1 // /** @file 2 // PCD PEIM produces PCD database to manage all dynamic PCD in PEI phase and install Pcd Ppi service. 3 // 4 // This version PCD PEIM depends on the external PCD database binary file, not built in PCD data base. 5 // There are two PCD PPIs as follows: 6 // 1) PCD_PPI 7 // It is EDKII implementation which support Dynamic/DynamicEx Pcds. 8 // 2) EFI_PEI_PCD_PPI 9 // It is defined by PI specification 1.2, Vol 3 which only support dynamicEx 10 // type Pcd. 11 // For dynamicEx type PCD, it is compatible between PCD_PPI and EFI_PEI_PCD_PPI. 12 // PCD PEIM driver will produce above two PPIs at same time. 13 // 14 // PCD database is generated as the separate binary image at build time. The binary image 15 // will be intergrated into Firmware volume together with PCD driver. 16 // 17 // //////////////////////////////////////////////////////////////////////////////// 18 // // // 19 // // Introduction of PCD database // 20 // // // 21 // //////////////////////////////////////////////////////////////////////////////// 22 // 23 // 1, Introduction 24 // PCD database hold all dynamic type PCD information. The structure of PEI PCD 25 // database is generated by build tools according to dynamic PCD usage for 26 // specified platform. 27 // 28 // 2, Dynamic Type PCD 29 // Dynamic type PCD is used for the configuration/setting which value is determined 30 // dynamic. In contrast, the value of static type PCD (FeatureFlag, FixedPcd, 31 // PatchablePcd) is fixed in final generated FD image in build time. 32 // 33 // 2.1 The "dynamic" determination means one of below cases: 34 // a) The PCD setting value is produced by someone driver and consumed by 35 // other driver in execution time. 36 // b) The PCD setting value is set/get by user from FrontPage. 37 // c) The PCD setting value is produced by platform OEM vendor in specified area. 38 // 39 // 2.2 According to module distribution way, dynamic PCD could be classfied as: 40 // a) Dynamic: 41 // If module is released in source code and will be built with platform 42 // DSC, the dynamic PCD used by this module can be accessed as: 43 // PcdGetxx(PcdSampleDynamicPcd); 44 // In building platform, build tools will translate PcdSampleDynamicPcd to 45 // pair of {Token Space Guid: Token Number} for this PCD. 46 // b) DynamicEx: 47 // If module is release as binary and will not pariticpate platform building, 48 // the dynamic PCD used by this module need be accessed as: 49 // PcdGetxxEx(gEfiMyTokenspaceGuid, PcdSampleDynamicPcd) 50 // Developer need explicity gives {Token Space Guid:Token Number} as parameter 51 // in writting source code. 52 // 53 // 2.3 According to PCD value's storage method, dynamic PCD could be classfied as: 54 // a) Default Storage: 55 // - The PCD value is stored in PCD database maintained by PCD driver in boot 56 // time memory. 57 // - This type is used for communication between PEIM/DXE driver, DXE/DXE 58 // driver. But all set/get value will be losted after boot-time memory 59 // is turn off. 60 // - [PcdsDynamicDefault] is used as section name for this type PCD in 61 // platform DSC file. [PcdsDynamicExDefault] is used for dynamicEx type PCD. 62 // 63 // b) Variable Storage: 64 // - The PCD value is stored in variable area. 65 // - As default storage type, this type PCD could be used for PEI/DXE driver 66 // communication. But beside it, this type PCD could also be used to store 67 // the value associate with a HII setting via variable interface. 68 // - In PEI phase, the PCD value could only be got but can not be set due 69 // to variable area is readonly. 70 // - [PcdsDynamicHii] is used as section name for this type PCD in platform 71 // DSC file. [PcdsDynamicExHii] is for dynamicEx type PCD. 72 // 73 // c) OEM specificed storage area: 74 // - The PCD value is stored in OEM specified area which base address is 75 // specified by a FixedAtBuild PCD setting - PcdVpdBaseAddress. 76 // - The area is read only for PEI and DXE phase. 77 // - [PcdsDynamicVpd] is used as section name for this type PCD in platform 78 // DSC file. [PcdsDynamicExVpd] is for dynamicex type PCD. 79 // 80 // 2.4 When and how to use dynamic PCD 81 // Module developer do not care the used PCD is dynamic or static when writting 82 // source code/INF. Dynamic PCD and dynamic type is pointed by platform integrator 83 // in platform DSC file. Please ref section 2.3 to get matching between dynamic 84 // PCD type and section name in DSC file. 85 // 86 // 3, PCD database: 87 // Although dynamic PCD could be in different storage type as above description, 88 // but the basic information and default value for all dynamic PCD is hold 89 // by PCD database maintained by PEI/DXE driver. 90 // 91 // As the whole EFI BIOS boot path is divided into PEI/DXE phase, the PCD database 92 // also is divided into Pei/Dxe database maintaied by PcdPeim/PcdDxe driver separatly. 