text: /** @file
  A driver allocates common SMM communication buffer in EfiReservedMemoryType.
  
  This driver allocates common SMM communication buffer in EfiReservedMemoryType,
  then it publishes the information to EFI configuration table with
  gEdkiiPiSmmCommunicationRegionTableGuid.
  Any other driver or application can get the table and know the common
  communication buffer.
  
  Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
  This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php
  
  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  
  **/
  
  #include <PiDxe.h>
  #include <Library/UefiBootServicesTableLib.h>
  #include <Library/UefiRuntimeServicesTableLib.h>
  #include <Library/BaseLib.h>
  #include <Library/BaseMemoryLib.h>
  #include <Library/MemoryAllocationLib.h>
  #include <Library/DebugLib.h>
  #include <Library/UefiLib.h>
  #include <Library/PcdLib.h>
  #include <Guid/PiSmmCommunicationRegionTable.h>
  
  #define DEFAULT_COMMON_PI_SMM_COMMUNIATION_REGION_PAGES  4
  
  /**
    Entry Point for SMM communication buffer driver.
  
    @param[in] ImageHandle  Image handle of this driver.
    @param[in] SystemTable  A Pointer to the EFI System Table.
  
    @retval EFI_SUCEESS
    @return Others          Some error occurs.
  **/
  EFI_STATUS
  EFIAPI
  SmmCommunicationBufferEntryPoint (
    IN EFI_HANDLE        ImageHandle,
    IN EFI_SYSTEM_TABLE  *SystemTable
    )
  {
    EFI_STATUS                               Status;
    UINT32                                   DescriptorSize;
    EDKII_PI_SMM_COMMUNICATION_REGION_TABLE  *PiSmmCommunicationRegionTable;
    EFI_MEMORY_DESCRIPTOR                    *Entry;
  
    DescriptorSize = sizeof(EFI_MEMORY_DESCRIPTOR);
    //
    // Make sure Size != sizeof(EFI_MEMORY_DESCRIPTOR). This will
    // prevent people from having pointer math bugs in their code.
    // now you have to use *DescriptorSize to make things work.
    //
    DescriptorSize += sizeof(UINT64) - (DescriptorSize % sizeof (UINT64));
  
    //
    // Allocate and fill PiSmmCommunicationRegionTable
    //
    PiSmmCommunicationRegionTable = AllocateReservedPool (sizeof(EDKII_PI_SMM_COMMUNICATION_REGION_TABLE) + DescriptorSize);
    ASSERT(PiSmmCommunicationRegionTable != NULL);
    ZeroMem (PiSmmCommunicationRegionTable, sizeof(EDKII_PI_SMM_COMMUNICATION_REGION_TABLE) + DescriptorSize);
  
    PiSmmCommunicationRegionTable->Version         = EDKII_PI_SMM_COMMUNICATION_REGION_TABLE_VERSION;
    PiSmmCommunicationRegionTable->NumberOfEntries = 1;
    PiSmmCommunicationRegionTable->DescriptorSize  = DescriptorSize;
    Entry = (EFI_MEMORY_DESCRIPTOR *)(PiSmmCommunicationRegionTable + 1);
    Entry->Type          = EfiConventionalMemory;
    Entry->PhysicalStart = (EFI_PHYSICAL_ADDRESS)(UINTN)AllocateReservedPages (DEFAULT_COMMON_PI_SMM_COMMUNIATION_REGION_PAGES);
    ASSERT(Entry->PhysicalStart != 0);
    Entry->VirtualStart  = 0;
    Entry->NumberOfPages = DEFAULT_COMMON_PI_SMM_COMMUNIATION_REGION_PAGES;
    Entry->Attribute     = 0;
  
    DEBUG ((EFI_D_INFO, "PiSmmCommunicationRegionTable:(0x%x)\n", PiSmmCommunicationRegionTable));
    DEBUG ((EFI_D_INFO, "  Version         - 0x%x\n", PiSmmCommunicationRegionTable->Version));
    DEBUG ((EFI_D_INFO, "  NumberOfEntries - 0x%x\n", PiSmmCommunicationRegionTable->NumberOfEntries));
    DEBUG ((EFI_D_INFO, "  DescriptorSize  - 0x%x\n", PiSmmCommunicationRegionTable->DescriptorSize));
    DEBUG ((EFI_D_INFO, "Entry:(0x%x)\n", Entry));
    DEBUG ((EFI_D_INFO, "  Type            - 0x%x\n", Entry->Type));
    DEBUG ((EFI_D_INFO, "  PhysicalStart   - 0x%lx\n", Entry->PhysicalStart));
    DEBUG ((EFI_D_INFO, "  VirtualStart    - 0x%lx\n", Entry->VirtualStart));
    DEBUG ((EFI_D_INFO, "  NumberOfPages   - 0x%lx\n", Entry->NumberOfPages));
    DEBUG ((EFI_D_INFO, "  Attribute       - 0x%lx\n", Entry->Attribute));
  
    //
    // Publish this table, so that other driver can use the buffer.
    //
    Status = gBS->InstallConfigurationTable (&gEdkiiPiSmmCommunicationRegionTableGuid, PiSmmCommunicationRegionTable);
    ASSERT_EFI_ERROR (Status);
  
    return Status;
  }
  