[Error] undefined symbol: _ZN7QWidget8qwsEventEP8QWSEvent

SGaist

What version of Qt do you have on your target ? What linux distribution are you running on it ?

rocket42

my target is using qt4
my linux distribution is ubuntu lts 14.04

SGaist

You also have an Ubuntu 14.04 running on your target ? If so, then you have a classic "desktop like" build of Qt on your target. That's why it can find the symbols related to QWS. Either rebuild your Qt without the embedded option or install your cross-compiled Qt on the target.

rocket42

No, my target use Angstrom os, which was distributed with board

SGaist

Then check how Qt was built for Angstrom but I suspect that it's a desktop like build rather than an embedded.

rocket42

I found cause of this error, but i dont know how to solve it. That is:
when create new project on Qt(Ctr+N). Qt automatically create new class called mainwindow
and automatically create code in main.cpp which show mainwindow. in main.cpp:
MainWindow w;
w.show();
if build, then run, this error raised
but i replace this two command in main.cpp as following:
...
#include <QMainWindow>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);

QMainWindow q;
q.show();

return a.exec();

}
it run ok.
we see that mainwindow class inherite from QMainWindow class.
when show QMainWindow is ok, but show mainwindow is not ok
that isn't understand

jsulm

Do you do something special in MainWindows constructor?

rocket42

No, Qt automatically create it. i don't change ever

SGaist

Silly question but, are you using the same kit for both projects ?

rocket42

yes, I use same kit for two

SGaist

Then as @jsulm asked, what are you doing in your MainWindow class that differs it from QMainWindow ?

rocket42

i don't change anything, MainWindow class is created automatically by Qt creator
let me post code here. i can't find how to attach it
mainwindow.h content:
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

Mainwindow.cpp content:
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow()
{
delete ui;
}

SGaist

Then there must be something else with your project.

rocket42

I created C++ class manually, this class calls abc and inherited from QMainWindow class
source code of abc.h:

#ifndef ABC_H
#define ABC_H
#include <QMainWindow>
class abc : public QMainWindow
{
    Q_OBJECT
public:
    explicit abc(QWidget *parent = 0);
signals:
public slots:
};
#endif // ABC_H

source code of abc.cpp:

#include "abc.h"
abc::abc(QWidget *parent) : QMainWindow(parent)
{

}

source of main.cpp:

#include "mainwindow.h"
#include <QApplication>
#include "abc.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
//    MainWindow w;
//    w.show();
//    QMainWindow q;
//    q.show();
    abc abc1;
    abc1.show();
    return a.exec();
}

when app run on beagbone black, this error still rises

SGaist

There's something illogical here so lets try to summaries things:
First case:

You create a default widget project with Qt Creator
Replace the MainWindow call in main.cpp by a QMainWindow
Build it with your cross-compiled Qt
Runs on BBB

Second case:

You create a default widget project with Qt Creator
You keep the MainWindow class
Build it with your cross-compiled Qt
Fails to run on BBB complaining about QWS

In both case, you use the exact same version of Qt to build (i.e. cross-compile) the projects.

Is the summary correct ?

rocket42

yes, you are right. but you miss the third case.
because i have three cases.
the third case:

I create a default widget project with Qt Creator
I create a new class (name is ABC) which inherite from QMainWindow (source code I posted at #21)
Replace the MainWindow class in main.cpp by ABC class
Build it with your cross-compiled Qt
Fails to run on BBB complaining about QWS
All of three cases, i use same KIT (included device, compiler, qmake,...)

SGaist

I must say that it defies logic...

rocket42

sorry, i don't understand
all three cases is different.
the third case i don't use class which automatically create by Qt creator, i created manually

SGaist

That's why it defies logic. I don't see why a simple derived class would trigger that error.

Can you run ldd on all three applications on your target and post the output ?

