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

[Avishek_Sharma]

Hi ,
 Thanks a lot for all the advice and suggestions.I will download Qt/X11 and try compiling qvfb from there(since,I am currently working on a Desktop system,no target device yet so,I believe I will need to compile qvfb).
Thanks once again for your time and patience.I hope I will get it right this time...or,I will be here asking questions again  :)
Regards,
Avi

________________________________________
From: Markus Franke [Franke.M at sebakmt.com]
Sent: Thursday, March 26, 2009 4:13 PM
To: Avishek_Sharma
Cc: Jeroen De Wachter; qt-embedded-interest at trolltech.com
Subject: Antwort: "error opening frame buffer device /dev/fb0"

Avishek_Sharma <Avishek_Sharma at satyam.com> schrieb am 26.03.2009 08:02:46:

> 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.

Strange behaviour but finally you got the correct path.

> 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

This is usually caused by improper settings of the permissions on "/dev/fb0".

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

That's strange.

> 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"

No. You don't need qvfb necessarily. QVFB from the Qt/X11 tools folder is only needed in case you want to have a virtual framebuffer on your host machine for testing. You don't need this on your target.

> 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).

If you want to use QVFB on your host you need to get a fresh Qt/X11 tarball from qtsoftware.com and compile the QVFB from there.

Mit freundlichen Grüßen / Best regards

Markus Franke
Entwicklung/ Development

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