OvmfPkg/PlatformDxe: eliminate unchecked PcdSetXX() calls

[mirror_edk2.git] / OvmfPkg / PlatformPei / MemDetect.c

/**@file\r
  Memory Detection for Virtual Machines.\r
\r
  Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>\r
  This program and the accompanying materials\r
  are licensed and made available under the terms and conditions of the BSD License\r
  which accompanies this distribution.  The full text of the license may be found at\r
  http://opensource.org/licenses/bsd-license.php\r
\r
  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
\r
Module Name:\r
\r
  MemDetect.c\r
\r
**/\r
\r
//\r
// The package level header files this module uses\r
//\r
#include <PiPei.h>\r
\r
//\r
// The Library classes this module consumes\r
//\r
#include <Library/BaseMemoryLib.h>\r
#include <Library/DebugLib.h>\r
#include <Library/HobLib.h>\r
#include <Library/IoLib.h>\r
#include <Library/PcdLib.h>\r
#include <Library/PeimEntryPoint.h>\r
#include <Library/ResourcePublicationLib.h>\r
#include <Library/MtrrLib.h>\r
#include <Library/QemuFwCfgLib.h>\r
\r
#include "Platform.h"\r
#include "Cmos.h"\r
\r
UINT8 mPhysMemAddressWidth;\r
\r
STATIC UINT32 mS3AcpiReservedMemoryBase;\r
STATIC UINT32 mS3AcpiReservedMemorySize;\r
\r
UINT32\r
GetSystemMemorySizeBelow4gb (\r
  VOID\r
  )\r
{\r
  UINT8 Cmos0x34;\r
  UINT8 Cmos0x35;\r
\r
  //\r
  // CMOS 0x34/0x35 specifies the system memory above 16 MB.\r
  // * CMOS(0x35) is the high byte\r
  // * CMOS(0x34) is the low byte\r
  // * The size is specified in 64kb chunks\r
  // * Since this is memory above 16MB, the 16MB must be added\r
  //   into the calculation to get the total memory size.\r
  //\r
\r
  Cmos0x34 = (UINT8) CmosRead8 (0x34);\r
  Cmos0x35 = (UINT8) CmosRead8 (0x35);\r
\r
  return (UINT32) (((UINTN)((Cmos0x35 << 8) + Cmos0x34) << 16) + SIZE_16MB);\r
}\r
\r
\r
STATIC\r
UINT64\r
GetSystemMemorySizeAbove4gb (\r
  )\r
{\r
  UINT32 Size;\r
  UINTN  CmosIndex;\r
\r
  //\r
  // CMOS 0x5b-0x5d specifies the system memory above 4GB MB.\r
  // * CMOS(0x5d) is the most significant size byte\r
  // * CMOS(0x5c) is the middle size byte\r
  // * CMOS(0x5b) is the least significant size byte\r
  // * The size is specified in 64kb chunks\r
  //\r
\r
  Size = 0;\r
  for (CmosIndex = 0x5d; CmosIndex >= 0x5b; CmosIndex--) {\r
    Size = (UINT32) (Size << 8) + (UINT32) CmosRead8 (CmosIndex);\r
  }\r
\r
  return LShiftU64 (Size, 16);\r
}\r
\r
\r
/**\r
  Return the highest address that DXE could possibly use, plus one.\r
**/\r
STATIC\r
UINT64\r
GetFirstNonAddress (\r
  VOID\r
  )\r
{\r
  UINT64               FirstNonAddress;\r
  UINT64               Pci64Base, Pci64Size;\r
  CHAR8                MbString[7 + 1];\r
  EFI_STATUS           Status;\r
  FIRMWARE_CONFIG_ITEM FwCfgItem;\r
  UINTN                FwCfgSize;\r
  UINT64               HotPlugMemoryEnd;\r
\r
  FirstNonAddress = BASE_4GB + GetSystemMemorySizeAbove4gb ();\r
\r
  //\r
  // If DXE is 32-bit, then we're done; PciBusDxe will degrade 64-bit MMIO\r
  // resources to 32-bit anyway. See DegradeResource() in\r
  // "PciResourceSupport.c".\r
  //\r
#ifdef MDE_CPU_IA32\r
  if (!FeaturePcdGet (PcdDxeIplSwitchToLongMode)) {\r
    return FirstNonAddress;\r
  }\r
#endif\r
\r
  //\r
