XCB QPA backend missing when configuring Qt

Bodo

Hi,

I'm currently trying to build Qt on a Nvidia Jetson AGX. Ready for use together with GStreamer.
When building the GStreamer plugins it told me that X11Extras are missing.

While investigating into this I stumbles across some other information in the dev forum but without a clear answer or hint to my problem.

But something is curious when I configure Qt -> there is no XCB QPA backend which is in my opinion the cause for the missing x11extras.

I'm using qt-everywhere-src-5.13.0.

My configure call:

./configure -prefix /opt/Qt5.13 -nomake examples -v

Relevant configure output:

Features used by QPA backends:
  evdev .................................. yes
  libinput ............................... no
  INTEGRITY HID .......................... no
  mtdev .................................. no
  tslib .................................. no
  xkbcommon .............................. no
  X11 specific:
    XLib ................................. yes
    XCB Xlib ............................. yes
    EGL on X11 ........................... yes
QPA backends:
  DirectFB ............................... no
  EGLFS .................................. yes
  EGLFS details:
    EGLFS OpenWFD ........................ no
    EGLFS i.Mx6 .......................... no
    EGLFS i.Mx6 Wayland .................. no
    EGLFS RCAR ........................... no
    EGLFS EGLDevice ...................... yes
    EGLFS GBM ............................ no
    EGLFS VSP2 ........................... no
    EGLFS Mali ........................... no
    EGLFS Raspberry Pi ................... no
    EGLFS X11 ............................ yes
  LinuxFB ................................ yes
  VNC .................................... yes
  Mir client ............................. no

The system should be an Ubuntu 18.04 and X11 is running. Is there a certain lib missing in order to have this qpa appearing or something like this?

Thanks,
Bodo

SGaist

Hi,

From the looks of it, you are missing the xkbcommon development package.

Bodo

@sgaist

Thanks, but this was already installed.

I now took another route. Instead of using the Qt from the tarball I cloned the 5.13.1 from the git repo and basically followed these steps: https://wiki.qt.io/Building_Qt_5_from_Git

When running configure I now see this:

Features used by QPA backends:
  evdev .................................. yes
  libinput ............................... yes
  INTEGRITY HID .......................... no
  mtdev .................................. yes
  tslib .................................. no
  xkbcommon .............................. yes
  X11 specific:
    XLib ................................. yes
    XCB Xlib ............................. yes
    EGL on X11 ........................... yes
QPA backends:
  DirectFB ............................... no
  EGLFS .................................. yes
  EGLFS details:
    EGLFS OpenWFD ........................ no
    EGLFS i.Mx6 .......................... no
    EGLFS i.Mx6 Wayland .................. no
    EGLFS RCAR ........................... no
    EGLFS EGLDevice ...................... yes
    EGLFS GBM ............................ yes
    EGLFS VSP2 ........................... no
    EGLFS Mali ........................... no
    EGLFS Raspberry Pi ................... no
    EGLFS X11 ............................ yes
  LinuxFB ................................ yes
  VNC .................................... yes
  Mir client ............................. no
  XCB:
    Using system-provided XCB libraries .. yes
    XCB XKB .............................. yes
    XCB XInput ........................... yes
    Native painting (experimental) ....... yes
    GL integrations:
      GLX Plugin ......................... yes
        XCB GLX .......................... yes
      EGL-X11 Plugin ..................... yes

.. which is looking way better and I can run my test app now.
Don't know what's the difference between the codebases..

Best,
Bodo

SGaist

Just a wild guess: you installed libxkbcommon-dev after running configure. You then called configure again but without cleaning up first. Hence the test wasn't run again.