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aglarond

Member

From: Texas, USA

Registered: 2008-11-20

Posts: 129

Getting external VGA monitor to work without cloning. [Solved]

Hey guys. I'm on a ThinkPad T42 with an older ATI card (ATI Technologies Inc Radeon Mobility M7 LW [Radeon Mobility 7500]). I'm using the open source drivers since I'm fairly sure the closed source drivers don't support this card.

Anyway, I can get an external monitor to work as a clone booting into X, but I can't get it to work as a separate screen. I've tried multiple xrandr commands, but it appears my card just won't do it.

This is my xrandr output when nothing's connected. Based on this, is it just not possible to do what I want?

# xrandr
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 1024 x 1024
VGA-0 disconnected (normal left inverted right x axis y axis)
DVI-0 disconnected (normal left inverted right x axis y axis)
LVDS connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1024x768       60.0*+   60.0
   800x600        60.3
   640x480        59.9
S-video disconnected (normal left inverted right x axis y axis)

I know it worked out of the box when this thing had Windows on it, so I know the hardware can do it. I'm wondering if it's just a driver restriction or if I just don't understand what I'm doing with randr.

Thanks
-mS

Last edited by aglarond (2009-02-10 03:24:01)

damjan

Member

Registered: 2006-05-30

Posts: 452

Re: Getting external VGA monitor to work without cloning. [Solved]

You need to setup a bigger Virtual screen size, look at my xorg.conf file. It's for intel, but nevertheless.. http://paste.lisp.org/display/74633 that "Virtual 2048 2048" is the important part. That allows me to have 2x 1024 wide screens side by side (or one 768 high + one 1280 high, one on top of the other).

Now my 945GM is limited to that total size, I don't know about your ATI, but you can try.

aglarond

Member

From: Texas, USA

Registered: 2008-11-20

Posts: 129

Re: Getting external VGA monitor to work without cloning. [Solved]

Awesome. I'll try those changes as soon as I get back to a desk wih a monitor. Thanks damjan.

-mS

aglarond

Member

From: Texas, USA

Registered: 2008-11-20

Posts: 129

Re: Getting external VGA monitor to work without cloning. [Solved]

I forgot to update this. Your solution was the right one, but it's not working. It won't let the virtual setting go as high as I want (looks to be a driver issue). Oh well.

Thanks again.

-mS

damjan

Member

Registered: 2006-05-30

Posts: 452

Re: Getting external VGA monitor to work without cloning. [Solved]

well, the usual workaround is to put the screens in vertical relation.
Since the vertical resolutions are most often smaller than the horizontal, you can put two screens one above the other and that will fit in your limited virtua screen.

BTW, what's the limit on your card and what driver are you using?

aglarond

Member

From: Texas, USA

Registered: 2008-11-20

Posts: 129

Re: Getting external VGA monitor to work without cloning. [Solved]

BTW, what's the limit on your card and what driver are you using?

It's giving me a 1600x1200 limit, no matter how far up I jack the virtual command in xorg. That's better than the 1024x1024 I was getting before the change, though.

Also, I'm using the GPL'd radeon kernel module (I assume it comes bundled with the kernel since I don't remember loading it) and the radeon driver from xf86-video-ati. I see that package also has an ati_drv.so, but I haven't used it.

I was pretty sure the Catalyst drivers don't support this card (ATI Technologies Inc Radeon Mobility M7 LW [Radeon Mobility 7500])

-mS