[TUTO] Build Qt to cross compile for arm

[Spader42]

Hi there, i didn't know where to post that, so i post it here. For a few days now i've been trying to build Qt from source to cross compile my apps for an arm architecture ( pcduino for me ). I've not find a lot of help online, so as i've finally managed to cross compile my qt projects, i've decided to post online what i've done.

I advice you to create a folder where you'll place everything you'll download below, I created the folder /home/<yourUserName>/installQt/

First : Download qt-sdk

I've used the 4.8.5 verson of Qt ( i've never tried with another version it might not function the same way )
You can download it here : QT 4.8.5
Or use : wget -c http://download.qt.io/archive/qt/4.8/4.8.5/qt-everywhere-opensource-src-4.8.5.tar.gz
Once it's downloaded, extract it.
You can use this to uncompress your tar.gz : tar xzvf qt-everywhere-opensource-src-4.8.5.tar.gz

Second : Download the ARM compiler

You can download it here : ARM Compiler
Or do just like before : wget -c https://launchpadlibrarian.net/155358238/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux.tar.xz
As you did with the Qt archive you can uncompress it with : tar xJf gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux.tar.xz

At this step you're supposed to have two folder in your installQt directory :

• qt-everywhere-opensource-src-4.8.5
• gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux

You can check the compiler by doing /home/<yourUserName>/installQt/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux/bin/arm-linux-gnueabihf-gcc --version

It should print you something like that :

arm-linux-gnueabihf-gcc (crosstool-NG linaro-1.13.1-4.8-2013.10 - Linaro GCC 2013.10) 4.8.2 20131014 (prerelease)
Copyright © 2013 Free Software Foundation, Inc.
Ce logiciel est libre; voir les sources pour les conditions de copie. Il n'y a PAS GARANTIE; ni implicite pour le MARCHANDAGE ou pour un BUT PARTICULIER.

I guess it adapts itself to your PC's langage, you should get something like that but in your langage.

Third : Adapt the qmake.conf file of the qt-sqk you've downloaded

Modify the file /home/<yourUserName>/installQt/qt-everywhere-opensource-src-4.8.5/mksepcs/qws/linux-arm-gnueabi-g++/qmake.conf
You can do it with your favorite text editor, for example : vi /home/<yourUserName>/installQt/qt-everywhere-opensource-src-4.8.5/mksepcs/qws/linux-arm-gnueabi-g++/qmake.conf
The not modified version should looks like this :

######################QMAKE.CONF####################
#
# qmake configuration for building with arm-none-linux-gnueabi-g++
#

include(../../common/linux.conf)
include(../../common/gcc-base-unix.conf)
include(../../common/g++-unix.conf)
include(../../common/qws.conf)

# modifications to g++.conf
QMAKE_CC = arm-none-linux-gnueabihf-gcc
QMAKE_CXX = arm-none-linux-gnueabihf-g++
QMAKE_LINK = arm-none-linux-gnueabihf-g++
QMAKE_LINK_SHLIB = arm-none-inux-gnueabihf-g++

# modifications to linux.conf
QMAKE_AR = arm-linux-gnueabihf-ar cqs
QMAKE_OBJCOPY = arm-linux-gnueabihf-objcopy*
QMAKE_STRIP = arm-linux-gnueabihf-strip*

load(qt_config)
################END_OF_QMAKE.CONF#################

So you have to modify that file so it references to the compiler you've just downloaded.
After you've modified it, it should looks like that :

######################QMAKE.CONF####################
#
# qmake configuration for building with arm-none-linux-gnueabi-g++
#

include(../../common/linux.conf)
include(../../common/gcc-base-unix.conf)
include(../../common/g++-unix.conf)
include(../../common/qws.conf)

