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Differences between EDK and EDK II

Differences between UDK2010 and EDK II

Build questions

Debug FAQ questions

DEC FAQ questions

ECP EFI Compatibility package questions

Execution order FAQ questions

GUID FAQ questions

NT32 questions

PCD questions

Shell questions

Virtualization FAQ questions

UEFI application questions

UEFI Drivers questions

USB stack questions

Table of Contents

Is an a priori file checked first?


Is DXE single threaded now as PEI is?

Yes, could be multithreaded but the current EDK II implementation is single threaded. However, It is possible to use the MP Services Protocol in the DXE Phase to execute code on more than one processor. The MP Services Protocol is typically used by the CPU initialization code to propagate settings to all logical processors in the platform. The UEFI/PI services, Protocols, and PPIs are not designed with threading in mind. As a result, even though the MP Services Protocol provides a capability to run code on another logical processor, the code that is executed must be very carefully designed to not use any of the UEFI Boot Services, UEFI Runtime Services, or Protocols services that are not explicitly documented to be MP safe. In addition, there are many library services that make use of underlying UEFI Boot Services, UEFI Runtime Services, or Protocols, so many of the library services cannot be used from code running on a logical processor other than the BSP.

Is SMI handled by BIOS or OS BIOS?

The OS does not see SMI.

Is there a type Intel Development Environment IDE or are there Visual Studio solution files?

There was a VS .sol for EDK 1, no plan for EDK II.

What specifies flash organization?

The flash layout is defined in the .FDF file for the platform

Why does EDK II use library classes? Are there different instances?

EDK II’s implementation uses library classes as a way of tying different implementations to the same library name. This will resolve reference and make it so the Firmware developer can map the implementations at different sections of the Boot sequence. This is done because the implementation may differ for PEI vs DXE or DXE vs Runtime, etc.

The primary benefit is that code can be highly portable and reusable between different phases. For example, code written originally for DXE can be rebuilt in PEI without requiring modification. There are limitations, but there are far fewer differences visible to a programmer if libraries are used properly.

Is there an example of VFR?

Yes, there is an example in EDKII in MdeModulePkg\Universal\DriverSampleDxe. The sample Vfr.vfr describes a sample forms, check boxes, action buttons, and etc. that can be drawn in HII

When Recovery runs what part of the firmware gets updated on the UEFI target system?

Recovery is invoked during PEI phase and it will look for an image on some media, typically USB thumb drive for the file whose name is defined in the .fdf file.”. The .fdf file defines the flash layout and each platform gets to define what parts of the FLASH device are updatable or not. For example, the recovery code will update the main part of the flash device for what might be defined as “FVMAIN” in the .Fdf file with this image. The other sections of the flash device would remain intact.

What do the Version numbers mean for Package and platforms in the build description files for EDK II?

A package is identified by a combination of the PACKAGE_GUID and PACKAGE_VERSION. Every time a new version of a package is released, the PACKAGE_VERSION must be set to a higher value. The package owner gets to decide when the major or minor parts of the version value are increased. If a non backward compatible change is made to a package, then a new PACKAGE_GUID must be generated, and the PACKAGE_VERSION values can be restarted with a low value determined by the package owner.

What does EDK II Flash mapping tool do?

The flash mapping tool will get platform, flash and module information from target.txt,platform.dsc, flashmap.fdf, package.dec and module.inf. it will generate Ffs, Fv, FD and Section data depending on command line options. The tool will generate a FV directory which includes a FFS directory, Fv file, Fv INf file and Fd file. The FFS directory contents all modules directory which contents Ffs files and section files. All output of Flash tool output will be in FV directory.

How do I convert non-EFI oproms or Legacy ROM to UEFI oproms?

There are no tools to convert a Legacy Option ROM in source/binary form to a UEFI Driver. There is no such thing as a “UEFI oprom”. There are PCI Option ROMs, and the PCI Specification defines the binary layout of a PCI Option ROM that may contains multiple images. These can be Legacy Option ROM images, UEFI Drivers, and many other image types. The EfiRom utility simply follows the PCI Specification for the binary layout of PCI Option ROMs and provides the ability to put multiple images into a single PCI Option ROM. The image types supported by the tool are Legacy Option ROM images and UEFI Drivers.

What about the libraries with EDK II?

EDK II makes use of libraries to allow different implementations for the same functionality. EDKII introduces the concept of Library Class/Library Instance. Library class is a set of standard interfaces for common support routines, and library instance supplies the implementation of these interfaces. Platform integrator can select different implementations upon various application scenarios.

Does EDK II support ASL code?

EDK II has full support for ASL compilers from Microsoft and ACPICA. The EDK II has include files for ACPI Specifications up through ACPI 4.0. These include files are in /MdePkg/Include/IndustryStandard/Acpi.*. The UDK 2010 supports a number of reference platforms including Lakeport, Stoutland, and Richford. All of these platforms have source modules for the ACPI Tables and ASL code required for these platforms to boot ACPI complaint operation systems.

