| // /** @file | |
| // PCD DXE driver manage database contains all dynamic PCD entries and produce the implementation of PCD protocol. | |
| // | |
| // This version PCD DXE depends on the external PCD database binary file, not built in PCD data base. | |
| // There are two PCD Protocols as follows: | |
| // 1) PCD_PROTOCOL | |
| // It is EDKII implementation which support Dynamic/DynamicEx type Pcds. | |
| // 2) EFI_PCD_PROTOCOL | |
| // It is defined by PI specification 1.2, Vol 3 which only support dynamicEx | |
| // type Pcd. | |
| // | |
| // For dynamicEx type PCD, it is compatible between PCD_PROTOCOL and EFI_PCD_PROTOCOL. | |
| // PCD DXE driver will produce above two protocols at same time. | |
| // | |
| // PCD database is generated as the separate binary image at build time. The binary image | |
| // will be intergrated into Firmware volume together with PCD driver. | |
| // | |
| // //////////////////////////////////////////////////////////////////////////////// | |
| // // // | |
| // // Introduction of PCD database // | |
| // // // | |
| // //////////////////////////////////////////////////////////////////////////////// | |
| // | |
| // 1, Introduction | |
| // PCD database hold all dynamic type PCD information. The structure of PEI PCD | |
| // database is generated by build tools according to dynamic PCD usage for | |
| // specified platform. | |
| // | |
| // 2, Dynamic Type PCD | |
| // Dynamic type PCD is used for the configuration/setting which value is determined | |
| // dynamic. In contrast, the value of static type PCD (FeatureFlag, FixedPcd, | |
| // PatchablePcd) is fixed in final generated FD image in build time. | |
| // | |
| // 2.1 The "dynamic" determination means one of below cases: | |
| // a) The PCD setting value is produced by someone driver and consumed by | |
| // other driver in execution time. | |
| // b) The PCD setting value is set/get by user from FrontPage. | |
| // c) The PCD setting value is produced by platform OEM vendor in specified area. | |
| // | |
| // 2.2 According to module distribution way, dynamic PCD could be classfied as: | |
| // a) Dynamic: | |
| // If module is released in source code and will be built with platform | |
| // DSC, the dynamic PCD used by this module can be accessed as: | |
| // PcdGetxx(PcdSampleDynamicPcd); | |
| // In building platform, build tools will translate PcdSampleDynamicPcd to | |
| // pair of {Token Space Guid: Token Number} for this PCD. | |
| // b) DynamicEx: | |
| // If module is release as binary and will not pariticpate platform building, | |
| // the dynamic PCD used by this module need be accessed as: | |
| // PcdGetxxEx(gEfiMyTokenspaceGuid, PcdSampleDynamicPcd) | |
| // Developer need explicity gives {Token Space Guid:Token Number} as parameter | |
| // in writting source code. | |
| // | |
| // 2.3 According to PCD value's storage method, dynamic PCD could be classfied as: | |
| // a) Default Storage: | |
| // - The PCD value is stored in PCD database maintained by PCD driver in boot | |
| // time memory. | |
| // - This type is used for communication between PEIM/DXE driver, DXE/DXE | |
| // driver. But all set/get value will be losted after boot-time memory | |
| // is turn off. | |
| // - [PcdsDynamicDefault] is used as section name for this type PCD in | |
| // platform DSC file. [PcdsDynamicExDefault] is used for dynamicEx type PCD. | |
| // | |
| // b) Variable Storage: | |
| // - The PCD value is stored in variable area. | |
| // - As default storage type, this type PCD could be used for PEI/DXE driver | |
| // communication. But beside it, this type PCD could also be used to store | |
| // the value associate with a HII setting via variable interface. | |
| // - In PEI phase, the PCD value could only be got but can not be set due | |
