FIXED_ACPI_DESCRIPTION_TABLE_SIGNATURE) {
      RemoveFromRsdt = FALSE;
    }

    //
    // Remove the table from RSDT and XSDT
    //

    //
    // This is a basic table, remove it from any lists and the Rsdt and/or Xsdt
    //
    if (Version & EFI_ACPI_TABLE_VERSION_NONE & Table->Version) {
      //
      // Remove this version from the table
      //
      Table->Version = Table->Version &~EFI_ACPI_TABLE_VERSION_NONE;
    }

    if (Version & EFI_ACPI_TABLE_VERSION_1_0B & Table->Version) {
      //
      // Remove this version from the table
      //
      Table->Version = Table->Version &~EFI_ACPI_TABLE_VERSION_1_0B;

      //
      // Remove from Rsdt.  We don't care about the return value because it is
      // acceptable for the table to not exist in Rsdt.
      // We didn't add some tables so we don't remove them.
      //
      if (RemoveFromRsdt) {
        RemoveTableFromRsdt (
          Table,
          &AcpiSupportInstance->NumberOfTableEntries1,
          AcpiSupportInstance->Rsdt1,
          NULL
          );
      }
    }

    if ((Version & EFI_ACPI_TABLE_VERSION_2_0 & Table->Version) ||
        (Version & EFI_ACPI_TABLE_VERSION_3_0 & Table->Version)) {
      //
      // Remove this version from the table
      //
      if (Version & EFI_ACPI_TABLE_VERSION_2_0 & Table->Version) {
        Table->Version = Table->Version &~EFI_ACPI_TABLE_VERSION_2_0;
      }
      if (Version & EFI_ACPI_TABLE_VERSION_3_0 & Table->Version) {
        Table->Version = Table->Version &~EFI_ACPI_TABLE_VERSION_3_0;
      }

      //
      // Remove from Rsdt and Xsdt.  We don't care about the return value
      // because it is acceptable for the table to not exist in Rsdt/Xsdt.
      // We didn't add some tables so we don't remove them.
      //
      if (RemoveFromRsdt) {
        RemoveTableFromRsdt (
          Table,
          &AcpiSupportInstance->NumberOfTableEntries3,
          AcpiSupportInstance->Rsdt3,
          AcpiSupportInstance->Xsdt
          );
      }
    }
    //
    // Free the table, clean up any dependent tables and our private data pointers.
    //
    switch (Table->Table->Signature) {

    case EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE_SIGNATURE:
      if ((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0) {
        AcpiSupportInstance->Fadt1 = NULL;
      }

      if ((Version & EFI_ACPI_TABLE_VERSION_2_0) != 0 ||
          (Version & EFI_ACPI_TABLE_VERSION_3_0) != 0) {
        AcpiSupportInstance->Fadt3 = NULL;
      }
      break;

    case EFI_ACPI_3_0_FIRMWARE_ACPI_CONTROL_STRUCTURE_SIGNATURE:
      if ((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0) {
        AcpiSupportInstance->Facs1 = NULL;

        //
        // Update FADT table pointers
        //
        if (AcpiSupportInstance->Fadt1 != NULL) {
          AcpiSupportInstance->Fadt1->FirmwareCtrl = 0;

          //
          // Checksum table
          //
          AcpiPlatformChecksum (
            AcpiSupportInstance->Fadt1,
            AcpiSupportInstance->Fadt1->Header.Length,
            OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
            Checksum)
            );
        }
      }

      if ((Version & EFI_ACPI_TABLE_VERSION_2_0) != 0 ||
          (Version & EFI_ACPI_TABLE_VERSION_3_0) != 0) {
        AcpiSupportInstance->Facs3 = NULL;

        //
        // Update FADT table pointers
        //
        if (AcpiSupportInstance->Fadt3 != NULL) {
          AcpiSupportInstance->Fadt3->FirmwareCtrl = 0;
          ZeroMem (&AcpiSupportInstance->Fadt3->XFirmwareCtrl, sizeof (UINT64));

          //
          // Checksum table
          //
          AcpiPlatformChecksum (
            AcpiSupportInstance->Fadt3,
            AcpiSupportInstance->Fadt3->Header.Length,
            OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
            Checksum)
            );
        }
      }
      break;

    case EFI_ACPI_3_0_DIFFERENTIATED_SYSTEM_DESCRIPTION_TABLE_SIGNATURE:
      if ((Version & EFI_ACPI_TABLE_VERSION_1_0B) != 0) {
        AcpiSupportInstance->Dsdt1 = NULL;

