[Qt-embedded-interest] "error opening frame buffer device /dev/fb0"

Peter.Walton at pace.com Peter.Walton at pace.com
Thu Mar 26 11:39:43 CET 2009 

I'm afraid that do you need to obtain the sources for the QT/X11 edition in order to build the 'qvfb' project.

It may well be worth your while to have 3 QT4.5 installations :

1. Full X11 implementation, (i.e. the SDK) - used to develop your application on the host.  
2. Embedded for x86, used to ensure that your applications runs ok with embedded QT - runs with qvfb.
3. Embedded for your final target.

In this way you can use QT Creator to rapidly switch your project between the 3 QT variants.

Regards,
Pete

p.s. The QT Creator that is part of the 4.5 SDK binary installation does not work correctly with Fedora Core 10.  I noted earlier that you are using FC8, hopefully you won't have a problem.  If you do, then you'll need to build QT Creator and support libraries from source.


-----Original Message-----
From: qt-embedded-interest-bounces at trolltech.com
[mailto:qt-embedded-interest-bounces at trolltech.com]On Behalf Of
Avishek_Sharma
Sent: 26 March 2009 07:03
To: qt-embedded-interest at trolltech.com
Subject: [Qt-embedded-interest] "error opening frame buffer device
/dev/fb0"


Hi again,
   am still stuck with the Qt embedded installation.I did try moving the PATH handling to ~./bashrc but after that,when I opened a terminal window,it shows up empty(even the 'root at localhost' didn't show)so,I changed it back to it's original form and made the changes in .bash_profile.Rebooted the system and now 'which qmake 'shows the one associated with Qt-embedded.

I tried running the 'textedit' demo again and it didn't show any errors when I ran 'make'.When I tried executing it './textedit -qws' ,I get a continuous stream of this message---
QScreenLinuxFb::connect:No such file or directory
Error opening framebuffer device /dev/fb0

The 'analogclock' widget example is working fine  when i run ./analogclock -qws'

I went over the link 'http://doc.trolltech.com/4.5/qvfb.html'.There it's written
"Ensure that you have all the necessary libraries needed to build the tool, then compile and run the qvfb tool as a normal Qt for X11 application (i.e., do not compile it as a Qt for Embedded Linux application):
 cd path/to/Qt/tools/qvfb
 make
 ./qvfb"

Now,the thing is I can't find the "tools" folder for Qt /X11. Qt/X11 was installed by someone else in my system(don't know who) and I can't find the original Qt/X11 folder which was downloaded from the internet(which contains "tools" folder)
I guess ,unless I do the above mentioned step,I won't have qvfb working properly.So,is there any other alternative(than reinstalling everything again).
Please advice.
Thank you for your time.
regards,
Avi

_______
Hi,

First of all, you should implement Markus Franke's suggestion and move
the PATH handling to ~/.bashrc
It will likely save you some future head aches.

 From your mail, we can see that the textedit application now compiles,
but it can't find a display.
That's why you're seeing the -qws warning.

I don't know which graphical back-end you're trying to use, but you need
to make sure you pass the correct parameters to Qt's configure script
before building the library and then set the correct environment
variables before running any Qt program.
The Display settings can be found here:
http://doc.trolltech.com/4.5/qt-embedded-displaymanagement.html
(more information on other configurable runtime settings can be found on
http://doc.trolltech.com/4.5/qt-embedded-running.html )
If you want to use the virtual frame buffer, read up on it here:
http://doc.trolltech.com/4.5/qvfb.html

