1## @file 2# PCD DXE driver manage database contains all dynamic PCD entries and produce the implementation of PCD protocol. 3# 4# This version PCD DXE depends on the external PCD database binary file, not built in PCD data base. 5# There are two PCD Protocols as follows: 6# 1) PCD_PROTOCOL 7# It is EDKII implementation which support Dynamic/DynamicEx type Pcds. 8# 2) EFI_PCD_PROTOCOL 9# It is defined by PI specification 1.2, Vol 3 which only support dynamicEx 10# type Pcd. 11# 12# For dynamicEx type PCD, it is compatible between PCD_PROTOCOL and EFI_PCD_PROTOCOL. 13# PCD DXE driver will produce above two protocols at same time. 14# 15# PCD database is generated as the separate binary image at build time. The binary image 16# will be intergrated into Firmware volume together with PCD driver. 17# 18# //////////////////////////////////////////////////////////////////////////////// 19# // // 20# // Introduction of PCD database // 21# // // 22# //////////////////////////////////////////////////////////////////////////////// 23# 24# 1, Introduction 25# PCD database hold all dynamic type PCD information. The structure of PEI PCD 26# database is generated by build tools according to dynamic PCD usage for 27# specified platform. 28# 29# 2, Dynamic Type PCD 30# Dynamic type PCD is used for the configuration/setting which value is determined 31# dynamic. In contrast, the value of static type PCD (FeatureFlag, FixedPcd, 32# PatchablePcd) is fixed in final generated FD image in build time. 33# 34# 2.1 The "dynamic" determination means one of below cases: 35# a) The PCD setting value is produced by someone driver and consumed by 36# other driver in execution time. 37# b) The PCD setting value is set/get by user from FrontPage. 38# c) The PCD setting value is produced by platform OEM vendor in specified area. 39# 40# 2.2 According to module distribution way, dynamic PCD could be classfied as: 41# a) Dynamic: 42# If module is released in source code and will be built with platform 43# DSC, the dynamic PCD used by this module can be accessed as: 44# PcdGetxx(PcdSampleDynamicPcd); 45# In building platform, build tools will translate PcdSampleDynamicPcd to 46# pair of {Token Space Guid: Token Number} for this PCD. 47# b) DynamicEx: 48# If module is release as binary and will not pariticpate platform building, 49# the dynamic PCD used by this module need be accessed as: 50# PcdGetxxEx(gEfiMyTokenspaceGuid, PcdSampleDynamicPcd) 51# Developer need explicity gives {Token Space Guid:Token Number} as parameter 52# in writting source code. 53# 54# 2.3 According to PCD value's storage method, dynamic PCD could be classfied as: 55# a) Default Storage: 56# - The PCD value is stored in PCD database maintained by PCD driver in boot 57# time memory. 58# - This type is used for communication between PEIM/DXE driver, DXE/DXE 59# driver. But all set/get value will be losted after boot-time memory 60# is turn off. 61# - [PcdsDynamicDefault] is used as section name for this type PCD in 62# platform DSC file. [PcdsDynamicExDefault] is used for dynamicEx type PCD. 63# 64# b) Variable Storage: 65# - The PCD value is stored in variable area. 66# - As default storage type, this type PCD could be used for PEI/DXE driver 67# communication. But beside it, this type PCD could also be used to store 68# the value associate with a HII setting via variable interface. 69# - In PEI phase, the PCD value could only be got but can not be set due 70# to variable area is readonly. 71# - [PcdsDynamicHii] is used as section name for this type PCD in platform 72# DSC file. [PcdsDynamicExHii] is for dynamicEx type PCD. 73# 74# c) OEM specificed storage area: 75# - The PCD value is stored in OEM specified area which base address is 76# specified by a FixedAtBuild PCD setting - PcdVpdBaseAddress. 