MergedFB/Xinerama/LUT with radeon driver

Alex Deucher alexdeucher at
Mon Aug 14 20:09:23 PDT 2006

On 8/14/06, Frédéric <frederic.mantegazza at> wrote:
> Hello,
> I'm trying to help the developper of the Argyllcms project to add support
> for Xinerama on ATI/NVidia cards. I personnaly use the free radeon driver
> comming with standard Xorg package, with a ATI M9 Mobility, in MergedFB
> mode. And there are some problems with dual screen detection with Argyll.
> As one other user of Argyll package has similar problems with its NVidia
> card using TwinView, I hope understanding how things work in the radeon
> driver will help.
> So, let me explain what are the problems.
> 1) When used MergedFB mode, the radeon driver provides Xinerama
> informations. So, with 2 monitors connected, the XineramaIsActive()
> function returns True, and XineramaQueryScreens() returns 2 as second
> argument. There is no problem to acces to first screen informations using
> XF86VidModeGetMonitor(), but then, it fails on second. Here is the error :
> X Error of failed request:  BadValue (integer parameter out of range for
> operation)
>   Major opcode of failed request:  136 (XFree86-VidModeExtension)
>   Minor opcode of failed request:  4 (XF86VidModeGetMonitor)
>   Value in failed request:  0x4c
>   Serial number of failed request:  12
>   Current serial number in output stream:  12
> I'm sure there is a way to do that, because KDE handles this mode correctly
> (some other apps, like gqview, also handle this correctly, but they light
> use KDE information rather than directly use Xinerama low level
> functions).
> So, could someone help me (us)? I attached the piece of code from Argyll
> project...
> 2) The second problem is about LUT. When using xcalib, the loaded LUT is
> common for both screens. Is there a way, when using MergedFB mode, to load
> a different LUT for each screen?

currently, you can't access the secondary CLUT in mergedfb mode.  If
you need to adjust it you'll have to use "regular" dualhead.
Hopefully keithp's new multi-head xrandr code will take this into


> Regards,
> PS : there is a parameter in radeon driver which disables Xinerama
> informations; if turned on, then KDE is unabled to maximize a window on
> only one screen, and fullscreen mode expand on both screens two. So, this
> is not an issue.
> --
>    Frédéric
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