5267c89b4d
The two functions introduced here allow the saving and loading of platform configuration to/from the non-volatile variable store. The PLATFORM_CONFIG structure and the two functions that take it / return it are generally meant for any DXE or UEFI driver that needs to access platform configuration. For now we keep this small "library" internal to PlatformDxe. The PLATFORM_CONFIG wire format is intended only to grow over time (as long as the variable GUID remains unchanged). At the introduction of new fields, new feature flags must be added, and recognized in PlatformConfigLoad(). Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com> git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15365 6f19259b-4bc3-4df7-8a09-765794883524
132 lines
4.1 KiB
C
132 lines
4.1 KiB
C
/** @file
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Utility functions for serializing (persistently storing) and deserializing
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OVMF's platform configuration.
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Copyright (C) 2014, Red Hat, Inc.
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This program and the accompanying materials are licensed and made available
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under the terms and conditions of the BSD License which accompanies this
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distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
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WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#include <Library/BaseMemoryLib.h>
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#include <Library/DebugLib.h>
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#include <Library/MemoryAllocationLib.h>
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#include <Library/UefiLib.h>
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#include <Library/UefiRuntimeServicesTableLib.h>
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#include <Guid/OvmfPlatformConfig.h>
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#include "PlatformConfig.h"
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//
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// Name of the UEFI variable that we use for persistent storage.
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//
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STATIC CHAR16 mVariableName[] = L"PlatformConfig";
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/**
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Serialize and persistently save platform configuration.
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@param[in] PlatformConfig The platform configuration to serialize and save.
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@return Status codes returned by gRT->SetVariable().
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**/
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EFI_STATUS
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EFIAPI
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PlatformConfigSave (
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IN PLATFORM_CONFIG *PlatformConfig
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)
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{
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EFI_STATUS Status;
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//
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// We could implement any kind of translation here, as part of serialization.
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// For example, we could expose the platform configuration in separate
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// variables with human-readable contents, allowing other tools to access
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// them more easily. For now, just save a binary dump.
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//
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Status = gRT->SetVariable (mVariableName, &gOvmfPlatformConfigGuid,
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EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS |
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EFI_VARIABLE_RUNTIME_ACCESS,
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sizeof *PlatformConfig, PlatformConfig);
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return Status;
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}
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/**
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Load and deserialize platform configuration.
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When the function fails, output parameters are indeterminate.
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@param[out] PlatformConfig The platform configuration to receive the
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loaded data.
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@param[out] OptionalElements This bitmap describes the presence of optional
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configuration elements that have been loaded.
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PLATFORM_CONFIG_F_DOWNGRADE means that some
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unknown elements, present in the wire format,
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have been ignored.
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@retval EFI_SUCCESS Loading & deserialization successful.
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@return Error codes returned by GetVariable2().
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**/
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EFI_STATUS
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EFIAPI
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PlatformConfigLoad (
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OUT PLATFORM_CONFIG *PlatformConfig,
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OUT UINT64 *OptionalElements
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)
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{
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VOID *Data;
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UINTN DataSize;
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EFI_STATUS Status;
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//
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// Any translation done in PlatformConfigSave() would have to be mirrored
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// here. For now, just load the binary dump.
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//
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// Versioning of the binary wire format is implemented based on size
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// (only incremental changes, ie. new fields), and on GUID.
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// (Incompatible changes require a GUID change.)
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//
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Status = GetVariable2 (mVariableName, &gOvmfPlatformConfigGuid, &Data,
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&DataSize);
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if (EFI_ERROR (Status)) {
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return Status;
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}
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*OptionalElements = 0;
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if (DataSize > sizeof *PlatformConfig) {
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//
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// Handle firmware downgrade -- keep only leading part.
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//
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CopyMem (PlatformConfig, Data, sizeof *PlatformConfig);
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*OptionalElements |= PLATFORM_CONFIG_F_DOWNGRADE;
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} else {
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CopyMem (PlatformConfig, Data, DataSize);
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//
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// Handle firmware upgrade -- zero out missing fields.
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//
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ZeroMem ((UINT8 *)PlatformConfig + DataSize,
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sizeof *PlatformConfig - DataSize);
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}
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//
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// Based on DataSize, report the optional features that we recognize.
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//
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if (DataSize >= (OFFSET_OF (PLATFORM_CONFIG, VerticalResolution) +
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sizeof PlatformConfig->VerticalResolution)) {
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*OptionalElements |= PLATFORM_CONFIG_F_GRAPHICS_RESOLUTION;
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}
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FreePool (Data);
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return EFI_SUCCESS;
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}
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