Virtualization #KVM

Virtualization #KVM

brandvpsbrandvps Member

Kernel-based Virtual Machine (KVM) is virtualization infrastructure for the Linux Kernel that turns it into a hypervisor. It was merged into the Linux kernel mainline in kernel version 2.6.20, which was released on February 5, 2007.KVM requires a processor with hardware virtualization extension. KVM has also been ported to FreeBSD and illumos in the form of loadable kernel modules.

A wide variety of guest operating systems work with KVM, including many flavours and versions of Linux, BSD ,Solaris ,Windows ,Haiku ,ReactOS ,Plan9 ,AROS Research Operating System and OS X.

Avi Kivity began the development of KVM at Qumranet, a technology startup comapany that was acquired by Red Hat in 2008. KVM was merged into the Linux kernel mainline in kernel version 2.6.20, which was released on 5 February 2007. KVM is maintained by Paolo Bonzini.Stable release was on 1.2.0 on September 5, 2012.

By itself, KVM does not perform any emulation. Instead, it exposes the /dev/kvm interface, which a userspace host can then use to: 1.Set up the guest VM's address space. The host must also supply a firmware image (usually a custom BIOS when emulating PCs) that the guest can use to bootstrap into its main OS. 2.Feed the guest simulated I/O. 3.Map the guest's video display back onto the host. On Linux,QEMU versions 0.10.1 and later is one such userspace host. QEMU uses KVM when available to virtualize guests at near-native speeds, but otherwise falls back to software-only emulation.

Comments

  • AlexBarakovAlexBarakov Member, Provider

    Spamming to increase your post count would not give you a Provider's tag ;)

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  • maldoviamaldovia Member

    thank you for this informative article, however i think it is important to also mention openvz:

    OpenVZ (Open Virtuozzo) is an operating system-level virtualization technology for Linux. It allows a physical server to run multiple isolated operating system instances, called containers, virtual private servers (VPSs), or virtual environments (VEs). OpenVZ is similar to Solaris Containers and LXC.

    While virtualization technologies like VMware and Xen provide full virtualization and can run multiple operating systems and different kernel versions, OpenVZ uses a single patched Linux kernel and therefore can run only Linux. All OpenVZ containers share the same architecture and kernel version. This can be a disadvantage in situations where guests require different kernel versions than that of the host. However, as it does not have the overhead of a true hypervisor, it is very fast and efficient.

    Memory allocation with OpenVZ is soft in that memory not used in one virtual environment can be used by others or for disk caching. While old versions of OpenVZ used a common file system (where each virtual environment is just a directory of files that is isolated using chroot), current versions of OpenVZ allow each container to have its own file system.

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  • brandvpsbrandvps Member

    @AlexBarakov well that will be taken care of better

  • ewrekewrek Member

    @brandvps You forget to tell that this info is from Wikipedia https://en.wikipedia.org/wiki/Kernel-based_Virtual_Machine

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