  // Otherwise, in order to calculate the highest address plus one, we must\r
  // consider the 64-bit PCI host aperture too. Fetch the default size.\r
  //\r
  Pci64Size = PcdGet64 (PcdPciMmio64Size);\r
\r
  //\r
  // See if the user specified the number of megabytes for the 64-bit PCI host\r
  // aperture. The number of non-NUL characters in MbString allows for\r
  // 9,999,999 MB, which is approximately 10 TB.\r
  //\r
  // As signaled by the "X-" prefix, this knob is experimental, and might go\r
  // away at any time.\r
  //\r
  Status = QemuFwCfgFindFile ("opt/ovmf/X-PciMmio64Mb", &FwCfgItem,\r
             &FwCfgSize);\r
  if (!EFI_ERROR (Status)) {\r
    if (FwCfgSize >= sizeof MbString) {\r
      DEBUG ((EFI_D_WARN,\r
        "%a: ignoring malformed 64-bit PCI host aperture size from fw_cfg\n",\r
        __FUNCTION__));\r
    } else {\r
      QemuFwCfgSelectItem (FwCfgItem);\r
      QemuFwCfgReadBytes (FwCfgSize, MbString);\r
      MbString[FwCfgSize] = '\0';\r
      Pci64Size = LShiftU64 (AsciiStrDecimalToUint64 (MbString), 20);\r
    }\r
  }\r
\r
  if (Pci64Size == 0) {\r
    if (mBootMode != BOOT_ON_S3_RESUME) {\r
      DEBUG ((EFI_D_INFO, "%a: disabling 64-bit PCI host aperture\n",\r
        __FUNCTION__));\r
      PcdSet64 (PcdPciMmio64Size, 0);\r
    }\r
\r
    //\r
    // There's nothing more to do; the amount of memory above 4GB fully\r
    // determines the highest address plus one. The memory hotplug area (see\r
    // below) plays no role for the firmware in this case.\r
    //\r
    return FirstNonAddress;\r
  }\r
\r
  //\r
  // The "etc/reserved-memory-end" fw_cfg file, when present, contains an\r
  // absolute, exclusive end address for the memory hotplug area. This area\r
  // starts right at the end of the memory above 4GB. The 64-bit PCI host\r
  // aperture must be placed above it.\r
  //\r
  Status = QemuFwCfgFindFile ("etc/reserved-memory-end", &FwCfgItem,\r
             &FwCfgSize);\r
  if (!EFI_ERROR (Status) && FwCfgSize == sizeof HotPlugMemoryEnd) {\r
    QemuFwCfgSelectItem (FwCfgItem);\r
    QemuFwCfgReadBytes (FwCfgSize, &HotPlugMemoryEnd);\r
\r
    ASSERT (HotPlugMemoryEnd >= FirstNonAddress);\r
    FirstNonAddress = HotPlugMemoryEnd;\r
  }\r
\r
  //\r
  // SeaBIOS aligns both boundaries of the 64-bit PCI host aperture to 1GB, so\r
  // that the host can map it with 1GB hugepages. Follow suit.\r
  //\r
  Pci64Base = ALIGN_VALUE (FirstNonAddress, (UINT64)SIZE_1GB);\r
  Pci64Size = ALIGN_VALUE (Pci64Size, (UINT64)SIZE_1GB);\r
\r
  //\r
  // The 64-bit PCI host aperture should also be "naturally" aligned. The\r
  // alignment is determined by rounding the size of the aperture down to the\r
  // next smaller or equal power of two. That is, align the aperture by the\r
  // largest BAR size that can fit into it.\r
  //\r
  Pci64Base = ALIGN_VALUE (Pci64Base, GetPowerOfTwo64 (Pci64Size));\r
\r
  if (mBootMode != BOOT_ON_S3_RESUME) {\r
    //\r
    // The core PciHostBridgeDxe driver will automatically add this range to\r
    // the GCD memory space map through our PciHostBridgeLib instance; here we\r
    // only need to set the PCDs.\r
    //\r
    PcdSet64 (PcdPciMmio64Base, Pci64Base);\r
    PcdSet64 (PcdPciMmio64Size, Pci64Size);\r
