I have an Ubuntu 9.04 guest running on a VirtualBox VM hosted by MacOS X Tiger. I'm trying to increase the screen resolution as the guest by default unfortunately supports only 800x600 and 640x480.

I have done some research and also studied the answers to question 1660 on this site. I understand that the change of screen resolution requires the installation of the "Linux Guest Additions". As described on this page, I tried Devices>>Install Guest Additions from the menu of the VM.

The according CD image was properly mounted to the Ubuntu desktop but after running "sudo bash ./VBoxLinux" in /media/cdrom all I got was "Detected unsupported X86 environment".

According to the VirtualBox manual it should also be possible to resize the VM window and thereby change the screen resolution of the guest. The menu item Machine>>Auto Resize Guest Display is activated and grayed out. Changing the actual window size of the VM window does not show any effect on the screen resolution of the Ubuntu guest.

This kind of concludes my effort so far. I'd like to know if someone managed to increase the screen resolution of an Ubuntu guest running on a VirtualBox/MacOS X.

2 Answers 2


Wes made a comment on the article you mentioned which helped several others that had the same problem:

Slight change for step 3 on new version of VirtualBox for Windows Hosts. there are different versions of the additions for x86 and amd64 platforms. between setps 2 and 3 you can type ‘ls’ and see what the exact name of the additions are for your platform, then do “sudo bash ./VBoxAdditions-###.run”, replacing the ### with x86 or amd64.

Try running the sudo bash ./VBoxLinuxAdditions-x86.run command after cd-ing to the guest additions installation CD.

  • great advice, I was missing that comment. For the record, I ran /media/cdrom/VBoxLinuxAdditions-x86.run which properly installed the Linux Guest Additions. This and giving a video mode hint using VBoxManage (I was browsing the manual for "video mode hint") got me the resolution I like to work with (MonoDevelop is so much more fun now ;-). Thanks a lot. Aug 28, 2009 at 4:27

I found a solution... while the VM is running...

  1. go to a command-prompt[windows+r,type cmd ,enter]...
  2. cd to C:\Program Files\Oracle\VirtualBox and
  3. run this command

VBoxManage controlvm "Ubuntu10.10" setvideomodehint 1280 800 32

where "Ubuntu10.10" is your VM name... and ur VM resolution would change on the fly.. :) and yes change the 1280 800 32 string to any resolution u want... note 32 is here the bit-depth..

i assume that u have installed the guest additions first..

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