Does EDK II address Legacy USB?

No, BIOS vendors provide that

What does the library code call?

Library functions are either full implementations of the library function with no additional calls, or a library function may call other library functions or services. It is up to the library implementation to decide if it needs to call another library or service or not.

What is recommended for compiling drivers and applications with 64bit?

Since the build requires the use of at least one .DSC file the OVMF package could be used as a platform package to insert a driver or applications for building. Then to just build that driver or platform if you invoke the build in the directory where your driver or application resides, then just your driver or application gets built.

Add the path to your Drivers and Applications INF files to your DSC file in the [Components.X64] section. When the build is started for that DSC file, the newly added Drivers and Applications will be built for X64 and the generated .EFI files will be placed in the build output directory. If you want the Drivers and Application placed in a FLASH/ROM image, then the paths to the INF files will also have to be added to your FDF file.

For Lib classes (E.G. debuglib) how do you know which packages go with which library class?

Search INF Libclass = . . .

In the FDF what is the list of order for final image?

Typically the order listed is order of appearance

How do you create additional FDF segments?

The FDF Spec should have information on specifying in the FDF for a platform. See EDK II Specifications

Any formal forum?

Yes, Join the Sourceforge and sign up for the developer for EDK II. http://sourceforge.net/apps/mediawiki/tianocore/index.php?title=Mailing_Lists and subscribe to the mailing lists.

What happens when there is no more temporary RAM?

Running out of temp RAM could cause problems

The results are not predictable. Temporary RAM is used for both the Stack and for storing HOBs. These two regions grow towards each other. If they overlap, then the most likely scenario is that the Stack will corrupt HOBs, and on a build with DEBUG() and ASSERT() messages enabled the next time the HOB list is accessed, an ASSERT() will fire.

What is the Macro CPU breakpoint?

CPU breakpoint –comes in as code to cause the processor to halt at that point.

The EDK II does not have a macro to generate a software breakpoint. Instead, the BaseLib in the MdePkg has a function called CpuBreakpoint(). When this function is called a SW breakpoint is generated. On IA32/X64 platforms, this is an INT 3.

Can we use the same serial port for FW debug sessions and for an OS channel session?

No. You can’t use same serial port for Firmware debug session & os channel session

Is there a prescribed method for adding an embedded legacy option ROM to be loaded for legacy boot?

The code to support this is part of the file PciPlatform.c found in the platformX example in the directory: R8platformX Pkg\Platform\IntelXpg\platformX\PciPlatform\Dxe

Basically, the Option ROM is included in the table (mPciOptionRomTable) where each embedded ROM is defined by: File Guid, and PCI Vendor and Device ID.

In the Procedure:

 GetPciRom (
  IN  EFI_HANDLE                        PciHandle,
  OUT VOID                              **RomImage,
  OUT UINTN                             *RomSize

A found device is checked against the table, and if there is an Option Rom available, a pointer to the Rom image is provided for load.

Is there documentation or a guide on the IA32FamilyCpuPkg as far as what needs to be done for the different processor support?

There is not a lot of document but the one to modify the most is the CpuMpDxe driver

Is there any other Native EDK II platform available?


Is there any porting guide available?

There is training material that has a high level list of the porting the different phases but there is no EDK I to EDK II porting guide.

How does the Intel® BLDK interact / interface with EDK II?

Intel® BLDK has EDKII within it. The biggest technical difference between Intel® BLDK and EDK II are that some of the options in the Intel® BLDK are routed to the VPD area of the platform which further enables binary editing. Some of the same options are also part of EDK II in that they are extracted by the PCDs but where they are stored may be different.

Is there a template for the BSF file but there is not a way to create one from scratch?

No, most take old BSF and then port it to a new platform. There isn’t a tool in existence to do one from scratch.

What is the biggest difference in the Intel ® BLDK vs. EDK II?

The biggest difference has to do with binary editing ability. Also reduced functionally (e.g. Intel® BLDK will not have CSM support )

What does “EFI API” mean and why?

A) It is used for function prototypes and declaration. It is for the source style for EDK II.It means that this function follows the calling convention as described by chapter 2 of the UEFI spec. Calling convention described for IA32, X64, IPF, and ARM. This forces the compiler to follow that exact calling convention for Boot services, Runtime services, also for Protocols and PPIs need to have EFI API. Internal worker functions do not need the EFI API.

B) MSFT vs UEFI calling conventions are similar so they would work.

Why do we have to put GUIDs and PPI, Libraries have to be under the /Include directory.

There is no assumption from the build tools on where things are located but for design and consistency there is a coding style of putting them under the /Include directory.

