4.3 Pre-Build Stage Overview
This section provides an overview of the first three meta-data files that are used to control different aspects of the build. There are three files of interest, build_rule.txt, tools_def.txt and target.txt. The next chapter defines the format of the tools_def.txt and target.txt files. The build_rule.txt file is not documented here, as it is internal to the EDK II build system. See the build_rule.txt file for additional information.

4.3.1 target.txt

The $(WORKSPACE)/Conf/target.txt file is created the first time edksetup script is run. The default version of this file is the $(EDK_TOOLS_PATH)/Conf/target.template file.
The target.txt file is used as a filter, allowing a developer to build items of interest without having to build everything. The variables set in this file include the target platform, the target architecture, the tool chain and pointers to the tool chain configuration and build rule files. If no options are provided on the build command-line, values from this file are used to determine what to build, what tool chain will be used and where to obtain the rules for processing the files.

4.3.2 tools_def.txt

The $(WORKSPACE)/Conf/tools_def.txt file is created the first time the edksetup script is run. The default version of this file is the $(EDK_TOOLS_PATH)/Conf/tools_def.template.
The tools_def.txt describes sets of user configurable paths, commands and default flags for external tools (as well as optional tools provided with the build system). Since advanced developers may have multiple versions of tool chains installed, this file allows setting up paths and flags for different tool chains. Each tool chain is identified by a unique name.

4.3.2.1 "Best Known Safe" flags

The tools_def.txt file flags for the supported (tested) compiler tool chains that contain "Best Known Safe" flags for generating libraries, drivers and applications. These flags are set for speed optimization. The build system does provide for modifying flags for individual modules and platforms, so flags may be modified for better debug ability.

4.3.3 build_rule.txt

The $(WORKSPACE)/Conf/build_rule.txt file is created the first time the edksetup script is run. The default version of this file is the $(EDK_TOOLS_PATH)/Conf/build_rule.template.
The build_rule.txt file is used by the tools to define how different file types are processed. This includes how different files and module types are compiled, as well as how the build tools manipulate the binary image files. Normally, users should not make changes to this file.

