Extended Video on the Macbook : Xrandr ftw!

Update: I wrote this quite a while ago and never posted it pending more testing.  I figure it can be helpful in its current state to more users than just myself.  So, in the spirit of release early, release often here are steps that I took for configuring extended display on my MacBook. 

Based on the flood of feedback yesterday with suggestions on getting the extended display setup I’m going to attempt to blog what I have figured out. I’m still not 100% on the steps yet but hopefully this’ll help people get started and perhaps work some of the kinks out of the setup. I would like to get a better proper tutorial, but for now I want to get this written down while its fresh in my memory.

1. I had some odd issues if both displays were connected at login prior to configuration. Login to your desktop without the external monitor connected. Connect the monitor after you’ve completely logged in.
2. Connect the external monitor and generate a new default xorg.conf (sudo dpkg-reconfigure -phigh xserver-xorg).
3. Figure out the highest resolution you want between the two screens (1440×900+1280×800 = 2720×1700). Calculate based on what you have. In my case my external does 1440×900. I add that to the 1280×800 of the macbook and get my total.
4. Edit your xorg.conf file and add the line to the Section “Screen” > SubSection “Display” area. Add Virtual 2720 1700 (your resolution).
5. Log out after saving the xorg.conf file (unplug the external monitor until after you’ve logged back in successfully)
6. xrandr –output VGA –auto
7. xrandr –output VGA –above LVDS

In further testing I no longer have the issue in step 1, 5 above, but I leave it there as others may have similar problems.  In regards to my hardware I am using a MacBook with an onboard intel video card.  Card information via lspci output:

00:00.0 Host bridge: Intel Corporation Mobile 945GM/PM/GMS, 943/940GML and 945GT Express Memory Controller Hub (rev 03)
00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)

I now use extended desktop quite a bit and the only “issue” is that compiz-fusion is disabled if the resolution goes this high.  Not a big issue, but something to be aware of.  I hope this helps some more of you get extended display working.  It’s very nice 🙂