X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=MdeModulePkg%2FUniversal%2FPCD%2FPei%2FService.h;h=ce786a90720264793755c9795b4ee876eabf89cc;hb=b6b3dc4410d0abbda01c76674b18f9c19e8edd9d;hp=3a25f57e2445c18e50e2ca8bbd3a1b954b11d03a;hpb=62c236c065720ee4ac7d9832aa806cd5f8269552;p=mirror_edk2.git diff --git a/MdeModulePkg/Universal/PCD/Pei/Service.h b/MdeModulePkg/Universal/PCD/Pei/Service.h index 3a25f57e24..ce786a9072 100644 --- a/MdeModulePkg/Universal/PCD/Pei/Service.h +++ b/MdeModulePkg/Universal/PCD/Pei/Service.h @@ -1012,263 +1012,3 @@ extern PEI_PCD_DATABASE_INIT gPEIPcdDbInit; #endif -//////////////////////////////////////////////////////////////////////////////// -// // -// Introduction of PCD database // -// // -//////////////////////////////////////////////////////////////////////////////// -/** - 1, Introduction - PEI PCD database hold all dynamic type PCD information used in PEI phase. - 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 designed for accessing 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: - a) The PCD value is produced by someone driver and consumed by other driver - in execution time. - b) The PCD value is set/get by user from FrontPage. - c) The PCD value is produced by platform OEM specified area. - - 2.2 According to distribution mehod, dynamic PCD could be classfied as: - a) Dynamic: - This type PCD is used for module in source distribution which will be - built in platform. - b) DynamicEx: - This type PCD is used for module in binary distribution which will be - will not built. - - 2.3 According to storage method, dynamic PCD could be classfied as: - a) Default Storage: - - The value is stored in PCD database maintained by PCD database in boot - time memory which is built as a guid hob in PEI phase. - - 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]/[PcdsDynamicExDefault] is used as section name - for this type PCD in platform DSC file. - - b) Variable Storage: - - The value is stored in variable area. - - As default storage type, this type PCD could used for communication. - But beside it, this type PCD could be used store the value associating - with HII setting via variable technology. - - In PEI phase, the PCD value could only be got but can not be set due - to variable area is readonly for PEI phase. - - [PcdsDynamicHii]/[PcdsDynamicExHii] is used as section name for this - type PCD in platform DSC file. - - c) OEM specificed storage area: - - The value is stored in OEM specified area, the base address is specified - by a FixedAtBuild PCD PcdVpdBaseAddress. - - The area is read only for PEI and DXE phase. - - [PcdsDynamicVpd]/[PcdsDynamicExVpd] is used as section name for this - type PCD in platform DSC file. - - Note: The default value of dynamic PCD are storaged in memory maintained - by PEI/DXE PCD drvier. - - 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 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 some C structure and variable 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 auto-generated C structure - 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_SKU_ENABLED - 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 C structure. - PCD Database C structure is generated 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. - - 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 - -**/