        //
        // Update FADT table pointers
        //
        if (AcpiSupportInstance->Fadt1 != NULL) {
          AcpiSupportInstance->Fadt1->Dsdt = 0;

          //
          // Checksum table
          //
          AcpiPlatformChecksum (
            AcpiSupportInstance->Fadt1,
            AcpiSupportInstance->Fadt1->Header.Length,
            OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
            Checksum)
            );
        }
      }


      if ((Version & EFI_ACPI_TABLE_VERSION_2_0) != 0 ||
          (Version & EFI_ACPI_TABLE_VERSION_3_0) != 0) {
        AcpiSupportInstance->Dsdt3 = NULL;

        //
        // Update FADT table pointers
        //
        if (AcpiSupportInstance->Fadt3 != NULL) {
          AcpiSupportInstance->Fadt3->Dsdt = 0;
          ZeroMem (&AcpiSupportInstance->Fadt3->XDsdt, sizeof (UINT64));

          //
          // Checksum table
          //
          AcpiPlatformChecksum (
            AcpiSupportInstance->Fadt3,
            AcpiSupportInstance->Fadt3->Header.Length,
            OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
            Checksum)
            );
        }
      }
      break;

    default:
      //
      // Do nothing
      //
      break;
    }
  }
  //
  // If no version is using this table anymore, remove and free list entry.
  //
  if (Table->Version == 0) {
    //
    // Free the Table
    //
    gBS->FreePages (Table->PageAddress, Table->NumberOfPages);
    RemoveEntryList (&(Table->Link));
    gBS->FreePool (Table);
  }
  //
  // Done
  //
  return EFI_SUCCESS;
}
/**
  This function finds and removes the table specified by the handle.

  @param  AcpiSupportInstance  Instance of the protocol.
  @param  Version              Bitmask of which versions to remove.
  @param  Handle               Table to remove.

  @return EFI_SUCCESS    The function completed successfully.
  @return EFI_ABORTED    An error occurred.
  @return EFI_NOT_FOUND  Handle not found in table list.
**/
EFI_STATUS
RemoveTableFromList (
  IN EFI_ACPI_SUPPORT_INSTANCE            *AcpiSupportInstance,
  IN EFI_ACPI_TABLE_VERSION               Version,
  IN UINTN                                Handle
  )
{
  EFI_ACPI_TABLE_LIST *Table;
  EFI_STATUS          Status;

  Table = NULL;

  //
  // Check for invalid input parameters
  //
  ASSERT (AcpiSupportInstance);

  //
  // Find the table
  //
  Status = FindTableByHandle (
            Handle,
            &AcpiSupportInstance->TableList,
            &Table
            );
  if (EFI_ERROR (Status)) {
    return EFI_NOT_FOUND;
  }
  //
  // Remove the table
  //
  Status = DeleteTable (AcpiSupportInstance, Version, Table);
  if (EFI_ERROR (Status)) {
    return EFI_ABORTED;
  }
  //
  // Completed successfully
  //
  return EFI_SUCCESS;
}
/**
  This function calculates and updates an UINT8 checksum.

  @param  Buffer          Pointer to buffer to checksum
  @param  Size            Number of bytes to checksum
  @param  ChecksumOffset  Offset to place the checksum result in

  @return EFI_SUCCESS             The function completed successfully.

**/
EFI_STATUS
AcpiPlatformChecksum (
  IN VOID       *Buffer,
  IN UINTN      Size,
  IN UINTN      ChecksumOffset
  )
{
  UINT8 Sum;
  UINT8 *Ptr;

  Sum = 0;
  //
  // Initialize pointer
  //
  Ptr = Buffer;

  //
  // set checksum to 0 first
  //
  Ptr[ChecksumOffset] = 0;

  //
  // add all content of buffer
  //
  while ((Size--) != 0) {
    Sum = (UINT8) (Sum + (*Ptr++));
  }
  //
  // set checksum
  //
  Ptr                 = Buffer;
  Ptr[ChecksumOffset] = (UINT8) (0xff - Sum + 1);

  return EFI_SUCCESS;
}
/**
  Checksum all versions of the common tables, RSDP, RSDT, XSDT.

  @param  AcpiSupportInstance  Protocol instance private data.

  @return EFI_SUCCESS        The function completed successfully.

