Differences between EDK and EDK II

Note: The original EFI Development Kit (EDK) is no longer supported. This document is maintained for historical purposes. Please use EDK II for current UEFI development.

Table of Contents What are the differences between EDK and EDK II? Are there similarities between EDK and EDK II? How can you find out what has changed between releases? In the past there were Libraries associated with PPI

What are the differences between EDK and EDK II?

The main differences are in build architecture. The build description files (.dsc .inf, etc) have been enhanced. The EDK II build can understand EDK build description files, so an EDK II build can include EDK source code (with limitations). There are also build tool differences: EDK II supports a larger number of operating systems and tool chains.

EDK II has richer libraries (MDELIB, etc.), which makes the source code structure very different. EDK II also uses a package concept, so that the directory and file layout is different.

EDK II uses Platform Configuration Database (PCD) for parameterization and binary patch support, and supports. newer UEFI/PI specifications (see table below for more info).

EDK II provides compatibility with EDK-style source code using EdkCompatiblityPkg (ECP). However, ECP support is being deprecated in current platforms. This is possible because ECP provides binary compatibility for EDK through libraies and thunk code.

EDK II is also designed to work with Doxygen to generate design level specifications.

In addition, since EDK II supports later versions of the UEFI and PI Specifications, there are newer protocols that will be part of EDK II that do not exist in EDK.

Are there similarities between EDK and EDK II?

The Platform Initialization boot execution phases are similar. EDK and EDK II have a similar boot (SEC-PEI-DXE-TSL) and runtime flow. Protocol interfaces supported in both EDK and EDK II will be the same. EDK II can include EDK source code though the use of ECP.

The following table is a side by side comparison.

	EDK	EDK II
Development OS	WinXP	WinXP/7/8/8.1/10, Linux, OS/X
Compiler/Linker	VS2003, VS2005, WinDDK	VS2003, VS2005, VS2008, VS2010, VS2013, VS2015, WinDDK, Intel, GCC4, GCC5, LLVM/CLANG
Build	nmake	nmake, gmake
Build Tools	C	POSIX C, Python
Target Platforms (open source)	NT32, DUET,	See EDK II Platforms
Distribution	ZIP Files – Entire Tree Packages with XML metadata	Packages Standard module distribution method (source/binary) XML – Allows packages/modules to be imported/exported to many build systems EDK Compatibility Package – Provides reuse of EDK source modules
Standards (UEFI)	EFI 1.10, UEFI 2.0, UEFI 2.1, Intel Framework, PI 1.0	Focus on UEFI 2.3+/PI 1.2+ Spec Updates. Includes Support for EFI 1.10, UEFI 2.0+, PI 1.0+ & Intel Framework. See UDK2018 & EDK II for info on specific releases.
Library	binary .Lib files	Library Classes/Library Instances Maximize reuse of source code Use library instances to optimize for size or speed
Configuration Method	#define	Platform Configuration Database Maximize reuse of source code Allows platform developer/integrator to modify settings without modifying module sources

How can you find out what has changed between releases?

The release notes will have a general summary of features and fixes for EDK II changes. See EDK II for the latest stable release and release notes.

In the past there were Libraries associated with PPI

EDK II does not use that model.