[Qt-embedded-interest] /dev/fb0

[Chris Pane]

Exactly,

You have to the Qt configure program what frame buffer support you want,
then run qvfb, then your program. -qvfb tells configure to build the shared
memory frame buffer driver.

Oh - And I checked, you need to install the standard linux/x11 Qt, and
manually build (typing make) qvfb.

Also - if you still stuck, you can also turn on some of the Qt internal
debug support, which will echo to the screen progress. The frame buffer open
code is pretty straight forward, if something more systemic is wrong, you
should be able to track it down.

Good luck !

-Chris


On Sun, Mar 22, 2009 at 1:54 PM, Donal <donaloconnor at gmail.com> wrote:

> Did you compile QT/Embedded with qvfb support on your development machine
> by specifying it in the configure option:
>
> eg: *./configure -prefix /usr/local/qte4 **-qvfb*
>
> Like Chris said, qvfb doesn't come with QT Embedded, so you must compile
> this from the QT X11 sources.
> Then once this is compiled, have qvfb running before you launch your
> applications.
>
> Donal
>
>
> On Sun, Mar 22, 2009 at 5:44 PM, pushparaj muthu <
> muthu.pushparaj at gmail.com> wrote:
>
>> Hi Chris
>>
>> Yes absolutely correct
>>
>> I want to run the Qt Frame buffer for development and have Qt UI interact
>> with it.
>>
>> But I did not get understand why it throws error message
>>
>> QscreenLinuxFb: Connect; No such file or directory
>> Error opening frame buffer device /dev/fbo
>>
>> How to solve this issue
>>
>> Regards
>> Raj
>>
>>
>>
>> On 3/22/09, Chris Pane <chris.pane at labxtechnologies.com> wrote:
>>>
>>> Are you trying to use the linux virtual frame buffer or the Qt
>>> virtual/simulator frame buffer?
>>>
>>> I do most of my host side Qt Embedded development using the qvfb
>>> simulator, which creates a Qt Virtual frame buffer w/ shared memory. So in
>>> that case, your Qt program would use the shared memory region as a frame
>>> buffer and the qvfb simulator program (qvfb is an example or tool Qt
>>> application in the standard host side linux Qt tarball (Last I checked, it
>>> was not part of the embedded kit)) displays the UI. You can even skin QVFB
>>> to look like your device.
>>>
>>> The linux virtual frame buffer is simply a mmaped region that sets itself
>>> up and allows programs to write to it. You can verify whats written by
>>> dumping /dev/fb0 but thats about it.
>>>
>>> It hink you want to run the Qt framebuffer for development as that lets
>>> you see you Qt UI and interact with it.
>>>
>>> -Chris
>>>
>>>
>>>
>>>
>>> If you want to run
>>>
>>> On Sat, Mar 21, 2009 at 3:35 PM, Donal <donaloconnor at gmail.com> wrote:
>>>
>>>> Are you sure you have permissions to open /dev/fb0
>>>>
>>>> You might not have read/write permission under your current user. Have
>>>> you tried modifying permissions or switching to root user.
>>>>
>>>> Donal
>>>>
>>>>   On Sat, Mar 21, 2009 at 6:58 PM, pushparaj muthu <
>>>> muthu.pushparaj at gmail.com> wrote:
>>>>
>>>>
>>>>>   Hi
>>>>>
>>>>>
>>>>>
>>>>> I have downloaded qt-embedded -Linux -open source-src -4.43 and
>>>>> compiled the code
>>>>>
>>>>>
>>>>>
>>>>> When I try to run example program with –qws (virtual frame buffer is
>>>>> working  )
>>>>>
>>>>>
>>>>>
>>>>> It gives error message QscreenLinuxFb: Connect; No such file or
>>>>> directory
>>>>>
>>>>>
>>>>>
>>>>> Error opening frame buffer device /dev/fbo
>>>>>
>>>>>
>>>>>
>>>>> But I have enabled frame buffer support in my desktop kernel (fedora 8)
>>>>>
>>>>>
>>>>>
>>>>> Please guide me in the right direction
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Regards
>>>>>
>>>>> Raj
>>>>>
>>>>>
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>>>>>
>>>>>
>>>>
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-- 
Chris Pane
Embedded Digital Engineer
Lab X Technologies, LLC
176 Anderson Ave, Suite 302
Rochester, NY 14607
http://www.labxtechnologies.com
chris.pane at labxtechnologies.com
(585) 271-7790 x208
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