Can a Package have multiple token spaces? And can they be shared across multiple packages? For instance is it possible to have 5 tokens in 1 package and 5 in another?

a) Yes, packages can have multiple token spaces. b) Because token space is a GUID with a name, and also a token (32 bit ) associated with it. It is assumed to only be part of one package. We would want to avoid splitting tokens across multiple packages because of coordination issues.

What are the different Packages in EDK II and what are their inner dependences. Can you give a brief description of the packages?

There it is supposed to be DEC has file header that has a description about the package and what the package is. We do Doxygen for DEC which will create a CHM and a description of the package. Inf has the description of modules and what each module does (what it consumes what it produces) EDK II may not have all the documentation and descriptions may be lacking. The plan is to improve over this over time.

Is there an example for read memory and or Memory mapped IO functions? Are there 2 separate calls for 32 and 64 bit?

There is an IO Library that supports both port IO and memory mapped IO and you give the exact size that you want to do the access (e.g. 8 bit, 16 bit, 32, etc). There are also a number of helper functions (ORing, masking,..) There is also a PCI library for doing PCI access.

Is there any EDK I code in the EDK II firmware?

No, There can be EDK I with the Edk Compatibility Package( ECP). EDK II can have EDK I if the ECP is used. ECP allows the building of EDK II with EDK I modules in the EDK II build base. ECP allows for EDK I to be brought up to the Latest UEFI Specs 2.3 and PI 1.2 . ECP does the translations from specs.

What is the meaning of the different status EFI Status vs other Status code?

EFI Status is related to the UEFI Spec “EFI Services” which is part of the DXE phase of the boot flow. One of the goals with the libraries was that there is a specific class of libraries that has a module type is “Base”. What is meant by “Base” is that library is compatible everywhere (SEC, PEI, DXE, SMM, etc.).To do this it cannot make any EFI assumptions so a subset of the EFI status codes was chosen for “return Status”.

Is there a doc template for listing dependencies?

Yes, – put this in the Module .INF dependences

Is there a good example of .Inf.?


Is there a good example in the mde pkg?


What is there in EDK II relating to the FV and COU microcode patch?

Not a way to just change the patch. It has to be part of the build. There is nothing to patch the .FD location. It needs to update the .fdf file. There has been a request for a tool to do this.

Is there a tool that can operate on a binary image?

The only type of information that can be patched in a binary image is of type PCD VPD (vital product data) that go into an uncompressed section of the binary/ROM image as defined in the .FDF file. Post Build. The only other type is Patch able in module that allows you to adjust values within a PECOF image within a PEIM or DXE driver. During build

Is the Dispatch order of modules recorded?

The report status code is the correct method. But this is not in place for the a priori files. To work around this, just put minimum to get the report status code available and working.

 -The order will be with the DXE dispatcher. The order of the protocols will be the same as by using “dh” from the shell
 -This is not available with PEI.
 Suggestion is adding the dispatch order to the end of the Pei and Dxe. It reports status of the exact order

Since a lot of boards no longer have a serial port can AMT be used for console redirection port?

This is possible but since AMT shows up as PCI device there are issues with serial on PCI because it can init early but the resources might not be the same when the PCI Bus driver enumerates so this method may lose connections.

How do you assign resource?

We are currently working on another library for covering a generic PCI device to manage the redirection port this.

What are the Core version to match which spec versions of EDK(s)?

EDK II is at the spec level: UEFI 2.3 / PI 1.2 Spec implementation – EDK II builds can use: EDK Compatibility Package (ECP) – with EDK 1117 (EDK 1.01) that are at the spec level: UEFI 2.0 and Intel Framework 0.9

How do I burn a CD that is bootable (IA32.ISO)?

The easiest way to make a fedora uefi cdrom/dvdrom is to use their boot.iso install image. It is buried on their site though Simply burn the boot.iso to a cdrom or dvdrom and boot from your uefi system (in the boot manager select EFI DVDROM/CDROM boot)

The following location is present on all mirrors (IE at univ of Oregon) boot.iso Should also see the efidisk.img and efiboot.img in the same directory. http://mirror.uoregon.edu/fedora/linux/development/14/x86_64/os/images/



so your favorite mirror /fedora/linux/development/14/x86_64/os/images then look for boot.iso and burn it with your burner software. If you want to make a usb stick fedora EFI bootable or want to do a netboot install see below. Minimal boot image method from fedora 14 docs.

http://docs.fedoraproject.org/en-US/Fedora/14/html/Installation_Guide/Making_Minimal_Boot_Media.html On the web there are 3 methods to install UEFI x64 fedora 14 to usb sticks:


For Ubuntu goto their cdimage to get the .iso images http://cdimage.ubuntu.com/

desktop would be maverick release


ubuntu-10.04-dvd-amd64.iso 29-Apr-2010 15:28 4.1G Install/live DVD for 64-bit PC (AMD64) computers (standard download)