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How To Check if CPU VT Extensions are Enabled in BIOS from Linux Command Line

Ubuntu 9

Virtualization Technology (VT) is a set of enhancements to newer processors that improve performance for running a virtual machine by offloading some of the work to the new cpu extensions. VT extensions can be enabled or disabled in your computer’s BIOS settings, but how do you check if they are enabled or disabled from the Linux command line? This article will guide you through the process.

Quick Answer

To check if CPU VT extensions are enabled in BIOS from the Linux command line, you can use either the kvm-ok command from the cpu-checker package or the rdmsr command from the msr-tools package. The kvm-ok command checks for the existence of the /dev/kvm file, while the rdmsr command reads the value of the VT extensions status register.

Prerequisites

Before we begin, you need to have a Linux-based operating system. The instructions in this article are based on Ubuntu 10.10, but they should work on other distributions with minor modifications. You should also have superuser (root) access to run the necessary commands.

Method 1: Using the cpu-checker Package

The cpu-checker package provides a command called kvm-ok that checks your processor’s capabilities for running hardware virtualization. To install it, open a terminal and type:

sudo apt-get install cpu-checker

After the installation is complete, you can run the kvm-ok command:

sudo kvm-ok

If VT extensions are enabled in the BIOS, you should see the following message:

INFO: /dev/kvm exists
KVM acceleration can be used

If they are disabled, you will see a message like this:

INFO: /dev/kvm does not exist
HINT: sudo modprobe kvm_intel
INFO: Your CPU supports KVM extensions
INFO: KVM (vmx) is disabled by your BIOS
HINT: Enter your BIOS setup and enable Virtualization Technology (VT),
 and then hard poweroff/poweron your system

The kvm-ok command checks the /dev/kvm file, which is a character device that allows user-space programs to utilize the KVM kernel extension. If this file exists, it means that KVM acceleration can be used, which implies that VT extensions are enabled.

Method 2: Using the msr-tools Package

The msr-tools package provides utilities to access the processor’s model-specific registers (MSRs). One of these registers, 0x3A, contains the status of the VT extensions. To install msr-tools, use the following command:

sudo apt-get install msr-tools

Next, you need to load the msr module, which provides an interface to read and write the MSRs:

sudo modprobe msr

Finally, you can check the status of the VT extensions with the rdmsr command:

sudo rdmsr 0x3A

If the command returns 5, it means that VT extensions are enabled. If it returns 1, they are disabled.

Conclusion

Checking the status of the VT extensions from the Linux command line can be a bit technical, but with the right tools and commands, it’s a straightforward process. Remember that even if your processor supports VT extensions, they might be disabled in the BIOS, so you might need to enable them manually to take full advantage of your hardware’s virtualization capabilities.

What is Virtualization Technology (VT)?

Virtualization Technology (VT) is a set of enhancements to newer processors that improve performance for running a virtual machine by offloading some of the work to the new CPU extensions.

How can I check if CPU VT extensions are enabled in the BIOS from the Linux command line?

There are two methods you can use to check if CPU VT extensions are enabled in the BIOS from the Linux command line. The first method involves using the cpu-checker package and running the kvm-ok command. The second method involves using the msr-tools package and running the rdmsr command.

How do I install the `cpu-checker` package?

To install the cpu-checker package, open a terminal and run the command sudo apt-get install cpu-checker.

What does the `kvm-ok` command do?

The kvm-ok command checks your processor’s capabilities for running hardware virtualization. It checks the existence of the /dev/kvm file, which indicates whether VT extensions are enabled or disabled.

How do I install the `msr-tools` package?

To install the msr-tools package, open a terminal and run the command sudo apt-get install msr-tools.

What does the `rdmsr` command do?

The rdmsr command reads the value of a specific model-specific register (MSR). In this case, we use it to read the status of the VT extensions by specifying the MSR address 0x3A.

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