    DEBUG ((EFI_D_INFO, "%a: Pci64Base=0x%Lx Pci64Size=0x%Lx\n",\r
      __FUNCTION__, Pci64Base, Pci64Size));\r
  }\r
\r
  //\r
  // The useful address space ends with the 64-bit PCI host aperture.\r
  //\r
  FirstNonAddress = Pci64Base + Pci64Size;\r
  return FirstNonAddress;\r
}\r
\r
\r
/**\r
  Initialize the mPhysMemAddressWidth variable, based on guest RAM size.\r
**/\r
VOID\r
AddressWidthInitialization (\r
  VOID\r
  )\r
{\r
  UINT64 FirstNonAddress;\r
\r
  //\r
  // As guest-physical memory size grows, the permanent PEI RAM requirements\r
  // are dominated by the identity-mapping page tables built by the DXE IPL.\r
  // The DXL IPL keys off of the physical address bits advertized in the CPU\r
  // HOB. To conserve memory, we calculate the minimum address width here.\r
  //\r
  FirstNonAddress      = GetFirstNonAddress ();\r
  mPhysMemAddressWidth = (UINT8)HighBitSet64 (FirstNonAddress);\r
\r
  //\r
  // If FirstNonAddress is not an integral power of two, then we need an\r
  // additional bit.\r
  //\r
  if ((FirstNonAddress & (FirstNonAddress - 1)) != 0) {\r
    ++mPhysMemAddressWidth;\r
  }\r
\r
  //\r
  // The minimum address width is 36 (covers up to and excluding 64 GB, which\r
  // is the maximum for Ia32 + PAE). The theoretical architecture maximum for\r
  // X64 long mode is 52 bits, but the DXE IPL clamps that down to 48 bits. We\r
  // can simply assert that here, since 48 bits are good enough for 256 TB.\r
  //\r
  if (mPhysMemAddressWidth <= 36) {\r
    mPhysMemAddressWidth = 36;\r
  }\r
  ASSERT (mPhysMemAddressWidth <= 48);\r
}\r
\r
\r
/**\r
  Calculate the cap for the permanent PEI memory.\r
**/\r
STATIC\r
UINT32\r
GetPeiMemoryCap (\r
  VOID\r
  )\r
{\r
  BOOLEAN Page1GSupport;\r
  UINT32  RegEax;\r
  UINT32  RegEdx;\r
  UINT32  Pml4Entries;\r
  UINT32  PdpEntries;\r
  UINTN   TotalPages;\r
\r
  //\r
  // If DXE is 32-bit, then just return the traditional 64 MB cap.\r
  //\r
#ifdef MDE_CPU_IA32\r
  if (!FeaturePcdGet (PcdDxeIplSwitchToLongMode)) {\r
    return SIZE_64MB;\r
  }\r
#endif\r
\r
  //\r
  // Dependent on physical address width, PEI memory allocations can be\r
  // dominated by the page tables built for 64-bit DXE. So we key the cap off\r
  // of those. The code below is based on CreateIdentityMappingPageTables() in\r
  // "MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c".\r
  //\r
  Page1GSupport = FALSE;\r
  if (PcdGetBool (PcdUse1GPageTable)) {\r
    AsmCpuid (0x80000000, &RegEax, NULL, NULL, NULL);\r
    if (RegEax >= 0x80000001) {\r
      AsmCpuid (0x80000001, NULL, NULL, NULL, &RegEdx);\r
      if ((RegEdx & BIT26) != 0) {\r
        Page1GSupport = TRUE;\r
      }\r
    }\r
  }\r
\r
  if (mPhysMemAddressWidth <= 39) {\r
    Pml4Entries = 1;\r
    PdpEntries = 1 << (mPhysMemAddressWidth - 30);\r
    ASSERT (PdpEntries <= 0x200);\r
  } else {\r
    Pml4Entries = 1 << (mPhysMemAddressWidth - 39);\r
    ASSERT (Pml4Entries <= 0x200);\r
    PdpEntries = 512;\r
  }\r
\r
  TotalPages = Page1GSupport ? Pml4Entries + 1 :\r
                               (PdpEntries + 1) * Pml4Entries + 1;\r
  ASSERT (TotalPages <= 0x40201);\r
\r
  //\r
  // Add 64 MB for miscellaneous allocations. Note that for\r
  // mPhysMemAddressWidth values close to 36, the cap will actually be\r
