< Windows‎ | Build
Revision as of 10:04, 21 February 2016 by Tfry (talk | contribs) (Assorted updates, "note" markup, shortening and re-sorting, where appropriate.)


emerge is a tool to build the KDE sources and its third-party requirements on MS Windows. It is the easy way to build KDE on MS Windows.

Setting up emerge

Root directory

Create a directory if possible in your harddrive's root e.g. C:\kderoot or D:\kderoot (You will need this PATH later). This directory will contain the whole kde installation later. We will refer to it as KDEROOT.

It is a good idea to keep this path as short as possible, e.g. just "C:\K", as too long paths may cause trouble while building some complex packages.

Be sure that you neither have the msys/bin nor the cygwin/bin in your path. If so you have to definitely remove it from the path. The applications gimp, inkscape and graphviz have also been reported to be a problem when in the %PATH%.

Python interpreter

The emerge tool is written in Python, so you first need to install the Python 3.5 Interpreter. The python installation directory will be added to the PATH later by KDEROOT\etc\kdesettings.ini. Some packages also need Python 2.7.

Git client

To fetch the actual emerge tool, you need a git client for the initial checkout. A git-scm.com command line client is good enough, however GUI programs like TortoiseGit are also available.

This git client is essentially just needed for the initial installation. Later, emerge will use its own git client for checking out all KDE source code. You can find it in KDEROOT\dev-utils\git\bin. It will be used by emerge even if you have another git executable installed.

Getting the emerge tool

Get the emerge tool via git with the following commands:

  • if you will only use anonymous (read-only) access to the KDE git repository:
    git clone git://anongit.kde.org/emerge.git
  • if the git and ssh ports are blocked, and only http is allowed, it is better to clone over the http port for getting (read-only) access to the KDE git repository:
    git clone http://anongit.kde.org/emerge.git
  • or, if you plan to use write access (commit) to the emerge repository using your existing account & OpenSSH private key:
    git clone [email protected]:emerge.git

Configure the emerge tool

  1. Create the directory KDEROOT\etc.
  2. Copy the file KDEROOT\emerge\kdesettings.ini as KDEROOT\etc\kdesettings.ini and change its contents according to your needs.

It is a good idea to read through all comments in that file, carefully. What you will definitely have to configure, is the path to Python.

[Optional, Advanced] emerge-boost-config.jam

Add a file emerge-boost-config.jam in the %KDEROOT%\etc directory to build boost in a specific way. The only current use case is for the following problem: If you build 32bit binaries with emerge on a 64bit system you need to link boost-python against a 32bit python library. In case your standard python installation is 64bit though, you can specify the python installation in the following way:

# ---------------------
# Python configuration.
# ---------------------

# Configure specific Python version.
using python : 3.2 : C:\\Python32_x86 ;

This way boost-python would be using the headers & libraries from C:\\Python32_x86 instead of the default one. Please remember that for mingw compilers you must regenerate the import library for the python dll (also for the mingw 64bit compiler):

R:\> emerge pexports
R:\> pexports C:\Python32_x86\python32.dll > C:\Python32_x86\libs\python32.def

NOTE: In case you generate the import library for the 64bit compiler, add the following line to the file python32.def:

Py_InitModule4 = Py_InitModule4_64

For both compilers you should now run:

dlltool -d C:\Python32_x86\libs\python32.def -l C:\Python32_x86\libs\libpython32.dll.a

Now you should be able to do emerge -i boost-python-src without errors.

Setting up a compiler

Currently emerge supports both the MinGW and MS Visual C++ (msvc) compilers. We did not add dependencies for the compilers, so you have to make sure to install a compiler by yourself. There are three ways to set up a compiler for emerge. We assumed you have set KDECOMPILER variable properly in the KDEROOT\etc\kdesettings.ini.

In the following sections you can find information on how to install or reuse an existing compiler.

Install the MinGW compiler with emerge

Let emerge install the MinGW compiler, as soon as emerge needs MinGW it will automatically fetch the correct version for you.

Install MS Visual C++

Read here.

Point to an existing MS Visual C++ installation

You need to point emerge to an existing msvc installation. This is run automatically for you from kdeenv.bat if configured properly in kdesettings.ini. Check your kdesettings.ini file to know where to set it.