| // to variable area is readonly. | |
| // - [PcdsDynamicHii] is used as section name for this type PCD in platform | |
| // DSC file. [PcdsDynamicExHii] is for dynamicEx type PCD. | |
| // | |
| // c) OEM specificed storage area: | |
| // - The PCD value is stored in OEM specified area which base address is | |
| // specified by a FixedAtBuild PCD setting - PcdVpdBaseAddress. | |
| // - The area is read only for PEI and DXE phase. | |
| // - [PcdsDynamicVpd] is used as section name for this type PCD in platform | |
| // DSC file. [PcdsDynamicExVpd] is for dynamicex type PCD. | |
| // | |
| // 2.4 When and how to use dynamic PCD | |
| // Module developer do not care the used PCD is dynamic or static when writting | |
| // source code/INF. Dynamic PCD and dynamic type is pointed by platform integrator | |
| // in platform DSC file. Please ref section 2.3 to get matching between dynamic | |
| // PCD type and section name in DSC file. | |
| // | |
| // 3, PCD database: | |
| // Although dynamic PCD could be in different storage type as above description, | |
| // but the basic information and default value for all dynamic PCD is hold | |
| // by PCD database maintained by PEI/DXE driver. | |
| // | |
| // As the whole EFI BIOS boot path is divided into PEI/DXE phase, the PCD database | |
| // also is divided into Pei/Dxe database maintaied by PcdPeim/PcdDxe driver separatly. | |
| // To make PcdPeim's driver image smaller, PEI PCD database only hold all dynamic | |
| // PCD information used in PEI phase or use in both PEI/DXE phase. And DXE PCD | |
| // database contains all PCDs used in PEI/DXE phase in memory. | |
| // | |
| // Build tool will generate PCD database into the separate binary file for | |
| // PEI/DXE PCD driver according to dynamic PCD section in platform DSC file. | |
| // | |
| // 3.1 PcdPeim and PcdDxe | |
| // PEI PCD database is maintained by PcdPeim driver run from flash. PcdPeim driver | |
| // build guid hob in temporary memory and copy the binary data base from flash | |
| // to temporary memory for PEI PCD database. | |
| // DXE PCD database is maintained by PcdDxe driver.At entry point of PcdDxe driver, | |
| // a new PCD database is allocated in boot-time memory which including all | |
| // PEI PCD and DXE PCD entry. | |
| // | |
| // Pcd driver should run as early as possible before any other driver access | |
| // dynamic PCD's value. PEI/DXE "Apriori File" mechanism make it possible by | |
| // making PcdPeim/PcdDxe as first dispatching driver in PEI/DXE phase. | |
| // | |
| // 3.2 Token space Guid/Token number, Platform token, Local token number | |
| // Dynamic PCD | |
| // +-----------+ +---------+ | |
| // |TokenSpace | |Platform | | |
| // | Guid | build tool | Token | | |
| // | + +-------------->| Number | | |
| // | Token | +---------+`._ | |
| // | Number | `. | |
| // +-----------+ `. +------+ | |
| // `-|Local | | |
| // |Token | | |
| // DynamicEx PCD ,-|Number| | |
| // +-----------+ ,-' +------+ | |
| // |TokenSpace | ,-' | |
| // | Guid | _,-' | |
| // | + +.' | |
| // | Token | | |
| // | Number | | |
| // +-----------+ | |
| // | |
| // | |
| // 3.2.1 Pair of Token space guid + Token number | |
| // Any type PCD is identified by pair of "TokenSpaceGuid + TokeNumber". But it | |
| // is not easy maintained by PCD driver, and hashed token number will make | |
| // searching slowly. | |
| // | |
| // 3.2.2 Platform Token Number | |
| // "Platform token number" concept is introduced for mapping to a pair of | |
| // "TokenSpaceGuid + TokenNumber". The platform token number is generated by | |
| // build tool in autogen.h and all of them are continual in a platform scope | |
| // started from 1.(0 meaning invalid internal token number) | |
