MdePkg/Include/Protocol/VariableWrite.h

   1 /** @file
   2   Variable Write Architectural Protocol as defined in PI Specification VOLUME 2 DXE
   3
   4   This provides the services required to set nonvolatile environment variables.
   5   This protocol must be produced by a runtime DXE driver and may be consumed only
   6   by the DXE Foundation.
   7
   8   The DXE driver that produces this protocol must be a runtime driver. This driver
   9   may update the SetVariable() field of the UEFI Runtime Services Table.
  10
  11   After the UEFI Runtime Services Table has been initialized, the driver must
  12   install the EFI_VARIABLE_WRITE_ARCH_PROTOCOL_GUID on a new handle with a NULL
  13   interface pointer. The installation of this protocol informs the DXE Foundation
  14   that the write services for nonvolatile environment variables are now available
  15   and that the DXE Foundation must update the 32-bit CRC of the UEFI Runtime Services
  16   Table. The full complement of environment variable services are not available
  17   until both this protocol and EFI_VARIABLE_ARCH_PROTOCOL are installed. DXE drivers
  18   that require read-only access or read/write access to volatile environment variables
  19   must have the EFI_VARIABLE_WRITE_ARCH_PROTOCOL in their dependency expressions.
  20   DXE drivers that require write access to nonvolatile environment variables must
  21   have this architectural protocol in their dependency expressions.
  22
  23   Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
  24   This program and the accompanying materials
  25   are licensed and made available under the terms and conditions of the BSD License
  26   which accompanies this distribution.  The full text of the license may be found at
  27   http://opensource.org/licenses/bsd-license.php
  28
  29   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  30   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  31
  32 **/
  33
  34 #ifndef __ARCH_PROTOCOL_VARIABLE_WRITE_ARCH_H__
  35 #define __ARCH_PROTOCOL_VARIABLE_WRITE_ARCH_H__
  36
  37 ///
  38 /// Global ID for the Variable Write Architectural Protocol
  39 ///
  40 #define EFI_VARIABLE_WRITE_ARCH_PROTOCOL_GUID \
  41   { 0x6441f818, 0x6362, 0x4e44, {0xb5, 0x70, 0x7d, 0xba, 0x31, 0xdd, 0x24, 0x53 } }
  42
  43 extern EFI_GUID gEfiVariableWriteArchProtocolGuid;
  44
  45 #endif