4.3.4 Parse EDK II Meta-Data - AutoGen stage

Once the build system knows the basic information needed for the build, the build system parses the additional EDK II meta-data files. The meta-data in the EDK II code base is stored in text-based, INI-style, documents. Refer to the EDK II INF Specification, EDK II DSC Specification, EDK II DEC Specification, and EDK II Flash Description File Specification to see the format of these files.
The DSC file is the first of the EDK II meta-data files that gets parsed. This file provides a list of the other EDK II meta-data files that need to be parsed. The DSC file may be parsed twice in order to resolve PCD values that are used are used in conditional directive statements.
The contents of current working directory (at the time the build command is executed) may alter what gets built. If the working directory contains one INF file, only the module gets built. This is useful when debugging a driver, as only the one module will be rebuilt. If more than one INF file exists, you will need to use an command-line option to select which INF file you want to build. (The INF filename must be listed in the ACTIVE_PLATFORM DSC file's [Components] section.)
Note: More than one INF file may exist in a module directory, however the BASENAME and FILE_GUID for these INF files must be different if both modules will be included in a single FV for platform.
Note: The build system has also been modified to support building multiple versions of a single INF using the format defined in the DSC specification. This permits having multiple versions of a module linked against different libraries.
The second file to be parsed will be the FDF file if one is specified in the DSC file or on the command-line. While the FDF file specified what content gets assembled into the final firmware device image, PCD values from this file may be required for building specific modules specified in the DSC file.
Note: INF files that are listed in the DSC file must include the package, MdePkg/MdePkg.dec in order to build properly (even if the module does not contain C files).
The parse stage creates individual module and library AutoGen.c, AutoGen.h and Makefiles. Since EDK II supports Microsoft, Intel and GCC complier tool chains, the Microsoft Build Tool, NMAKE/Makefile is for Windows developer Workstations using Microsoft or Intel tool chains on a Microsoft Windows operating system development workstation. For UNIX based development workstations, the GCC build tool, MAKE/GNUmakefile is used.
All third party tools and flags for those tools get expanded in the generated Makefiles. The following is an example of makefile statements that support this mode.
...
PP = C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\bin\cl.exe
CC = C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\bin\cl.exe
APP = C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\bin\cl.exe
VFRPP = C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\bin\cl.exe
DLINK = C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\bin\link.exe
PCH = C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\bin\cl.exe
ASM = C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\bin\ml.exe
TIANO = TianoCompress.exe
SLINK = C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\bin\lib.exe
ASMLINK = C:\WINDDK\3790.1830\bin\bin16\link.exe ASL = C:\ASL\iasl.exe
...
DEFAULT_PP_FLAGS = /nologo /E /TC /FI$(DEST_DIR_DEBUG)/AutoGen.h
DEFAULT_CC_FLAGS = /nologo /W4 /WX /Gy /c /D UNICODE /O1ib2 /GL / FI$(DEST_DIR_DEBUG)/AutoGen.h /EHs-c- /GF /Gs8192 /Zi /Gm
DEFAULT_APP_FLAGS = /nologo /E /TC
DEFAULT_VFRPP_FLAGS = /nologo /E /TC /DVFRCOMPILE /FIAutoGen.h
DEFAULT_DLINK_FLAGS = /NOLOGO /NODEFAULTLIB /IGNORE:4086 /OPT:REF /OPT:ICF=10 /MAP /ALIGN:32 /MACHINE:I386 /LTCG /DLL /ENTRY:$(ENTRYPOINT) /SUBSYSTEM:CONSOLE /SAFESEH:NO /BASE:0 /DRIVER /DEBUG /PDB:$(DEST_DIR_DEBUG)/$(BASE_NAME).pdb
DEFAULT_PCH_FLAGS = /nologo /W4 /WX /Gy /c /D UNICODE /O1ib2 /GL /FI$(DEST_DIR_DEBUG)/AutoGen.h /EHs-c- /GF /Gs8192 /Fp$(DEST_DIR_OUTPUT)/AutoGen.h.gch /Yc /TC /Zi /Gm
DEFAULT_ASM_FLAGS = /nologo /W3 /WX /c /coff /Cx /Zd /W0 /Zi
DEFAULT_TIANO_FLAGS =
DEFAULT_SLINK_FLAGS = /nologo /LTCG
DEFAULT_ASMLINK_FLAGS = /link /nologo /tiny
DEFAULT_ASL_FLAGS =
...
$(OUTPUT_DIR)\Ia32\WriteGdtr.obj : $(COMMON_DEPS)
$(OUTPUT_DIR)\Ia32\WriteGdtr.obj :
$(WORKSPACE)\MdePkg\Include\Library\DebugLib.h
$(OUTPUT_DIR)\Ia32\WriteGdtr.obj : $(WORKSPACE)\MdePkg\Include\Library\BaseLib.h
$(OUTPUT_DIR)\Ia32\WriteGdtr.obj :
$(WORKSPACE)\MdePkg\Include\Library\TimerLib.h
$(OUTPUT_DIR)\Ia32\WriteGdtr.obj :
$(WORKSPACE)\MdePkg\Include\Library\BaseMemoryLib.h
$(OUTPUT_DIR)\Ia32\WriteGdtr.obj : $(WORKSPACE)\MdePkg\Include\Library\PcdLib.h
$(OUTPUT_DIR)\Ia32\WriteGdtr.obj :
$(WORKSPACE)\MdePkg\Library\BaseLib\Ia32\WriteGdtr.c
$(OUTPUT_DIR)\Ia32\WriteGdtr.obj :
$(WORKSPACE)\MdePkg\Library\BaseLib\BaseLibInternals.h
"$(CC)" /Fo$(OUTPUT_DIR)\Ia32\WriteGdtr.obj $(CC_FLAGS) $(INC) $(WORKSPACE)\MdePkg\Library\BaseLib\Ia32\WriteGdtr.c
$(OUTPUT_DIR)\Ia32\WriteDr3.obj : $(COMMON_DEPS)
$(OUTPUT_DIR)\Ia32\WriteDr3.obj :
$(WORKSPACE)\MdePkg\Library\BaseLib\Ia32\WriteDr3.c
"$(CC)" /Fo$(OUTPUT_DIR)\Ia32\WriteDr3.obj $(CC_FLAGS) $(INC)
$(WORKSPACE)\MdePkg\Library\BaseLib\Ia32\WriteDr3.c
...
One makefile is generated for each module under a combination of $(TARGET)_$(TOOL_CHAIN_TAG) and $(ARCH), package name, module directory, directory name and the BASE_NAME of the module's INF file.

