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2.8 PCD Sections

2.8.1 [PcdsFeatureFlag] section

The required content for the FeatureFlag PCD is the PCD Token Space Guid C name, the PCD's C name (these two entries are separated by the period character), and a Boolean value of either TRUE, FALSE, 1 or 0. The PCD name and value entries are separated by the pipe "|" character.

FeatureFlag PCDs can be used in conditional directive statements within the DSC and FDF files. These PCDs may also be used to select execution paths in some code routines. The build tools will generate a const variable for each PcdsFeatureFlag used by a module.

The section modifier, SkuIdentifier, can be used by the build tools to create images for one specific SKU. Unlike the PcdsDynamic and PcdsDynamicEx entries, no access methods are allowed for having different values during runtime for different SKUs. Do not use the SkuIdentifier when building all SKUs.

The following are typical entries, with a supported module type qualifier omitted in these examples:

[PcdsFeatureFlag]
[PcdsFeatureFlag.common]
[PcdsFeatureFlag.IA32]
[PcdsFeatureFlag.X64]
[PcdsFeatureFlag.EBC]

Format of an entry in this section is:

PcdTokenSpaceGuidCName.PcdCName|Value

Example

[PcdsFeatureFlag.common]
  gEfiMdeModulePkgTokenSpaceGuid.PcdDxePcdDatabaseTraverseEnabled|1

2.8.2 [PcdsFixedAtBuild] and [PcdsPatchableInModule] sections

The section modifier, SkuIdentifier, can be used by the build tools to create images for one specific SKU. Unlike the PcdsDynamic and PcdsDynamicEx entries, no access methods are allowed for having different values during runtime for different SKUs. Do not use the SkuIdentifier when building all SKUs.

2.8.2.1 PcdsFixedAtBuild

The FixedAtBuild PCD access method cannot be used in a Binary Module.

The required content for the FixedAtBuild PCD are the PCD Token Space Guid C name, the PCD's C name (these two entries are separated by the period character) and the Value (any one of Boolean, numeric or pointer types). The PCD name and value entries are separated by the pipe "|" character.

If the Datum Type for the PCD is VOID*, then a fourth field that specifies the maximum datum size is required. This is the maximum size allocated by the Platform Integrator. Module developers won't know how much size will be allocated, and just use it. The platform integrator must figure out what the maximum length will be, based on the usage from the modules included.

FixedAtBuild PCDs can be used in conditional directive statements in the DSC and FDF files. The build tools will generate a const variable for each FixedAtBuild PCD used by a module.

The following are typical examples of the [PcdsFixedAtBuild] section tag (the $(arch) and $(SkuIdentifier) would be replaced with real values).

[PcdsFixedAtBuild]
[PcdsFixedAtBuild.common]
[PcdsFixedAtBuild.IA32]
[PcdsFixedAtBuild.X64]
[PcdsFixedAtBuild.EBC]
[PcdsFixedAtBuild.$(arch).$(SkuIdentifier)]

Format of a point (VOID*) entry in this section is:

PcdTokenSpaceGuidCName.PcdCName|Value[|DatumType|MaximumDatumSize]

Format for Boolean and numeric entries in this section is:

PcdTokenSpaceGuidCName.PcdCName|Value

Examples

[PcdsFixedAtBuild.common]
  gEfiMdePkgTokenSpaceGuid.PcdFSBClock|200000000
  gEfiMdeModulePkgTokenSpaceGuid.PcdVpdBaseAddress|0x0
  gEfiEdkNt32PkgTokenSpaceGuid.PcdWinNtPhysicalDisk|L"E:RW;245760;512"|VOID*|32

2.8.2.2 PcdsPatchableInModule

The PatchableInModule PCD access method can be used with modules that are distributed in binary form. The PCD's value can be patched by tools that know the offset of the PCD into the binary file.

The required content for the PatchableInModule PCD are the PCD Token Space Guid C name, the PCD's C name (these two entries are separated by the period character) and Value. The PCD name and value entries are separated by the pipe "|" character. If the Datum Type for the PCD is VOID*, then a fourth field that specifies the maximum datum size is also required.

PatchableInModule PCDs cannot be used in conditional directive statements. Build tools will generate a volatile variable for each PatchableInModule PCD that is used by a module.

The following are typical examples of the [PcdsPatchableInModule] section tag (the $(arch) and $(SkuIdentifier) would be replaced with real values).

