Dumping this here… from my blog…

VirtualBox EFI Screen Resolution

vbox_screenres.txt

The window of a VirtualBox VM with EFI boot simply cannot fit my laptop screen - and I hate running a VM with scrollbars. So, after looking around for while, I found the solution. Understandably, it requires running command line.
 
    VBoxManage setextradata LiveBox VBoxInternal2/EfiGraphicsResolution 800x600
 
I want the window for my VM (LiveBox) to be at most 800x600. We can check that value by running,
 
     VBoxManage getextradata LiveBox VBoxInternal2/EfiGraphicsResolution
 
While we are at it, to view the current firmware used by a VM,
 
    VBoxManage showvminfo LiveBox | grep Firmware
 
And, finally, to actually select a firmware (options: bios / efi),
 
    VBoxManage modifyvm LiveBox --firmware efi
 
That's about that.

VirtualBox EFI Shell

vbox_efi_shell.txt

I am using VirtualBox quite a bit (I occasionally go qemu from time to time), especially to test my live Linux builds. I now mostly setup my virtual machines to have the EFI boot enabled. However, whenever I do an installation, the machine will most of the time stop at a UEFI shell prompt.
 
To boot the previously installed system, you need to identity your EFI partition (e.g. fs0) from the listed devices and look for the path to the bootloader (e.g. grubx64.efi). You can type (these are case insensitive),
 
    FS0:
    \EFI\ubuntu\grubx64.efi
 
It should now boot. But, you will still get that prompt on the next boot. To make it permanent,
 
    FS0:
    edit startup.nsh
 
That will start a text editor. Write exactly what we typed before to boot. Press <Ctrl+s> and <Enter> to save, and <Ctrl+q> to quit. Now, your bootloader should execute when the system starts.

more coming soon…