rocket42

output of case1 (application run ok):
libQtGui.so.4 => /usr/lib/arm-linux-gnueabihf/libQtGui.so.4 (0xb681e000)
libQtCore.so.4 => /usr/lib/arm-linux-gnueabihf/libQtCore.so.4 (0xb6616000)
libstdc++.so.6 => /usr/lib/arm-linux-gnueabihf/libstdc++.so.6 (0xb656b000)
libgcc_s.so.1 => /lib/arm-linux-gnueabihf/libgcc_s.so.1 (0xb6547000)
libc.so.6 => /lib/arm-linux-gnueabihf/libc.so.6 (0xb6462000)
libfontconfig.so.1 => /usr/lib/arm-linux-gnueabihf/libfontconfig.so.1 (0xb6436000)
libpthread.so.0 => /lib/arm-linux-gnueabihf/libpthread.so.0 (0xb641a000)
libaudio.so.2 => /usr/lib/arm-linux-gnueabihf/libaudio.so.2 (0xb6402000)
libglib-2.0.so.0 => /lib/arm-linux-gnueabihf/libglib-2.0.so.0 (0xb6343000)
libpng12.so.0 => /lib/arm-linux-gnueabihf/libpng12.so.0 (0xb6322000)
libz.so.1 => /lib/arm-linux-gnueabihf/libz.so.1 (0xb6309000)
libfreetype.so.6 => /usr/lib/arm-linux-gnueabihf/libfreetype.so.6 (0xb62a4000)
libgobject-2.0.so.0 => /usr/lib/arm-linux-gnueabihf/libgobject-2.0.so.0 (0xb6265000)
libSM.so.6 => /usr/lib/arm-linux-gnueabihf/libSM.so.6 (0xb6258000)
libICE.so.6 => /usr/lib/arm-linux-gnueabihf/libICE.so.6 (0xb6240000)
libXrender.so.1 => /usr/lib/arm-linux-gnueabihf/libXrender.so.1 (0xb6232000)
libXext.so.6 => /usr/lib/arm-linux-gnueabihf/libXext.so.6 (0xb621f000)
libX11.so.6 => /usr/lib/arm-linux-gnueabihf/libX11.so.6 (0xb6136000)
libm.so.6 => /lib/arm-linux-gnueabihf/libm.so.6 (0xb60cb000)
/lib/ld-linux-armhf.so.3 (0xb6f02000)
libdl.so.2 => /lib/arm-linux-gnueabihf/libdl.so.2 (0xb60c0000)
librt.so.1 => /lib/arm-linux-gnueabihf/librt.so.1 (0xb60b2000)
libexpat.so.1 => /lib/arm-linux-gnueabihf/libexpat.so.1 (0xb6090000)
libXt.so.6 => /usr/lib/arm-linux-gnueabihf/libXt.so.6 (0xb604e000)
libXau.so.6 => /usr/lib/arm-linux-gnueabihf/libXau.so.6 (0xb6044000)
libpcre.so.3 => /lib/arm-linux-gnueabihf/libpcre.so.3 (0xb600b000)
libgthread-2.0.so.0 => /usr/lib/arm-linux-gnueabihf/libgthread-2.0.so.0 (0xb6001000)
libffi.so.5 => /usr/lib/arm-linux-gnueabihf/libffi.so.5 (0xb5fef000)
libuuid.so.1 => /lib/arm-linux-gnueabihf/libuuid.so.1 (0xb5fe3000)
libxcb.so.1 => /usr/lib/arm-linux-gnueabihf/libxcb.so.1 (0xb5fc8000)
libXdmcp.so.6 => /usr/lib/arm-linux-gnueabihf/libXdmcp.so.6 (0xb5fbd000)
output of case2 ( keep the MainWindow class):
libQtGui.so.4 => /usr/lib/arm-linux-gnueabihf/libQtGui.so.4 (0xb68fd000)
libQtCore.so.4 => /usr/lib/arm-linux-gnueabihf/libQtCore.so.4 (0xb66f5000)
libstdc++.so.6 => /usr/lib/arm-linux-gnueabihf/libstdc++.so.6 (0xb664a000)
libgcc_s.so.1 => /lib/arm-linux-gnueabihf/libgcc_s.so.1 (0xb6626000)
libc.so.6 => /lib/arm-linux-gnueabihf/libc.so.6 (0xb6541000)
libfontconfig.so.1 => /usr/lib/arm-linux-gnueabihf/libfontconfig.so.1 (0xb6515000)
libpthread.so.0 => /lib/arm-linux-gnueabihf/libpthread.so.0 (0xb64f9000)
libaudio.so.2 => /usr/lib/arm-linux-gnueabihf/libaudio.so.2 (0xb64e1000)
libglib-2.0.so.0 => /lib/arm-linux-gnueabihf/libglib-2.0.so.0 (0xb6422000)
libpng12.so.0 => /lib/arm-linux-gnueabihf/libpng12.so.0 (0xb6401000)
libz.so.1 => /lib/arm-linux-gnueabihf/libz.so.1 (0xb63e8000)
libfreetype.so.6 => /usr/lib/arm-linux-gnueabihf/libfreetype.so.6 (0xb6383000)
libgobject-2.0.so.0 => /usr/lib/arm-linux-gnueabihf/libgobject-2.0.so.0 (0xb6344000)
libSM.so.6 => /usr/lib/arm-linux-gnueabihf/libSM.so.6 (0xb6337000)