  // dominated by this increment.\r
  //\r
  return (UINT32)(EFI_PAGES_TO_SIZE (TotalPages) + SIZE_64MB);\r
}\r
\r
\r
/**\r
  Publish PEI core memory\r
\r
  @return EFI_SUCCESS     The PEIM initialized successfully.\r
\r
**/\r
EFI_STATUS\r
PublishPeiMemory (\r
  VOID\r
  )\r
{\r
  EFI_STATUS                  Status;\r
  EFI_PHYSICAL_ADDRESS        MemoryBase;\r
  UINT64                      MemorySize;\r
  UINT32                      LowerMemorySize;\r
  UINT32                      PeiMemoryCap;\r
\r
  LowerMemorySize = GetSystemMemorySizeBelow4gb ();\r
  if (FeaturePcdGet (PcdSmmSmramRequire)) {\r
    //\r
    // TSEG is chipped from the end of low RAM\r
    //\r
    LowerMemorySize -= FixedPcdGet8 (PcdQ35TsegMbytes) * SIZE_1MB;\r
  }\r
\r
  //\r
  // If S3 is supported, then the S3 permanent PEI memory is placed next,\r
  // downwards. Its size is primarily dictated by CpuMpPei. The formula below\r
  // is an approximation.\r
  //\r
  if (mS3Supported) {\r
    mS3AcpiReservedMemorySize = SIZE_512KB +\r
      PcdGet32 (PcdCpuMaxLogicalProcessorNumber) *\r
      PcdGet32 (PcdCpuApStackSize);\r
    mS3AcpiReservedMemoryBase = LowerMemorySize - mS3AcpiReservedMemorySize;\r
    LowerMemorySize = mS3AcpiReservedMemoryBase;\r
  }\r
\r
  if (mBootMode == BOOT_ON_S3_RESUME) {\r
    MemoryBase = mS3AcpiReservedMemoryBase;\r
    MemorySize = mS3AcpiReservedMemorySize;\r
  } else {\r
    PeiMemoryCap = GetPeiMemoryCap ();\r
    DEBUG ((EFI_D_INFO, "%a: mPhysMemAddressWidth=%d PeiMemoryCap=%u KB\n",\r
      __FUNCTION__, mPhysMemAddressWidth, PeiMemoryCap >> 10));\r
\r
    //\r
    // Determine the range of memory to use during PEI\r
    //\r
    // Technically we could lay the permanent PEI RAM over SEC's temporary\r
    // decompression and scratch buffer even if "secure S3" is needed, since\r
    // their lifetimes don't overlap. However, PeiFvInitialization() will cover\r
    // RAM up to PcdOvmfDecompressionScratchEnd with an EfiACPIMemoryNVS memory\r
    // allocation HOB, and other allocations served from the permanent PEI RAM\r
    // shouldn't overlap with that HOB.\r
    //\r
    MemoryBase = mS3Supported && FeaturePcdGet (PcdSmmSmramRequire) ?\r
      PcdGet32 (PcdOvmfDecompressionScratchEnd) :\r
      PcdGet32 (PcdOvmfDxeMemFvBase) + PcdGet32 (PcdOvmfDxeMemFvSize);\r
    MemorySize = LowerMemorySize - MemoryBase;\r
    if (MemorySize > PeiMemoryCap) {\r
      MemoryBase = LowerMemorySize - PeiMemoryCap;\r
      MemorySize = PeiMemoryCap;\r
    }\r
  }\r
\r
  //\r
  // Publish this memory to the PEI Core\r
  //\r
  Status = PublishSystemMemory(MemoryBase, MemorySize);\r
  ASSERT_EFI_ERROR (Status);\r
\r
  return Status;\r
}\r
\r
\r
/**\r
  Peform Memory Detection for QEMU / KVM\r
\r
**/\r
STATIC\r
VOID\r
QemuInitializeRam (\r
  VOID\r
  )\r
{\r
  UINT64                      LowerMemorySize;\r
  UINT64                      UpperMemorySize;\r
  MTRR_SETTINGS               MtrrSettings;\r
  EFI_STATUS                  Status;\r
\r
  DEBUG ((EFI_D_INFO, "%a called\n", __FUNCTION__));\r
\r
  //\r
  // Determine total memory size available\r
  //\r
  LowerMemorySize = GetSystemMemorySizeBelow4gb ();\r
  UpperMemorySize = GetSystemMemorySizeAbove4gb ();\r
