Setting up cross compiling environment & Qt/X11 ... - Bytemark Hosting

Setting up cross compiling environment & Qt/X11
for the DX4 with the ELDK cross compiler
Table of Contents
1 About this document.......................................................................................................................2
2 Revision History..............................................................................................................................2
3 Conventions.....................................................................................................................................2
4 Setting up ELDK............................................................................................................................2
5 Eclipse..............................................................................................................................................3
5.1 Install Eclipse..........................................................................................................................3
5.2 Cross compile with Eclipse.....................................................................................................4
5.3 Executing with Eclipse............................................................................................................7
5.3.1 Create a connection to the DX4.....................................................................................7
5.3.2 Set up Run and Debug Configuration.........................................................................10
6 Qt....................................................................................................................................................13
6.1 Setting up Qt/X11..................................................................................................................13
6.2 Using Qt.................................................................................................................................14
6.2.1 Using Qt in the Terminal..............................................................................................14
6.2.2 Installing QtCreator......................................................................................................14
6.2.3 Using Qt with QtCreator 1.x.x.....................................................................................14
6.2.4 Using Qt with QtCreator 2.x.x.....................................................................................15
6.2.5 Using Qt with Eclipse....................................................................................................16
7 Running an application................................................................................................................19
7.1 Copy files to DX4..................................................................................................................19
7.1.1 Using Nautilus...............................................................................................................19
7.2 Installing Qt on the DX4......................................................................................................20
7.3 Special libraries.....................................................................................................................20
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1 About this document
This documents describes how to set up a cross compiling environment for the DX4 using the
ELKD cross compiler. The whole environment is set up using the Ubuntu 32Bit Linux distribution.
Additionally there are two ways described to use QtCreator and Eclipse to cross compile an
application for the DX4. With Eclipse it is also possible to remote launch the application from
within the IDE on the DX4.
Anders Electronics provides a completely set up Ubuntu 10.04 32 Bit within a VirtualBox virtual
machine.
2 Revision History
Revision Date Changes
A 24/07/2012 • Initial version
B 27/07/2012 • Added a lot of pictures
• Added a chapter on how to copy files to the DX4
3 Conventions
All kinds of code and file snippets are shown like the line below.
This is a code line
If there is a $ at the beginning like in the line below, this means that this is a command to be
executed in a terminal as a normal user.
$ user command
If there is a # in front of the line it is a command to be executed as root (super user):
# root command
All names from menues, folders and file names are written in italic.
When commands have to be split in multiple lines it looks like this:
export PATH=/opt/eldk­5.2.1/armv7a/sysroots/i686­eldk­linux/
usr/bin/armv7a­vfp­neon­linux­gnueabi/:$PATH
4 Setting up ELDK
Install an Ubuntu 10.04 LTS, 32 Bit system on a computer or a virtual machine. This will probably
also work with other distributions. It is recommended to use 10.04 LTS because there where
problems with Drag&Drop in the Qt integration for Eclipse when using Ubuntu 12.04 LTS.
Make sure all updates are installed.
Download the ELDK iso file for armv7a from http://ftp.denx.de/pub/eldk/.
For example: http://ftp.denx.de/pub/eldk/5.2.1/iso/eldk-5.2.1-armv7a.iso
This mirror can be used alternatively because the denx.de server seems to be very slow: http://ftpstud.hs-esslingen.de/pub/Mirrors/eldk/
Extract the iso file to a folder like /home/anders/eldk-5.2.1.
Open a terminal and go to the directory where you put the installer:
$ cd eldk­5.2.1
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Make sure that the installer script is executable:
$ chmod +x install.sh
Install the ELDK:
$ ./install.sh armv7a
He asks for the user password to get root privileges and then he will install the ELDK into
/opt/eldk-5.2.1/armv7a/. It is possible to install the ELDK into a different directory, see
$ ./install ­­help
for more information.