**/
EFI_STATUS
ChecksumCommonTables (
  IN OUT EFI_ACPI_SUPPORT_INSTANCE                 *AcpiSupportInstance
  )
{
  //
  // RSDP ACPI 1.0 checksum for 1.0 table.  This is only the first 20 bytes of the structure
  //
  AcpiPlatformChecksum (
    AcpiSupportInstance->Rsdp1,
    sizeof (EFI_ACPI_1_0_ROOT_SYSTEM_DESCRIPTION_POINTER),
    OFFSET_OF (EFI_ACPI_1_0_ROOT_SYSTEM_DESCRIPTION_POINTER,
    Checksum)
    );

  //
  // RSDP ACPI 1.0 checksum for 2.0/3.0 table.  This is only the first 20 bytes of the structure
  //
  AcpiPlatformChecksum (
    AcpiSupportInstance->Rsdp3,
    sizeof (EFI_ACPI_1_0_ROOT_SYSTEM_DESCRIPTION_POINTER),
    OFFSET_OF (EFI_ACPI_1_0_ROOT_SYSTEM_DESCRIPTION_POINTER,
    Checksum)
    );

  //
  // RSDP ACPI 2.0/3.0 checksum, this is the entire table
  //
  AcpiPlatformChecksum (
    AcpiSupportInstance->Rsdp3,
    sizeof (EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_POINTER),
    OFFSET_OF (EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_POINTER,
    ExtendedChecksum)
    );

  //
  // RSDT checksums
  //
  AcpiPlatformChecksum (
    AcpiSupportInstance->Rsdt1,
    AcpiSupportInstance->Rsdt1->Length,
    OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
    Checksum)
    );

  AcpiPlatformChecksum (
    AcpiSupportInstance->Rsdt3,
    AcpiSupportInstance->Rsdt3->Length,
    OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
    Checksum)
    );

  //
  // XSDT checksum
  //
  AcpiPlatformChecksum (
    AcpiSupportInstance->Xsdt,
    AcpiSupportInstance->Xsdt->Length,
    OFFSET_OF (EFI_ACPI_DESCRIPTION_HEADER,
    Checksum)
    );

  return EFI_SUCCESS;
}
/**
  Constructor for the ACPI support protocol to initializes instance data.

  @param AcpiSupportInstance   Instance to construct

  @retval EFI_SUCCESS             Instance initialized.
  @retval  EFI_OUT_OF_RESOURCES  Unable to allocate required resources.
**/
EFI_STATUS
AcpiSupportAcpiSupportConstructor (
  IN EFI_ACPI_SUPPORT_INSTANCE                 *AcpiSupportInstance
  )
{
  EFI_STATUS            Status;
  UINT64                CurrentData;
  UINTN                 TotalSize;
  UINTN                 RsdpTableSize;
  UINT8                 *Pointer;
  EFI_PHYSICAL_ADDRESS  PageAddress;

  //
  // Check for invalid input parameters
  //
  ASSERT (AcpiSupportInstance);

  InitializeListHead (&AcpiSupportInstance->TableList);
  AcpiSupportInstance->CurrentHandle              = 1;
  AcpiSupportInstance->AcpiSupport.GetAcpiTable   = GetAcpiTable;
  AcpiSupportInstance->AcpiSupport.SetAcpiTable   = SetAcpiTable;
  AcpiSupportInstance->AcpiSupport.PublishTables  = PublishTables;

  AcpiSupportInstance->AcpiTableProtocol.InstallAcpiTable   = InstallAcpiTable;
  AcpiSupportInstance->AcpiTableProtocol.UninstallAcpiTable = UninstallAcpiTable;

  //
  // Create RSDP table
  //
  RsdpTableSize = sizeof (EFI_ACPI_1_0_ROOT_SYSTEM_DESCRIPTION_POINTER) +
                  sizeof (EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_POINTER);

  PageAddress = 0xFFFFFFFF;
  Status = gBS->AllocatePages (
                  AllocateMaxAddress,
                  EfiACPIReclaimMemory,
                  EFI_SIZE_TO_PAGES (RsdpTableSize),
                  &PageAddress
                  );

  if (EFI_ERROR (Status)) {
    return EFI_OUT_OF_RESOURCES;
  }

  Pointer = (UINT8 *) (UINTN) PageAddress;
  ZeroMem (Pointer, RsdpTableSize);

  AcpiSupportInstance->Rsdp1 = (EFI_ACPI_1_0_ROOT_SYSTEM_DESCRIPTION_POINTER *) Pointer;
  Pointer += sizeof (EFI_ACPI_1_0_ROOT_SYSTEM_DESCRIPTION_POINTER);
  AcpiSupportInstance->Rsdp3 = (EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_POINTER *) Pointer;