| // With auto-generated "platform token number", PcdGet(PcdSampleDynamicPcd) | |
| // in source code is translated to LibPcdGet(_PCD_TOKEN_PcdSampleDynamicPcd) | |
| // in autogen.h. | |
| // Notes: The mapping between pair of "tokenspace guid + token number" and | |
| // "internal token number" need build tool establish, so "platform token number" | |
| // mechanism is not suitable for binary module which use DynamicEx type PCD. | |
| // To access a dynamicEx type PCD, pair of "token space guid/token number" all need | |
| // to be specificed for PcdSet/PcdGet accessing macro. | |
| // | |
| // Platform Token Number is started from 1, and inceased continuous. From whole | |
| // platform scope, there are two zones: PEI Zone and DXE Zone | |
| // | Platform Token Number | |
| // ----------|---------------------------------------------------------------- | |
| // PEI Zone: | 1 ~ PEI_LOCAL_TOKEN_NUMBER | |
| // DXE Zone: | (PEI_LOCAL_TOKEN_NUMBER + 1) ~ (PEI_LOCAL_TOKEN_NUMBER + DXE_LOCAL_TOKEN_NUMBER) | |
| // | |
| // 3.2.3 Local Token Number | |
| // To fast searching a PCD entry in PCD database, PCD driver translate | |
| // platform token number to local token number via a mapping table. | |
| // For binary DynamicEx type PCD, there is a another mapping table to translate | |
| // "token space guid + token number" to local token number directly. | |
| // Local token number is identifier for all internal interface in PCD PEI/DXE | |
| // driver. | |
| // | |
| // A local token number is a 32-bit value in following meaning: | |
| // 32 ------------- 28 ---------- 24 -------- 0 | |
| // | PCD type mask | Datum Type | Offset | | |
| // +-----------------------------------------+ | |
| // where: | |
| // PCd type mask: indicate Pcd type from following macro: | |
| // PCD_TYPE_DATA | |
| // PCD_TYPE_HII | |
| // PCD_TYPE_VPD | |
| // PCD_TYPE_STRING | |
| // Datum Type : indicate PCD vaue type from following macro: | |
| // PCD_DATUM_TYPE_POINTER | |
| // PCD_DATUM_TYPE_UINT8 | |
| // PCD_DATUM_TYPE_UINT16 | |
| // PCD_DATUM_TYPE_UINT32 | |
| // PCD_DATUM_TYPE_UINT64 | |
| // Offset : indicate the related offset of PCD value in PCD database array. | |
| // Based on local token number, PCD driver could fast determine PCD type, value | |
| // type and get PCD entry from PCD database. | |
| // | |
| // 3.3 PCD Database binary file | |
| // PCD Database binary file will be created at build time as the standalone binary image. | |
| // To understand the binary image layout, PCD Database C structure is still generated | |
| // as comments by build tools in PCD driver's autogen.h/ | |
| // autogen.c file. In generated C structure, following information is stored: | |
| // - ExMapTable: This table is used translate a binary dynamicex type PCD's | |
| // "tokenguid + token" to local token number. | |
| // - LocalTokenNumberTable: | |
| // This table stores all local token number in array, use "Internal | |
| // token number" as array index to get PCD entry's offset fastly. | |
| // - SizeTable: This table stores the size information for all PCD entry. | |
| // - GuidTable: This table stores guid value for DynamicEx's token space, | |
| // HII type PCD's variable GUID. | |
| // - SkuIdTable: TBD | |
| // - SystemSkuId: TBD | |
| // - PCD value structure: | |
| // Every PCD has a value record in PCD database. For different | |
| // datum type PCD has different record structure which will be | |
| // introduced in 3.3.1 | |
| // | |
| // In a PCD database structure, there are two major area: Init and UnInit. | |
| // Init area is use stored above PCD internal structure such as ExMapTable, | |
| // LocalTokenNumberTable etc and the (default) value of PCD which has default | |
| // value specified in platform DSC file. | |
