Segmentation fault while creating Object for QApplication

[wysota]

It's not required but you probably have to somehow tell QApplication not to try to connect to X server With Qtopia you would use QtopiaApplication but with bare Qt/Embedded you probably need to use QApplication. You did compile Qt/Embedded for your device, right? You didn't just cross-compile the desktop edition for ARM?

[nrabara]

I do remember that i have used qt-embedded-linux-open-source-4.5.
I am getting following message when i try to run qt application.

# ./JS
QWSSocket::connectToLocalFile could not connect :: Connection refused
No Qt for embedded linux server appears to be running
If you want to run the program as a server
add -qws

when I run with # ./JS -qws
Segmentation fault

any suggestion would be appreciable....

[wysota]

Did you read Qt Embedded Display Management?

[nrabara]

Yes I have read it,

I have used following..
export QT_DIR=/home/qt
export LD_LIBRARY_PATH=$QT_DIR/lib
export QWD_DISPLAY=LinuxFb

I have intalled libQtGui.so.4 , libQtCore.so.4 ,libQtNetwork.so.4 in my board at /home/qt/lib.(same path user while cross compiling with arm-linux-gcc)
I have also intalled fonts to /home/qt/fonts
i have place qmake in /usr/bin or my board

I dont under understand why it's(segmentation fault) happening with QApplication only why not with QCoreApplicaton.

Your suggestion would be a great help for me.

[wysota]

Does the user have access rights to write to the framebuffer?

QCoreApplication works because the application doesn't try to access the framebuffer.

[nrabara]

Yes user have rights to access /dev/fb0
Even I can run qt example code of frambuffer(examples/qws/framebuffer.) on board, and Its show me three rectangles on my display.

[wysota]

Do other examples work as well?

[nrabara]

All the example having QApplication object show segmentation fault.

But for QCoreApplication object, i can use QDateTime, QDate etc.. sub classes of QCoreApplication. It's works fine with QCoreApplication.

Is there any other way to test QApplication object, I mean
Can ./configure affect Qt Gui ?? I have tried with full configuration also.

Your suggestion would be great help for me..

[wysota]

Your problem is deployment, not compilation. Could you post a backtrace of an exemplory crash? An strace showing files being opened (and statuses of the calls) would be nice as well.

[nrabara]

Below is my test application code

main.cpp file

#include <QtGui/QApplication>
#include <QLabel>
#include "widget.h"
 
int main(int argc, char *argv[])
{
    printf("Inside main\n");
    unsigned int loop;
    QApplication a(argc, argv);
    printf("argc = %d \n",argc);
    for(loop=0;loop<argc;loop++)
    {
        printf("argv[%d] = %s \n",argc,argv[loop]);
    }
    Widget w;
    w.setFixedSize(200,200);
    w.show();
    return a.exec();
}
 
[B][U]widget.cpp file[/U][/B]
 
#include "widget.h"
 
Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
}
 
Widget::~Widget()
{
 
}
 
[U][B]widget.h file[/B][/U]
 
#ifndef WIDGET_H
#define WIDGET_H
 
#include <QtGui/QWidget>
 
class Widget : public QWidget
{
    Q_OBJECT
 
public:
    Widget(QWidget *parent = 0);
    ~Widget();
};
 
#endif // WIDGET_H

#include <QtGui/QApplication>
#include <QLabel>
#include "widget.h"

int main(int argc, char *argv[])
{
    printf("Inside main\n");
    unsigned int loop;
    QApplication a(argc, argv);
    printf("argc = %d \n",argc);
    for(loop=0;loop<argc;loop++)
    {
        printf("argv[%d] = %s \n",argc,argv[loop]);
    }
    Widget w;
    w.setFixedSize(200,200);
    w.show();
    return a.exec();
}

[B][U]widget.cpp file[/U][/B]

#include "widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
}

Widget::~Widget()
{

}

[U][B]widget.h file[/B][/U]

#ifndef WIDGET_H
#define WIDGET_H

#include <QtGui/QWidget>

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = 0);
    ~Widget();
};

#endif // WIDGET_H

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Back trace of the above code is attached - file : QApplication_backtrace.txt

I have also attached back trace of qt's example code - framebuffer , file : QtFramebuffer_exampleCode.txt

Your suggestion would be a great help for me..

[wysota]

This is an strace. What about a debugger backtrace?

The strace suggests there is a problem with mapping the framebuffer to memory.

[nix]

Can you post result for the following command "fbset --info" too, thx.