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Line 1: <!-- {{Redirect\|KVM}} --> {{Infobox software \| name = KVM \| logo = Kvmbanner-logo2 1.png \| logo size = 160px \| screenshot = Kvm running various guests.png \| screenshot size = 300px \| caption = Screenshot of QEMU/KVM running [[NetBSD]], [[OpenSolaris]] and [[Kubuntu]] guests on an [[Arch Linux]] host. \| author = [[Qumranet]] \| developer = [[Open Virtualization Alliance]] (OVA) \| operating_system = [[Unix-like]] \| programming_language = [[C (programming language)\|C]] \| platform = [[ARM architecture\|ARM]], [[IA-64]], [[PowerPC]], [[IBM ESA/390\|S/390]], [[x86]], [[x86-64]] \| genre = [[Hypervisor]] \| license = [[GNU General Public License\|GNU GPL]] or [[GNU Lesser General Public License\|LGPL]] \| website = {{URL\|www.linux-kvm.org}} }} {{Distinguish\|KVM switch}} '''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 Linux kernel mainline in kernel version 2.6.20, which was released on February 5, 2007.<ref name="2620notes">{{cite web \| url = http://kernelnewbies.org/Linux_2_6_20#head-bca4fe7ffe454321118a470387c2be543ee51754 \| title = Linux kernel 2.6.20, Section 2.2. Virtualization support through KVM \| date = 2007-02-05 \| accessdate = 2014-06-16 \| website = kernelnewbies.org}}</ref> KVM requires a processor with hardware virtualization extensions, such as Intel VT or AMD-V.<ref>[http://www.linux-kvm.org/page/FAQ#What_do_I_need_to_use_KVM.3F KVM FAQ: What do I need to use KVM?]</ref> KVM has also been ported to other operating systems such as [[FreeBSD]]<ref>{{cite web\|url=http://www.freebsd.org/news/status/report-2007-07-2007-10.html#Porting-Linux-KVM-to-FreeBSD\|title=FreeBSD Quarterly Status Report: Porting Linux KVM to FreeBSD}}</ref> and [[illumos]]<ref>{{cite web\|url=http://dtrace.org/blogs/bmc/2011/08/15/kvm-on-illumos/\|title=KVM on illumos}}</ref> in the form of loadable kernel modules.▼ ~~\| website = kernelnewbies.org~~ ▲}}</ref> KVM requires a processor with hardware virtualization extensions, such as Intel VT or AMD-V.<ref>[http://www.linux-kvm.org/page/FAQ#What_do_I_need_to_use_KVM.3F KVM FAQ: What do I need to use KVM?]</ref> KVM has also been ported to other operating systems such as [[FreeBSD]]<ref>{{cite web\|url=http://www.freebsd.org/news/status/report-2007-07-2007-10.html#Porting-Linux-KVM-to-FreeBSD\|title=FreeBSD Quarterly Status Report: Porting Linux KVM to FreeBSD}}</ref> and [[illumos]]<ref>{{cite web\|url=http://dtrace.org/blogs/bmc/2011/08/15/kvm-on-illumos/\|title=KVM on illumos}}</ref> in the form of loadable kernel modules. KVM was originally designed for [[x86]] processors and has since been [[porting\|ported]] to [[IBM ESA/390\|S/390]],<ref>{{Cite web \|url=http://article.gmane.org/gmane.comp.emulators.kvm.devel/2570 \|title=Gmane - Mail To News And Back Again<!-- Bot generated title --> \|access-date=2007-05-07 \|archive-url=https://web.archive.org/web/20070929124348/http://article.gmane.org/gmane.comp.emulators.kvm.devel/2570 \|archive-date=2007-09-29 \|url-status=dead }}</ref> [[PowerPC]],<ref>[http://news.gmane.org/gmane.comp.emulators.kvm.devel/2595 Gmane Loom<!-- Bot generated title -->] {{webarchive\|url=https://web.archive.org/web/20070929103042/http://news.gmane.org/gmane.comp.emulators.kvm.devel/2595 \|date=2007-09-29 }}</ref> [[IA-64]], and [[ARM architecture\|ARM]].<ref>{{Cite web \|url=https://columbia.github.com/linux-kvm-arm \|title=KVM/ARM Open Source Project \|access-date=2017-11-01 \|archive-url=https://web.archive.org/web/20130310052146/http://columbia.github.com/linux-kvm-arm/ \|archive-date=2013-03-10 \|url-status=dead }}</ref> Line 29: KVM provides [[hardware-assisted virtualization]] for a wide variety of guest operating systems including Linux, BSD, [[Solaris (operating system)\|Solaris]], [[Microsoft Windows\|Windows]], [[Haiku (operating system)\|Haiku]], [[ReactOS]], [[Plan 9 from Bell Labs\|Plan 9]], [[AROS Research Operating System]]<ref>{{cite web \| url = http://www.linux-kvm.org/page/Guest_Support_Status \| title = KVM wiki: Guest support status \| accessdate =2007-05-27 }}</ref> and [[macOS]].