EmbeddedPkg/Library/NvVarStoreFormattedLib/NvVarStoreFormattedLib.c

   1 /** @file
   2   A hook-in library for:
   3   - MdeModulePkg/Universal/Variable/Pei/VariablePei.inf
   4   - MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe.inf
   5   - MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.inf
   6
   7   Plugging this library instance into one of the above modules makes that
   8   variable service backend wait for another platform module to dynamically
   9   initialize or verify EFI_FIRMWARE_VOLUME_HEADER and VARIABLE_STORE_HEADER in
  10   the non-volatile variable store FVB device. The initialization / verification
  11   is signaled by installing gEdkiiNvVarStoreFormattedGuid into the
  12   phase-matching PPI or protocol database, with a NULL interface. (Note that
  13   installing gEdkiiNvVarStoreFormattedGuid into either the DXE or the MM
  14   protocol database will unblock VariableSmm -- refer to EFI_SECTION_MM_DEPEX
  15   in the PI spec.)
  16
  17   Copyright (C) 2018, Red Hat, Inc.
  18
  19   SPDX-License-Identifier: BSD-2-Clause-Patent
  20 **/
  21
  22 #include <Base.h>
  23
  24 RETURN_STATUS
  25 EFIAPI
  26 NvVarStoreFormattedInitialize (
  27   VOID
  28   )
  29 {
  30   //
  31   // Do nothing, just imbue VariablePei / VariableRuntimeDxe / VariableSmm with
  32   // a PPI or protocol dependency on EDKII_NV_VAR_STORE_FORMATTED_GUID.
  33   //
  34   return RETURN_SUCCESS;
  35 }