libICE.so.6 => /usr/lib/arm-linux-gnueabihf/libICE.so.6 (0xb631f000)
libXrender.so.1 => /usr/lib/arm-linux-gnueabihf/libXrender.so.1 (0xb6311000)
libXext.so.6 => /usr/lib/arm-linux-gnueabihf/libXext.so.6 (0xb62fe000)
libX11.so.6 => /usr/lib/arm-linux-gnueabihf/libX11.so.6 (0xb6215000)
libm.so.6 => /lib/arm-linux-gnueabihf/libm.so.6 (0xb61aa000)
/lib/ld-linux-armhf.so.3 (0xb6fe1000)
libdl.so.2 => /lib/arm-linux-gnueabihf/libdl.so.2 (0xb619f000)
librt.so.1 => /lib/arm-linux-gnueabihf/librt.so.1 (0xb6191000)
libexpat.so.1 => /lib/arm-linux-gnueabihf/libexpat.so.1 (0xb616f000)
libXt.so.6 => /usr/lib/arm-linux-gnueabihf/libXt.so.6 (0xb612d000)
libXau.so.6 => /usr/lib/arm-linux-gnueabihf/libXau.so.6 (0xb6123000)
libpcre.so.3 => /lib/arm-linux-gnueabihf/libpcre.so.3 (0xb60ea000)
libgthread-2.0.so.0 => /usr/lib/arm-linux-gnueabihf/libgthread-2.0.so.0 (0xb60e0000)
libffi.so.5 => /usr/lib/arm-linux-gnueabihf/libffi.so.5 (0xb60ce000)
libuuid.so.1 => /lib/arm-linux-gnueabihf/libuuid.so.1 (0xb60c2000)
libxcb.so.1 => /usr/lib/arm-linux-gnueabihf/libxcb.so.1 (0xb60a7000)
libXdmcp.so.6 => /usr/lib/arm-linux-gnueabihf/libXdmcp.so.6 (0xb609c000)
output of case3 (use abc class):
libQtGui.so.4 => /usr/lib/arm-linux-gnueabihf/libQtGui.so.4 (0xb681c000)
libQtCore.so.4 => /usr/lib/arm-linux-gnueabihf/libQtCore.so.4 (0xb6614000)
libstdc++.so.6 => /usr/lib/arm-linux-gnueabihf/libstdc++.so.6 (0xb6569000)
libgcc_s.so.1 => /lib/arm-linux-gnueabihf/libgcc_s.so.1 (0xb6545000)
libc.so.6 => /lib/arm-linux-gnueabihf/libc.so.6 (0xb6460000)
libfontconfig.so.1 => /usr/lib/arm-linux-gnueabihf/libfontconfig.so.1 (0xb6434000)
libpthread.so.0 => /lib/arm-linux-gnueabihf/libpthread.so.0 (0xb6418000)
libaudio.so.2 => /usr/lib/arm-linux-gnueabihf/libaudio.so.2 (0xb6400000)
libglib-2.0.so.0 => /lib/arm-linux-gnueabihf/libglib-2.0.so.0 (0xb6341000)
libpng12.so.0 => /lib/arm-linux-gnueabihf/libpng12.so.0 (0xb6320000)
libz.so.1 => /lib/arm-linux-gnueabihf/libz.so.1 (0xb6307000)
libfreetype.so.6 => /usr/lib/arm-linux-gnueabihf/libfreetype.so.6 (0xb62a2000)
libgobject-2.0.so.0 => /usr/lib/arm-linux-gnueabihf/libgobject-2.0.so.0 (0xb6263000)
libSM.so.6 => /usr/lib/arm-linux-gnueabihf/libSM.so.6 (0xb6256000)
libICE.so.6 => /usr/lib/arm-linux-gnueabihf/libICE.so.6 (0xb623e000)
libXrender.so.1 => /usr/lib/arm-linux-gnueabihf/libXrender.so.1 (0xb6230000)
libXext.so.6 => /usr/lib/arm-linux-gnueabihf/libXext.so.6 (0xb621d000)
libX11.so.6 => /usr/lib/arm-linux-gnueabihf/libX11.so.6 (0xb6134000)
libm.so.6 => /lib/arm-linux-gnueabihf/libm.so.6 (0xb60c9000)
/lib/ld-linux-armhf.so.3 (0xb6f00000)
libdl.so.2 => /lib/arm-linux-gnueabihf/libdl.so.2 (0xb60be000)
librt.so.1 => /lib/arm-linux-gnueabihf/librt.so.1 (0xb60b0000)
libexpat.so.1 => /lib/arm-linux-gnueabihf/libexpat.so.1 (0xb608e000)
libXt.so.6 => /usr/lib/arm-linux-gnueabihf/libXt.so.6 (0xb604c000)
libXau.so.6 => /usr/lib/arm-linux-gnueabihf/libXau.so.6 (0xb6042000)
libpcre.so.3 => /lib/arm-linux-gnueabihf/libpcre.so.3 (0xb6009000)
libgthread-2.0.so.0 => /usr/lib/arm-linux-gnueabihf/libgthread-2.0.so.0 (0xb5fff000)
libffi.so.5 => /usr/lib/arm-linux-gnueabihf/libffi.so.5 (0xb5fed000)
libuuid.so.1 => /lib/arm-linux-gnueabihf/libuuid.so.1 (0xb5fe1000)
libxcb.so.1 => /usr/lib/arm-linux-gnueabihf/libxcb.so.1 (0xb5fc6000)
libXdmcp.so.6 => /usr/lib/arm-linux-gnueabihf/libXdmcp.so.6 (0xb5fbb000)