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 46