[PATCH v3 2/5] OvmfPkg: add library to track boot option loading/starting on the console

[Laszlo Ersek <lersek@redhat.com>]

Introduce the Platform Boot Manager Print Status Code Library (for short,
PlatformBmPrintScLib) class for catching and printing the LoadImage() /
StartImage() preparations, and return statuses, that are reported by
UefiBootManagerLib.

In the primary library instance, catch only such status codes that
UefiBootManagerLib reports from the same module that contains
PlatformBmPrintScLib. The intent is to establish a reporting-printing
channel within BdsDxe, between UefiBootManagerLib and
PlatformBmPrintScLib. Ignore status codes originating elsewhence, e.g.
from UiApp's copy of UefiBootManagerLib.

Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Julien Grall <julien.grall@linaro.org>
Cc: Ray Ni <ray.ni@intel.com>
Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1515418
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---

Notes:
    v3:
    
    - Refresh leading comment on HandleStatusCode(): the highest permitted
      TPL is TPL_CALLBACK. No code change.
    
    - pick up Ard's R-b
    
    v2:
    
    - Split the status code handling to a separate library, so that it's
      easy to reuse in ArmVirtPkg.
    
    - Rework the logic based on
      <https://bugzilla.tianocore.org/show_bug.cgi?id=1398> and
      <https://mantis.uefi.org/mantis/view.php?id=1885>, and follow Ray's
      advice in
      <http://mid.mail-archive.com/734D49CCEBEEF84792F5B80ED585239D5BACE29B@SHSMSX104.ccr.corp.intel.com>:
    
      - The boot option details are fetched via BootCurrent.
    
      - For reporting LoadImage() and StartImage() preparations, replace the
        originally proposed PcdDebugCodeOsLoaderDetail status code with the
        existent (edk2-specific) PcdProgressCodeOsLoaderLoad and
        PcdProgressCodeOsLoaderStart status codes.
    
      - For reporting LoadImage() and StartImage() return values, replace
        the originally proposed PcdDebugCodeOsLoaderDetail status code with
        the standard EFI_SW_DXE_BS_EC_BOOT_OPTION_LOAD_ERROR and
        EFI_SW_DXE_BS_EC_BOOT_OPTION_FAILED status codes.
    
      - For all four kinds of reports, replace the originally proposed "OS
        Loader Detail" structure (and GUID) with the recently standardized
        EFI_RETURN_STATUS_EXTENDED_DATA structure.

 OvmfPkg/OvmfPkg.dec                                           |   5 +
 OvmfPkg/OvmfPkgIa32.dsc                                       |   1 +
 OvmfPkg/OvmfPkgIa32X64.dsc                                    |   1 +
 OvmfPkg/OvmfPkgX64.dsc                                        |   1 +
 OvmfPkg/Include/Library/PlatformBmPrintScLib.h                |  41 +++
 OvmfPkg/Library/PlatformBmPrintScLib/PlatformBmPrintScLib.inf |  66 +++++
 OvmfPkg/Library/PlatformBmPrintScLib/StatusCodeHandler.c      | 310 ++++++++++++++++++++
 7 files changed, 425 insertions(+)

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 7666297cf8f1..e50c6179a249 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -45,6 +45,11 @@ [LibraryClasses]
   #                  access.
   PciCapPciSegmentLib|Include/Library/PciCapPciSegmentLib.h
 