Now you have to set up some environment variables that are required to use the cross compiler. Add
this at the end of your .profile file in the users home directory. It may be required to modify it to the
version number and paths according to the version of ELDK you are using (there are no spaces in
the lines!).
export PATH=/opt/eldk­5.2.1/armv7a/sysroots/i686­eldk­linux/usr/bin/armv7avfp­neon­linux­gnueabi/:$PATH
export PATH=/opt/eldk­5.2.1/armv7a/sysroots/i686­eldk­linux/usr/bin/:$PATH
export ARCH=arm
export PKG_CONFIG_PATH="/opt/eldk­5.2.1/armv7a/sysroots/i686­eldklinux/usr/lib/pkgconfig"
export PKG_CONFIG_SYSROOT_DIR="/opt/eldk­5.2.1/armv7a/sysroots/i686­eldklinux"
export CROSS_COMPILE=arm­linux­gnueabi­
You will need to log off and on again that the changes will take effect.
Now the basic cross compiling environment is set up. To compile a simple C program you type
$ ${CROSS_COMPILE}gcc ­o hello hello.c
5 Eclipse
An more comfortable way of cross compiling is Eclipse. Besides the basic features you get from an
IDE like syntax highlighting and automatic makefile generation Eclipse also provides functions for
a remote launch of your application.
5.1 Install Eclipse
Before you can install Eclipse you have to make sure that you have installed a Java Runtime
Environment. Open a Terminal and execute this command:
$ apt­get install default­jre
Now go to http://www.eclipse.org/downloads/ and download the Eclipse Classic version for Linux
32Bit. Extract the archive to your desktop.
Start Eclipse by executing the file called eclipse in the extracted folder.
Go the Help → Install new Software and add a new Repository by clicking on Add on the top right
of the window. Call it CDT and use this link: http://download.eclipse.org/tools/cdt/releases/juno
This path may be adjusted, when you are not using Eclipse Juno. Click OK to add the new
repository.
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Select --All Available Sites-- from the drop down menu and wait for Eclipse to refresh the list
below.
Under “CDT Main Features” select:
• C/C++ Development Tools
• C/C++ Development Tools SDK
Under “CDT Optional Features” select:
• C/C++ GCC Cross Compiler Support
• C/C++ Remote Launch
Under “Mobile and Device Development” select:
• Remote System Explorer End-User Runtime
• Remote System Explorer User Actions
Install the selected packages by following the instructions of the wizard.
5.2 Cross compile with Eclipse
Eclipse offers some nice functions which allow you to cross compile your application.
Create a new C project by going to File → New → Other. Select the C Project under C/C++ and
click Next.
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Set a name for the project, we will use cross1 in this example. Set the project type to Executable →
Empty Project. Set the Toolchains to Cross GCC and click Next.
On the second page are no settings to be changed, just click Next.
On the third page set the Cross compiler prefix to arm-linux-gnueabi- and the Cross compiler path
to /opt/eldk-5.2.1/armv7a/sysroots/i686-eldk-linux/usr/bin/armv7a-vfp-neon-linux-gnueabi.
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Press Finish to create the project.
Create a new source file by clicking on File → New → Source File, call it main.c.
Press Finish to create the file and add a small hello world program in the file:
#include
int main(int argc, char* argv[])
{
printf("Hello world\n");
return 0;
}
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Compile the program by hitting the button with a hammer. When you open the Console at the
bottom of Eclipse you should see him invoking the arm-linux-gnueabi-gcc cross compiler to
compile the program.
In the project directory you will find a file called cross1. This is the executable which you have to
copy to the DX4. How to do this will be described later in chapter 7.
5.3 Executing with Eclipse
Now you can just copy the created file cross1 to the target and execute it. A better and easier way is
to let Eclipse do that for you by a remote execution.
5.3.1 Create a connection to the DX4
First of all you will need to create a connection to the DX4. Go to Window → Show View → Other,
expand Remote Systems and select the Remote System Explorer and click OK.
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At the bottom of Eclipse you should see a Remote Systems tab which should look like this:
Create a new connection by clicking on the small symbol with a “+” in the Remote Systems tab.
As Remote System Type select Linux and press Next.
For the Host Name enter the IP address of your DX4 and press Next.
In the Files tab select ssh.files for Configuration and press Next.
In the Process tab select process.shell.linux for Configuration and press Next.
In the Shells tab select ssh.shells for Configuration and press Next.
In the SSH Terminals tab select ssh.terminals for Configuration and press Finish.
Now you have a new connection in the Remote Systems tab. It is better to move the Remote Systems
tab with Drag&Drop on the left side of Eclipse.