\r
  if (mBootMode == BOOT_ON_S3_RESUME) {\r
    //\r
    // Create the following memory HOB as an exception on the S3 boot path.\r
    //\r
    // Normally we'd create memory HOBs only on the normal boot path. However,\r
    // CpuMpPei specifically needs such a low-memory HOB on the S3 path as\r
    // well, for "borrowing" a subset of it temporarily, for the AP startup\r
    // vector.\r
    //\r
    // CpuMpPei saves the original contents of the borrowed area in permanent\r
    // PEI RAM, in a backup buffer allocated with the normal PEI services.\r
    // CpuMpPei restores the original contents ("returns" the borrowed area) at\r
    // End-of-PEI. End-of-PEI in turn is emitted by S3Resume2Pei before\r
    // transferring control to the OS's wakeup vector in the FACS.\r
    //\r
    // We expect any other PEIMs that "borrow" memory similarly to CpuMpPei to\r
    // restore the original contents. Furthermore, we expect all such PEIMs\r
    // (CpuMpPei included) to claim the borrowed areas by producing memory\r
    // allocation HOBs, and to honor preexistent memory allocation HOBs when\r
    // looking for an area to borrow.\r
    //\r
    AddMemoryRangeHob (0, BASE_512KB + BASE_128KB);\r
  } else {\r
    //\r
    // Create memory HOBs\r
    //\r
    AddMemoryRangeHob (0, BASE_512KB + BASE_128KB);\r
\r
    if (FeaturePcdGet (PcdSmmSmramRequire)) {\r
      UINT32 TsegSize;\r
\r
      TsegSize = FixedPcdGet8 (PcdQ35TsegMbytes) * SIZE_1MB;\r
      AddMemoryRangeHob (BASE_1MB, LowerMemorySize - TsegSize);\r
      AddReservedMemoryBaseSizeHob (LowerMemorySize - TsegSize, TsegSize,\r
        TRUE);\r
    } else {\r
      AddMemoryRangeHob (BASE_1MB, LowerMemorySize);\r
    }\r
\r
    if (UpperMemorySize != 0) {\r
      AddMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);\r
    }\r
  }\r
\r
  //\r
  // We'd like to keep the following ranges uncached:\r
  // - [640 KB, 1 MB)\r
  // - [LowerMemorySize, 4 GB)\r
  //\r
  // Everything else should be WB. Unfortunately, programming the inverse (ie.\r
  // keeping the default UC, and configuring the complement set of the above as\r
  // WB) is not reliable in general, because the end of the upper RAM can have\r
  // practically any alignment, and we may not have enough variable MTRRs to\r
  // cover it exactly.\r
  //\r
  if (IsMtrrSupported ()) {\r
    MtrrGetAllMtrrs (&MtrrSettings);\r
\r
    //\r
    // MTRRs disabled, fixed MTRRs disabled, default type is uncached\r
    //\r
    ASSERT ((MtrrSettings.MtrrDefType & BIT11) == 0);\r
    ASSERT ((MtrrSettings.MtrrDefType & BIT10) == 0);\r
    ASSERT ((MtrrSettings.MtrrDefType & 0xFF) == 0);\r
\r
    //\r
    // flip default type to writeback\r
    //\r
    SetMem (&MtrrSettings.Fixed, sizeof MtrrSettings.Fixed, 0x06);\r
    ZeroMem (&MtrrSettings.Variables, sizeof MtrrSettings.Variables);\r
    MtrrSettings.MtrrDefType |= BIT11 | BIT10 | 6;\r
    MtrrSetAllMtrrs (&MtrrSettings);\r
\r
    //\r
    // Set memory range from 640KB to 1MB to uncacheable\r
    //\r
    Status = MtrrSetMemoryAttribute (BASE_512KB + BASE_128KB,\r
               BASE_1MB - (BASE_512KB + BASE_128KB), CacheUncacheable);\r
    ASSERT_EFI_ERROR (Status);\r
\r
    //\r