[PcdsPatchableInModule]
[PcdsPatchableInModule.IA32]
[PcdsPatchableInModule.X64]
[PcdsPatchableInModule.EBC]
[PcdsPatchableInModule.$(arch).$(SkuIdentifier)]

Format of an entry in this section is:

PcdTokenSpaceGuidCName.PcdCName|Value[|DatumType|MaximumDatumSize]

Example

[PcdsPatchableInModule.common]
  gEfiMdePkgTokenSpaceGuid.PcdDebugPrintErrorLevel|0x80000000|UINT32|4

2.8.3 [PcdsDynamic*] and [PcdsDynamicEx*] sections

PCDs listed in these sections cannot be used in conditional directive statements.

The Dynamic PCD access method cannot be used for modules that are distributed in binary form.

For Dynamic PCD settings, the section labels must include one of Default, Vpd or Hii with optional architecture and an optional SKUID_IDENTIFIER name. The Dynamic entry fields are separated by the pipe "|" character. If the Datum Type for the PCD is VOID*, then a field that specifies the maximum datum size is also required.

The use of the SkuIdentifier in the PcdsDynamic and PcdsDynamicEx sections may be needed for creating the PCD database when a single platform binary image supports multiple SKUs. The SKU selection based on things like a hardware jumper, or some other method that is outside the scope of this document.

For using the standard PCD Get/Set PPI or Protocol.

2.8.3.1 PcdsDynamicDefault

The Dynamic Default PCD access method will generate a volatile variable that can be accessed at runtime using PCD a Get PPI or Protocol.

[PcdsDynamic.$(arch).DEFAULT]
[PcdsDynamicDefault.$(arch).$(SkuIdentifier)]
[PcdsDynamicHii.$(arch).$(SkuIdentifier)]
[PcdsDynamicVpd.$(arch).$(SkuIdentifier)]

The format for a boolean or numeric datum type PCD entry in this section is:

PcdTokenSpaceGuidCName.PcdCName|Value

The format for a VOID* PCD entry in this section is:

PcdTokenSpaceGuidCName.PcdCName|Value[|DatumType[|MaximumDatumSize]]

Examples

[PcdsDynamicDefault]
gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableBase|0x0
gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableSize|0x0

2.8.3.2 PcdsDynamicHII

The Dynamic Hii PCD access method will generate HII data content that can be accessed at runtime.

For using the HII for PCD data, the section name is as follows:

[PcdsDynamicHii.$(arch).DEFAULT]

Specifying a SKUID_IDENTIFIER name for an Hii Pcd selection is optional, for example:

[PcdsDynamicHii.common.Sku1]

While the format for content of this section is as follows, note that the backslash character is used here to indicate the continuation of the line:

PcdTokenSpaceGuidCName.PcdCName|VariableName|VariableGuid|VariableOffset[|[HiiDefaultValue][|HiiAttrubte]]

For VOID* PCDs, the HiiDefaultValue will be a pointer; specifying the optional HiiDefaultValue has no meaning.

The optional HII Attribute entry is a comma separated list of attributes as described in the following table.

Table 9 HII Attributes
Keyword C Flag Value
NV EFI_VARIABLE_NON_VOLATILE 0x00000001
BS EFI_VARIABLE_BOOTSERVICE_ACCESS 0x00000002
RT EFI_VARIABLE_RUNTIME_ACCESS 0x00000004
RO VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY BIT0

Note: The VariableName field in the HII format PCD entry must not be an empty string.

Examples

[PcdsDynamicHii.common.Sku_Two]
  NoSuchTokenSpaceGuid.PcdPreAllocatedMem|L"TestVariable"|gSysconfigGuid|0x000000A9|0x3

[PcdsDynamicHii.common.DEFAULT]
  gEfiMdeModulePkgTokenSpaceGuid.PcdValidRange|L"PcdValidRange"|gEfiGlobalVariableGuid|0x07|0|BS,RT,NV

2.8.3.3 PcdsDynamicVpd

The Dynamic Vpd PCD access method will generate macros that allow the data content (stored in read-only memory) to be accessed at runtime. Note that the PCD drivers may use a copy of the VPD data to allow runtime changes to these variables.