| // Unint area is used stored the value of PCD which has no default value in | |
| // platform DSC file, the value of NULL, 0 specified in platform DSC file can | |
| // be seemed as "no default value". | |
| // | |
| // 3.3.1 Simple Sample PCD Database C Structure | |
| // A general sample of PCD database structue is as follows: | |
| // typedef struct _PCD_DATABASE { | |
| // typedef struct _PCD_DATABASE_INIT { | |
| // //===== Following is PCD database internal maintain structures | |
| // DYNAMICEX_MAPPING ExMapTable[PEI_EXMAPPING_TABLE_SIZE]; | |
| // UINT32 LocalTokenNumberTable[PEI_LOCAL_TOKEN_NUMBER_TABLE_SIZE]; | |
| // GUID GuidTable[PEI_GUID_TABLE_SIZE]; | |
| // SIZE_INFO SizeTable[PEI_SIZE_TABLE_SIZE]; | |
| // UINT8 SkuIdTable[PEI_SKUID_TABLE_SIZE]; | |
| // SKU_ID SystemSkuId; | |
| // | |
| // //===== Following is value structure for PCD with default value | |
| // .... | |
| // .... | |
| // .... | |
| // } Init; | |
| // typedef struct _PCD_DATABSE_UNINIT { | |
| // //==== Following is value structure for PCD without default value | |
| // .... | |
| // .... | |
| // } UnInit; | |
| // } | |
| // | |
| // 3.3.2 PCD value structure in PCD database C structure | |
| // The value's structure is generated by build tool in PCD database C structure. | |
| // The PCDs in different datum type has different value structure. | |
| // | |
| // 3.3.2.1 UINT8/UINT16/UINT32/UINT64 datum type PCD | |
| // The C structure for these datum type PCD is just a UINT8/UINT16/UINT32/UINT64 | |
| // data member in PCD database, For example: | |
| // UINT16 PcdHardwareErrorRecordLevel_d3705011_bc19_4af7_be16_f68030378c15_VariableDefault_0; | |
| // Above structure is generated by build tool, the member name is "PcdCName_Guidvalue" | |
| // Member type is UINT16 according to PcdHardwareErrorRecordLevel declaration | |
| // in DEC file. | |
| // | |
| // 3.3.2.2 VOID* datum type PCD | |
| // The value of VOID* datum type PCD is a UINT8/UINT16 array in PCD database. | |
| // | |
| // 3.3.2.2.1 VOID* - string type | |
| // If the default value for VOID* datum type PCD like L"xxx", the PCD is | |
| // used for unicode string, and C structure of this datum type PCD is | |
| // UINT16 string array in PCD database, for example: | |
| // UINT16 StringTable[29]; | |
| // The number of 29 in above sample is max size of a unicode string. | |
| // | |
| // If the default value for VOID* datum type PCD like "xxx", the PCD is | |
| // used for ascii string, and C structure of this datum type PCD is | |
| // UINT8 string array in PCD database, for example: | |
| // UINT8 StringTable[20]; | |
| // The number of 20 in above sample is max size of a ascii string. | |
| // | |
| // 3.3.2.2.2 VOID* - byte array | |
| // If the default value of VOID* datum type PCD like {'0x29', '0x01', '0xf2'} | |
| // the PCD is used for byte array. The generated structrue is same as | |
| // above ascii string table, | |
| // UINT8 StringTable[13]; | |
| // The number of 13 in above sample is max size of byte array. | |
| // | |
| // 3.3.3 Some utility structures in PCD Database | |
| // 3.3.3.1 GuidTable | |
| // GuidTable array is used to store all related GUID value in PCD database: | |
| // - Variable GUID for HII type PCD | |
| // - Token space GUID for dynamicex type PCD | |
| // | |
| // Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR> | |
| // | |
| // SPDX-License-Identifier: BSD-2-Clause-Patent | |
| // | |
| // **/ | |
| #string STR_MODULE_ABSTRACT #language en-US "PCD DXE driver manages the database that contains all dynamic PCD entries and produce the implementation of PCD protocol" | |
| #string STR_MODULE_DESCRIPTION #language en-US "PCD DXE driver manages the database that contains all dynamic PCD entries and produces the implementation of PCD protocol." | |