# modifications to g++.conf
QMAKE_CC = /home/<yourUserName>/installQt/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux/bin/arm-linux-gnueabihf-gcc
QMAKE_CXX = /home/<yourUserName>/installQt/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux/bin/arm-linux-gnueabihf-g++
QMAKE_LINK = /home/<yourUserName>/installQt/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux/bin/arm-linux-gnueabihf-g++
QMAKE_LINK_SHLIB = /home/<yourUserName>/installQt/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux/bin/arm-linux-gnueabihf-g++

# modifications to linux.conf
QMAKE_AR = /home/<yourUserName>/installQt/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux/bin/arm-linux-gnueabihf-ar cqs
QMAKE_OBJCOPY = /home/<yourUserName>/installQt/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux/bin/arm-linux-gnueabihf-objcopy
QMAKE_STRIP = /home/<yourUserName>/installQt/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux/bin/arm-linux-gnueabihf-strip

load(qt_config)
################END_OF_QMAKE.CONF#################

When it's all done your qmake.conf is adapted and you're ready for the next part

Fourth : Execute the Qt configure

Go to /home/<yourUserName>/qt-everywhere-opensource-src-4.8.5/

Execute this command to install Qt in the /usr/local/Qt-4.8.5-arm/ directory : ./configure -opensource -confirm-license -prefix /usr/local/Qt-4.8.5-arm -embedded arm -little-endian -no-pch -xplatform qws/linux-arm-gnueabi-g++

This might take a little while don't worry that's normal.

Fifth : Execute the make

When the ./configure is done, you just have to execute a make.
It's an operation that can really take a long time, to reduce it you can use all your CPU's cores for the make. To know how many cores you have execute : grep -c ^processor /proc/cpuinfo
Once you'll know how many core your CPU has you can use the option -j<numberOfCore + 1> with the make.

On the machine i've executed the make I had 8 cores, so I used the option -j9 for the make

To execute the make use : make -j<numberOfCore + 1> ARCH=arm CROSS_COMPILE=home/<yourUserName>/installQt/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux/bin/arm-linux-gnueabihf-

Note : The first time i launched the make i had an error about QSharedMemory line 65:5, something like that, if that happens, repete the fourth step : Execute the Qt configure. it should fix it, i've no idea how but it does.

When the make is finished you can run : sudo make install

Sixth : Configuring Qt

In Qtcreator, the basical Qt IDE :

• just select the right qmake, here it's the one in the /usr/local/Qt-4.8.5-arm/bin/ directory
• And select the right compiler which in our case is this one : /home/<yourUserName>/installQt/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux/bin/arm-linux-gnueabihf-g++

Then in the project tab add :

• The argument -spec linux-arm-gnueabi-g++ for the qmake
• And the argument ARCH=arm CROSS_COMPILE=/home/franck/gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_linux/bin/arm-linux-gnueabihf- for the make

At this step, the qmake executes itself correctly, it creates a Makefile, this one is fine and the make executes correctly aswell

Seventh : Compilation in command line

For some reason i had to compile my project in command line, so i put it here just in case someone would have to aswell.

First you have to run the qmake

The command line that shall execute the qmake is : "<PathToTheQMake" '<PathToYour.pro>' -r CONFIG+=debug -spec <Compiler>

So lets imagine i've created a project, let's call it random for exemple the command for my configuration and the project random would be : "/usr/local/Qt-4.8.5-arm/bin/qmake" 'home/<yourUserName>/projetQt/Random/random.pro' CONFIG+=debug -spec linux-arm-gnueabihf-g++

Once the qmake is done, it has create for you a Makefile, so you just have to run : make to obtain your executable.

You can check your executable by doing : file <NameOfExecutable>
It should print you some stuff and somewhere in it you should find ARCH=arm or something like that.

Eighth : Script that does it for you

For the lazy ones i've created a litlle script, that i know can be improved by many ways but that works and is enough for me for now.
Here is a functionnal version just adapt the lines 90 to 96, change the username felix by your's.
GitHub Link

Here is another on that should adapt itself, but that i've not tested yet. As soon as i can confirm it works i'll comfirm it
GitHub Link

[koahnig]

Hi and welcome

thanks for sharing. I think that would still go into the wiki section.

