Raspberry Pi Beginners Guide

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h1. Beginner's guide to cross-compile Qt5 on RaspberryPi

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Introduction

This is a step by step guide to help beginners to: cross-compile QT5 for RaspberryPi(wheezy), create, deploy and run an example project. This article will focus on simplicity, so if you are looking for additional customization, please check a more "detailed guide":http://wiki.qt.io/RaspberryPi.

For an easy install, try "this script.":https://gist.github.com/raw/3488286/d1d301946297be999d96df632a0ad0095a4d77e7/bakeqtpi.bash
Or get a later version "here":http://gitorious.org/bakeqtpi
For help, run

$ ./bakeqtpi.bash —help

Getting Started

First we create a folder to hold the source code and all the required files to do the cross-compilation. We chose to create a directory named "opt" in the home folder:
paulo
westeros:$ mkdir/opt
paulowesteros:$ cd/opt

Now, download the following files:
* Raspbian Wheezy image from ("here":http://www.raspberrypi.org/downloads):
paulo
westeros:/opt$ wget http://downloads.raspberrypi.org/raspbian_latest/ -O wheezy-raspbian-latest.zip
paulowesteros:
/opt$ unzip wheezy-raspbian-latest.zip
And mount it:
paulo
westeros:/opt$ sudo mkdir /mnt/rasp-pi-rootfs
paulowesteros:
/opt$ sudo mount -o loop,offset=62914560 2015-02-16-raspbian-wheezy.img /mnt/rasp-pi-rootfs

It is a 32-bit build so if you are running on a 64-bit machine (you probably are) you need to install ia32-libs:
paulo
westeros:/opt$ sudo apt-get install ia32-libs
* Clone the cross-compile-tools repository:
paulowesteros:
/opt$ git clone git://gitorious.org/cross-compile-tools/cross-compile-tools.git

  • Clone and init the Qt5 repository:
    paulo
    westeros:/opt$ git clone git://gitorious.org/qt/qt5.git
    paulowesteros:
    /opt$ cd qt5
    paulo
    westeros:/opt/qt5$ ./init-repository

    If you're behind a firewall ./init-repository might fail. First run this command:
    paulowesteros:/opt/qt5$ sed i 's/git:/https:git./' .gitmodules
    Then retry:
    paulo
    westeros:/opt/qt5$ ./init-repository -f


* Finally, apply a patch on the qtjsbackend repository:
paulowseteros:/opt/qt5$ cd /opt/qt5/qtjsbackend
paulo
wseteros:/opt/qt5/qtjsbackend$ git fetch https://codereview.qt.io/p/qt/qtjsbackend refs/changes/56/27256/4 && git cherry-pick FETCH_HEAD

h2. Compiling qtbase
Now the we have all the resources needed to compile qt5 for raspberry, we need to execute a script to fix symlinks and lib paths:
paulowesteros:$ cd/opt/cross-compile-tools
paulo
westeros:$ sudo ./fixQualifiedLibraryPaths /mnt/rasp-pi-rootfs//opt/gcc-4.7-linaro-rpi-gnueabihf/bin/arm-linux-gnueabihf-gcc

Go to the qt5/qtbase folder and run:
paulowesteros:/opt/qt5/qtbase$ ./configure -opengl es2 -device linux-rasp-pi-g++ -device-option CROSS_COMPILE=/opt/gcc-4.7-linaro-rpi-gnueabihf/bin/arm-linux-gnueabihf
-sysroot /mnt/rasp-pi-rootfs -opensource -confirm-license -optimized-qmake -reduce-exports -release -make libs -prefix /usr/local/qt5pi
paulo
westeros:/opt/qt5/qtbase$ make -j 4
paulowesteros:
/opt/qt5/qtbase$ sudo make install
Note: if you want the qmlscene binary you should add -make tools to the ./configure command.