    // Set memory range from the "top of lower RAM" (RAM below 4GB) to 4GB as\r
    // uncacheable\r
    //\r
    Status = MtrrSetMemoryAttribute (LowerMemorySize,\r
               SIZE_4GB - LowerMemorySize, CacheUncacheable);\r
    ASSERT_EFI_ERROR (Status);\r
  }\r
}\r
\r
/**\r
  Publish system RAM and reserve memory regions\r
\r
**/\r
VOID\r
InitializeRamRegions (\r
  VOID\r
  )\r
{\r
  if (!mXen) {\r
    QemuInitializeRam ();\r
  } else {\r
    XenPublishRamRegions ();\r
  }\r
\r
  if (mS3Supported && mBootMode != BOOT_ON_S3_RESUME) {\r
    //\r
    // This is the memory range that will be used for PEI on S3 resume\r
    //\r
    BuildMemoryAllocationHob (\r
      mS3AcpiReservedMemoryBase,\r
      mS3AcpiReservedMemorySize,\r
      EfiACPIMemoryNVS\r
      );\r
\r
    //\r
    // Cover the initial RAM area used as stack and temporary PEI heap.\r
    //\r
    // This is reserved as ACPI NVS so it can be used on S3 resume.\r
    //\r
    BuildMemoryAllocationHob (\r
      PcdGet32 (PcdOvmfSecPeiTempRamBase),\r
      PcdGet32 (PcdOvmfSecPeiTempRamSize),\r
      EfiACPIMemoryNVS\r
      );\r
\r
    //\r
    // SEC stores its table of GUIDed section handlers here.\r
    //\r
    BuildMemoryAllocationHob (\r
      PcdGet64 (PcdGuidedExtractHandlerTableAddress),\r
      PcdGet32 (PcdGuidedExtractHandlerTableSize),\r
      EfiACPIMemoryNVS\r
      );\r
\r
#ifdef MDE_CPU_X64\r
    //\r
    // Reserve the initial page tables built by the reset vector code.\r
    //\r
    // Since this memory range will be used by the Reset Vector on S3\r
    // resume, it must be reserved as ACPI NVS.\r
    //\r
    BuildMemoryAllocationHob (\r
      (EFI_PHYSICAL_ADDRESS)(UINTN) PcdGet32 (PcdOvmfSecPageTablesBase),\r
      (UINT64)(UINTN) PcdGet32 (PcdOvmfSecPageTablesSize),\r
      EfiACPIMemoryNVS\r
      );\r
#endif\r
  }\r
\r
  if (mBootMode != BOOT_ON_S3_RESUME) {\r
    if (!FeaturePcdGet (PcdSmmSmramRequire)) {\r
      //\r
      // Reserve the lock box storage area\r
      //\r
      // Since this memory range will be used on S3 resume, it must be\r
      // reserved as ACPI NVS.\r
      //\r
      // If S3 is unsupported, then various drivers might still write to the\r
      // LockBox area. We ought to prevent DXE from serving allocation requests\r
      // such that they would overlap the LockBox storage.\r
      //\r
      ZeroMem (\r
        (VOID*)(UINTN) PcdGet32 (PcdOvmfLockBoxStorageBase),\r
        (UINTN) PcdGet32 (PcdOvmfLockBoxStorageSize)\r
        );\r
      BuildMemoryAllocationHob (\r
        (EFI_PHYSICAL_ADDRESS)(UINTN) PcdGet32 (PcdOvmfLockBoxStorageBase),\r
        (UINT64)(UINTN) PcdGet32 (PcdOvmfLockBoxStorageSize),\r
        mS3Supported ? EfiACPIMemoryNVS : EfiBootServicesData\r
        );\r
    }\r
\r
    if (FeaturePcdGet (PcdSmmSmramRequire)) {\r
      UINT32 TsegSize;\r
\r
      //\r
      // Make sure the TSEG area that we reported as a reserved memory resource\r
      // cannot be used for reserved memory allocations.\r
      //\r
      TsegSize = FixedPcdGet8 (PcdQ35TsegMbytes) * SIZE_1MB;\r
      BuildMemoryAllocationHob (\r
        GetSystemMemorySizeBelow4gb() - TsegSize,\r
        TsegSize,\r
        EfiReservedMemoryType\r
        );\r
    }\r
  }\r
}\r