radeon MergedFB and vertical monitor offsets

Keith Lea keith at cs.oswego.edu
Sat Nov 27 18:16:27 PST 2004

> Date: Sat, 27 Nov 2004 15:54:16 -0500
> From: Alex Deucher <alexdeucher at gmail.com>
> Subject: Re: radeon MergedFB and vertical monitor offsets
> On Sat, 27 Nov 2004 13:21:36 -0500, Keith Lea <keith at cs.oswego.edu> wrote:
>>Hi, I'm using the radeon MergedFB mode to use dual monitors on my IBM
>>T30 laptop with Radeon 7500 Mobile.
>>I have a problem: my external monitor sits about 4 inches above my
>>laptop LCD screen. So, for example, when I move my mouse to the right,
>>onto the external monitor screen, the mouse jumps up 4 inches visually.
>>It's disorienting for me.
>>On Windows XP, you can drag around the screens to tell Windows where the
>>monitors are physically located relative to each other. This makes it so
>>when I move the mouse over to the second screen, it moves down 300
>>pixels or so, but visually, it's at the same vertical location.
>>I was wondering if there's a way to do this with MergedFB mode.
> if you are talking about locking the viewports (so the frame doesn't
> move within the virtual desktop), then, no.  there was a patch posted
> a while back the locked the crtcs into position, but the mouse and
> non-xinerama aware windows could still end up in the dead space.  The
> other option is to run the same resolution on both heads so that the
> viewport doesn't move.
> Another option is to use "regular" dualhead + xinerama and then set up
> the offsets in the serverlayout.
> Alex

No, this isn't what I meant, I don't think. I don't know what "locking 
the viewports" or "frame doesn't move within the virtual desktop" mean.

Maybe this will explain it better: I have an LCD and a monitor. I set 
both to 1024x768. I use MergedFB mode to get one giant desktop which 
spans the two, so my desktop is 2048x768. I want to create a virtual 
desktop which contains 2048*768 pixels, but they are not in a rectangle. 
They are in a shape like this:

+-----+     |
|           |
|     +-----+

The lower-left box's pixels would be shown on my laptop LCD screen. The 
upper-right box's pixels would be shown on my external monitor. This 
way, my desktop matches the physical locations of my computer screens, 
and when I move my mouse between the two screens, it stays at the same 
vertical visual position.

Now, again, my question, is there a way to do this with MergedFB mode of 
radeon driver?


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