Kernel-based Virtual Machine
|Developer(s)||The Linux Kernel community|
|Platform||ARM, IA-64, PowerPC, S/390, x86, x86-64|
|License||GNU GPL or LGPL|
Kernel-based Virtual Machine (KVM) is a virtualization module in the Linux kernel that allows the kernel to function as a hypervisor. It was merged into the mainline Linux kernel in version 2.6.20, which was released on February 5, 2007. KVM requires a processor with hardware virtualization extensions, such as Intel VT or AMD-V. KVM has also been ported to other operating systems such as FreeBSD and illumos in the form of loadable kernel modules.
KVM provides hardware-assisted virtualization for a wide variety of guest operating systems including Linux, BSD, Solaris, Windows, Haiku, ReactOS, Plan 9, AROS Research Operating System and macOS. In addition, Android 2.2, GNU/Hurd (Debian K16), Minix 3.1.2a, Solaris 10 U3 and Darwin 8.0.1, together with other operating systems and some newer versions of these listed, are known to work with certain limitations.
Additionally, KVM provides paravirtualization support for Linux, OpenBSD, FreeBSD, NetBSD, Plan 9 and Windows guests using the VirtIO API. This includes a paravirtual Ethernet card, disk I/O controller, balloon driver, and a VGA graphics interface using SPICE or VMware drivers.
KVM is maintained by Paolo Bonzini.
KVM provides device abstraction but no processor emulation. It exposes the /dev/kvm interface, which a user mode host can then use to:
- 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.
- Feed the guest simulated I/O.
- Map the guest's video display back onto the system 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.
KVM itself emulates very little hardware, instead deferring to a higher level client application such as QEMU, crosvm, or Firecracker for device emulation.
KVM provides the following emulated devices:
Graphical management tools
- Kimchi – web-based virtualization management tool for KVM
- Virtual Machine Manager – supports creating, editing, starting, and stopping KVM-based virtual machines, as well as live or cold drag-and-drop migration of VMs between hosts.
- Proxmox Virtual Environment – an open-source virtualization management package including KVM and LXC. It has a bare-metal installer, a web-based remote management GUI, a HA cluster stack, unified storage, flexible network, and optional commercial support.
- OpenQRM – management platform for managing heterogeneous data center infrastructures.
- GNOME Boxes – Gnome interface for managing libvirt guests on Linux.
- oVirt – open-source virtualization management tool for KVM built on top of libvirt
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- Official website
- Best practices for the Kernel-based Virtual Machine, IBM, second edition, April 2012
- Virtio-blk Performance Improvement, KVM Forum 2012, November 8, 2012, by Asias He
- Wikibook QEMU & KVM
- crosvm - chrome OS virtual machine monitor
- Firecracker VMM for KVM