93 // To make PcdPeim's driver image smaller, PEI PCD database only hold all dynamic 94 // PCD information used in PEI phase or use in both PEI/DXE phase. And DXE PCD 95 // database contains all PCDs used in PEI/DXE phase in memory. 96 // 97 // Build tool will generate PCD database into the separate binary file for 98 // PEI/DXE PCD driver according to dynamic PCD section in platform DSC file. 99 // 100 // 3.1 PcdPeim and PcdDxe 101 // PEI PCD database is maintained by PcdPeim driver run from flash. PcdPeim driver 102 // build guid hob in temporary memory and copy the binary data base from flash 103 // to temporary memory for PEI PCD database. 104 // DXE PCD database is maintained by PcdDxe driver.At entry point of PcdDxe driver, 105 // a new PCD database is allocated in boot-time memory which including all 106 // PEI PCD and DXE PCD entry. 107 // 108 // Pcd driver should run as early as possible before any other driver access 109 // dynamic PCD's value. PEI/DXE "Apriori File" mechanism make it possible by 110 // making PcdPeim/PcdDxe as first dispatching driver in PEI/DXE phase. 111 // 112 // 3.2 Token space Guid/Token number, Platform token, Local token number 113 // Dynamic PCD 114 // +-----------+ +---------+ 115 // |TokenSpace | |Platform | 116 // | Guid | build tool | Token | 117 // | + +-------------->| Number | 118 // | Token | +---------+`._ 119 // | Number | `. 120 // +-----------+ `. +------+ 121 // `-|Local | 122 // |Token | 123 // DynamicEx PCD ,-|Number| 124 // +-----------+ ,-' +------+ 125 // |TokenSpace | ,-' 126 // | Guid | _,-' 127 // | + +.' 128 // | Token | 129 // | Number | 130 // +-----------+ 131 // 132 // 133 // 3.2.1 Pair of Token space guid + Token number 134 // Any type PCD is identified by pair of "TokenSpaceGuid + TokeNumber". But it 135 // is not easy maintained by PCD driver, and hashed token number will make 136 // searching slowly. 137 // 138 // 3.2.2 Platform Token Number 139 // "Platform token number" concept is introduced for mapping to a pair of 140 // "TokenSpaceGuid + TokenNumber". The platform token number is generated by 141 // build tool in autogen.h and all of them are continual in a platform scope 142 // started from 1.(0 meaning invalid internal token number) 143 // With auto-generated "platform token number", PcdGet(PcdSampleDynamicPcd) 144 // in source code is translated to LibPcdGet(_PCD_TOKEN_PcdSampleDynamicPcd) 145 // in autogen.h. 146 // Notes: The mapping between pair of "tokenspace guid + token number" and 147 // "internal token number" need build tool establish, so "platform token number" 148 // mechanism is not suitable for binary module which use DynamicEx type PCD. 149 // To access a dynamicEx type PCD, pair of "token space guid/token number" all need 150 // to be specificed for PcdSet/PcdGet accessing macro. 151 // 152 // Platform Token Number is started from 1, and inceased continuous. From whole 153 // platform scope, there are two zones: PEI Zone and DXE Zone 154 // | Platform Token Number 155 // ----------|---------------------------------------------------------------- 156 // PEI Zone: | 1 ~ PEI_LOCAL_TOKEN_NUMBER 157 // DXE Zone: | (PEI_LOCAL_TOKEN_NUMBER + 1) ~ (PEI_LOCAL_TOKEN_NUMBER + DXE_LOCAL_TOKEN_NUMBER) 158 // 159 // 3.2.3 Local Token Number 160 // To fast searching a PCD entry in PCD database, PCD driver translate 161 // platform token number to local token number via a mapping table. 162 // For binary DynamicEx type PCD, there is a another mapping table to translate 163 // "token space guid + token number" to local token number directly. 164 // Local token number is identifier for all internal interface in PCD PEI/DXE 165 // driver. 166 // 167 // A local token number is a 32-bit value in following meaning: 168 // 32 ------------- 28 ---------- 24 -------- 0 169 // | PCD type mask | Datum Type | Offset | 170 // +-----------------------------------------+ 171 // where: 172 // PCd type mask: indicate Pcd type from following macro: 173 // PCD_TYPE_DATA 174 // PCD_TYPE_HII 175 // PCD_TYPE_VPD 176 // PCD_TYPE_SKU_ENABLED 177 // PCD_TYPE_STRING 178 // Datum Type : indicate PCD vaue type from following macro: 179 // PCD_DATUM_TYPE_POINTER 180 // PCD_DATUM_TYPE_UINT8 181 // PCD_DATUM_TYPE_UINT16 182 // PCD_DATUM_TYPE_UINT32 183 // PCD_DATUM_TYPE_UINT64 184 // Offset : indicate the related offset of PCD value in PCD database array. 185 // Based on local token number, PCD driver could fast determine PCD type, value 186 // type and get PCD entry from PCD database. 187 // 188 // 3.3 PCD Database binary file 189 // PCD Database binary file will be created at build time as the standalone binary image. 190 // To understand the binary image layout, PCD Database C structure is still generated 191 // as comments by build tools in PCD driver's autogen.h/ 192 // autogen.c file. In generated C structure, following information is stored: 193 // - ExMapTable: This table is used translate a binary dynamicex type PCD's 194 // "tokenguid + token" to local token number. 