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