Phyllome OS targets [x86-64 systems](https://en.wikipedia.org/wiki/X86-64) supporting hardware-assisted virtualization, with a strong preference for those providing IOMMU-based virtualization as well (AMD Vi or Intel VT-d).
> *Sitting idle, Phyllome OS consumes approximately 1 CPU core and 1.5 GB of RAM. This requirement scales up with the number of virtual machines running on any dedicated host: the more the virtual machines are running, the more ressources Phyllome OS will use*
> *A CPU that supports hardware-assisted virtualization is not be enough, as the motherboard also requires to support this feature. Laptop motherboards seem to be lagging behind desktop motherboards when it comes to supporting this feature. As a result of this, **desktop motherboards** are usually better candidates for Phyllome OS*
> *For Intel-based configurations, you can check if your model supports **Intel VT-x** by following [this link](https://ark.intel.com/content/www/us/en/ark/search/featurefilter.html?productType=873&2_VTX=true).*
> *For Intel-based configurations, you can check if your model supports **Intel VT-d** by following [this link](https://ark.intel.com/content/www/us/en/ark/search/featurefilter.html?productType=873&0_VTD=True).*
Unfortunately, even on supported computer platforms, hardware-assisted virtualization is rarely turned on by default. In other words, it is not enough for a computer platform to support hardware-assisted virtualization: it needs to be explicitly enabled.
The process to activate this feature requires accessing the firmware configuration tool for your motherboard, which is part of your BIOS or UEFI. This process, which differs depending on your current OS, is described in the following section.
> *Did you know that the Open Virtual Machine Firmware (OVMF), which is based on [TianoCore](https://www.tianocore.org/), is the default firmware for EFI-based virtual machines? Its configuration utility can be accessed using the <kbd>Esc</kbd> key.*
The process to access the main motherboard firmware configuration utility differ depending on which operating system is currently installed on your computer.
#### Windows 8 and newer: command-line instructions
Press the <kbd>Win</kbd> and <kbd>X</kbd> keys simultaneously to make a context menu appears. Then press <kbd>Shift</kbd> and <kbd>a</kbd> to politely ask Windows to open `Powershell` using elevated privileges, and click on the `Yes` button to bypass the User Account Control pop-up. Finally, input the following command inside the command prompt and press `enter`.
Hardware-assisted virtualization is a hit or miss on Apple computers, as there is no way to access the firmware configuration tool on these computers. Apple users can go to the [install section](https://wiki.phyllo.me/deploy/medium) directly, create a USB stick and hope that hardware-assisted virtualization will be supported.
During the POST phase, you need to press a certain key to access the firmware configuration tool for your motherboard, which is part of your BIOS or UEFI.
Just after pressing the <kbd>power</kbd> button, hit the right key to access the firmware configuration tool, usually <kbd>F2</kbd> or <kbd>Del</kbd>, but it may be another keystroke on your model.
Unfortunately, most firmware configuration tool do differ, and the steps here might not be identical on your current platform. In general, the sought after features are found under the *Security* tab.
For an AMD-based computer, you need to look for references to *AMD SVM*, AMD V or AMD Vi. For an Intel-based computer, you need to look for *Intel VT-x* and *Intel VT-d*. It is also possible that the feature will be referred simply to as *Virtualization*. In that case, you may not know if it actually refers to IOMMU-based hardware-assisted virtualization.
Here is a visual walk-through for an Intel NUC computer.
* After you have pressed the <kbd>F2</kbd> key on boot, this screen should appear.
* Go to the *Security* tab. Under the *Security Features* menu, you will find two options, *Intel Virtualization Technology* and *Intel VT for Directed I/O (VT-d)*.
* Check these boxes
Then *save and exit* the configuration tool, which will reboot your computer.
> *While you are there, you could also change the boot order, to make sure that your computer will boot from an attached USB thumb drive first when it will be time to try out Phyllome OS.*
This section will show you how to modify the boot order permanently, so you can boot from a USB flash drive attached to your computer, a necessary step to install or use Phyllome OS as a live system.
* That's it. Save changes and exist. Note that it is advisable to revert these changes after a successful installation, or to only change the bootloader temporary.
> ***Failing to activate hardware-assisted virtualization** will make running virtual machines extremly **slow**, or not possible at all. If, for some reasons, it cannot be activated on your computer, for example because of a lack of hardware support, you would be better off picking a Linux distribution which doesn't require it, such as [Debian](https://www.debian.org/distrib/).*