77# - The area is read only for PEI and DXE phase. 78# - [PcdsDynamicVpd] is used as section name for this type PCD in platform 79# DSC file. [PcdsDynamicExVpd] is for dynamicex type PCD. 80# 81# 2.4 When and how to use dynamic PCD 82# Module developer do not care the used PCD is dynamic or static when writting 83# source code/INF. Dynamic PCD and dynamic type is pointed by platform integrator 84# in platform DSC file. Please ref section 2.3 to get matching between dynamic 85# PCD type and section name in DSC file. 86# 87# 3, PCD database: 88# Although dynamic PCD could be in different storage type as above description, 89# but the basic information and default value for all dynamic PCD is hold 90# by PCD database maintained by PEI/DXE driver. 91# 92# As the whole EFI BIOS boot path is divided into PEI/DXE phase, the PCD database 93# also is divided into Pei/Dxe database maintaied by PcdPeim/PcdDxe driver separatly. 94# To make PcdPeim's driver image smaller, PEI PCD database only hold all dynamic 95# PCD information used in PEI phase or use in both PEI/DXE phase. And DXE PCD 96# database contains all PCDs used in PEI/DXE phase in memory. 97# 98# Build tool will generate PCD database into the separate binary file for 99# PEI/DXE PCD driver according to dynamic PCD section in platform DSC file. 100# 101# 3.1 PcdPeim and PcdDxe 102# PEI PCD database is maintained by PcdPeim driver run from flash. PcdPeim driver 103# build guid hob in temporary memory and copy the binary data base from flash 104# to temporary memory for PEI PCD database. 105# DXE PCD database is maintained by PcdDxe driver.At entry point of PcdDxe driver, 106# a new PCD database is allocated in boot-time memory which including all 107# PEI PCD and DXE PCD entry. 108# 109# Pcd driver should run as early as possible before any other driver access 110# dynamic PCD's value. PEI/DXE "Apriori File" mechanism make it possible by 111# making PcdPeim/PcdDxe as first dispatching driver in PEI/DXE phase. 112# 113# 3.2 Token space Guid/Token number, Platform token, Local token number 114# Dynamic PCD 115# +-----------+ +---------+ 116# |TokenSpace | |Platform | 117# | Guid | build tool | Token | 118# | + +-------------->| Number | 119# | Token | +---------+`._ 120# | Number | `. 121# +-----------+ `. +------+ 122# `-|Local | 123# |Token | 124# DynamicEx PCD ,-|Number| 125# +-----------+ ,-' +------+ 126# |TokenSpace | ,-' 127# | Guid | _,-' 128# | + +.' 129# | Token | 130# | Number | 131# +-----------+ 132# 133# 134# 3.2.1 Pair of Token space guid + Token number 135# Any type PCD is identified by pair of "TokenSpaceGuid + TokeNumber". But it 136# is not easy maintained by PCD driver, and hashed token number will make 137# searching slowly. 138# 139# 3.2.2 Platform Token Number 140# "Platform token number" concept is introduced for mapping to a pair of 141# "TokenSpaceGuid + TokenNumber". The platform token number is generated by 142# build tool in autogen.h and all of them are continual in a platform scope 143# started from 1.(0 meaning invalid internal token number) 144# With auto-generated "platform token number", PcdGet(PcdSampleDynamicPcd) 145# in source code is translated to LibPcdGet(_PCD_TOKEN_PcdSampleDynamicPcd) 146# in autogen.h. 147# Notes: The mapping between pair of "tokenspace guid + token number" and 148# "internal token number" need build tool establish, so "platform token number" 149# mechanism is not suitable for binary module which use DynamicEx type PCD. 150# To access a dynamicEx type PCD, pair of "token space guid/token number" all need 151# to be specificed for PcdSet/PcdGet accessing macro. 