+  ##  @libraryclass  Register a status code handler for printing the Boot
+  #                  Manager's LoadImage() and StartImage() preparations, and
+  #                  return codes, to the UEFI console.
+  PlatformBmPrintScLib|Include/Library/PlatformBmPrintScLib.h
+
   ##  @libraryclass  Access QEMU's firmware configuration interface
   #
   QemuFwCfgLib|Include/Library/QemuFwCfgLib.h
diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
index f9216af479f4..5b885590b275 100644
--- a/OvmfPkg/OvmfPkgIa32.dsc
+++ b/OvmfPkg/OvmfPkgIa32.dsc
@@ -348,6 +348,7 @@ [LibraryClasses.common.DXE_DRIVER]
   UdpIoLib|MdeModulePkg/Library/DxeUdpIoLib/DxeUdpIoLib.inf
   DpcLib|MdeModulePkg/Library/DxeDpcLib/DxeDpcLib.inf
   PlatformBootManagerLib|OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf
+  PlatformBmPrintScLib|OvmfPkg/Library/PlatformBmPrintScLib/PlatformBmPrintScLib.inf
   QemuBootOrderLib|OvmfPkg/Library/QemuBootOrderLib/QemuBootOrderLib.inf
   CpuExceptionHandlerLib|UefiCpuPkg/Library/CpuExceptionHandlerLib/DxeCpuExceptionHandlerLib.inf
 !if $(SMM_REQUIRE) == TRUE
diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index 1e470de74434..bbf0853ee6b9 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -353,6 +353,7 @@ [LibraryClasses.common.DXE_DRIVER]
   UdpIoLib|MdeModulePkg/Library/DxeUdpIoLib/DxeUdpIoLib.inf
   DpcLib|MdeModulePkg/Library/DxeDpcLib/DxeDpcLib.inf
   PlatformBootManagerLib|OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf
+  PlatformBmPrintScLib|OvmfPkg/Library/PlatformBmPrintScLib/PlatformBmPrintScLib.inf
   QemuBootOrderLib|OvmfPkg/Library/QemuBootOrderLib/QemuBootOrderLib.inf
   CpuExceptionHandlerLib|UefiCpuPkg/Library/CpuExceptionHandlerLib/DxeCpuExceptionHandlerLib.inf
 !if $(SMM_REQUIRE) == TRUE
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index e4929d8cf4a8..d81460f52041 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -353,6 +353,7 @@ [LibraryClasses.common.DXE_DRIVER]
   UdpIoLib|MdeModulePkg/Library/DxeUdpIoLib/DxeUdpIoLib.inf
   DpcLib|MdeModulePkg/Library/DxeDpcLib/DxeDpcLib.inf
   PlatformBootManagerLib|OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf
+  PlatformBmPrintScLib|OvmfPkg/Library/PlatformBmPrintScLib/PlatformBmPrintScLib.inf
   QemuBootOrderLib|OvmfPkg/Library/QemuBootOrderLib/QemuBootOrderLib.inf
   CpuExceptionHandlerLib|UefiCpuPkg/Library/CpuExceptionHandlerLib/DxeCpuExceptionHandlerLib.inf
 !if $(SMM_REQUIRE) == TRUE
diff --git a/OvmfPkg/Include/Library/PlatformBmPrintScLib.h b/OvmfPkg/Include/Library/PlatformBmPrintScLib.h
new file mode 100644
index 000000000000..1777f9d7c947
--- /dev/null
+++ b/OvmfPkg/Include/Library/PlatformBmPrintScLib.h
@@ -0,0 +1,41 @@
+/** @file
+  Register a status code handler for printing the Boot Manager's LoadImage()
+  and StartImage() preparations, and return codes, to the UEFI console.
+
+  This feature enables users that are not accustomed to analyzing the firmware
+  log to glean some information about UEFI boot option processing (loading and
+  starting).
+
+  Copyright (C) 2019, Red Hat, Inc.
+
+  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.
+**/
+
+#ifndef __PLATFORM_BM_PRINT_SC_LIB__
+#define __PLATFORM_BM_PRINT_SC_LIB__
+
+#include <Uefi/UefiBaseType.h>
+
+/**
+  Register a status code handler for printing the Boot Manager's LoadImage()
+  and StartImage() preparations, and return codes, to the UEFI console.
+
+  @retval EFI_SUCCESS  The status code handler has been successfully
+                       registered.
+
+  @return              Error codes propagated from boot services and from
+                       EFI_RSC_HANDLER_PROTOCOL.
+**/
+EFI_STATUS
+EFIAPI
+PlatformBmPrintScRegisterHandler (
+  VOID
+  );
+
+#endif // __PLATFORM_BM_PRINT_SC_LIB__
diff --git a/OvmfPkg/Library/PlatformBmPrintScLib/PlatformBmPrintScLib.inf b/OvmfPkg/Library/PlatformBmPrintScLib/PlatformBmPrintScLib.inf
new file mode 100644
index 000000000000..8f02e0b48236
--- /dev/null
+++ b/OvmfPkg/Library/PlatformBmPrintScLib/PlatformBmPrintScLib.inf
@@ -0,0 +1,66 @@
+## @file
+# Register a status code handler for printing the Boot Manager's LoadImage()