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Right click on the connection and select Connect. He may ask you to accept the SSH connection
and other things, accept that. After that you should be able to browse the remote file system by
going to Sftp Files → Root. He will also ask for a user name and password to use, use the user and
password of the DX4. He may also ask you to create a new password for the Eclipse password
storage.
It is now possible to Drag&Drop files from your local file browser to a folder in Eclipse. We will
later introduce a even more comfortable way of copying files.
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5.3.2 Set up Run and Debug Configuration
To tell Eclipse to run the current application cross1 on the DX4 a special Run Configuration has to
be created. Click on Run → Run Configurations. Here are all the Run Configurations listed. If there
is already any configuration you should remove it, because it will not be used.
Double click on C/C++ Remote Application to create a new remote launch configuration.
Next to Connection select the connection you created before and click on Properties next to it. Here
you have to set the remote workspace path. This path must exist! For example use /home/root/ and
press OK.
Make sure the box Select configuration using C/C++ Application is not checked.
In Remote Absolute File Path For C/C++ Application set the complete path where to put the
executable including the name of the file. For example /home/root/cross1.
Put this in the field Commands to execute before application to make the file executable after
Eclipse copied it to the DX4: chmod 777 /home/root/cross1
After that click Apply and Close to save the settings. Now open Run → Debug Configurations.
There should already be a C/C++ Remote Application where Eclipse made the same settings as in
the Run Configuration.
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Go the the Debugger tab. In the area Debugger Option go to the tab Main and set this in the field
GDB Debugger (there is no space in the line!):
/opt/eldk­5.2.1/armv7a/sysroots/i686­eldk­linux/usr/bin/armv7a­vfp­neonlinux­gnueabi/arm­linux­gnueabi­gdb
Click Apply and close the configuration dialogue.
To support debugging on the DX4 you will have to install the gdbserver on it. The gdbserver is not
required if you don't want to debug the application. When you are in the Remote System Explorer
view of Eclipse you can open a terminal in Eclipse by right clicking on Ssh Terminals under your
connection and select Launch Terminal.
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Type this to install the gdbserver type this in the new created terminal:
# opkg update
# opkg install gdbserver
The DX4 has to be connected to the internet.
When you want to run or debug the application for the first time you have to go to Run →
Run/Debug Configurations, select the configuration you created and click the Run or Debug button.
After that is is possible to run the application from the small arrow next to the run and debug
buttons at the top of Eclipse. Here you click on the name of your run or debug configuration and he
will automatically load the executable to the DX4 and execute it.
You can see the output of the application in the Console tab of Eclipse.
6 Qt
Qt is a powerful C++ library for creating graphical user interfaces and many more things. It is
portable over many operation systems and platforms. There is also a embedded version of Qt called
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Qt/embedded which doesn't need a X server which makes systems very lightweight and fast. In this
document we will discuss how to set up Qt using the X server but compiling it for embedded use is
not a big difference.
6.1 Setting up Qt/X11
You first need to set up the terminal compilation method described above. Download the Qt sources
from http://qt.nokia.com/downloads. Scroll a bit down to "Qt libraries". The file should have a
name like qt-everywhere-opensource-src-4.8.2.tar.gz. Extract the sources into you home directory:
$ tar xzf Downloads/qt­everywhere­opensource­src­4.8.2.tar.gz
Change into the Qt directory:
$ cd qt­everywhere­opensource­src­4.8.2
Copy the modified configuration for Qt and replace the existing one. You will find the modified file
in the Anders DX4 wiki:
$ cp ../Downloads/qmake.conf mkspecs/qws/linux­arm­gnueabi­g++/qmake.conf
Then open the file in mkspecs/qws/linux-arm-gnueabi-g++/qmake.conf and make sure that all the
paths to the ELDK are correct.
Make sure all required tools like make are installed:
$ sudo apt­get install build­essential
After that use the following command line to configure Qt. The path behind -prefix defines the
folder where Qt will be installed. This is the folder for the local computer and the DX4. You should
not install it in / because this will cause problems with a local x86 installation of Qt. Execute the
following command to configure the Qt sources (hit return after each line):
./configure ­arch arm ­xplatform qws/linux­arm­gnueabi­g++ \
­force­pkg­config ­nomake demos ­nomake examples ­no­openssl \
­no­sql­sqlite ­no­phonon ­no­phonon­backend ­no­webkit \
­prefix /usr/local/Trolltech/Qt­arm­X11 \
­D QT_RX71_MULTITOUCH ­confirm­license
When the script finishes without any error continue compiling Qt:
$ make ­j X
Where X is the number of cores your CPU has plus one. So type
$ make ­j 5
on a quad core machine. This will speed up things by using parallel compilation.
