Dualboot under VirtualBox?

[Pete_5]

Hi all,
for testing purposes I'd like to configure a dualboot system (Windows 10 + Kubuntu 20.04) with EFI using VirtualBox 6.1 on a Kubuntu 20.04 host.

I've tried to set it up like on a real machine: First install Windows, then install Ubuntu on a free partition, then start the wanted OS using the bootmanager grub installed by Ubuntu.
But this way doesn't work under VirtualBox, the grub bootmanager doesn't show up, always windows starts.

Any ideas how to configure a dualboot under VirtualBox with EFI?

Kind Regards
Pete

[mpack]

I've tried to set it up like on a real machine: ...
But this way doesn't work under VirtualBox

The fact that's it's EFI is probably significant: the boot mechanism is totally different, i.e. EFI specifies a boot manager in a "system partition" (usually around 100MB). You would have to replace or reconfigure that boot manager.

Why did you select EFI? It seems like an unnecessary complication.