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I am new to virtual box (v6.1.12), I am trying to create a new virtual pc running centOS 8.2.2004. I set up the machine in an acceptable manner, creating a virtual HDD 20GB, 4GB ram and selecting my CentOS ISO file. I then boot my machine and it makes it to the install promt. As soon as I select install my screen goes black and all I have is a flashing underscore (_) in the top left of the screen. I cannot get beyond this point. Checking my logs I have noticed an error:

Guest Log: int13_harddisk: function 02, unmapped device for ELDL=8e
Guest Log: int13_harddisk_ext: function 41, unmapped device for ELDL=8f

Not really sure what it means, can it not find the virtual hard disk to install to? I will attach full logs. I am running windows 10 which I upgraded from 7, Don't know if that is relevant. Sorry if this is a repeat question but I can't find someone with my exact situation and problem. Virtualisation is enabled and Microsoft hyper V is disabled. Although I have managed to run a kali machine previously on Microsoft hyper v, I just cannot get virtual box to work. I need to use it to participate in my class, so any advice or help would be greatly appreciated.

Your log contains these lines:

{timestamp} HM: HMR3Init: Attempting fall back to NEM: VT-x is not available
{timestamp} NEM: WHvCapabilityCodeHypervisorPresent is TRUE, so this might work...

You might notice in the guest window's Status Bar the green turtle: The choice of animal is appropriate: Your guest is running, just really slow. Or it might guru-meditate or crash. This is because a service that uses Microsoft Hyper-V is running on your host PC. Normally Hyper-V blocks Virtualbox. But your PC is of the type and OS where Virtualbox can attempt to run the guest using the Hyper-V engine. This arrangement is still being developed and isn't 100% yet.

If VirtualBox is running without Hyper-V enabled, and nothing else is interfering with hardware virtualization (VT-x / AMD-V), then the usual virtualization icon () will be seen in the Status Bar.

To turn Hyper-V off completely, do this:

1. Shut down all programs. You will have to reboot your host.

2. Look into I have a 64bit host, but can't install 64bit guests, 2nd post, points 2 & 3 and ensure that none of these things are running.

3. Find the Command Prompt icon, right click it and choose Run As Administrator.

4. Enter this command:

bcdedit /set hypervisorlaunchtype off

5. Enter this command:

shutdown -s -t 2

6. When the computer turns off, unplug it for 20 seconds. Then plug it in again and boot up Windows 10.

Your Virtualbox should be running now. If the green turtle still appears and the tell-tale lines are in the log, try all the steps again. If you don't get the standard virtualization icon, post back exactly what you did and we'll try to help some more.

For further info, see https://www.tenforums.com/tutorials/139 ... puter.html

Once you have resolved the problem highlighted by scottgus1 you probably also need re-visit your resource allocation:

You say you have allocated 4GB RAM to the CentOS VM but the log contains this line:

0:00:02.978687 Host RAM: 8109MB (7.9GB) total, 2647MB (2.5GB) available

So you are were overcommitting RAM when the Log was recorded. I would suggest reducing the CentOS RAM allocation to 2GB, which should be sufficient, but set the Video RAM allocation to ether 64 or 128MB if you want a functional GUI; and, In my experience, most modern 64-bit Linux Installers expect to 'see' (or require) at least a Dual Core Processor to perform an installation, so also make sure you have allocated 2 CPUs to the VM.