Fine Tuning

For Fine Tuning see here: Fine-tuning

Using emerge

To use emerge you need to start a Powershell window and point that to KDEROOT\emerge. For example:

cd KDEROOT\emerge

Then in the windows powershell you have to load the script with

". .\kdeenv.ps1"

This tells emerge about your environment settings (e.g. paths). It will load your configuration from KDEROOT\etc\kdesettings.ini. It should not give any error messages, otherwise emerge will not work as expected. The output should look similar to this one (of course with your paths):

PS C:\kderoot\emerge>.\kdeenv.ps1
KDEROOT     : r:\
KDECOMPILER : mingw-w64
PYTHONPATH  : C:\python34

PS C:\kderoot\emerge>

Note: There is a short path option in kdesettings which you will need if you want to build Qt in a directory that has a pathlength of more then around 5 characters. This problem is due to limitations of the command line length and the Qt build system.

Next, if you have configured your kdesettings.ini to use svn+ssh for your subversion checkout, then you need to run:

plink <your-svn-username>@svn.kde.org
plink <your-kde-username>@git.kde.org

This will prompt you to accept the fingerprint of the server, otherwise svn will hang forever when trying to download from the server.

Now you should be able to use emerge. To get some help on usage:

emerge --help

To get a list of available packages:

emerge --print-installable

To get a list of currently installed packages:

emerge --print-installed

Installing the base system

Once you have emerge and a compiler installed and working, try:

You are now ready to start building KDE, it is recommended to do so progressively, relying on emerge to automatically resolve the required dependencies at each set step:

  • Enter emerge qt. This will fetch and install Windows versions of numerous UNIX-like utilities and libraries, then checkout, compile and install Qt. This will take several hours.
  • Enter emerge frameworks. This will checkout, compile and install the kde frameworks 5 modules.

You will now have successfully installed a base KDE system and can now install other KDE modules as required.

Note that this will install the development version of KDE (master in most git repositories), if you wish to install a particular stable branch then you should change the branch of emerge to the specific branch of that release. NOTE: You should not mix kde packages from different branches.

It is strongly recommended you do not choose to manually install any of the utilities and libraries yourself, as you may install the wrong version and cause installation failures. Instead allow emerge to resolve the dependencies for you.

Every time you want to update or install a package, you should first update your emerge checkout (simply run emerge --update emerge) to ensure you are using the latest package recipies.

emerge command line options and settings

There are some options that can be used when building with emerge.

Command line switch Command line argument Description
-v EMERGE_VERBOSE This option sets the verbosity level. Currently the highest verbosity level is 3 (-v -v -v). A verbosity level of 0 should give no output and equals to -q. You can set EMERGE_VERBOSE=3 instead in the environment of the commandline or within your kdesettings.ini file.
--offline This option suppresses the update step of the local tree - which needs some time. Be aware though that you have to have existing sources already if you want to use this option.
-t EMERGE_BUILDTESTS This option enables or disables KDE4 buildtests for KDE modules. Other packages will not change. Use EMERGE_BUILDTESTS=True or =False.
--print-targets This option will display all "targets" a certain package has. Normally targets are fixed releases or different branches. They are defined in the portage file.
--target=TARGET This sets a specific target for this package. If not added, the default target is used, which can be checked by looking at the output of --print-targets.
-i This option ignores that a package is already installed. It builds it completely new, but keeps the dependencies.
--update This option ignores that a package is already installed but doesn't cleanup an already existing build directory. Thus you will only rebuild files that have changed since the last build.

Updating packages

  • Once you have packagename built, type
    emerge --update packagename
    to update packagename from the Subversion and compile it without removing the build dir or
    emerge --update-all
    to update all packages that can be rebuild (they are rebuild with --update).

Building a specific version of KDE

emerge has several branches which contain specific package versions. E.g. if you want to build the 4.13 branch of KDE (or one of the 4.13 releases) you should checkout the kde-4.13 branch of emerge; in the master branch, you can find the KDE Frameweorks 5. At the moment, only the master branch is actively maintained, so you will likely experience problems (outdated package urls etc.) on the other branches.

To view all branches, use the following command:
git branch -a

To change the branch of emerge, do the following:

cd emerge && git checkout kde-4.13


Vista issues

  • jstaniek 12:02, 15 January 2008 (CET): UAC has infamous heuristics that make programs like patch.exe treat as installers and try to run them with admin rights (!). This heuristics can be tricked by renaming patch.exe to something like pch.exe (example) but we did not want to add item to our infrastructure. Instead it is possibleto turn off the heuristics (see the screenshot here in the security blog calling the heuristics 'severe hole in the design of UAC'). If you happen to disable the UAC, as many annoyed users and devs do (msvc demands admin rights anyway!), patch.exe should already work for you as in older Windows. Alternatively you may want to disable UAC for admins only, but this makes no sense if you are the only user of your machine and use only the admin account.
  • This wiki page lists instructions on how to use program manifest to disable privilege elevation for a single binary and makes patch play nice with UAC. This should eventually be integrated to emerge scripts.

