ati driver dual head 2nd monitor incorrect resolution

Alex Deucher alexdeucher at
Mon Oct 11 14:06:59 PDT 2004

On Mon, 11 Oct 2004 12:49:04 -0700 (PDT), John H. <mistamaila at> wrote:
> Ok
> I upgraded to 6.8.1 on my fc2 machine.
> I have a radeon 9600, and told my xorg.conf to use ati
> driver.
> If I have the following...
>         Option      "MetaModes" "1600x1200-1024x768"
> xinerama seems to work, but my second monitor, a flat
> panel LCD at 1024x768, scrolls vertically once I log
> in from xdm/gdm, so when I maximize apps in it I have
> to scroll down or up to see them all.
> If I do
> Option      "MetaModes" "1024x768-1024x768"
> Neither monitor needs to scroll(maximized apps work
> fine) but obviously I want a higher resolution on the
> first monitor, 1600x1200.
> any ideas?

use xinerama instead of mergedfb.  the scrolling is because with
mergedfb, there is one big framebuffer that both crtcs point into.  it
has be to big enough for both, so you get teh scrolling affect. you
can lock the frame movement if you feel like editing the code in
radeon_mergedfb.c, but then you risk having apps appear on a non
visible part of the framebuffer.   The behavior you want is "regular"
dualhead with xinerama.  to do that, set up  read the xinerama howto.
In "regular" dualhead, each screen has it's own framebuffer and
xinerama is used to stich them together as one single logical screen.


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