152# 153# Platform Token Number is started from 1, and inceased continuous. From whole 154# platform scope, there are two zones: PEI Zone and DXE Zone 155# | Platform Token Number 156# ----------|---------------------------------------------------------------- 157# PEI Zone: | 1 ~ PEI_LOCAL_TOKEN_NUMBER 158# DXE Zone: | (PEI_LOCAL_TOKEN_NUMBER + 1) ~ (PEI_LOCAL_TOKEN_NUMBER + DXE_LOCAL_TOKEN_NUMBER) 159# 160# 3.2.3 Local Token Number 161# To fast searching a PCD entry in PCD database, PCD driver translate 162# platform token number to local token number via a mapping table. 163# For binary DynamicEx type PCD, there is a another mapping table to translate 164# "token space guid + token number" to local token number directly. 165# Local token number is identifier for all internal interface in PCD PEI/DXE 166# driver. 167# 168# A local token number is a 32-bit value in following meaning: 169# 32 ------------- 28 ---------- 24 -------- 0 170# | PCD type mask | Datum Type | Offset | 171# +-----------------------------------------+ 172# where: 173# PCd type mask: indicate Pcd type from following macro: 174# PCD_TYPE_DATA 175# PCD_TYPE_HII 176# PCD_TYPE_VPD 177# PCD_TYPE_SKU_ENABLED 178# PCD_TYPE_STRING 179# Datum Type : indicate PCD vaue type from following macro: 180# PCD_DATUM_TYPE_POINTER 181# PCD_DATUM_TYPE_UINT8 182# PCD_DATUM_TYPE_UINT16 183# PCD_DATUM_TYPE_UINT32 184# PCD_DATUM_TYPE_UINT64 185# Offset : indicate the related offset of PCD value in PCD database array. 186# Based on local token number, PCD driver could fast determine PCD type, value 187# type and get PCD entry from PCD database. 188# 189# 3.3 PCD Database binary file 190# PCD Database binary file will be created at build time as the standalone binary image. 191# To understand the binary image layout, PCD Database C structure is still generated 192# as comments by build tools in PCD driver's autogen.h/ 193# autogen.c file. In generated C structure, following information is stored: 194# - ExMapTable: This table is used translate a binary dynamicex type PCD's 195# "tokenguid + token" to local token number. 196# - LocalTokenNumberTable: 197# This table stores all local token number in array, use "Internal 198# token number" as array index to get PCD entry's offset fastly. 199# - SizeTable: This table stores the size information for all PCD entry. 200# - GuidTable: This table stores guid value for DynamicEx's token space, 201# HII type PCD's variable GUID. 202# - SkuIdTable: TBD 203# - SystemSkuId: TBD 204# - PCD value structure: 205# Every PCD has a value record in PCD database. For different 206# datum type PCD has different record structure which will be 207# introduced in 3.3.1 208# 209# In a PCD database structure, there are two major area: Init and UnInit. 210# Init area is use stored above PCD internal structure such as ExMapTable, 211# LocalTokenNumberTable etc and the (default) value of PCD which has default 212# value specified in platform DSC file. 213# Unint area is used stored the value of PCD which has no default value in 214# platform DSC file, the value of NULL, 0 specified in platform DSC file can 215# be seemed as "no default value". 216# 217# 3.3.1 Simple Sample PCD Database C Structure 218# A general sample of PCD database structue is as follows: 219# typedef struct _PCD_DATABASE { 220# typedef struct _PCD_DATABASE_INIT { 221# //===== Following is PCD database internal maintain structures 222# DYNAMICEX_MAPPING ExMapTable[PEI_EXMAPPING_TABLE_SIZE]; 223# UINT32 LocalTokenNumberTable[PEI_LOCAL_TOKEN_NUMBER_TABLE_SIZE]; 224# GUID GuidTable[PEI_GUID_TABLE_SIZE]; 225# SIZE_INFO SizeTable[PEI_SIZE_TABLE_SIZE]; 226# UINT8 SkuIdTable[PEI_SKUID_TABLE_SIZE]; 227# SKU_ID SystemSkuId; 228# 229# //===== Following is value structure for PCD with default value 230# .... 231# .... 232# .... 233# } Init; 234# typedef struct _PCD_DATABSE_UNINIT { 235# //==== Following is value structure for PCD without default value 236# .... 237# .... 