For every computer-related project I undertake, challenges inevitably arise. Regardless of how much I think I know about a subject, there’s always a new obstacle that pushes me to expand my understanding. Yet, these challenges often broaden my horizons and ultimately serve me well. That said, I can’t help but feel a bit sorry for my beleaguered computer, which has endured countless experiments and adjustments. As a result, I’ve decided it’s more practical to preserve its stability and instead rely on virtual machines (VMs) as a sandbox for my projects.
When working on a project, it always seems like the tasks you anticipate being the easiest turn out to be the most time-consuming and frustrating. This was precisely the case when I hit a roadblock in setting up Docker in a Linux Virtual Machine. I booted up Ubuntu through Oracle VirtualBox and started downloading Docker—a platform designed to run applications in lightweight, isolated containers. Docker, however, requires KVM (Kernel-based Virtual Machine), which provides hardware acceleration for virtualization. To my surprise, I was met with this error message:
“Your CPU does not support KVM extensions. KVM acceleration can NOT be used.”
Ok… why?
To investigate, I ran the command lscpu | grep -i virtualization in my terminal, which returned:
Virtualization type: full
This confirmed that my host system supports full virtualization but didn’t clarify whether nested virtualization was enabled inside the VirtualBox VM.
So, I tried the command egrep -c ‘(vmx|svm)’ /proc/cpuinfo to check for CPU virtualization extensions. Result: 0.
This indicated that the virtual CPU presented to my Ubuntu VM lacked the required VT-x (Intel) or SVM (AMD) extensions. These extensions are necessary for nested virtualization, and their absence usually means the hypervisor (VirtualBox) hasn’t enabled them.
To be thorough, I checked the VM’s BIOS settings and confirmed through Task Manager on my Windows host that nested virtualization was supported. I also discovered that VirtualBox had a setting to “Enable Nested VT-x/AMD-V.” Great! Problem solved, right? Wrong. The checkbox was greyed out. Why??
Time to investigate further. I ran systeminfo in my Windows PowerShell and found this message: A hypervisor has been detected. Features required for Hyper-V will not be displayed.
This suggested that Hyper-V, a competing hypervisor, was interfering with VirtualBox’s ability to access VT-x/AMD-V. To disable it, I ran: dism.exe /Online /Disable-Feature:Microsoft-Hyper-V and bcdedit /set hypervisorlaunchtype off. After rebooting, I checked again—no luck. Hyper-V was still causing issues.
Next, I went into Windows settings to disable related features. From Control Panel > Programs > Turn Windows features on or off, I unchecked:
- Hyper-V
- Windows Subsystem for Linux (WSL 2)
- Virtual Machine Platform
- Containers
After restarting the computer, I returned to VirtualBox, and finally, the “Enable Nested VT-x/AMD-V” checkbox was no longer greyed out. I enabled the setting, started the VM, and ran the egrep -c ‘(vmx|svm)’ /proc/cpuinfo command again. This time, it returned 1. Success! KVM was now functional, and Docker installed without further issues.
This roadblock perfectly illustrates how a single issue can spiral into a labyrinth of interconnected challenges with endless variables to consider. While it was tedious to troubleshoot, this is the lifeblood of computer science, and there’s nothing quite like the satisfaction of finally getting things to work. The irony of it all? Setting up Docker was merely the first step.
If you ever encounter this specific issue, I hope this blog post can serve as a helpful guide through the same tangled maze I faced. Whether it’s shedding light on an obscure error, offering a solution, or simply reassuring you that you’re not alone in the frustration, I want this to be a resource you can turn to when you find yourself staring at a seemingly insurmountable problem. After all, the best part of solving a tough technical challenge isn’t just figuring it out for yourself—it’s being able to share what you’ve learned to make someone else’s journey a little bit easier.
