Virtualization
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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
Many 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
Hypervisors | Virtualization type | Description | Gentoo package name |
---|---|---|---|
qemu | full[1]/software-emulation | QEMU's own Tiny Code Generator. This is the default. More frequently denoted as qemu and not qemu/tcg so often. | app-emulation/qemu |
VMware ESXi | native | VMware, Inc. sells a variety of closed-source hypervisors. Type-1 virtualization. Also uses libvirt driver. | app-emulation/open-vm-tools |
Xen | native, paravirtualization[2] | Native, bare-metal, hypervisor that allows multiple distinct virtual machines (referred to as domains) to share a single physical machine. Type-1 Virtualization; supports Microsoft Windows as a guest OS. Also can do Type-2 Virtualization which does not support Microsoft Windows as a guest OS[3] | app-emulation/xen |
VirtualBox | paravirtualization[4] | Cross-platform virtualization software that allows users to run guest operating systems inside a Virtualbox host operating system. | app-emulation/virtualbox |
Bhyve (FreeBSD) | paravirtualization[5] | bhyve, the "BSD hypervisor" is a hypervisor/virtual machine manager available on FreeBSD, macOS, and Illumos. | |
User-Mode Linux (UML) | paravirtualization[6] | The UML driver for libvirt allows use and management of paravirtualized guests built for User Mode Linux. UML is a software-assist, Type-2 virtualization. | incorporated into mainstream Linux repository in 2016 |
Wikipedia has more on virtualization this over at Libvirt#Supported Hypervisors.
Containers
Containers provide isolated user space instances.
Containers
All containers are OS-level virtualization type.
Virtualizer | Description | Gentoo package name |
---|---|---|
Buildah | Tool that facilitates building OCI images | app-containers/buildah |
Docker | Container virtualization environment which can establish development or runtime environments without modifying the environment of the base operating system. | app-containers/docker |
Incus | System container and virtual machine manager, fork of LXD | app-containers/incus |
LXC (Linux Containers) | Virtualization system making use of the cgroups and namespaces features of the Linux kernel. | app-containers/lxc |
LXD | Next generation system container manager. | app-containers/lxd |
Podman | Daemonless container engine for developing, managing, and running OCI Containers on linux. | app-containers/podman |
systemd-nspawn | systemd nspawn | sys-apps/gentoo-systemd-integration |
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.
Command-Line Interfaces
Name | Package | Description |
---|---|---|
Libvirt | app-emulation/libvirt | CLI toolkit to manage virtual machines. |
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
Most virtualization systems provide software to be installed inside the guest operating systems, to provide extra functionality.
These packages are for Gentoo guests running inside virtual machines. See respective hypervisor documentation for tools helping to run other operating systems inside virtual machines.
Name | Package | Description |
---|---|---|
VirtualBox | app-emulation/virtualbox-guest-additions | VirtualBox Guest Additions |
VMware | app-emulation/open-vm-tools | VMware, Inc. sells a variety of closed-source hypervisors. |
See also
- Comparison of virtual machines — compares the features of several platform virtual machines.
- GPU passthrough with virt-manager, QEMU, and KVM — directly present an internal PCI GPU to a virtual machine
- Recommended applications — applications recommended for use in a graphical environment (X11, Wayland)
- QEMU — a generic, open source hardware emulator and virtualization suite.
- QEMU/Front-ends — facilitate VM management and use
- Libvirt — a virtualization management toolkit.
- Libvirt/QEMU_networking — details the setup of Gentoo networking by Libvirt for use by guest containers and QEMU-based virtual machines.
- Libvirt/QEMU_guest — covers libvirt and its creation of a virtual machine (VM) for use under the soft-emulation mode QEMU hypervisor Type-2, notably using virsh command.
- Virt-manager — desktop user interface for management of virtual machines and containers through the libvirt library
- Virt-manager/QEMU_guest — QEMU creation of a guest (VM or container)
- QEMU/Linux guest — describes the setup of a Gentoo Linux guest in QEMU using Gentoo bootable media.
External resources
- Libvirt#Supported Hypervisors (Wikipedia)
References
- ↑ https://en.wikipedia.org/wiki/Full_virtualization
- ↑ https://en.wikipedia.org/wiki/Paravirtualization
- ↑ https://documentation.suse.com/sles/15-GA/html/SLES-all/cha-virt-support.html
- ↑ https://en.wikipedia.org/wiki/Paravirtualization
- ↑ https://en.wikipedia.org/wiki/Paravirtualization
- ↑ https://en.wikipedia.org/wiki/Paravirtualization