MdeModulePkg: Replace BSD License with BSD+Patent License

[mirror_edk2.git] / MdeModulePkg / Universal / PCD / Pei / PcdPeim.uni

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