accessing bios/uefi of windows 10 virtual machine

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sleepy12345
Posts: 1
Joined: 20. Jul 2022, 12:38

accessing bios/uefi of windows 10 virtual machine

Post by sleepy12345 »

On a windows 10 host machine, the bios/uefi is usually accessed by spamming a certain key(esc, f2,f10 etc..) or going through the advanced startup options and going into uefi firmware settings. But, in a vm these options do not work. I have seen people accessing their bios with linux based distros set up as there vm though.

What i tried:
I tried to access the bios the traditional way, but that didnt work.
I tried to enable efi in the virtual box gui for that vm but it just starts up in a uefi interactive shell when i try to access it, and i cant get to the desktop from there.
I also enabled nested vt-x/amd from the virtual box gui, but that didnt solve any issues. I looked up youtube videos and tech articles about the matter but they all suggest similar stuff. I went through the virtual box posts but didnt find anything(if im wrong about that, please link the relevant posts)

why i want to access the bios/uefi:
Is there any way to access the bios/uefi? I want to access the bios to enable virtualization option, which will allow me to use the windows subsystem for linux on that vm and to host another vm from it which i currently cant do. I consulted the windows subsystem for linux documentation and it mentions for windows virtual machines, i must access the bios of the vm and enable virtualization.

host machine info:
linux mint 20.3(if you need any more info let me know)

I attached the virtual box logs. any other info you need, let me know and ill provide it.
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scottgus1
Site Moderator
Posts: 20965
Joined: 30. Dec 2009, 20:14
Primary OS: MS Windows 10
VBox Version: PUEL
Guest OSses: Windows, Linux

Re: accessing bios/uefi of windows 10 virtual machine

Post by scottgus1 »

It's good that you included the "why", because that situation is a non-starter. Although Virtualbox supports nested virtualization now, it's only for Virtualbox/KVM inside Virtualbox, not for Hyper-V inside Virtualbox. If I remember correctly, Hyper-V (the backbone behind WSL2) needs SLAT/Nested Paging, which Virtualbox does not pass through to the nested VM.

To answer the first question, Virtualbox has two kinds of BIOS: Legacy and EFI.

Legacy does not have a BIOS environment inside the VM. All the settings that could be adjusted in the VM's BIOS are actually set in the VM's settings in the main Virtualbox window.

EFI BIOS settings can be accessed by pressing ESC during the few seconds of EFI BIOS booting, before the VM's OS starts. The EFI environment will be a black text on gray background menu system. One can also get this environment if the VM boots to the EFI Shell, by executing the 'exit' command at the prompt.
fth0
Volunteer
Posts: 5668
Joined: 14. Feb 2019, 03:06
Primary OS: Mac OS X other
VBox Version: PUEL
Guest OSses: Linux, Windows 10, ...
Location: Germany

Re: accessing bios/uefi of windows 10 virtual machine

Post by fth0 »

scottgus1 wrote:Legacy does not have a BIOS environment inside the VM.
That's not true. Pressing "F12" as indicated in the VirtualBox legacy BIOS splash screen gives a BIOS menu which allows to select the boot device.
scottgus1
Site Moderator
Posts: 20965
Joined: 30. Dec 2009, 20:14
Primary OS: MS Windows 10
VBox Version: PUEL
Guest OSses: Windows, Linux

Re: accessing bios/uefi of windows 10 virtual machine

Post by scottgus1 »

fth0 wrote:Pressing "F12" as indicated in the VirtualBox legacy BIOS splash screen gives a BIOS menu which allows to select the boot device.
That's true. I was thinking of the usual expectations of a full text BIOS like on older PCs, which isn't there in Virtualbox's legacy BIOS.
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