Virtualization

Resources

Virtualization is the concept and technique that permits running software in an environment separate from a computer operating system.

The operating system actually running on the hardware is referred to as the host. On this host resides a hypervisor (aka virtual machine manager), which runs virtual machines containing guest software.

Hardware feature

Most modern computer architectures include support for virtualization at the hardware level.

For the AMD64 and x86 computer architectures, hardware virtualization is supported via AMD's AMD-V (svm) or Intel's Vt-x (vmx) virtualization extensions. The virtualization extensions must be supported by the processor and enabled in the system's firmware (typically the motherboard's firmware menu) in order to be accessible by guest operating system(s).

System firmware

Accessing the appropriate menu for enabling virtualization support in the system firmware is beyond the scope of this article. Each manufacture has a sightly different navigation and title for the setting. Generally, there is a toggle for "Virtualization" under the CPU settings of the motherboard firmware.

Once enabled at the firmware level, validate support is available in the kernel.

Kernel support

AMD CPUs

To inspect hardware for virtualization support issue the following command:

user $grep --color -E "svm" /proc/cpuinfo

The running kernel supports hardware virtualization when "svm" is visible in the output.

Intel CPUs

Hardware virtualization support for Intel based systems can be tested by running the following command:

user $grep --color -E "vmx" /proc/cpuinfo

The running kernel supports hardware virtualization when "vmx" is visible in the output.

Available software

Hypervisors

Name	Package	Description
QEMU	app-emulation/qemu	Quick EMUlator, a generic, open source, hardware emulator and virtualization suite.
VirtualBox	app-emulation/virtualbox	Cross-platform virtualization software that allows users to run guest operating systems inside a host operating system.
Xen	app-emulation/xen	Native, bare-metal, hypervisor that allows multiple distinct virtual machines (referred to as domains) to share a single physical machine.

Containers

Containers provide isolated user space instances.

Name	Package	Description
Buildah	app-containers/buildah	Tool that facilitates building OCI images.
Docker	app-containers/docker	Container virtualization environment which can establish development or runtime environments without modifying the environment of the base operating system.
LXC (Linux Containers)	app-containers/lxc	Virtualization system making use of the cgroups feature of the Linux kernel.
LXD	app-containers/lxd	Next generation system container manager.
Podman	app-containers/podman	Daemonless container engine for developing, managing, and running OCI Containers on linux.

Orchestration

Container orchestration concerns the details of managing multiple Linux containers. This management layer spins up and spins down individual containers. Examples of container managers are Docker and Mesos, although others exist. There is also container orchestration where K8/docker swarm and related software compete for similar management functions.

GUIs

Name	Package	Description
GNOME Boxes	gnome-extra/gnome-boxes	Simple GNOME application to access remote or virtual systems.
virt-manager	app-emulation/virt-manager	Graphical tool for administering virtual machines.
VirtualBox	app-emulation/virtualbox	A GUI is included by default with VirtualBox. The `headless` USE flag is can be enabled to remove GUI support.

Guest facilities

Guest facilities are packages that are installed and configured inside the guest domain (VM) that enables better interactions with its VM manager on the host platform. Such extra functionality may entail power-switch handling, graphic card passthrough, battery-level, or keyboard handling.

Note
While guest facilities deals with Linux-centric guest OS, there are some tools that are specific to the host's (non-Linux) operating system.

The following packages are for Gentoo guests running inside virtual machines. See Category:QEMU Guests for tools helping to run other operating systems inside virtual machines.

Name	Package	Description	Host O/S
ACPI	sys-power/acpid	for proper shutdown handling by libvirt	Linux
USB	net-misc/spice-gtk	USB redirection	Linux
VirtualBox	app-emulation/virtualbox-guest-additions	VirtualBox Guest Additions	Windows/Linux/macOS
VMware	app-emulation/open-vm-tools	VMware, Inc. sells a variety of closed-source hypervisors.	Windows/Linux/macOS