[wowy]

Hello (ou plutôt bonjour ;) )

After QT is configured, installed, everything is configured in QT creator and i make an application.
Can i simply copy/paste it in the bin folder of my embedded device or must i copy first some libraries or others stuff on the device ? I tried your tuto and had no problem (aside from a very slow "make"...). I went in QT creator and created a single QT widget application (a window with a button launching a message box), it built in the release folder. But when trying to run it on my board with a ./nameofthefile (and with chmod 755 it) i have an error "applet not found" which make me think either i am missing things on my board or i needed to add somethign to the configuration.

Still thank you for this help !

[Spader42]

@wowy
Hello

In my case after compiling the app, i copied it on my pcDuino, I didn't have the same problem than you but another one, i've no interface, my application is started ( a tcpclient that connect to a tcpserver over internet ) i receive it's connection on the PC that run the tcp server. But at the launch of the app it prints me two things, the first one libicui18n.so.48 cannot open shared object file no such file or directory and another one releving to DBUS.

EDIT : Those problems don't come from a bad compilation but from the pcDuino itself, don't worry this tuto is functionnal.

I'm sorry i can't help you on that point, and i'll only can get back to work on the pcDuino by monday or tuesday next week to solve these 2 problems.

I only can advice you to google the message the executable prints you.
I've made a quick research online for you, it seems to be some problem with the PATH or with some links, i'm sorry i can't help on that, i'll edit my main post by next week with my solution for the pcDuino problems.

Hope you'll find a solution asap.

Au revoir ;)

[Spader42]

@koahnig Thank you for the fast answer, it's my pleisure to share that little tuto.
By the way should I move it to the wiki section ?

[wowy]

@Spader42
On your arm device, do you have a screen/touch screen and needed to use tslib for it ?

[josegua94]

@Spader42

Hi, I am sorry to bother you, but could you tell me if I could use that cross-compile toolchain and procedure for a BeagleBone Black running Debian?

[josegua94]

I am sorry to bother you guys but I'm trying to follow this tutorial and I get stuck in the next part:

./configure -opensource...

I get the following message: "make: g++: Command not found" AND "make: *** [project.o] Error 127
I am currently working on a ubuntu 64 bits Machine mounted on VirtualBox and my target is a BeagleBone Black running Debian. Take it as if I had no knowledge what so ever because it is practically that way. Any advice that you could give me is greatly appreciated.

Thank you.

[citiustech]

I have follow all the steps...and i am able to create a makefile for arm architecture...but getting error in make...i am working on qt5.5

[jsulm]

@citiustech Hi! What is the error you get?

[citiustech]

do you have any steps for cross compile qt5.5 for arm

[citiustech]

QOpenglwidget file is included in my application..it is build on qt5.5. but giving file error while make using QT4.8 that QOpenGLWidget no such file.

[SGaist]

Hi,

That's because QOpenGLWidget is a new class of Qt 5. Qt 4 has QGLWidget.

[citiustech]

Thank for your valueable reply

[citiustech]

i am trying to build qt5.5 for arm but getting error while build.
i am using ./configue -xplatform inux-arm-gnueabi-g++ command. it gives openssl error. openssl.h no such file?

can you please suggest

[SGaist]

Unless you specified that you want OpenSSL support it should not stop the build. If you want OpenSSL support then you need to provide that dependencies for your target.

[citiustech]

DO you have any Build steps like QT4.8.5 for QT5.5?

[SGaist]

That usually depends partly on the device you are targeting.

[citiustech]

i am cross compiling qt for cubieboard 4.
can you please suggest me ./configure command ?

[SGaist]

I don't know this board but a quick search returns this blog entry which step 4 is likely what you are looking for to get started.