Compiling other modules

Now that you have qmake, you can cross-compile the other modules. To avoid dependencies errors, the following order is sugested:
qtimageformats, qtsvg, qtjsbackend, qtscript, qtxmlpatterns, qtdeclarative, qtsensors, qt3d, qtgraphicaleffects, qtjsondb, qtlocation, qtdocgallery.

To compile, you must do like the example below:
paulo
westeros:/opt/qt5$ cd qtimageformats
paulowesteros:
/opt/qt5/qtimageformats$ /usr/local/qt5pi/bin/qmake .
paulo
westeros:/opt/qt5/qtimageformats$ make -j4
paulowesteros:
/opt/qt5/qtimageformats$ sudo make install

We have all the modules installed in the wheezy image, now we can copy it to the sdcard using dd:
paulo
westeros:/opt/qt5$ cd/opt/
paulowesteros:/opt$ sync; sudo umount /mnt/rasp-pi-rootfs
paulo
westeros:/opt$ sudo dd bs=1M if=2012-07-15-wheezy-raspbian.img of=/dev/sdb; sync

obs: Check the entry point of your sdcard. Mine was /dev/sdb.

Notes for OSX

  • Because your sdcard will be partitioned, OSX won't let you umount it, so you'll need to type:
    sudo diskutil umountDisk /dev/disk3

where "disk3" will be the /dev/diskXsY where your sdcard first appeared.

  • To perform dd you will need to use the *r*disk index, so if your sdcard is disk3 you will need to type:
    sudo dd bs=1M if=2012-07-15-wheezy-raspbian.img of=/dev/rdisk3; sync

Boot up your pi.

Configuring Qt Creator

To use Qt Creator properly, you must configure the "Qt Version" and "Tool Chains" sections.

Tool Chain Settings

go to Tools > Options..> Build & Run -> Compilers tab.
click in "Add -> GCC".
On "Compiler Path" set to "/home/<you>/opt/gcc-4.7-linaro-rpi-gnueabihf/bin/arm-linux-gnueabihf-g+".
Name it "ARM GCC" or similar.
obs: Adjust it to your username.

h3. Qt Version settings.
Now go to Tools > Options..> Build & Run -> Qt Versions tab.
Click in "Add.." and choose you qmake for raspberry "/usr/local/qt5pi/bin/qmake".
Note for OSX
* Because /usr is not visible by default, you first need to open a terminal and type:
sudo SetFile -a v /usr

* After you've completed the qmake selection, if you wish to make /usr invisible again, type the same command with a capital V :
sudo SetFile -a V /usr
h3. Configure Linux Devices
Go to Tools > Options…> Devices -> Devices tab.
Add a new configuration setting a "Generic Linux Device"
Hostname or IP address is the IP of your raspberry
user is pi
password is raspberry
obs: if your not did change it.
Now you are ready to run your first Qt raspberry pi project.
h2. Example Project
You can download a hello world project:
paulo
westeros:$ git clone https://git.gitorious.org/qt5-raspberrypi-example/qt5-raspberrypi-example.git
Open the project in Qt Creator and go to the Projects pane.
Click Manage Kits and then Add.
Fill in:
Name: Raspberry Pi
Device Type: Generic Linux Device
Device: Raspberry Pi
Compiler: ARM GCC
Debugger->Manage->Edit->"/home/<you>/opt/gcc-4.7-linaro-rpi-gnueabihf/bin/arm-linux-gnueabihf-gdb" (change your username)
Qt version: Qt 5.x.x (qt5pi)
Ok->Add Kit->Raspberry Pi
Then go to the "Rasperry Pi" kit tab->System Environment and add LD_LIBRARY_PATH which is set to /usr/local/qt5pi/lib
Now you can build and run your application from Qt Creator.
h2. Troubleshooting
h3. Qt version not properly installed
You need to keep the SD card image mounted during development!
If QtCreator still reports this after mounting the SD card image, then you may need to create the directories missing from
/mnt/rasp-pi-rootfs/usr/local/qt5pi/
or whatever the mount path is (these will probably include bin, translations, and so on). You can create empty directories using the mkdir command.
h3. The default mkspec symlink is broken.
It means that mkspec is not found on your sysroot, so your must copy it.
paulo
westeros:
$ sudo cp -r /usr/local/qt5pi/mkspecs/ /mnt/rasp-pi-rootfs/usr/local/qt5pi/
If the problem persists, create the missing symlink, e.g.
sudo ln -s /usr/local/qt5pi/mkspecs/devices/linux-rasp-pi-g+ /usr/local/qt5pi/mkspecs/default