+# and StartImage() preparations, and return codes, to the UEFI console.
+#
+# This feature enables users that are not accustomed to analyzing the firmware
+# log to glean some information about UEFI boot option processing (loading and
+# starting).
+#
+# This library instance filters out (ignores) status codes that are not
+# reported by the containing firmware module. The intent is to link this
+# library instance into BdsDxe via PlatformBootManagerLib (which BdsDxe depends
+# upon), then catch only those status codes that BdsDxe reports (which happens
+# via UefiBootManagerLib). Status codes reported by other modules (such as
+# UiApp), via UefiBootManagerLib or otherwise, are meant to be ignored.
+#
+# Copyright (C) 2019, Red Hat, Inc.
+#
+# 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.
+##
+
+[Defines]
+  INF_VERSION    = 1.27
+  BASE_NAME      = PlatformBmPrintScLib
+  FILE_GUID      = 3417c705-903e-41a7-9485-3fafebf60917
+  MODULE_TYPE    = DXE_DRIVER
+  VERSION_STRING = 1.0
+  LIBRARY_CLASS  = PlatformBmPrintScLib|DXE_DRIVER
+
+[Sources]
+  StatusCodeHandler.c
+
+[Packages]
+  MdeModulePkg/MdeModulePkg.dec
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  BaseMemoryLib
+  DebugLib
+  DevicePathLib
+  MemoryAllocationLib
+  PcdLib
+  PrintLib
+  UefiBootManagerLib
+  UefiBootServicesTableLib
+  UefiLib
+  UefiRuntimeServicesTableLib
+
+[Pcd]
+  gEfiMdeModulePkgTokenSpaceGuid.PcdProgressCodeOsLoaderLoad  ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdProgressCodeOsLoaderStart ## CONSUMES
+
+[Protocols]
+  gEfiRscHandlerProtocolGuid                                  ## CONSUMES
+
+[Guids]
+  gEfiGlobalVariableGuid                                      ## CONSUMES
+  gEfiStatusCodeSpecificDataGuid                              ## CONSUMES
+
+[Depex.common.DXE_DRIVER]
+  gEfiRscHandlerProtocolGuid AND gEfiVariableArchProtocolGuid
diff --git a/OvmfPkg/Library/PlatformBmPrintScLib/StatusCodeHandler.c b/OvmfPkg/Library/PlatformBmPrintScLib/StatusCodeHandler.c
new file mode 100644
index 000000000000..3afe9d9690c7
--- /dev/null
+++ b/OvmfPkg/Library/PlatformBmPrintScLib/StatusCodeHandler.c
@@ -0,0 +1,310 @@
+/** @file
+  Register a status code handler for printing the Boot Manager's LoadImage()
+  and StartImage() preparations, and return codes, to the UEFI console.
+
+  This feature enables users that are not accustomed to analyzing the firmware
+  log to glean some information about UEFI boot option processing (loading and
+  starting).
+
+  This library instance filters out (ignores) status codes that are not
+  reported by the containing firmware module. The intent is to link this
+  library instance into BdsDxe via PlatformBootManagerLib (which BdsDxe depends
+  upon), then catch only those status codes that BdsDxe reports (which happens
+  via UefiBootManagerLib). Status codes reported by other modules (such as
+  UiApp), via UefiBootManagerLib or otherwise, are meant to be ignored.
+
+  Copyright (C) 2019, Red Hat, Inc.
+
+  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 <Library/BaseMemoryLib.h>
+#include <Library/DebugLib.h>
+#include <Library/DevicePathLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/PcdLib.h>
+#include <Library/PrintLib.h>
+#include <Library/UefiBootManagerLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+#include <Library/UefiRuntimeServicesTableLib.h>
+
+#include <Protocol/ReportStatusCodeHandler.h>
+
+#include <Guid/GlobalVariable.h>
+#include <Guid/StatusCodeDataTypeId.h>
+
+#include <Pi/PiStatusCode.h>
+
+
+//
+// Convenience variables for the status codes that are relevant for LoadImage()
+// and StartImage() preparations and return codes.
+//
+STATIC EFI_STATUS_CODE_VALUE mLoadPrep;
+STATIC EFI_STATUS_CODE_VALUE mLoadFail;
+STATIC EFI_STATUS_CODE_VALUE mStartPrep;
+STATIC EFI_STATUS_CODE_VALUE mStartFail;
+
+
+/**
+  Handle status codes reported through ReportStatusCodeLib /
+  EFI_STATUS_CODE_PROTOCOL.ReportStatusCode(). Format matching status codes to
+  the system console.
+
+  The highest TPL at which this handler can be registered with
