Does Xfbdev support dual-head configuration??

prudhvi raj prudhviraj.v at gmail.com
Thu Dec 17 03:12:41 PST 2009


Thank you very much for your valuable inputs Mr Alex and Adam.

I am still a bit confused about where exactly this dual-head implementation
exists and how to make it up using tinyx server.

As per your replies i understand that in order to make dual-head working
using an Xserver it should have one of the below features
- XRandR extension with dual-head support or
- graphics driver associated with the X server (fbdev incase of Xfbdev
server) should implement the logic of mapping the framebuffer on to two
monitors. As fbdev being a generic driver written for linux framebuffer
device it does not have dual head implemented as all cards may not have
hardware configuration required to support dual-head.

Am i right??

Actually my objective is to run a tinyx server (preferably Xfbdev as it
succesfully runs on my target) on an e-book target and enable dual-head
display on it.

So In order to acheive this should i alter the fbdev driver (in Xfbdev) to
map it on to two different displays?? Or a is this the job of RnadR/XINERAMA
extensions??

Or Tinyx does not support dual-head at all?? I mean Kdrive itself does not
support dual-head??

i am mentioning some of the observations i made during my attmpts:

I am using the latest Xfbdev from X11R7.5 release and its having Xrandr
version 1.3. I think this is same as the Xrandr running on fedora 11. Does
this  Xrandr 1.3 has dual-head support?? But usinf this also giving the same
ouput as
> Screen 0: minimum 1024 x 768, current 1024 x 768, maximum 1024 x 768
> default connected 1024x768+0+0 (normal left inverted right x axis y
> axis) 0mm x 0mm
>   1024x768  0.0*

But on fedora Xrandr -q clearly giving the output mentioning the VGA1, VGA2
ouptupts and their current configuration.

I have tried to run Xnvidia server present in KDrive (X11R7.4 release) and
the Xrandr version present in it is 1.2. The graphics card is Nvidia Quadro
fx 1700. In this case also the server is showing display on one monitor
only. I guess its because the driver implemented in Xnvidia is out of date
and it could not properly configure some advanced graphics card like nvidia
Quadro fx 1700. is it so??

your inputs are highly valuable as not much information is available on net
regarding dual-head support in tinyX.


On Wed, Dec 16, 2009 at 8:35 PM, Alex Deucher <alexdeucher at gmail.com> wrote:

> On Wed, Dec 16, 2009 at 8:44 AM, prudhvi raj <prudhviraj.v at gmail.com>
> wrote:
> > I want to enable dual-head display using the KDrive tinyx server - Xfbdev
> > (X11R7.5 version). I am using Nvidia graphics card with two outputs
> > connected to two samsung monitors.
> >
> > When i boot up the system with Fedora 11, the server is auto detecting
> both
> > monitors and both the monitors are getting up and the screen is spanned
> > among the two monitors.
> >
> > But When i run the Xfbdev server the display is coming on only one
> monitor.
> >
> > xrandr -q is giving the below output
> > Screen 0: minimum 1024 x 768, current 1024 x 768, maximum 1024 x 768
> > default connected 1024x768+0+0 (normal left inverted right x axis y axis)
> > 0mm x 0mm
> >   1024x768  0.0*
> >
> > Why is Xrandr unable to detect the second monitor??
> >
> > The Xfbdev has been compiled with XINERAMA and XRANDR extensions.
> >
> > Should i need to configure Xfbdev in order to detect the dual head
> > configuration and show the display spanned among them??
>
> fbdev doesn't support dualhead.  You'll need to use a native driver
> for your GPU.
>
> Alex
>
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