Kind regards,

Jeroen

Avishek_Sharma wrote:
> Hello Jereon,
>     I am not quite familar with Linux terms so,I guess when you say 'start a new shell' you mean ,do I open a new terminal window to run the 'textedit' example after modifying my .bash_profile.
> I did that but it didn't make any difference.But,when I tried your suggestion 'source ~/.bash_profile',I got the following messages on trying to run the demo.
> [root at localhost ~]# source ~/.bash_profile
> [root at localhost ~]# cd /usr/local/Trolltech/QtEmbedded-4.5.0-tp1/demos/textedit
> [root at localhost textedit]# qmake textedit.pro
>
> [root at localhost textedit]# make
> g++ -c -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_SHARED -I../../mkspecs/qws/linux-x86-g++ -I. -I../../include/QtCore -I../../include/QtNetwork -I../../include/QtGui -I../../include -I. -I. -o textedit.o textedit.cpp
> g++ -c -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_SHARED -I../../mkspecs/qws/linux-x86-g++ -I. -I../../include/QtCore -I../../include/QtNetwork -I../../include/QtGui -I../../include -I. -I. -o main.o main.cpp
> /usr/local/Trolltech/QtEmbedded-4.5.0-tp1/bin/moc -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_SHARED -I../../mkspecs/qws/linux-x86-g++ -I. -I../../include/QtCore -I../../include/QtNetwork -I../../include/QtGui -I../../include -I. -I. textedit.h -o moc_textedit.cpp
> g++ -c -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_SHARED -I../../mkspecs/qws/linux-x86-g++ -I. -I../../include/QtCore -I../../include/QtNetwork -I../../include/QtGui -I../../include -I. -I. -o moc_textedit.o moc_textedit.cpp
> /usr/local/Trolltech/QtEmbedded-4.5.0-tp1/bin/rcc -name textedit textedit.qrc -o qrc_textedit.cpp
> g++ -c -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_SHARED -I../../mkspecs/qws/linux-x86-g++ -I. -I../../include/QtCore -I../../include/QtNetwork -I../../include/QtGui -I../../include -I. -I. -o qrc_textedit.o qrc_textedit.cpp
> g++ -Wl,-O1 -Wl,-rpath,/usr/local/Trolltech/QtEmbedded-4.5.0-tp1/lib -o textedit textedit.o main.o moc_textedit.o qrc_textedit.o    -L/usr/local/Trolltech/QtEmbedded-4.5.0-tp1/lib -lQtGui -L/usr/local/Trolltech/QtEmbedded-4.5.0-tp1/lib -lpng -lfreetype -lQtNetwork -lQtCore -lz -lm -lrt -ldl -lpthread
>
> [root at localhost textedit]# ./textedit
> QWSSocket::connectToLocalFile could not connect:: No such file or directory
> QWSSocket::connectToLocalFile could not connect:: No such file or directory
> QWSSocket::connectToLocalFile could not connect:: No such file or directory
> QWSSocket::connectToLocalFile could not connect:: No such file or directory
> QWSSocket::connectToLocalFile could not connect:: No such file or directory
> QWSSocket::connectToLocalFile could not connect:: No such file or directory
> No Qt for Embedded Linux server appears to be running.
> If you want to run this program as a server,
> add the "-qws" command-line option.
> ******************************************
> Earlier running 'make' used to generate errors  but this time it didn't show errors .Only when I try to execute the program,it shows the above messages.
> Also 'which qmake' still shows /usr/local/Trolltech/Qt-4.4.3/bin/qmake
> ******************************************
> (contents of .bash_profile are as follows)
>  #!/bin/bash
> # .bash_profile
>
> # Get the aliases and functions
> if [ -f ~/.bashrc ]; then
>         . ~/.bashrc
> fi
>
> # User specific environment and startup programs
>
> PATH=$PATH:$HOME/bin
> PATH=/usr/local/Trolltech/QtEmbedded-4.5.0-tp1/bin:$PATH
> export PATH
> unset USERNAME
> *********************************************
>
> Any idea/advice on what else I could try?
> Thank you for your time and advice.
> regards,
> Avishek
>
>
>
>
> ________________________________________
> From: Jeroen De Wachter [jeroen.dewachter at barco.com]
> Sent: Tuesday, March 24, 2009 2:44 PM
> To: Avishek_Sharma
> Cc: Markus Franke; qt-embedded-interest at trolltech.com
> Subject: Re: [Qt-embedded-interest] problems in installing Qt-embedded 4.5 in   Linux fedora 8
>
> Hi Avishek,
>
> Do you start a new shell after modifying .bash_profile ?
> The new settings will only take effect in new shell instances (or if you
> execute 'source ~/.bash_profile' ).
>
> Regards,
>
> Jeroen
>
> Avishek_Sharma wrote:
>
>> Hi Markus,
>>     I tried your suggestion but couldn't get the demo to work.There was already a .bash_profile in ' /root'.So,I changed the contents of the PATH there to this -
>>      PATH=/usr/local/Trolltech/QtEmbedded-4.5.0-tp1/bin:$PATH
>>         export PATH
>> I also added #!/bin/bash as the first line in the file(and also tried without it) .Then did the chmod u+x .bash_profile and then tried running the 'textedit' demo .It showed the same errors as before and even now when I run 'which qmake' it shows -
>>  root at localhost:-which qmake
>> /usr/local/Trolltech/Qt-4.4.3/bin/qmake.
>>
>> Any other ideas or suggestions you might have would be welcome.Also,thank you very much for your time and advice.
>> regards,
>> Avishek
>>
>>
>>
>> ________________________________________
>> From: Markus Franke [Franke.M at sebakmt.com]
>> Sent: Tuesday, March 24, 2009 2:03 PM
>> To: Avishek_Sharma
>> Cc: qt-embedded-interest at trolltech.com
>> Subject: Antwort: problems in installing Qt-embedded 4.5 in     Linux fedora 8
>>
>> Avishek_Sharma <Avishek_Sharma at satyam.com> schrieb am 24.03.2009 08:57:05:
>>
>>
>>
>>> How do I change it?I did try  setting
>>> PATH=/usr/local/Trolltech/QtEmbedded-4.5.0-tp1/bin:$PATH   export PATH
>>> (directly copied from the install.txt  ) in  .profile(which I created in
>>> 'root' directory as I  didn't find any pre existing '.profile' in my
>>> 'root' directory(even after ls -a) ).Do I need to do something else or ,
>>> am I pasting it in the wrong directory?I am new to Linux,so,I assumed
>>> '/root' is 'home directory for root user...right.
>>>
>>>
>> Maybe you need to rename the file to ".bash_profile". Then make it executable by "chmod u+x .bash_profile".
>> The first line of the file might need to contain the line "#!/bin/bash". The file needs to be located in the "/root" directory.
>>
>> Mit freundlichen Grüßen / Best regards
>>
>> Markus Franke
>> Entwicklung/ Development
>>
>> SebaKMT
>> Hagenuk KMT Kabelmesstechnik GmbH
>> Röderaue 41
>> 01471 Radeburg / Germany
>> Reg.Gericht (01067 Dresden) HRB 12567
>> Geschäftsf.: Dr. Max Iann
>>
>> Phone +49 (0)35208 84 29142
>> Fax      +49 (0)35208 84 29249
>>
>> e-mail: franke.m at sebaKMT.com
>> web: http//www.sebaKMT.com
>>
>> DISCLAIMER:
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>
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