  //
  // Create RSDT, XSDT structures
  //
  TotalSize = sizeof (EFI_ACPI_DESCRIPTION_HEADER) +         // for ACPI 1.0 RSDT
              mEfiAcpiMaxNumTables * sizeof (UINT32) +
              sizeof (EFI_ACPI_DESCRIPTION_HEADER) +         // for ACPI 2.0/3.0 RSDT
              mEfiAcpiMaxNumTables * sizeof (UINT32) +
              sizeof (EFI_ACPI_DESCRIPTION_HEADER) +         // for ACPI 2.0/3.0 XSDT
              mEfiAcpiMaxNumTables * sizeof (UINT64);

  //
  // Allocate memory in the lower 32 bit of address range for
  // compatibility with ACPI 1.0 OS.
  //
  // This is done because ACPI 1.0 pointers are 32 bit values.
  // ACPI 2.0 OS and all 64 bit OS must use the 64 bit ACPI table addresses.
  // There is no architectural reason these should be below 4GB, it is purely
  // for convenience of implementation that we force memory below 4GB.
  //
  PageAddress = 0xFFFFFFFF;
  Status = gBS->AllocatePages (
                  AllocateMaxAddress,
                  EfiACPIReclaimMemory,
                  EFI_SIZE_TO_PAGES (TotalSize),
                  &PageAddress
                  );

  if (EFI_ERROR (Status)) {
    gBS->FreePages ((EFI_PHYSICAL_ADDRESS)(UINTN)AcpiSupportInstance->Rsdp1, EFI_SIZE_TO_PAGES (RsdpTableSize));
    return EFI_OUT_OF_RESOURCES;
  }

  Pointer = (UINT8 *) (UINTN) PageAddress;
  ZeroMem (Pointer, TotalSize);

  AcpiSupportInstance->Rsdt1 = (EFI_ACPI_DESCRIPTION_HEADER *) Pointer;
  Pointer += (sizeof (EFI_ACPI_DESCRIPTION_HEADER) + EFI_ACPI_MAX_NUM_TABLES * sizeof (UINT32));
  AcpiSupportInstance->Rsdt3 = (EFI_ACPI_DESCRIPTION_HEADER *) Pointer;
  Pointer += (sizeof (EFI_ACPI_DESCRIPTION_HEADER) + EFI_ACPI_MAX_NUM_TABLES * sizeof (UINT32));
  AcpiSupportInstance->Xsdt = (EFI_ACPI_DESCRIPTION_HEADER *) Pointer;

  //
  // Initialize RSDP
  //
  CurrentData = EFI_ACPI_1_0_ROOT_SYSTEM_DESCRIPTION_POINTER_SIGNATURE;
  CopyMem (&AcpiSupportInstance->Rsdp1->Signature, &CurrentData, sizeof (UINT64));
  CopyMem (AcpiSupportInstance->Rsdp1->OemId, PcdGetPtr (PcdAcpiDefaultOemId), sizeof (AcpiSupportInstance->Rsdp1->OemId));
  AcpiSupportInstance->Rsdp1->Reserved    = EFI_ACPI_RESERVED_BYTE;
  AcpiSupportInstance->Rsdp1->RsdtAddress = (UINT32) (UINTN) AcpiSupportInstance->Rsdt1;

  CurrentData = EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_POINTER_SIGNATURE;
  CopyMem (&AcpiSupportInstance->Rsdp3->Signature, &CurrentData, sizeof (UINT64));
  CopyMem (AcpiSupportInstance->Rsdp3->OemId, PcdGetPtr (PcdAcpiDefaultOemId), sizeof (AcpiSupportInstance->Rsdp3->OemId));
  AcpiSupportInstance->Rsdp3->Revision    = EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_POINTER_REVISION;
  AcpiSupportInstance->Rsdp3->RsdtAddress = (UINT32) (UINTN) AcpiSupportInstance->Rsdt3;
  AcpiSupportInstance->Rsdp3->Length      = sizeof (EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_POINTER);
  CurrentData = (UINT64) (UINTN) AcpiSupportInstance->Xsdt;
  CopyMem (&AcpiSupportInstance->Rsdp3->XsdtAddress, &CurrentData, sizeof (UINT64));
  SetMem (AcpiSupportInstance->Rsdp3->Reserved, 3, EFI_ACPI_RESERVED_BYTE);