Note: Depending on the speed of your computer this process can take several hours.
To install Qt on your local machine (which is required to cross compile) just type
$ sudo make install
Now you should add /usr/local/Trolltech/Qt-arm-X11/bin to your PATH variable by adding the
following line to your users .profile file:
export PATH=/usr/local/Trolltech/Qt­arm­X11/bin/:$PATH
To open the file type:
$ gedit ~/.profile
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You will have to log out and log in again for changes to take effect.
6.2 Using Qt
There are tree different ways of using Qt for compilation. You can simply use the terminal to
compile your Qt code, you can use the QtCreator or you can use Eclipse. For the QtCreator there
are two guides, depending on which version of QtCreator you are using. It is recommended to use
version 2 of QtCreator because it is much easier to set up cross compiling.
6.2.1 Using Qt in the Terminal
To use Qt in the terminal you simply need to go into the folder where your sources are and run
$ qmake ­project
to create the .pro file. This is required only once for each project but it needs to be done again when
you add source files. After that you can create a make file by invoking
$ qmake
Qt will take care of cross compilation and you just have to run
$ make
to compile the project.
6.2.2 Installing QtCreator
Install the normal QtCreator for X86 on your desktop machine. You do not need to install the whole
Qt libraries, only what is required for the QtCreator itself. To install QtCreator on a Debian based
system (like Ubuntu) type this in a terminal:
$ sudo apt­get install qtcreator
If you also want to install Qt for a local compilation invoke this command:
$ sudo apt­get install libqt4­dev
6.2.3 Using Qt with QtCreator 1.x.x
Start your QtCreator and create a simple project.
Now go to Tools → Options → Debugger → Gdb and select the ARM cross gdb:
/opt/eldk­5.2.1/armv7a/sysroots/i686­eldk­linux/usr/bin/armv7a­vfp­neonlinux­gnueabi/arm­linux­gnueabi­gdb
On the left side go to Qt4 → Qt Versions and add a new Qt version to Manual. Call it something
like Qt 4.8.2 for ARM and add the qmake executable:
/usr/local/Trolltech/Qt­arm­X11/bin/qmake
Now the QtCreator is ready for cross compiling. There is one issue with the ELDK which causes g+
+ to complain about this:
note: the mangling of 'va_list' has changed in GCC 4.4
This is a known issue and can be ignored. To tell GCC to suppress this message you can pass the
argument -Wno-psabi to it. To do this in a Qt project add the following line at the end of your .pro
file:
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QMAKE_CXXFLAGS += ­Wno­psabi
6.2.4 Using Qt with QtCreator 2.x.x
First create your project like you would do it for a normal desktop application. Therefore click on
File → New File or Project and select the type of project you want to create. For example a Qt GUI
Application like below.
Click Choose to continue. After that you will be asked to choose a project name:
Enter a name and click Next to continue. The next step is to select which compilers to use. Normally
you should let the default setting "For Each Qt Version One Debug And One Release". This will
create a build configuration for your local Qt (if you have installed it) and the cross compiling
version.
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Follow the instructions to finish the wizard.
Normally the QtCreator should automatically detect the cross compiler and the self build Qt. To
check this click on the button above the Run button on the left side of QtCreator and click on the
drop down menu next to Build. If the cross compiler was detected it should look like in the picture
below.
There should be two build targets with Qt-arm-X11 in the brackets, one for release and one for
debug. If this does not work for you this normally means that you does not have set up your .profile
file in your home directory correctly. Double check the paths in the .profile file. Or you forgot to log
out and log in again. It is also possible to set it up manually by clicking on the Projects button on
the left side of QtCreator. Here you can add the Qt libraries and the cross compiler tool chain
manually.
6.2.5 Using Qt with Eclipse
It is possible to combine Qt with Eclipse. This will make it possible to remote launch Qt
applications like you maybe did already with a normal C/C++ application. First you have to follow
the instructions above to install Eclipse and Qt for command line usage.