+  EFI_RSC_HANDLER_PROTOCOL.Register() is TPL_CALLBACK. That's because
+  HandleStatusCode() uses the UEFI variable services.
+
+  The parameter list of this function precisely matches that of
+  EFI_STATUS_CODE_PROTOCOL.ReportStatusCode().
+
+  The return status of this function is ignored by the caller, but the function
+  still returns sensible codes:
+
+  @retval EFI_SUCCESS               The status code has been processed; either
+                                    as a no-op, due to filtering, or by
+                                    formatting it to the system console.
+
+  @retval EFI_INVALID_PARAMETER     Unknown or malformed contents have been
+                                    detected in Data.
+
+  @retval EFI_INCOMPATIBLE_VERSION  Unexpected UEFI variable behavior has been
+                                    encountered.
+
+  @return                           Error codes propagated from underlying
+                                    services.
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+HandleStatusCode (
+  IN EFI_STATUS_CODE_TYPE  CodeType,
+  IN EFI_STATUS_CODE_VALUE Value,
+  IN UINT32                Instance,
+  IN EFI_GUID              *CallerId,
+  IN EFI_STATUS_CODE_DATA  *Data
+  )
+{
+  UINTN                        VariableSize;
+  UINT16                       BootCurrent;
+  EFI_STATUS                   Status;
+  CHAR16                       BootOptionName[ARRAY_SIZE (L"Boot####")];
+  EFI_BOOT_MANAGER_LOAD_OPTION BmBootOption;
+  BOOLEAN                      DevPathStringIsDynamic;
+  CHAR16                       *DevPathString;
+
+  //
+  // Ignore all status codes that are irrelevant for LoadImage() and
+  // StartImage() preparations and return codes.
+  //
+  if (Value != mLoadPrep && Value != mLoadFail &&
+      Value != mStartPrep && Value != mStartFail) {
+    return EFI_SUCCESS;
+  }
+  //
+  // Ignore status codes that are not reported by the same containing module.
+  //
+  if (!CompareGuid (CallerId, &gEfiCallerIdGuid)) {
+    return EFI_SUCCESS;
+  }
+
+  //
+  // Sanity-check Data in case of failure reports.
+  //
+  if ((Value == mLoadFail || Value == mStartFail) &&
+      (Data == NULL ||
+       Data->HeaderSize != sizeof *Data ||
+       Data->Size != sizeof (EFI_RETURN_STATUS_EXTENDED_DATA) - sizeof *Data ||
+       !CompareGuid (&Data->Type, &gEfiStatusCodeSpecificDataGuid))) {
+    DEBUG ((DEBUG_ERROR, "%a:%a: malformed Data\n", gEfiCallerBaseName,
+      __FUNCTION__));
+    return EFI_INVALID_PARAMETER;
+  }
+
+  //
+  // Get the number of the Boot#### option that the status code applies to.
+  //
+  VariableSize = sizeof BootCurrent;
+  Status = gRT->GetVariable (EFI_BOOT_CURRENT_VARIABLE_NAME,
+                  &gEfiGlobalVariableGuid, NULL /* Attributes */,
+                  &VariableSize, &BootCurrent);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "%a:%a: failed to get %g:\"%s\": %r\n",
+      gEfiCallerBaseName, __FUNCTION__, &gEfiGlobalVariableGuid,
+      EFI_BOOT_CURRENT_VARIABLE_NAME, Status));
+    return Status;
+  }
+  if (VariableSize != sizeof BootCurrent) {
+    DEBUG ((DEBUG_ERROR, "%a:%a: got %Lu bytes for %g:\"%s\", expected %Lu\n",
+      gEfiCallerBaseName, __FUNCTION__, (UINT64)VariableSize,
+      &gEfiGlobalVariableGuid, EFI_BOOT_CURRENT_VARIABLE_NAME,
+      (UINT64)sizeof BootCurrent));
+    return EFI_INCOMPATIBLE_VERSION;
+  }
+
+  //
+  // Get the Boot#### option that the status code applies to.
+  //
+  UnicodeSPrint (BootOptionName, sizeof BootOptionName, L"Boot%04x",
+    BootCurrent);
+  Status = EfiBootManagerVariableToLoadOption (BootOptionName, &BmBootOption);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR,
+      "%a:%a: EfiBootManagerVariableToLoadOption(\"%s\"): %r\n",
+      gEfiCallerBaseName, __FUNCTION__, BootOptionName, Status));
+    return Status;
+  }
+
+  //
+  // Format the device path.
+  //
+  DevPathStringIsDynamic = TRUE;
+  DevPathString = ConvertDevicePathToText (
+                    BmBootOption.FilePath,
+                    FALSE,                 // DisplayOnly
+                    FALSE                  // AllowShortcuts
+                    );