For using the VPD for PCD data, the section name is:

[PcdsDynamicVpd.$(arch).DEFAULT]

Specifying a SKUID_IDENTIFIER for a VPD PCD selection is optional, for example:

[PcdsDynamicVpd.common.Vpd.SkuSeven]

The format for boolean and numeric datum type content of this section is as follows:

PcdTokenSpaceGuidCName.PcdCName|VpdOffset [|Value]

The format for VOID* datum type content in this section is:

PcdTokenSpaceGuidCName.PcdCName|VpdOffset [|MaximumDatumSize [|Value]]

Examples

[PcdsDynamicVpd.IA32.DEFAULT, PcdsDynamicVpd.x64.DEFAULT]
  gEfiPhonyTokenSpaceGuidCName.PcdVpdCopyrightLine|0x000000A0
  gNoSuchTokenSpaceGuid.PcdPciDevice0Name    | 0x2282 | 64  | "None" # VOID*
  gNoSuchTokenSpaceGuid.PcdPciDevice50Info   | 0x22C2 | 18  | {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}  # |VOID*
  gNoSuchTokenSpaceGuid.PcdOemBootOptionName | 0x22D4 | 100 | " "    # VOID*
  gNoSuchTokenSpaceGuid.PcdOemBootOptionPath | 0x2338 | 100 | " "    # VOID*
  gNoSuchTokenSpaceGuid.PcdEnableFastBoot    | 0x239C | 1   | FALSE  # BOOLEAN

2.8.3.4 PcdsDynamicExDefault

The DynamicEx access method of PCD is recommended for modules that are distributed in binary form.

Entries for DynamicEx are identical to the Dynamic entries. The DynamicEx entry fields are separated by the pipe "|" character. If the Datum Type for the PCD is VOID*, then MaximumDatumSize field that specifies the maximum datum size is required.

[PcdsDynamicExDefault.$(arch).Default]
[PcdsDynamicExDefault.$(arch).$(SkuIdentifier)]

The format for a boolean or numeric datum type PCD entry in this section is:

PcdTokenSpaceGuidCName.PcdCName|Value

The format for a VOID* PCD entry in this section is:

PcdTokenSpaceGuidCName.PcdCName|Value[|DatumType[|MaximumDatumSize]]

Examples

[PcdsDynamicExDefault.common.DEFAULT]
gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableBase|0x0
gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableSize|0x0

2.8.3.5 PcdsDynamicEx Hii

For using the HII for PCD data, the section name is as follows:

[PcdsDynamicExHii.$(arch).$(SKUID_IDENTIFIER)]

Specifying a SKUID for an HII PCD selection is optional, for example:

[PcdsDynamicExHii.common.Sku1]

While the format for content of this section is as follows, note that the backslash character is used here to indicate the continuation of the line:

PcdTokenSpaceGuidCName.PcdCName|VariableName|VariableGuid|VariableOffset[|[HiiDefaultValue]]

The optional HII Attribute entry is a comma separated list of attributes as described in Table 9 HII Attributes.

Note: The VariableName field in the HII format PCD entry must not be an empty string.

Examples

[PcdsDynamicExHii.IA32.Sku_Two]
  gNoSuchTokenSpaceGuid.PcdPreAllocatedMem|L"TestVariable"|gSysconfigGuid|0x000000A9|0x11

[PcdsDynamicExHii.common.DEFAULT]
  gEfiMdeModulePkgTokenSpaceGuid.PcdValidRange|L"PcdValidRange"|gEfiGlobalVariableGuid|0x07|0|BS,RT,NV

2.8.3.6 PcdsDynamicExVpd

For using the VPD for PCD data, the section name is:

[PcdsDynamicExVpd.$(arch).$(SKUID_IDENTIFIER)]

Specifying a SKUID for a VPD PCD selection is optional, for example:

[PcdsDynamicExVpd.common.SkuTwo]

The format for boolean and numeric datum type content of this section is as follows:

Method

PcdTokenSpaceGuidCName.PcdCName|VpdOffset[|Value]

The format for VOID* datum type content in this section is:

PcdTokenSpaceGuidCName.PcdCName|VpdOffset[|MaximumDatumSize[|Value]]

Examples

[PcdsDynamicExVpd.common.DEFAULT]
  gEfiPhonyTokenSpaceGuidCName.PcdVpdCopyrightLine|0x000000A0
  gNoSuchTokenSpaceGuid.PcdPciDevice0Name   |0x2282|64 | "None"  # VOID*
  gNoSuchTokenSpaceGuid.PcdPciDevice50Info  |0x22C2|18 | {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF} #|VOID*
  gNoSuchTokenSpaceGuid.PcdOemBootOptionName|0x22D4|100| " "     # VOID*
  gNoSuchTokenSpaceGuid.PcdOemBootOptionPath|0x2338|100| " "     # VOID*
  gNoSuchTokenSpaceGuid.PcdEnableFastBoot   |0x239C|1  | FALSE   # BOOLEAN