195 // - LocalTokenNumberTable: 196 // This table stores all local token number in array, use "Internal 197 // token number" as array index to get PCD entry's offset fastly. 198 // - SizeTable: This table stores the size information for all PCD entry. 199 // - GuidTable: This table stores guid value for DynamicEx's token space, 200 // HII type PCD's variable GUID. 201 // - SkuIdTable: TBD 202 // - SystemSkuId: TBD 203 // - PCD value structure: 204 // Every PCD has a value record in PCD database. For different 205 // datum type PCD has different record structure which will be 206 // introduced in 3.3.1 207 // 208 // In a PCD database structure, there are two major area: Init and UnInit. 209 // Init area is use stored above PCD internal structure such as ExMapTable, 210 // LocalTokenNumberTable etc and the (default) value of PCD which has default 211 // value specified in platform DSC file. 212 // Unint area is used stored the value of PCD which has no default value in 213 // platform DSC file, the value of NULL, 0 specified in platform DSC file can 214 // be seemed as "no default value". 215 // 216 // 3.3.1 Simple Sample PCD Database C Structure 217 // A general sample of PCD database structue is as follows: 218 // typedef struct _PCD_DATABASE { 219 // typedef struct _PCD_DATABASE_INIT { 220 // //===== Following is PCD database internal maintain structures 221 // DYNAMICEX_MAPPING ExMapTable[PEI_EXMAPPING_TABLE_SIZE]; 222 // UINT32 LocalTokenNumberTable[PEI_LOCAL_TOKEN_NUMBER_TABLE_SIZE]; 223 // GUID GuidTable[PEI_GUID_TABLE_SIZE]; 224 // SIZE_INFO SizeTable[PEI_SIZE_TABLE_SIZE]; 225 // UINT8 SkuIdTable[PEI_SKUID_TABLE_SIZE]; 226 // SKU_ID SystemSkuId; 227 // 228 // //===== Following is value structure for PCD with default value 229 // .... 230 // .... 231 // .... 232 // } Init; 233 // typedef struct _PCD_DATABSE_UNINIT { 234 // //==== Following is value structure for PCD without default value 235 // .... 236 // .... 237 // } UnInit; 238 // } 239 // 240 // 3.3.2 PCD value structure in PCD database C structure 241 // The value's structure is generated by build tool in PCD database C structure. 242 // The PCDs in different datum type has different value structure. 243 // 244 // 3.3.2.1 UINT8/UINT16/UINT32/UINT64 datum type PCD 245 // The C structure for these datum type PCD is just a UINT8/UINT16/UINT32/UINT64 246 // data member in PCD database, For example: 247 // UINT16 PcdHardwareErrorRecordLevel_d3705011_bc19_4af7_be16_f68030378c15_VariableDefault_0; 248 // Above structure is generated by build tool, the member name is "PcdCName_Guidvalue" 249 // Member type is UINT16 according to PcdHardwareErrorRecordLevel declaration 250 // in DEC file. 251 // 252 // 3.3.2.2 VOID* datum type PCD 253 // The value of VOID* datum type PCD is a UINT8/UINT16 array in PCD database. 254 // 255 // 3.3.2.2.1 VOID* - string type 256 // If the default value for VOID* datum type PCD like L"xxx", the PCD is 257 // used for unicode string, and C structure of this datum type PCD is 258 // UINT16 string array in PCD database, for example: 259 // UINT16 StringTable[29]; 260 // The number of 29 in above sample is max size of a unicode string. 261 // 262 // If the default value for VOID* datum type PCD like "xxx", the PCD is 263 // used for ascii string, and C structure of this datum type PCD is 264 // UINT8 string array in PCD database, for example: 265 // UINT8 StringTable[20]; 266 // The number of 20 in above sample is max size of a ascii string. 267 // 268 // 3.3.2.2.2 VOID* - byte array 269 // If the default value of VOID* datum type PCD like {'0x29', '0x01', '0xf2'} 270 // the PCD is used for byte array. The generated structrue is same as 271 // above ascii string table, 272 // UINT8 StringTable[13]; 273 // The number of 13 in above sample is max size of byte array. 274 // 275 // 3.3.3 Some utility structures in PCD Database 276 // 3.3.3.1 GuidTable 277 // GuidTable array is used to store all related GUID value in PCD database: 278 // - Variable GUID for HII type PCD 279 // - Token space GUID for dynamicex type PCD 280 // 281 // Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR> 282 // 283 // This program and the accompanying materials 284 // are licensed and made available under the terms and conditions of the BSD License 285 // which accompanies this distribution. The full text of the license may be found at 286 // http://opensource.org/licenses/bsd-license.php 287 // THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 288 // WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 289 // 290 // **/ 291 292 293 #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." 294 295 #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." 296 297