  //
  // Initialize Rsdt
  //
  // Note that we "reserve" one entry for the FADT so it can always be
  // at the beginning of the list of tables.  Some OS don't seem
  // to find it correctly if it is too far down the list.
  //
  AcpiSupportInstance->Rsdt1->Signature = EFI_ACPI_1_0_ROOT_SYSTEM_DESCRIPTION_TABLE_SIGNATURE;
  AcpiSupportInstance->Rsdt1->Length    = sizeof (EFI_ACPI_DESCRIPTION_HEADER);
  AcpiSupportInstance->Rsdt1->Revision  = EFI_ACPI_1_0_ROOT_SYSTEM_DESCRIPTION_TABLE_REVISION;
  CopyMem (AcpiSupportInstance->Rsdt1->OemId, PcdGetPtr (PcdAcpiDefaultOemId), sizeof (AcpiSupportInstance->Rsdt1->OemId));
  CurrentData = PcdGet64 (PcdAcpiDefaultOemTableId);
  CopyMem (&AcpiSupportInstance->Rsdt1->OemTableId, &CurrentData, sizeof (UINT64));
  AcpiSupportInstance->Rsdt1->OemRevision     = PcdGet32 (PcdAcpiDefaultOemRevision);
  AcpiSupportInstance->Rsdt1->CreatorId       = PcdGet32 (PcdAcpiDefaultCreatorId);
  AcpiSupportInstance->Rsdt1->CreatorRevision = PcdGet32 (PcdAcpiDefaultCreatorRevision);
  //
  // We always reserve first one for FADT
  //
  AcpiSupportInstance->NumberOfTableEntries1  = 1;
  AcpiSupportInstance->Rsdt1->Length          = AcpiSupportInstance->Rsdt1->Length + sizeof(UINT32);

  AcpiSupportInstance->Rsdt3->Signature       = EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_TABLE_SIGNATURE;
  AcpiSupportInstance->Rsdt3->Length          = sizeof (EFI_ACPI_DESCRIPTION_HEADER);
  AcpiSupportInstance->Rsdt3->Revision        = EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_TABLE_REVISION;
  CopyMem (AcpiSupportInstance->Rsdt3->OemId, PcdGetPtr (PcdAcpiDefaultOemId), sizeof (AcpiSupportInstance->Rsdt3->OemId));
  CurrentData = PcdGet64 (PcdAcpiDefaultOemTableId);
  CopyMem (&AcpiSupportInstance->Rsdt3->OemTableId, &CurrentData, sizeof (UINT64));
  AcpiSupportInstance->Rsdt3->OemRevision     = PcdGet32 (PcdAcpiDefaultOemRevision);
  AcpiSupportInstance->Rsdt3->CreatorId       = PcdGet32 (PcdAcpiDefaultCreatorId);
  AcpiSupportInstance->Rsdt3->CreatorRevision = PcdGet32 (PcdAcpiDefaultCreatorRevision);
  //
  // We always reserve first one for FADT
  //
  AcpiSupportInstance->NumberOfTableEntries3  = 1;
  AcpiSupportInstance->Rsdt3->Length          = AcpiSupportInstance->Rsdt3->Length + sizeof(UINT32);

  //
  // Initialize Xsdt
  //
  AcpiSupportInstance->Xsdt->Signature  = EFI_ACPI_3_0_EXTENDED_SYSTEM_DESCRIPTION_TABLE_SIGNATURE;
  AcpiSupportInstance->Xsdt->Length     = sizeof (EFI_ACPI_DESCRIPTION_HEADER);
  AcpiSupportInstance->Xsdt->Revision   = EFI_ACPI_3_0_EXTENDED_SYSTEM_DESCRIPTION_TABLE_REVISION;
  CopyMem (AcpiSupportInstance->Xsdt->OemId, PcdGetPtr (PcdAcpiDefaultOemId), sizeof (AcpiSupportInstance->Xsdt->OemId));
  CurrentData = PcdGet64 (PcdAcpiDefaultOemTableId);
  CopyMem (&AcpiSupportInstance->Xsdt->OemTableId, &CurrentData, sizeof (UINT64));
  AcpiSupportInstance->Xsdt->OemRevision      = PcdGet32 (PcdAcpiDefaultOemRevision);
  AcpiSupportInstance->Xsdt->CreatorId        = PcdGet32 (PcdAcpiDefaultCreatorId);
  AcpiSupportInstance->Xsdt->CreatorRevision  = PcdGet32 (PcdAcpiDefaultCreatorRevision);
  //
  // We always reserve first one for FADT
  //
  AcpiSupportInstance->Xsdt->Length           = AcpiSupportInstance->Xsdt->Length + sizeof(UINT64);

  ChecksumCommonTables (AcpiSupportInstance);

  //
  // Completed successfully
  //
  return EFI_SUCCESS;
}