Tutorials

Building Qt6 from source

Building Qt6 from source is not easy. There are a couple of common pitfalls, which make the build process a nuisance. Here is how to avoid those pitfalls:

On Ubuntu 21.10 Qt6 requires a variety of additional uncommon dev packages like Clang, XCB and XKB to be installed. If not all of the required dev packages are installed, the QPA GLX plugin will not be built, which prevents Qt applications from opening a window with GLX/OpenGL. It is quite tedious to find out, which packages are missing, so here is the list of the required packages: 

sudo apt-get install g++
sudo apt-get install freeglut3-dev # for OpenGL
sudo apt-get install xorg-dev
sudo apt-get install libx11-xcb-dev
sudo apt-get install libxcb-icccm4-dev 
sudo apt-get install libxcb-shm0-dev 
sudo apt-get install libxcb-render0-dev
sudo apt-get install libxcb-render-util0-dev
sudo apt-get install libxcb-randr0-dev
sudo apt-get install libxcb-image0-dev
sudo apt-get install libxcb-sync-dev
sudo apt-get install libxcb-shape0-dev
sudo apt-get install libxcb-xfixes0-dev
sudo apt-get install libxcb-glx0-dev
sudo apt-get install libxcb-xinput-dev
sudo apt-get install libxcb-keysyms1-dev
sudo apt-get install libxcb-xkb-dev
sudo apt-get install libxkbcommon-x11-dev
sudo apt-get install libclang-11-dev
sudo apt-get install libclang-common-11-dev

We download and unpack Qt6 from:

https://download.qt.io/official_releases/qt/6.1/6.1.3/single/qt-everywhere-src-6.1.3.tar.xz

We configure it with OpenGL support, but we disable certain modules, which are known to cause build errors: 

./configure -opengl -no-pch \
            -skip qtmultimedia -skip qtwebengine -skip qt3d -skip qtquick3d \
            -prefix /usr/local/qt6 -release -nomake examples -nomake tests \
            -opensource -confirm-license

If all required packages were installed properly, the QPA GLX plugin is shown to be enabled in the configuration log: 

  XCB:
    Using system-provided xcb-xinput ..... yes
    GL integrations:
      GLX Plugin ......................... yes
        XCB GLX .......................... yes
      EGL-X11 Plugin ..................... yes

Now we can build and install Qt6 in /usr/local/qt6: 

make -j4
sudo make install

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