how do I get my ubuntu VM to auto adjust the screen resolution to fit my macbook pro or an external monitor?

Question

I'm running an ubuntu guest on a mac osx host using virtual box. I'm trying to get the screen resolution to auto adjust to both my macbook pro as well as an external (2nd) monitor.

The tutorials available on line have me using the CLI to add resolutions like

xrandr --addmode 1440x900

I've already tried:

xrandry --newmode "1440x900_60.00"  106.50  1440 1528 1672 1904  900 903 909 934 -hsync +vsync

so, when I type 'xrandr" this is the output:

Screen 0: minimum 64 x 64, current 1024 x 768, maximum 32000 x 32000
VBOX0 connected 1024x768+0+0 0mm x 0mm
1024x768       60.0*+
800x600        60.0  
640x480        60.0  

So, how do I get my ubuntu VM to auto adjust the screen resolution to fit my macbook pro or an external monitor?

Answer 1

The key was to increase the Video Memory in VirtualBox for my ubuntu VM. See this link for the answer. See this question on the ubuntu forums.

Answer 2

What worked for me was installing virtualbox-guest-x11.

Host: mid 2014 MacBookPro 15in

Guest: Ubuntu 12.04.5 LTS Desktop AMD64

sudo apt-get install virtualbox-guest-x11

Answer 3

I have be struggling to fix this for some time now. I am using Mac OS Catalina 10.15.3 and Trying to install Ubuntu 16.04 on Virtual Box version 6.0.14.

I had tried adding 'Guest Additions CD' image, installing virtualbox-guest-x11 etc but didn't work. At last what worked for me was this

Created a new VM then before installing OS I changed below configuration

Virtual Box > Settings > Display

Increased Video Memory from default 16Mb to 128 Mb and graphics controller to 'VBoxSVGA'

Then installed Ubuntu 16.04, and by default the resolution is perfect.