Is there a way to make the Mac OS X guest OS adapt the resolution of the host OS given that there's no guest additions yet as of the moment?
There is no way for it to automatically adjust, but you can specify a custom resolution for the guest to use.
You can manually edit the VirtualBox configuration, and the boot file in OS X to use a custom resolution. It's a two part (Host VM/Guest) process to enable the resolution.
Here are the steps:
First, make sure VirtualBox is not running. Close it if it is.
Add the following setting to the
<ExtraData>section of your VM's XML file (location
<ExtraDataItem name="CustomVideoMode1" value="1680x1050x32"/>
You can change the value above to your preferred display resolution, e.g. 1280x1024x32.
Save the file and start your VM.
In Mac open the
/Extrafolder in the Finder.
com.app.Boot.plistfile to the desktop.
Open the file on the desktop in the editor.
<key>Graphics Mode</key>entry, following that there should be a
<string>xxxxxx</string>entry. Edit this entry to match the Custom Video entry from step 2 above. i.e.
Put file back, Restart your VM and the new display resolution should be effective.
This is a bit late, but none of the other answers helped me. This video helped me. The instructions are very simple:
Power off your VM
Close VirtualBox, and any background processes (if applicable).
In the following code, edit "VM Name" to be your VM name and "N" to be 0 for a screen resolution of 640 x 480, 1 for 800 x 600, 2 for 1024 x 768, 3 for 1280 x 1024, 4 for 1440 x 900, and 5 for 1900 x 1200:
cd "C:\Program Files\Oracle\Virtualbox"
VBoxManage setextradata "VM Name" VBoxInternal2/EfiGopMode N
- Run the code in command prompt as admin
That should get the job done. If anything is unclear, check out the linked video.