+  if (DevPathString == NULL) {
+    DevPathStringIsDynamic = FALSE;
+    DevPathString = L"<out of memory while formatting device path>";
+  }
+
+  //
+  // Print the message to the console.
+  //
+  if (Value == mLoadPrep || Value == mStartPrep) {
+    Print (
+      L"%a: %a %s \"%s\" from %s\n",
+      gEfiCallerBaseName,
+      Value == mLoadPrep ? "loading" : "starting",
+      BootOptionName,
+      BmBootOption.Description,
+      DevPathString
+      );
+  } else {
+    Print (
+      L"%a: failed to %a %s \"%s\" from %s: %r\n",
+      gEfiCallerBaseName,
+      Value == mLoadFail ? "load" : "start",
+      BootOptionName,
+      BmBootOption.Description,
+      DevPathString,
+      ((EFI_RETURN_STATUS_EXTENDED_DATA *)Data)->ReturnStatus
+      );
+  }
+
+  //
+  // Done.
+  //
+  if (DevPathStringIsDynamic) {
+    FreePool (DevPathString);
+  }
+  EfiBootManagerFreeLoadOption (&BmBootOption);
+  return EFI_SUCCESS;
+}
+
+
+/**
+  Unregister HandleStatusCode() at ExitBootServices().
+
+  (See EFI_RSC_HANDLER_PROTOCOL in Volume 3 of the Platform Init spec.)
+
+  @param[in] Event    Event whose notification function is being invoked.
+
+  @param[in] Context  Pointer to EFI_RSC_HANDLER_PROTOCOL, originally looked up
+                      when HandleStatusCode() was registered.
+**/
+STATIC
+VOID
+EFIAPI
+UnregisterAtExitBootServices (
+  IN EFI_EVENT Event,
+  IN VOID      *Context
+  )
+{
+  EFI_RSC_HANDLER_PROTOCOL *StatusCodeRouter;
+
+  StatusCodeRouter = Context;
+  StatusCodeRouter->Unregister (HandleStatusCode);
+}
+
+
+/**
+  Register a status code handler for printing the Boot Manager's LoadImage()
+  and StartImage() preparations, and return codes, to the UEFI console.
+
+  @retval EFI_SUCCESS  The status code handler has been successfully
+                       registered.
+
+  @return              Error codes propagated from boot services and from
+                       EFI_RSC_HANDLER_PROTOCOL.
+**/
+EFI_STATUS
+EFIAPI
+PlatformBmPrintScRegisterHandler (
+  VOID
+  )
+{
+  EFI_STATUS               Status;
+  EFI_RSC_HANDLER_PROTOCOL *StatusCodeRouter;
+  EFI_EVENT                ExitBootEvent;
+
+  Status = gBS->LocateProtocol (&gEfiRscHandlerProtocolGuid,
+                  NULL /* Registration */, (VOID **)&StatusCodeRouter);
+  ASSERT_EFI_ERROR (Status);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  //
+  // Set the EFI_STATUS_CODE_VALUE convenience variables.
+  //
+  mLoadPrep  = PcdGet32 (PcdProgressCodeOsLoaderLoad);
+  mLoadFail  = (EFI_SOFTWARE_DXE_BS_DRIVER |
+                EFI_SW_DXE_BS_EC_BOOT_OPTION_LOAD_ERROR);
+  mStartPrep = PcdGet32 (PcdProgressCodeOsLoaderStart);
+  mStartFail = (EFI_SOFTWARE_DXE_BS_DRIVER |
+                EFI_SW_DXE_BS_EC_BOOT_OPTION_FAILED);
+
+  //
+  // Register the handler callback.
+  //
+  Status = StatusCodeRouter->Register (HandleStatusCode, TPL_CALLBACK);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "%a:%a: failed to register status code handler: %r\n",
+      gEfiCallerBaseName, __FUNCTION__, Status));
+    return Status;
+  }
+
+  //
+  // Status code reporting and routing/handling extend into OS runtime. Since
+  // we don't want our handler to survive the BDS phase, we have to unregister
+  // the callback at ExitBootServices(). (See EFI_RSC_HANDLER_PROTOCOL in
+  // Volume 3 of the Platform Init spec.)
+  //
+  Status = gBS->CreateEvent (
+                  EVT_SIGNAL_EXIT_BOOT_SERVICES, // Type
+                  TPL_CALLBACK,                  // NotifyTpl
+                  UnregisterAtExitBootServices,  // NotifyFunction
+                  StatusCodeRouter,              // NotifyContext
+                  &ExitBootEvent                 // Event
+                  );
+  if (EFI_ERROR (Status)) {
+    //
+    // We have to unregister the callback right now, and fail the function.
+    //
+    DEBUG ((DEBUG_ERROR, "%a:%a: failed to create ExitBootServices() event: "
+      "%r\n", gEfiCallerBaseName, __FUNCTION__, Status));
+    StatusCodeRouter->Unregister (HandleStatusCode);
+    return Status;
+  }
+
+  return EFI_SUCCESS;
+}
-- 
2.19.1.3.g30247aa5d201