Fixing Resolution Problem of Ubuntu On Paralles Desktop

Problem

After installing Ubuntu 8.04 Hardy Heron in Parallels Desktop on my Macbook Pro, the default resolution is 1024*768. I want to use my Macbook pro's 1440*900 full resolution. I tried to use System->Preference->Screen Resolution, but there are not 1440*900 at all.

Solution

Basic idea: The problem arises because Ubuntu fails to detect the settings of my monitor automatically. Then can I mannually modify xorg.conf to set the right resolution? Let's go!

Open up a terminal. First Backup the original xorg.conf

sudo cp /etc/X11/xorg.conf  /etc/X11/xorg.conf.backup

Next open, open xorg.conf with your favorite editor

sudo vi /etc/X11/xorg.conf

Search the section "Screen" like below.

Section "Screen"
   Identifier "Default Screen"
   Device  "Generic Video Card"
   Monitor  "Generic Monitor"
EndSection

Probabably your file contains more lines similar to the following

SubSection "Display"
   Depth  24
   Modes  "1024x768" "800x600" "640x480"
EndSubSection

Note the line "Modes "1024x768" "800x600" "640x480"". It says that there are three different kinds resolutions, but our desired resolution 1440x900 is omitted. So we can simply add this resolution option. It is like the following after modification

SubSection "Display"
   Depth  24
   Modes  "1440x900" "1024x768" "800x600" "640x480"
EndSubSection

It’ll appear several times throughout the file. Each time you see it, just add your desired resolution (in your case, 1440×900).

If your file doesn't contain a similar Subsection "Display" inside the Section "Screen" (as shown above), you just add the Subsection "Display" yourself. And th final result looks like

Section "Screen"
   Identifier "Default Screen"
   Device  "Generic Video Card"
   Monitor  "Generic Monitor"
   DefaultDepth 24
   SubSection "Display"
       Depth  1
       Modes  "1440x900" "1024x768" "800x600" "640x480"
   EndSubSection
   SubSection "Display"
       Depth  4
       Modes  "1440x900" "1024x768" "800x600" "640x480"
   EndSubSection
   SubSection "Display"
       Depth  8
       Modes  "1440x900" "1024x768" "800x600" "640x480"
   EndSubSection
   SubSection "Display"
       Depth  15
       Modes  "1440x900" "1024x768" "800x600" "640x480"
   EndSubSection
   SubSection "Display"
       Depth  16
       Modes  "1440x900" "1024x768" "800x600" "640x480"
   EndSubSection
   SubSection "Display"
       Depth  24
       Modes  "1440x900" "1024x768" "800x600" "640x480"
   EndSubSection
EndSection

Finally save the above modifications. Restart your X session by pressing Ctrl-Atl-Breakspace (or reboot your ubuntu), it just works!

If you encounter total messy after this modificaion, don't panic because you still have the backup of the original xorg.conf!

Reference
1. http://gonz.wordpress.com/2007/09/22/fixing-screen-resolution-on-ubuntu-linux-in-parallels-desktop/
2. http://www.simplehelp.net/2007/04/30/how-to-increase-the-screen-resolutions-available-to-ubuntu-while-running-in-parallels-for-os-x/