From: klu2 Date: Sun, 29 Mar 2009 07:43:05 +0000 (+0000) Subject: Add introduction of PCD database in PCD PEIM. X-Git-Tag: edk2-stable201903~18289 X-Git-Url: https://git.proxmox.com/?p=mirror_edk2.git;a=commitdiff_plain;h=a5eca427cbfa3ea43cd4a0938d538d66a46613f9 Add introduction of PCD database in PCD PEIM. git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@7973 6f19259b-4bc3-4df7-8a09-765794883524 --- diff --git a/MdeModulePkg/Universal/PCD/Pei/Service.h b/MdeModulePkg/Universal/PCD/Pei/Service.h index be0d5023a5..9ac393f032 100644 --- a/MdeModulePkg/Universal/PCD/Pei/Service.h +++ b/MdeModulePkg/Universal/PCD/Pei/Service.h @@ -893,7 +893,7 @@ typedef struct { space guid: token number} to local token number. @param Guid Token space guid for dynamic-ex PCD entry. - @param ExTokenNumber EDES_TODO: Add parameter description + @param ExTokenNumber Token number for dynamic-ex PCD. @return local token number for dynamic-ex PCD. @@ -1011,3 +1011,251 @@ SetPtrTypeSize ( extern PEI_PCD_DATABASE_INIT gPEIPcdDbInit; #endif + +//////////////////////////////////////////////////////////////////////////////// +// // +// Introduction of PEI 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. + + 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. + +**/