an error: 'undefined symbol: _ZN7QWidget8qwsEventEP8QWSEvent'

I have cross-compiled a Qt program and put it on the Raspberry Pi B+.

On my PC platform, the Qt version is 'qt-embedded-linux-opensource-src-4.5.3.tar.gz'. It is installed under directory ' /Qt4_5_3forARM ' on my PC.
So I copied all the files under ' /Qt4_5_3forARM/lib ' to the board with the same directory.

And I added the following two commands into '/etc/profile' on the raspberry-pi board:

Code:

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export QTDIR=/Qt4_5_3forARM
export LD_LIBRARY_PATH=$QTDIR/lib:$LD_LIBRARY_PATH

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Then

Code:

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#source /etc/profile

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But when I run the executable file(it has been cross-compiled, and for example, its name is 'Paint') on the board, it has an error: './Paint: symbol lookup error: ./Paint: undefined symbol: _ZN7QWidget8qwsEventEP8QWSEvent'.

So who knows what's the reason and how to solve it ?
Thank you !

Does ldd ./Paint find all the needed libs?

Quote:

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Originally Posted by wysota

Does ldd ./Paint find all the needed libs?

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Oh, no, it prints out:' not a dynamic executable'.
But I don't know what problem this information indicates.

What about readelf -h ./Paint and readelf -d ./Paint?

Quote:

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Originally Posted by wysota

What about readelf -h ./Paint and readelf -d ./Paint?

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when execute 'readelf -h ./Paint', it shows:

Code:

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ELF Header:
  Magic:   7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF32
  Data:                              2's complement, little endian
  Version:                          1 (current)
  OS/ABI:                          UNIX - System V
  ABI Version:                    0
  Type:                              EXEC (Executable file)
  Machine:                         ARM
  Version:                          0x1
  Entry point address:                        0xa9a0
  Start of program headers:                52 (bytes into file)
  Start of section headers:                  17112 (bytes into file)
  Flags:                                             0x5000002, has entry point, Version5 EABI
  Size of this header:                          52 (bytes)
  Size of program headers:                 32 (bytes)
  Number of program headers:            10
  Size of section headers:                   40 (bytes)
  Number of section headers:              31
  Section header string table index:     28

---

when execute 'readelf -d ./Paint', it shows:

Code:

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Dynamic section at offset 0x3eb8 contains 36 entries:
       Tag           Type                          Name/Value
 0x00000001 (NEEDED)                     Shared library: [libQtGui.so.4]
 0x00000001 (NEEDED)                     Shared library: [libQtNetwork.so.4]
 0x00000001 (NEEDED)                     Shared library: [libQtCore.so.4]
 0x00000001 (NEEDED)                     Shared library: [librt.so.1]
 0x00000001 (NEEDED)                     Shared library: [libdl.so.2]
 0x00000001 (NEEDED)                     Shared library: [libpthread.so.0]
 0x00000001 (NEEDED)                     Shared library: [libstdc++.so.6]
 0x00000001 (NEEDED)                     Shared library: [libm.so.6]
 0x00000001 (NEEDED)                     Shared library: [libgcc_s.so.1]
 0x00000001 (NEEDED)                     Shared library: [libc.so.6]
 0x0000000f (RPATH)                        Library rpath: [/Qt4_5_3forARM/lib]
 0x0000001d (RUNPATH)                   Library runpath: [/Qt4_5_3forARM/lib]
 0x0000000c (INIT)                           0xa538
 0x0000000d (FINI)                           0xb130
 0x00000019 (INIT_ARRAY)               0x13eac
 0x0000001b (INIT_ARRAYSZ)           4 (bytes)
 0x0000001a (FINI_ARRAY)               0x13eb0
 0x0000001c (FINI_ARRAYSZ)           4 (bytes)
 0x00000004 (HASH)                        0x81a8
 0x6ffffef5 (GNU_HASH)                    0x86a0
 0x00000005 (STRTAB)                     0x92e0
 0x00000006 (SYMTAB)                    0x8c10
 0x0000000a (STRSZ)                      3598 (bytes)
 0x0000000b (SYMENT)                    16 (bytes)
 0x00000015 (DEBUG)                     0x0
 0x00000003 (PLTGOT)                    0x14000
 0x00000002 (PLTRELSZ)                 728 (bytes)
 0x00000014 (PLTREL)                     REL
 0x00000017 (JMPREL)                     0xa260
 0x00000011 (REL)                          0xa238
 0x00000012 (RELSZ)                      40 (bytes)
 0x00000013 (RELENT)                    8 (bytes)
 0x6ffffffe (VERNEED)                      0xa1c8
 0x6fffffff (VERNEEDNUM)                3
 0x6ffffff0 (VERSYM)                       0xa0ee
 0x00000000 (NULL)                       0x0

