Kernel-based Virtual Machine

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KVM
Kvm running various guests.png
Screenshot of QEMU/KVM running NetBSD, OpenSolaris and Kubuntu on an Arch Linux host.
Developer(s) Red Hat, Inc.
Stable release 1.2.0 / September 5, 2012; 9 months ago (2012-09-05)
Written in C
Operating system Unix-like
Type Platform virtualization
License GNU General Public License or GNU Lesser General Public License
Website www.linux-kvm.org
(unofficial)

Kernel-based Virtual Machine (KVM) is a virtualization infrastructure for the Linux kernel. KVM requires a processor with hardware virtualization extension.[1] KVM has also been ported to FreeBSD[2] and Illumos[3] in the form of loadable kernel modules.

KVM originally supported x86 processors and has been ported to S/390,[4] PowerPC,[5] and IA-64. An ARM port was merged during the 3.9 kernel merge window.[6]

A wide variety of guest operating systems work with KVM, including many flavours of Linux, BSD, Solaris, Windows, Haiku, ReactOS, Plan 9, and AROS Research Operating System.[7] A modified version of QEMU can use KVM to run Mac OS X.[8]

Paravirtualization support for certain devices is available for Linux, FreeBSD,[9] Plan 9[10] and Windows guests using the VirtIO framework. This supports a paravirtual Ethernet card, a paravirtual disk I/O controller,[11] a balloon device for adjusting guest memory usage, and a VGA graphics interface using SPICE or VMware drivers.

KVM uses SeaBIOS.

Linux 2.6.20 (released February 2007) was the first to include KVM.[12]

Contents

Design[edit]

By itself, KVM does not perform any emulation. Instead, it simply exposes the /dev/kvm interface, with which a user-space host can then:

  • Set up the guest VM's address space. The host must also supply a firmware image (usually a custom BIOS when emulating PCs) with which the guest can bootstrap into its main OS.
  • Feed it simulated I/O.
  • Map its video display back onto the host.

On Linux, QEMU versions 0.10.1 and later is one such host. It will use KVM when available to emulate guests at near-native speeds, but otherwise fall back to software-only virtualization.

Licensing[edit]

KVM's parts are licensed under various GNU licenses:[13]

  • KVM kernel module: GPL v2
  • KVM user module: LGPL v2
  • QEMU virtual CPU core library (libqemu.a) and QEMU PC system emulator: LGPL
  • Linux user mode QEMU emulator: GPL
  • BIOS files (bios.bin, vgabios.bin and vgabios-cirrus.bin): LGPL v2 or later

History[edit]

Avi Kivity began the development of KVM at Qumranet, a technology startup company.[14] Red Hat bought Qumranet in 2008.[15] KVM is maintained by Marcelo Tosatti and Gleb Natapov.

Graphical management tools[edit]

  • Archipel - An opensource libvirt-based Web UI, which uses XMPP to communicate with its "agents" installed on servers
  • Witsbits – A simplified end-to-end solution for SMB IT staff and IT services providers.
  • 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.
  • ConVirt – Manages 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 – Free virtualization management package including KVM and OpenVZ. It has a bare-metal installer, a web-based remote management GUI, and optional commercial support.
  • OpenNode – RHEL/CentOS-based open-source server virtualization and management solution with a simple bare-metal installer, providing KVM+OpenVZ host and standard libvirt, func management interfaces together with standard CLI tools like virsh and vzctl.
  • OpenQRM
  • SolusVM – Supports the management of KVM-based virtual machines as well as Xen and OpenVZ.
  • Virtualbricks – Python/GTK+-based management of KVM and QEMU virtual machines with a complete set of networking tools to emulate a real switched network using VDE.

Emulated hardware[edit]

Class Device
Video card Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESA extensions[16]
PCI i440FX host PCI bridge and PIIX3 PCI to ISA bridge[16]
Input device PS/2 Mouse and Keyboard[16]
Sound card Sound Blaster 16, ENSONIQ AudioPCI ES1370, Gravis Ultrasound GF1, CS4231A compatible[16]
Ethernet Network card AMD Am79C970A (Am7990), E1000 (Intel 82540EM, 82573L, 82544GC), NE2000, and Realtek RTL8139
Watchdog timer Intel 6300ESB or IB700
RAM 50 MB – 32 TB
CPU 1–160 CPUs

Implementations[edit]

See also[edit]

Portal icon Free software portal
Portal icon Linux portal

References[edit]

  1. ^ KVM FAQ: What do I need to use KVM?
  2. ^ "FreeBSD Quarterly Status Report: Porting Linux KVM to FreeBSD". 
  3. ^ "KVM on illumos". 
  4. ^ Gmane - Mail To News And Back Again
  5. ^ Gmane Loom
  6. ^ KVM/ARM Open Source Project
  7. ^ "KVM wiki: Guest support status". Retrieved 2007-05-27. 
  8. ^ "Howto: Mac OS X on KVM". 
  9. ^ "virtio binary packages for FreeBSD". Retrieved 2012-10-29. 
  10. ^ "plan9front". Retrieved 2013-02-11. 
  11. ^ "SCSI target for KVM wiki". linux-iscsi.org. 2012-08-07. Retrieved 2012-08-12. 
  12. ^ "Linux: 2.6.20 Kernel Released". KernelTrap. 
  13. ^ Licensing info from Ubuntu 7.04 /usr/share/doc/kvm/copyright
  14. ^ Interview: Avi Kivity on KernelTrap
  15. ^ Red Hat press release on Qumranet purchase
  16. ^ a b c d wiki.qemu.org – QEMU Emulator User Documentation, read 2010-05-06

External links[edit]
Hypervisors
Native
Hosted
Desktop virtualization
Application virtualization
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