<ref>{{cite web\|url=http://www.contrib.andrew.cmu.edu/~somlo/OSXKVM/\|title=Running Mac OS X as a QEMU/KVM Guest\|accessdate=2014-08-20}}</ref> In addition, Android 2.2, GNU/Hurd<ref>{{cite web\|url=https://www.gnu.org/software/hurd/hurd/status.html \|title=status \|publisher=Gnu.org \|date= \|accessdate=2014-02-12}}</ref> (Debian K16), [[MINIX 3\|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.<ref>{{cite web\|url=http://www.linux-kvm.org/page/Guest_Support_Status \|title=Guest Support Status - KVM \|publisher=Linux-kvm.org \|date= \|accessdate=2014-02-12}}</ref> Additionally, KVM provides [[paravirtualization]] support for Linux, OpenBSD,<ref>{{cite web \|url=https://man.openbsd.org/virtio.4\|title=OpenBSD man page virtio(4) \|accessdate=2018-02-04}}</ref> FreeBSD,<ref>{{cite web \|url=http://people.freebsd.org/~kuriyama/virtio/\|title=virtio binary packages for FreeBSD\|accessdate=2012-10-29}}</ref> NetBSD,<ref>{{cite web \|url=http://netbsd.gw.com/cgi-bin/man-cgi?virtio++NetBSD-current \|title= NetBSD man page virtio(4) \|accessdate=2013-07-15}}</ref> Plan 9<ref>{{cite web \|url=https://code.google.com/p/plan9front/wiki/qemu \|title=plan9front \|accessdate=2013-02-11}}</ref> and Windows guests using the VirtIO<ref>{{cite web \|url=https://lwn.net/Articles/239238/ \|title=An API for virtual I/O: virtio \|date=2007-07-11 \|accessdate=2014-04-16 \|publisher=[[LWN.net]]}}</ref> API. This includes a paravirtual Ethernet card, disk I/O controller,<ref>{{cite web \|url=http://linux-iscsi.org/wiki/vHost \|title=SCSI target for KVM wiki \|publisher=linux-iscsi.org \|date=2012-08-07 \|accessdate=2012-08-12}}</ref> balloon device, and a VGA graphics interface using [[SPICE (protocol)\|SPICE]] or [[VMware]] drivers. ==History== Avi Kivity began the development of KVM in mid-2006 at [[Qumranet]], a technology [[startup company]]<ref>[http://kerneltrap.org/node/8088 Interview: Avi Kivity] {{webarchive\|url=https://web.archive.org/web/20070426033902/http://kerneltrap.org/node/8088 \|date=2007-04-26 }} on [[KernelTrap]]</ref> that was acquired by [[Red Hat]] in 2008.<ref>{{cite web \| url = http://www.redhat.com/en/about/press-releases/qumranet \| title = Red Hat Advances Virtualization Leadership with Qumranet, Inc. Acquisition \| date = 4 September 2008 \| accessdate = 16 June 2015 \| publisher = [[Red Hat]]}}</ref> ~~}}</ref>~~ KVM surfaced in October, 2006<ref>https://www.itworldcanada.com/article/kvm-15-equipped-with-live-migration/7901</ref> and was merged into the Linux kernel mainline in kernel version 2.6.20, which was released on 5 February 2007.<ref name="2620notes" /> KVM is maintained by Paolo Bonzini.<ref>{{cite web \| url = http://www.linux.com/news/featured-blogs/200-libby-clark/821899-git-success-stories-and-tips-from-kvm-maintainer-paolo-bonzini▼ ~~{{cite web~~ \| title = Git Success Stories and Tips from KVM Maintainer Paolo Bonzini▼ ▲ \| url = http://www.linux.com/news/featured-blogs/200-libby-clark/821899-git-success-stories-and-tips-from-kvm-maintainer-paolo-bonzini \| date = 7 April 2015 ▲ \| title = Git Success Stories and Tips from KVM Maintainer Paolo Bonzini \| ~~date~~accessdate = 717 ~~April~~June 2015 \| author = Libby Clark▼ ~~\| accessdate = 17 June 2015~~ \| publisher = [[Linux.com]]▼ ▲ \| author = Libby Clark \| archive-url = https://web.archive.org/web/20160315095510/http://www.linux.com/news/featured-blogs/200-libby-clark/821899-git-success-stories-and-tips-from-kvm-maintainer-paolo-bonzini▼ ▲ \| publisher = [[Linux.com]] ▲ \| archive-url = https://web.archive.org/web/20160315095510/http://www.linux.com/news/featured-blogs/200-libby-clark/821899-git-success-stories-and-tips-from-kvm-maintainer-paolo-bonzini \| archive-date = 15 March 2016 \| url-status = dead \| df = dmy-all}}</ref> }} ~~</ref>~~ == Internals == [[File:Kernel-based Virtual Machine.svg\|thumb\|right\|upright=1.8\|A high-level overview of the KVM/QEMU virtualization environment<ref>{{cite web \| url = http://www-01.ibm.com/support/knowledgecenter/api/content/nl/en-us/linuxonibm/liaav/LPCKVMSSPV2.1.pdf \| title = KVM/QEMU Storage Stack Performance Discussion \| year = 2010 \| accessdate = January 3, 2015 \| author1 = Khoa Huynh \| author2 = Stefan Hajnoczi \| publisher = Linux Plumbers Conference \| website = ~~ibm.com~~IBM \| format = PDF}}{{dead link \| date = January 2018 ~~}}{{dead link\|date=January 2018 \|bot=InternetArchiveBot \|fix-attempted=yes }}</ref>{{rp\|3}}]]~~ \| bot = InternetArchiveBot \| fix-attempted = yes}}</ref>{{rp\|3}}]] KVM provides device abstraction but no processor emulation. It exposes the <tt>/dev/kvm</tt> 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. Line 78 ⟶ 77: Internally, KVM uses [[SeaBIOS]] as an open source implementation of a 16-bit x86 [[BIOS]].<ref>{{cite web\|url=http://www.seabios.org/SeaBIOS \|title=SeaBIOS \|publisher=seabios.org \|date=2013-12-21 \|accessdate=2014-06-16}}</ref> == Features == KVM supports [[hot plug vCPUs]] ,<ref>https://access.redhat.com/articles/1339413</ref>, dynamic memory management,<ref>https://www.linux-kvm.org/page/FAQ#Is_dynamic_memory_management_for_guests_supported.3F</ref> and [[Live Migration]] since February 2007.<ref>https://lwn.net/Articles/223754/</ref><ref>https://www.linux-kvm.org/page/Migration</ref>, memory write intensive workload impacts in migration process<ref>https://www.berrange.com/posts/2016/05/12/analysis-of-techniques-for-ensuring-migration-completion-with-kvm/</ref>. == Emulated hardware ==▼ ▲== Emulated hardware == {{Confusing\|reason=previous sections says KVM does no emulate anything by itself, but this section lists emulated hardware. Some clarification from experts is welcome.\|date=February 2019}} {\| class="wikitable" \|- ! Class !! Device \|- \| [[Video card]] \|\| Cirrus CLGD 5446 PCI VGA card, dummy VGA card with [[Bochs]] [[VESA]] extensions,<ref name=qemu-doc>[http://wiki.qemu.org/download/qemu-doc.html wiki.qemu.org – QEMU Emulator User Documentation], read 2010-05-06</ref> or [[Virgil (software)\|Virgil]] as a virtual 3D GPU<ref>{{cite web\|url=http://airlied.livejournal.com/77553.html \|title=Introducing Virgil - 3D virtual GPU for qemu \|date=2013-07-18 \|url-status=dead \|archiveurl=https://web.archive.org/web/20130725063318/http://airlied.livejournal.com/77553.html \|archivedate=2013-07-25 }}</ref> \|- \| [[PCI (bus)\|PCI]] \|\| [[Intel 440FX\|i440FX]] host [[Conventional PCI#PCI bus bridges\|PCI bridge]] and [[PIIX3]] PCI to ISA bridge<ref name=qemu-doc/> \|- \| [[Input device]] \|\| [[PS/2 connector\|PS/2]] Mouse and Keyboard<ref name=qemu-doc/> \|- \| [[Sound card]] \|\| [[Sound Blaster 16]], ENSONIQ AudioPCI [[ES1370]], [[Gravis Ultrasound GF1]], CS4231A compatible<ref name=qemu-doc/> \|- \| [[Ethernet]] [[Network card]] \|\| AMD Am79C970A ([[Am7990]]), E1000 (Intel 82540EM, 82573L, 82544GC), [[NE2000]], and Realtek [[RTL8139]] Line 106 ⟶ 104: \|} == Graphical management tools == [[File:Libvirt support.svg\|thumb\|300px\|[[libvirt]] supports KVM]] Line 124 ⟶ 122: * BIOS files (bios.bin, vgabios.bin and vgabios-cirrus.bin): LGPL v2 or later == See also == {{Portal\|Free and open-source software\|Linux}} Line 147 ⟶ 145: {{Reflist\|30em}} == Bibliography == * {{cite web\|accessdate=2017-02-10\|title=Ten years of KVM\|url=https://lwn.net/Articles/705160/\|website=lwn.net\|author=Amit Shah\|date=2016-11-02}}

Kernel-based Virtual Machine: Difference between revisions