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Hmm... when running ldd on the binary you did run it on Pi and not on your desktop, right?

Quote:

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Originally Posted by wysota

Hmm... when running ldd on the binary you did run it on Pi and not on your desktop, right?

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Yes, I executed the command '$ldd ./Paint' on the terminal of Pi.

It's hard to believe ldd told you it wasn't a dynamic executable. Especially that readelf does report a dynamic section.

Anyway... run readelf -s (or nm) on libQtGui.so.4.5.3 in /Qt4_5_3forARM and grep the result for qws. See if the missing symbol is there. If not, then the library is compiled without qws support.

Quote:

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Originally Posted by wysota

It's hard to believe ldd told you it wasn't a dynamic executable. Especially that readelf does report a dynamic section.

Anyway... run readelf -s (or nm) on libQtGui.so.4.5.3 in /Qt4_5_3forARM and grep the result for qws. See if the missing symbol is there. If not, then the library is compiled without qws support.

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I have run 'readelf -s libQtGui.so.4.5.3' in '/Qt4_5_3forARM/lib' and grep the result.
There is no '_ZN7QWidget8qwsEventEP8QWSEvent'.
But there are two lines of '_ZN7QWidget8qwsEventEP8QW':

Code:

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13651: OO1b7b8c      8    FUNC      GLOBAL   DEFAULT      11  _ZN7QWidget8qwsEventEP8QW
49614: OO1b7b8c      8    FUNC      GLOBAL   DEFAULT      11  _ZN7QWidget8qwsEventEP8QW

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Is it normal? If so, does it mean the missing symbol is not there?

Hi,
I got the same problem.
Did you solve the issue?

Thanks a lot,
Orian.

Dear All,
I have the same error and here are some information that can help to solve.
I use cross compilation on Ubuntu14.04 with qt-everywhere-opensource-src-4.8.2.tar.gz and the target is a BeagleBone Black RevC where libraries Qt4.8.2 were installed.

The goal is to run a graphical window created with QtCreator 3.4.2 onto the BBB (under debian/Angström).

First, I created manually this simple program that runs perfectly on the BBB:

Code:

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#include <QApplication>
#include <QLabel>
 
int main(int argc, char *argv[]){
   QApplication app(argc, argv);
   QLabel label("Hello BeagleBone!");
   label.resize(200, 100);
   label.show();
   return app.exec();
}

---

Then I created the same program with QtCreator and this program does not run on the BBB, it says:

undefined symbol: _ZN7QWidget8qwsEventEP8QWSEvent

The two programs were compiled using the same Makefile except that the QtCreator Makefile contains 4 more files:
- mainwindow.cpp
- mainwindow.h
- ui_mainwindow.h
- moc_mainwindow.cpp

The both programs gives same results with the command readelf -h and readelf -d (executed on BBB).
The both programs uses exactly the same libraries.

So what's missing on the BBB to run the QtCreator's program ?
Thanks for help.

Another interresting thing is that if I use QtDesigner Version 4.8.6 to build the popup, it works also very well on the BeagleBone Black.
So it means there is some specific call created by QtCreator Version 3.4.2, but which one ?

Hi there,

did someone found the solution to this problem?

I am facing the same error when i use QT to crosscompile to the BBB.

Hello michaelll,

I think there will never be a solution about this problem...
For my side, I changed to Qt 5 and the problem is gone!

Good luck