Windows 10 specifics

  • To allow scripts such as kdeenv.ps1 to run, you may need to set execution policy for scripts to unrestricted. Of course, this means you should know what you're doing when you run scripts etc. The way to do this is to first get a powershell as administrator:

PS> Start-Process powershell -Verb runAs

Then, once you get an administrative powershell, run:

Set-ExecutionPolicy Unrestricted

This should let scripts run

  • To allow .exe files that are downloaded by emerge to run, you need to have permissions. Otherwise, emerge will give you an "Access denied" error and quit. The details of which program failed can be found by running emerge --verbose <packagename>.

There's got to be a better, global way to fix this issue just like in the above case, but a work-around is to go to the containing folder in Windows Explorer, Right click on the .exe file, click properties, go to the permissions tab, say "edit" permissions, and set it to Read & Execute "Allow" for everyone.

The author of this blurb had to do this for the following programs: wget (wget.exe) 7zip (7za.exe)

Technical background

What emerge does

Emerge can be thought of as performing many of the functions of automated tools like cmake, but in a flexible Python scripting framework. The benefit of this is that new libraries with idiosyncratic installation procedures, conflicting library and header installation names, and complex rules for building on different setups can be generated automatically, and all directory management should be taken care of without the user's input.

The primary logic for the program is contained in the /bin folder of the Git repository. The script emerge.py serves as the entry point to the system; it runs appropriate code according to the command line arguments. The basic command emerge packageName performs the five most important actions --fetch, --unpack, --compile, --install, and --qmerge. The definition for each of these steps is defined using a flexible system called Portage, after the Gentoo package management system. The basic goals are:

1. Fetch action retrieves either a binary or the source code for the package.

2. Unpack action installs the source code in a source folder and applies KDE-specific patches.

3. Compile action runs package-dependent configure make steps.

4. Install action installs the headers and compiled library and executable outputs.

5. Qmerge action does something, but what?

Emerge also offers functionality to document dependency trees, create patches to upload tweaks and fixes, and update and clean existing installs.

The actual commands for fetching, unpacking etc. are defined by three increasingly specialized levels of logic. The first level is the code in the /bin folder and determines the overall order, steps should be taken, reading environment variables to configure the build environment and compiler set by kdeenv.bat, and parsing the directory tree.

The second set of logic is found in the /bin/BuildSystem, /bin/Package, /bin/Packager, and /bin/Source folders. This is used to determine general procedures for different classes of packages. For example, the "Source" folder contains the logic for running the --fetch step for compressed files, git repositories, SVN, and so on. The "Package" system contains logic for libraries that need to be configured with e.g. CMake, QMake, or internal make systems.

The final set of logic is at the per-package level. This is what is contained in the /portage/ directory. Emerge is able to automatically search through the Portage folders to find the name of the package you specify. This is where dependencies, special build configurations and special commands are set up. Individual patch files and different version configuration information is also stored here. It is relatively straightforward to add a new package to Portage, especially if the package itself can be downloaded and installed with CMake using minimal configuration.

A good way to prepare a package for wider distribution is to create a simple CMakeLists.txt it. You can format the addition of this file as a patch, and create a Portage script which merges the patch into the public code repository.


Emerge is a tool that can build the different parts of KDE and its dependencies under Windows. We created this tool to automate and simplify the build process under Windows. We try to build all packages that we offer in the KDE installer with emerge. That has some advantages for us:

Easy for people to join us

Before emerge it was quite some work to set a system up for development. There were some quirks, which were documented in some mailing lists, but you had to remember them or you ran into an already solved problem again, etc. Now to get a development machine you need a Windows computer, need to install Python and Git and do the emerge checkout. Then execute emerge to build what you want to build. This is easy for developers coming from Windows to KDE, and also for KDE developers coming to Windows.

Easy for us to do build

With emerge you can build the whole software stack (low-level libs, Qt, kdelibs, things above that) with only one command. You can start that build, and some hours later you can check if it worked, or if something broke. So we can spot problems easier and earlier. We can also start with a "naked" Windows computer without any other installed software and bootstrap kde on it. That ensures, that no hidden dependencies on some pieces of software sneak in, because then the builds on a "naked" computer would break and show the problem.

Easy to collaborate

We can test the same emerge build description for a package on different Windows versions/computers before we do binary releases. People can also add build descriptions for new packages to the Subversion repository.

This emerge tool was inspired by the Gentoo emerge tool.

This page was last edited on 18 March 2016, at 14:58. Content is available under Creative Commons License SA 4.0 unless otherwise noted.