Parse DSC file

  1. 1.
    Obtain platform FixedAtBuild and FeatureFlag PCD values and Macro values that are used in the Conditional Directives - if the value of a Macro, FixedAtBuild PCD or FeatureFlag PCD used in the conditional directives cannot be determined, the build will break with an appropriate error message. The use of FixedAtBuild or FeatureFlag PCD names which are defined by SET statements in the FDF file cannot be used in conditional directive statements in the DSC file.
  2. 2.
    Second pass over the DSC files will crush out any conditional directives where the feature flag expression used in the conditional directive is False.
  3. 3.
    Obtain platform PCD values which will go into the individual module AutoGen.h files where needed.
    • If VPD_TOOL_GUID was specified in the DSC file's [Defines] section, the build processes is suspended while the tool specified by the GUID is called after the build process generates a text file containing the VPD PCDs. If the tool returns successfully (an exit code of 0), the build system parses the name of the 'map' file that contains an ordered list of VPD PCDs.
    • There are some PCD values that get set on the command line, in the FDF file, listed in binary INF files or listed in source INF files, so generating the C files is delayed until all PCD values have been finalized.
  4. 4.
    Obtain the FDF filename and obtain the Flash related PCDs from the FDF file. FeatureFlag and FixedAtBuild PCD names which are defined in the DSC file can be used in conditional directives within the FDF file.
  5. 5.
    For each component listed in the DSC file, parse the Module's INF file
    • Create a directed graph list of the EDK II Library Instances that will be used for the EDK II modules.
    • Create the PEI, DXE or SMM DEPEX file
    • Create the Library Instance's AutoGen.c files containing PCD, Guid, Protocol, Ppi and EntryPoint definitions and data structures. PCD values come from command line, FDF file, DSC's INF scoped section, DSC's global PCD sections, default values in the INF file's PCD section, or the DEC file's default values.
    • Create the module's library instance Makefiles
      • Individual modules may require different compilation options, over-riding
        any global definitions.
    • Create the AutoGen.c files containing PCD, Guid, Protocol, Ppi and EntryPoint definitions and data structures.
    • Create any Strings header file required for VFR processing.
      • The VFR file name cannot be same as a C file name in a module directory.
        If so, the same output files will be generated and overwritten.
        (A.vfr --> A.c --> A.obj, A.c --> A.obj)
    • Create the module Makefiles
    Individual modules may require different compilation options, over-riding any global definitions. If an INF file is not listed in the DSC file and is listed in the FDF file, the parsing tools must check if the INF in the FDF file contains PatchableInModule or DynamicEX entries. If the INF lists other PCD access methods (FeatureFlag, FixedAtBuild or Dynamic), and the INF contains files listed in a [Sources] section and does not contain a [Binaries] section, then the build tools must break the build with an appropriate error message.
  6. 6.
    The tools are also responsible for creating binary files containing all DynamicEx PCDs that are listed in the DSC, FDF and Binary INF files (listed in the FDF file). These binaries are automatically placed into the (PEIM and DXE) PCD driver FFS files.
  7. 7.
    If the build option, --ignore-sources is present on the build command-line, none of the source files listed in a [Sources] section will be processed, even if the module is listed in the DSC file and no files (AutoGen.h, AutoGen.c or Makefile) will be generated; the INF must be treated as a Binary only INF file.
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4.3.1 target.txt
4.3.2 tools_def.txt
4.3.2.1 "Best Known Safe" flags
4.3.3 build_rule.txt
4.3.4 Parse EDK II Meta-Data - AutoGen stage
Parse DSC file