Radeon and dri dual head

Alex Deucher alexdeucher at gmail.com
Mon Jun 13 14:21:29 PDT 2005

On 6/13/05, Loren A. Linden Levy <lindenle at uiuc.edu> wrote:
> Hi,
> I have an ATI Technologies Inc Radeon IGP 330M in my Compaq laptop,
> and I am using X.org vers 6.8.2. Forst thanks a bunch for everything
> this is the first radeon drivcer I have used that actually gives me
> dual head and dri support with this hardware. My xorg.conf has:
> Section "Device"
>         Identifier      "ATI RADEON 0"
>         Driver          "ati"
> #       Driver          "radeon
>         VendorName "ATI"
>         BoardName "Radeon Mobility U2"
>         VideoRam 65536
>         BusID "PCI:1:5:0"
>         Option "AGPMode" "4"
>         Option "DPMS"
>         Option "AGPFastWrite" "On"
>         Option "EnablePageFlip" "On"
>         Option "MonitorLayout" "LVDS, CRT"
>         Option "CRT2Position" "RightOf"
>         Option "CRT2HSync" "30-94"
>         Option "CRT2VRefresh" "50-75"
>         Option "MergedFB" "true"
>         Screen 0
> EndSection
> My problem is two things:
> 1. If I run glxgears(or any other openGL code) on either of the two
> monitors it changes back from Xinerama to cloned mode.

that was a bug with pageflipping in 6.8.x  you can either try
xorg/mesa/drm from cvs, or turn off pageflipping:
         Option "EnablePageFlip" "False"

If you want to try cvs you can either build from source or grab teh
nightly binary snapshots here:

> 2. When there is no second monitor it still uses Xinerama mode.

when you set mergedfb to true it will force mergedfb on regardless of
whether you have a second monitor attached or not.  you can try
removing these lines:
         Option "MonitorLayout" "LVDS, CRT"
         Option "MergedFB" "true"
from your config.  However, you may have to add them back if the
driver is not able to detect the attached displays properly.

you can also leave those lines and add metamodes that include a clone
mode, then you can switch between dualhead and single head with


> So is there any way to fix my configuration so these two things dont
> happen or is it just the limitation of the driver.
> P.S. I also tried to run Xinerama using a dual screen configuration
> but did not have any luck.
> Thanks for any help.
> --
> ---------------------------------------------
> Loren A. Linden Levy
> 481 Loomis, Department of Physics
> University of Illinois at Urbana-Champaign
> 1110 W. Green St., Urbana, IL 61801-3080
> Tel:   217-244-7995   Fax: 217-333-1215
> Email: lindenle at uiuc.edu
> url:   http://w3.physics.uiuc.edu/~lindenle/

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