- Identify the resolution that your VirtualBox environment supports.
- Reboot the system and keep the Shift key till the grub windows appears then hit c.
- This will drop you into the grub console.
- Enter the commend vbeinfo to see a list of resolutions.
- Select the resolution that works for you (in my case, 1024x768x24).
- Edit /etc/default/grub to modify/create a line GRUB_GFXMODE=1024x768x24 (where you replace the resolution with the one appropriate for your environment).
- Update grub and reboot: sudo update-grub2 && shutdown -r now
After the reboot you should now have the new console screen size showing.