It is probably a good idea to do the same for the sysroot mkspecs.

Include <QtGui/QtGui&gt;: No such file or directory

It seems Qt's include was not found and you must add it to you .pro file:

INCLUDEPATH = /mnt/rasp-pi-rootfs/usr/local/qt5pi/include/
h3. cc1: fatal error: .pch/release-shared/QtGui: No such file or directory
Some people have seen this error. Adding the "-no-pch&quot; option when running configure should prevent it.
h3. Getting Could not determine the target architecture! and Could not determine the host architecture!
If you are getting this kind of error, it is possible that your current git branch is something other than master. To be sure, do the following:
danieldaniel-t3500 : /opt/qt5/qtbase $ git branch
If it shows like this:
* (no branch)
master
Then you must checkout to master branch before running ./configure:
daniel
daniel-t3500 :/opt/qt5/qtbase $ git checkout master
danieldaniel-t3500 : /opt/qt5/qtbase $ git branch
* master

It is also good to fetch the latest commits and apply them by doing:
danieldaniel-t3500 :/opt/qt5/qtbase $ git pull
Also, check for the installation of libz (32 bits) in yor system. In ubuntu (64 bits) you might just:
sudo apt-get install lib32z1-dev

After the ./configure script has failed first run these commands before restarting ./configure:
danieldaniel-t3500 : /opt/qt5/qtbase $ git reset —hard
daniel
daniel-t3500 :/opt/qt5/qtbase $ git git clean -dxf

h3. EGL Error : Could not create the egl surface: error = 0x3000
Try allocating more memory to video (try 64 or 128MB). Use the raspi-config utility to change this.
piraspberrypi ~ $ sudo raspi-config
h3. ABI detection failed
You will need Qt Creator 2.6 for Qt5 up to and including beta2.
Any Qt 5 later than that will need to use nightly snapshots (or will have to wait for Qt Creator 2.6.1): After the beta2 all libraries were renamed again.
See "this forum thread for more details&quot;:http://forum.qt.io/viewthread/22023
h3. ./configure: 2654: ./configure: /home/&lt;you&gt;/opt/gcc-4.7-linaro-rpi-gnueabihf/bin/arm-linux-gnueabihf-g: not found -reduce-exports was requested but this compiler does not support it
The error message is totally misleading. The real cause is that the precompile toolchain is 32-bit, so you need to:
sudo apt-get install ia32-libs

h3. make: g: Command not found
Qt requires a native (non-cross-compiling) copy of g+ to be installed in order to build qmake. You can't use clang. Fix with:
sudo apt-get install g++

/mnt/rasp-pi-rootfs/usr/lib/arm-linux-gnueabihf/libdl.a(dlopen.o): In function `dlopen': (.text+0xc): undefined reference to `__dlopen'

You need to run the ./fixQualifiedLibraryPaths again.

See: http://stackoverflow.com/questions/13626726/an-error-building-qt-libraries-for-the-raspberry-pi for more info.

cc1: fatal error: .pch/release-shared/Qt5Gui: No such file or directory

Try adding -no-pch to the ./configure command line.

Cannot create forwarding script Betrete 'qtactiveqt'.git/hooks/commit-msg: Datei oder Verzeichnis nicht gefunden

Try:
unset LANG
./init-repository -f