how Can i cross-compile QT for RPI with XCB plugin

dziko147

Hello ,
currently I cross compiled a Qt app on RPi3 .
I run it normally using eglfs platform but it misses some things like a title bar , can't move or resize window . (eglfs is full screen .....)

So I read in many documentation that I need :

1- a window manager
2- run the app with -platform xcb or run using wayland .

I am really new in cross compilation and linux .

So this problem seem very hard to me .

I will appreciate any suggestion .
thank you

jsulm

@dziko147 Run "configure". Then check its output: is XCB enabled ot not? If not check config.log file to get exact information why XCB was not anabled and install missing packages (and resync your sysroot).

dziko147

@jsulm run "configure" on my target ?

jsulm

@dziko147 Since you are talking about cross-compiling you call configure on your host machine.
You wrote that you already cross-compiled - so you should know.
Or do you misunderstand what cross-compiling means (because "I cross compiled a Qt app on RPi3" does not make sense).

jsulm

@dziko147 You should read https://wiki.qt.io/Raspberry_Pi_Beginners_Guide

KH-219Design

Here is a script that I used recently to cross-compile Qt4 for rPi.

Note: yes, I said Qt4 (with a 4, not a 5).

However, the procedure would be almost identical for Qt5.

the script: https://github.com/219-design/build_qt4_binaries_armv8/blob/456e211c9d/make_framework_qt-x11-4.4.3_embedded_armv8_rpi.sh

When @jsulm advises you ( @dziko147 ) to run configure, the configure being spoken of would be the configure script that is provided with the Qt source code at the root of a Qt sources directory. Concretely, this maps to configure being called in the above script at line 63 (see here).

The output of configure will produce a summary like so:

Building on:   qws/linux-x86_64-g++
Building for:  qws/linux-arm-g++
Architecture:  arm
Host architecture: x86_64

Build ............... libs
Configuration .......  cross_compile release shared dll embedded largefile stl precompile_header exceptions_off  accessibility minimal-config small-config medium-config large-config full-config embedded reduce_exports ipv6 clock-gettime clock-monotonic mremap getaddrinfo ipv6ifname getifaddrs inotify png gif freetype zlib svg release
Debug ............... no
Qt 3 compatibility .. no
QtDBus module ....... no
QtXmlPatterns module  no
Phonon module ....... no
SVG module .......... yes
WebKit module ....... no
%MNG support ......... plugin (qt)
zlib support ........ yes
Embedded support .... arm
Freetype2 support ... auto (yes)
Graphics (qt) ....... linuxfb multiscreen
Graphics (plugin) ... 
Decorations (qt) .... styled windows default
Decorations (plugin)  
Keyboard driver (qt). tty
Keyboard driver (plugin) 
Mouse driver (qt) ... pc linuxtp
Mouse driver (plugin) 
OpenGL support ...... no
OpenSSL support ..... no

This is where you would check to see if XCB shows as "enabled" or not.

@dziko147 you have said:

I am really new in cross compilation and linux . So this problem seem very hard to me .

Cross compilation is tricky, even for people who are not new to it. By the nature of cross-compilation, there are "more moving parts", because you have the build PC (probably x86_64 architecture) and the target PC (ARM for rpi).

Please be patient, and take one small step at a time.

You will need to ask very specific questions and provide clear and accurate details (what is the OS on the build PC? what version of Qt sources are you building? etc)

To echo @jsulm , I also wonder if the verb "cross-compile" is being misapplied.

You may or may not be confident in your usage of the terminology.

Just in case...
Cross-compilation means that you compile a binary by performing the compilation step on one computer, and then you copy that binary to a different computer (such as an rPi) where the binary is ultimately used.

If you are performing the compilation steps on the rPi, then that is just plain old "compilation". When working with an rPi, it is possible to just perform compilation on the rPi. And it is also possible to cross-compile from a separate x86_64 build PC. Both are feasible. You may choose either. Just double-check you are using the accurate terminology.