238# } UnInit; 239# } 240# 241# 3.3.2 PCD value structure in PCD database C structure 242# The value's structure is generated by build tool in PCD database C structure. 243# The PCDs in different datum type has different value structure. 244# 245# 3.3.2.1 UINT8/UINT16/UINT32/UINT64 datum type PCD 246# The C structure for these datum type PCD is just a UINT8/UINT16/UINT32/UINT64 247# data member in PCD database, For example: 248# UINT16 PcdHardwareErrorRecordLevel_d3705011_bc19_4af7_be16_f68030378c15_VariableDefault_0; 249# Above structure is generated by build tool, the member name is "PcdCName_Guidvalue" 250# Member type is UINT16 according to PcdHardwareErrorRecordLevel declaration 251# in DEC file. 252# 253# 3.3.2.2 VOID* datum type PCD 254# The value of VOID* datum type PCD is a UINT8/UINT16 array in PCD database. 255# 256# 3.3.2.2.1 VOID* - string type 257# If the default value for VOID* datum type PCD like L"xxx", the PCD is 258# used for unicode string, and C structure of this datum type PCD is 259# UINT16 string array in PCD database, for example: 260# UINT16 StringTable[29]; 261# The number of 29 in above sample is max size of a unicode string. 262# 263# If the default value for VOID* datum type PCD like "xxx", the PCD is 264# used for ascii string, and C structure of this datum type PCD is 265# UINT8 string array in PCD database, for example: 266# UINT8 StringTable[20]; 267# The number of 20 in above sample is max size of a ascii string. 268# 269# 3.3.2.2.2 VOID* - byte array 270# If the default value of VOID* datum type PCD like {'0x29', '0x01', '0xf2'} 271# the PCD is used for byte array. The generated structrue is same as 272# above ascii string table, 273# UINT8 StringTable[13]; 274# The number of 13 in above sample is max size of byte array. 275# 276# 3.3.3 Some utility structures in PCD Database 277# 3.3.3.1 GuidTable 278# GuidTable array is used to store all related GUID value in PCD database: 279# - Variable GUID for HII type PCD 280# - Token space GUID for dynamicex type PCD 281# 282# Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR> 283# 284# This program and the accompanying materials 285# are licensed and made available under the terms and conditions of the BSD License 286# which accompanies this distribution. The full text of the license may be found at 287# http://opensource.org/licenses/bsd-license.php 288# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 289# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 290# 291# 292## 293 294[Defines] 295 INF_VERSION = 0x00010005 296 BASE_NAME = PcdDxe 297 MODULE_UNI_FILE = PcdDxe.uni 298 FILE_GUID = 80CF7257-87AB-47f9-A3FE-D50B76D89541 299 MODULE_TYPE = DXE_DRIVER 300 VERSION_STRING = 4.0 301 PCD_IS_DRIVER = DXE_PCD_DRIVER 302 ENTRY_POINT = PcdDxeInit 303 304# 305# The following information is for reference only and not required by the build tools. 306# 307# VALID_ARCHITECTURES = IA32 X64 IPF EBC 308# 309 310[Sources] 311 Pcd.c 312 Service.c 313 Service.h 314 315[Packages] 316 MdePkg/MdePkg.dec 317 MdeModulePkg/MdeModulePkg.dec 318 319[LibraryClasses] 320 UefiRuntimeServicesTableLib 321 BaseMemoryLib 322 UefiBootServicesTableLib 323 MemoryAllocationLib 324 HobLib 325 UefiDriverEntryPoint 326 UefiLib 327 DebugLib 328 BaseLib 329 PcdLib 330 DxeServicesLib 331 332[Guids] 333 gPcdDataBaseHobGuid ## SOMETIMES_CONSUMES ## HOB 334 gPcdDataBaseSignatureGuid ## CONSUMES ## GUID # PCD database signature GUID. 335 336[Protocols] 337 gPcdProtocolGuid ## PRODUCES 338 gEfiPcdProtocolGuid ## PRODUCES 339 gGetPcdInfoProtocolGuid ## SOMETIMES_PRODUCES 340 gEfiGetPcdInfoProtocolGuid ## SOMETIMES_PRODUCES 341 ## NOTIFY 342 ## SOMETIMES_CONSUMES 343 gEdkiiVariableLockProtocolGuid 344 345[Pcd] 346 gEfiMdeModulePkgTokenSpaceGuid.PcdVpdBaseAddress ## SOMETIMES_CONSUMES 347 348[Depex] 349 TRUE 350 351[UserExtensions.TianoCore."ExtraFiles"] 352 PcdDxeExtra.uni 353