ArmPkg: only attempt buildin MmCommunicationDxe for AArch64
[mirror_edk2.git] / MdeModulePkg / Universal / PCD / Pei / PcdPeim.uni
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_STRING
177 // Datum Type : indicate PCD vaue type from following macro:
178 // PCD_DATUM_TYPE_POINTER
179 // PCD_DATUM_TYPE_UINT8
180 // PCD_DATUM_TYPE_UINT16
181 // PCD_DATUM_TYPE_UINT32
182 // PCD_DATUM_TYPE_UINT64
183 // Offset : indicate the related offset of PCD value in PCD database array.
184 // Based on local token number, PCD driver could fast determine PCD type, value
185 // type and get PCD entry from PCD database.
186 //
187 // 3.3 PCD Database binary file
188 // PCD Database binary file will be created at build time as the standalone binary image.
189 // To understand the binary image layout, PCD Database C structure is still generated
190 // as comments by build tools in PCD driver's autogen.h/
191 // autogen.c file. In generated C structure, following information is stored:
192 // - ExMapTable: This table is used translate a binary dynamicex type PCD's
193 // "tokenguid + token" to local token number.
194 // - LocalTokenNumberTable:
195 // This table stores all local token number in array, use "Internal
196 // token number" as array index to get PCD entry's offset fastly.
197 // - SizeTable: This table stores the size information for all PCD entry.
198 // - GuidTable: This table stores guid value for DynamicEx's token space,
199 // HII type PCD's variable GUID.
200 // - SkuIdTable: TBD
201 // - SystemSkuId: TBD
202 // - PCD value structure:
203 // Every PCD has a value record in PCD database. For different
204 // datum type PCD has different record structure which will be
205 // introduced in 3.3.1
206 //
207 // In a PCD database structure, there are two major area: Init and UnInit.
208 // Init area is use stored above PCD internal structure such as ExMapTable,
209 // LocalTokenNumberTable etc and the (default) value of PCD which has default
210 // value specified in platform DSC file.
211 // Unint area is used stored the value of PCD which has no default value in
212 // platform DSC file, the value of NULL, 0 specified in platform DSC file can
213 // be seemed as "no default value".
214 //
215 // 3.3.1 Simple Sample PCD Database C Structure
216 // A general sample of PCD database structue is as follows:
217 // typedef struct _PCD_DATABASE {
218 // typedef struct _PCD_DATABASE_INIT {
219 // //===== Following is PCD database internal maintain structures
220 // DYNAMICEX_MAPPING ExMapTable[PEI_EXMAPPING_TABLE_SIZE];
221 // UINT32 LocalTokenNumberTable[PEI_LOCAL_TOKEN_NUMBER_TABLE_SIZE];
222 // GUID GuidTable[PEI_GUID_TABLE_SIZE];
223 // SIZE_INFO SizeTable[PEI_SIZE_TABLE_SIZE];
224 // UINT8 SkuIdTable[PEI_SKUID_TABLE_SIZE];
225 // SKU_ID SystemSkuId;
226 //
227 // //===== Following is value structure for PCD with default value
228 // ....
229 // ....
230 // ....
231 // } Init;
232 // typedef struct _PCD_DATABSE_UNINIT {
233 // //==== Following is value structure for PCD without default value
234 // ....
235 // ....
236 // } UnInit;
237 // }
238 //
239 // 3.3.2 PCD value structure in PCD database C structure
240 // The value's structure is generated by build tool in PCD database C structure.
241 // The PCDs in different datum type has different value structure.
242 //
243 // 3.3.2.1 UINT8/UINT16/UINT32/UINT64 datum type PCD
244 // The C structure for these datum type PCD is just a UINT8/UINT16/UINT32/UINT64
245 // data member in PCD database, For example:
246 // UINT16 PcdHardwareErrorRecordLevel_d3705011_bc19_4af7_be16_f68030378c15_VariableDefault_0;
247 // Above structure is generated by build tool, the member name is "PcdCName_Guidvalue"
248 // Member type is UINT16 according to PcdHardwareErrorRecordLevel declaration
249 // in DEC file.
250 //
251 // 3.3.2.2 VOID* datum type PCD
252 // The value of VOID* datum type PCD is a UINT8/UINT16 array in PCD database.
253 //
254 // 3.3.2.2.1 VOID* - string type
255 // If the default value for VOID* datum type PCD like L"xxx", the PCD is
256 // used for unicode string, and C structure of this datum type PCD is
257 // UINT16 string array in PCD database, for example:
258 // UINT16 StringTable[29];
259 // The number of 29 in above sample is max size of a unicode string.
260 //
261 // If the default value for VOID* datum type PCD like "xxx", the PCD is
262 // used for ascii string, and C structure of this datum type PCD is
263 // UINT8 string array in PCD database, for example:
264 // UINT8 StringTable[20];
265 // The number of 20 in above sample is max size of a ascii string.
266 //
267 // 3.3.2.2.2 VOID* - byte array
268 // If the default value of VOID* datum type PCD like {'0x29', '0x01', '0xf2'}
269 // the PCD is used for byte array. The generated structrue is same as
270 // above ascii string table,
271 // UINT8 StringTable[13];
272 // The number of 13 in above sample is max size of byte array.
273 //
274 // 3.3.3 Some utility structures in PCD Database
275 // 3.3.3.1 GuidTable
276 // GuidTable array is used to store all related GUID value in PCD database:
277 // - Variable GUID for HII type PCD
278 // - Token space GUID for dynamicex type PCD
279 //
280 // Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
281 //
282 // SPDX-License-Identifier: BSD-2-Clause-Patent
283 //
284 // **/
285
286
287 #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."
288
289 #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."
290