Then download the Qt integration for Eclipse from and install it:
http://qt.nokia.com/products/eclipse-integration/
Start Eclipse and create a Qt Project by clicking on File → New → Other. Select Qt → Qt GUI
Project and press Next.
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Enter a name for the project, I will use QtCross1 and press Finish.
When creating the first project he will complain about a missing Qt at the end of the creation
process. It is also possible to open this dialogue by clicking on Window → Preferences → Qt →
Add afterwords.
Click on Open preferences and click on Add. Enter a version name like Qt 4.8.2 ARM, the Qt bin
path is /usr/local/Trolltech/Qt-arm-X11/bin and the Qt include path is /usr/local/Trolltech/Qt-arm-
X11/include.
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Press Finish to finish the set up.
After that the project is ready to compile. Click on Project → Build project to compile the project.
If you want to set up a remote launch do it like described above with one extra thing. Set this in the
field Commands to execute before application:
chmod 777 /home/root/Qtcross1;export DISPLAY=:0.0
Important is the additional export command which will tell your application where to find the X
server.
There are some problems with Eclipse to find the correct include paths and it shows some errors
which are no errors, the application will compile just fine but Eclipse will not let you start the
application. To solve this you have to disable the Code Analysis in Eclipse. Go to Window →
Preferences → C/C++ → Code Analysis. Uncheck all check boxes for the Code Analysis.
After that Eclipse may still have some Warnings about not finding some include files. To fix this
right click on your Qt project and select Properties. Click on C/C++ Include Paths and Symbols
and add these two paths with Add External Include Path:
/opt/eldk­5.2.1/armv7a/sysroots/armv7a­vfp­neon­linux­gnueabi/usr/include
/opt/eldk­5.2.1/armv7a/sysroots/armv7a­vfp­neon­linux­gnueabi/usr/include/c++
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7 Running an application
After you have compiled your application with you preferred IDE simply copy the application to
the DX4 and run it. Follow the instructions below to copy the executable to the DX4.
7.1 Copy files to DX4
When you are running Linux with Nautilus as file browser it is very simple to copy files to the
DX4. Nautilus is used for example in Ubuntu.
7.1.1 Using Nautilus
First of all you have to set a password for the user you are going to use on the DX4. Probably this
will be root. Log in as the user and type
$ passwd
to change the password. After that open Nautilus on your host machine and click on File →
Connect to Server. As Type select SSH, enter the IP address of the DX4 in the field Server and type
your user name and password. This should look like the picture below.
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Click on Connect to connect to the DX4. Nautilus will create a SFTP network connection and
mount it for you. You can right click on the mounted folder on the left side and select Add
Bookmark to add this connection as a bookmark.
Keep in mind that you are acting as the user you selected when you created the connection. Means
that as a normal user you don't have write access to files except those in you home directory. If you
are logged in as root and create files in the home directory of an other user, the other use will not be
able to delete or modify the files you created.
7.2 Installing Qt on the DX4
To run a Qt application on the DX4 it is required to copy the Qt libraries and some other stuff to the
DX4. You should first set up the connection to copy files to the DX4 like described in chapter 7.1.
Now you have to copy the files from /usr/local/Trolltech/ on your host machine in the same
directory on the DX4. It is required to be connected as root to the DX4.
The folder /usr/local/ may not exist on the DX4, just create it.
7.3 Special libraries
If you need special libraries and special versions from ELDK which already exist on the DX4 you
need to run the application with a dynamic linker because it is not recommended to overwrite the
existing libraries. To do this copy the rootfs of ELDK to the target system in a subdirectory, for
example in /eldk. The rootfs of ELDK is located in /opt/eldk-5.2.1/armv7a/sysroots/i686-eldk-linux/
You should end up with a folder structure like /eldk/usr/lib/ on the DX4. You do not have to copy
the full rootfs. Required are only the folders /lib and /usr/lib. It is also possible to remove unneeded
libraries from this folders.
To run you application with a dynamic linker that uses special paths use the following command
(this is a single line with a space at the line break):
$ /eldk/lib/ld­linux.so.3 ­­library­path /eldk/lib:/eldk/usr/lib
/path/to/your/program
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