<s>
Kernel-based	B-Application
Virtual	I-Application
Machine	I-Application
(	O
KVM	O
)	O
is	O
a	O
free	B-License
and	I-License
open-source	I-License
virtualization	B-General_Concept
module	O
in	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
that	O
allows	O
the	O
kernel	B-Operating_System
to	O
function	O
as	O
a	O
hypervisor	B-Operating_System
.	O
</s>
<s>
It	O
was	O
merged	O
into	O
the	O
mainline	B-Application
Linux	I-Application
kernel	I-Application
in	O
version	O
2.6.20	O
,	O
which	O
was	O
released	O
on	O
February	O
5	O
,	O
2007	O
.	O
</s>
<s>
KVM	O
requires	O
a	O
processor	O
with	O
hardware	B-General_Concept
virtualization	I-General_Concept
extensions	O
,	O
such	O
as	O
Intel	O
VT	O
or	O
AMD-V	O
.	O
KVM	O
has	O
also	O
been	O
ported	O
to	O
other	O
operating	O
systems	O
such	O
as	O
FreeBSD	B-Operating_System
and	O
illumos	B-Application
in	O
the	O
form	O
of	O
loadable	O
kernel	B-Operating_System
modules	O
.	O
</s>
<s>
KVM	O
was	O
originally	O
designed	O
for	O
x86	B-Operating_System
processors	O
but	O
has	O
since	O
been	O
ported	O
to	O
S/390	B-Device
,	O
PowerPC	B-Architecture
,	O
IA-64	B-General_Concept
,	O
and	O
ARM	B-Architecture
.	O
</s>
<s>
The	O
IA-64	B-General_Concept
port	O
was	O
removed	O
in	O
2014	O
.	O
</s>
<s>
KVM	O
provides	O
hardware-assisted	B-General_Concept
virtualization	I-General_Concept
for	O
a	O
wide	O
variety	O
of	O
guest	B-General_Concept
operating	I-General_Concept
systems	I-General_Concept
including	O
Linux	B-Operating_System
,	O
BSD	B-Operating_System
,	O
Solaris	B-Application
,	O
Windows	B-Application
,	O
Haiku	B-Language
,	O
ReactOS	B-Application
,	O
Plan	B-Operating_System
9	I-Operating_System
,	O
AROS	B-Application
Research	I-Application
Operating	I-Application
System	I-Application
and	O
macOS	B-Application
.	O
</s>
<s>
In	O
addition	O
,	O
Android	O
2.2	O
,	O
GNU/Hurd	B-Application
(	O
Debian	O
K16	O
)	O
,	O
Minix	B-Application
3.1.2a	I-Application
,	O
Solaris	B-Application
10	I-Application
U3	O
and	O
Darwin	B-Operating_System
8.0.1	O
,	O
together	O
with	O
other	O
operating	O
systems	O
and	O
some	O
newer	O
versions	O
of	O
these	O
listed	O
,	O
are	O
known	O
to	O
work	O
with	O
certain	O
limitations	O
.	O
</s>
<s>
Additionally	O
,	O
KVM	O
provides	O
paravirtualization	O
support	O
for	O
Linux	B-Operating_System
,	O
OpenBSD	B-Operating_System
,	O
FreeBSD	B-Operating_System
,	O
NetBSD	B-Device
,	O
Plan	B-Operating_System
9	I-Operating_System
and	O
Windows	B-Application
guests	O
using	O
the	O
VirtIO	B-Application
API	B-General_Concept
.	O
</s>
<s>
This	O
includes	O
a	O
paravirtual	O
Ethernet	B-Protocol
card	I-Protocol
,	O
disk	O
I/O	O
controller	O
,	O
balloon	B-General_Concept
driver	I-General_Concept
,	O
and	O
a	O
VGA	B-Protocol
graphics	I-Protocol
interface	O
using	O
SPICE	B-Protocol
or	O
VMware	O
drivers	O
.	O
</s>
<s>
KVM	O
surfaced	O
in	O
October	O
,	O
2006	O
and	O
was	O
merged	O
into	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
mainline	O
in	O
kernel	B-Operating_System
version	O
2.6.20	O
,	O
which	O
was	O
released	O
on	O
5	O
February	O
2007	O
.	O
</s>
<s>
The	O
host	O
must	O
also	O
supply	O
a	O
firmware	O
image	O
(	O
usually	O
a	O
custom	O
BIOS	B-Operating_System
when	O
emulating	O
PCs	O
)	O
that	O
the	O
guest	O
can	O
use	O
to	O
bootstrap	O
into	O
its	O
main	O
OS	O
.	O
</s>
<s>
Originally	O
a	O
forked	O
version	O
of	O
QEMU	B-Application
was	O
provided	O
to	O
launch	O
guests	O
and	O
deal	O
with	O
hardware	O
emulation	O
that	O
is	O
n't	O
handled	O
by	O
the	O
kernel	B-Operating_System
.	O
</s>
<s>
There	O
are	O
now	O
numerous	O
Virtual	B-Operating_System
Machine	I-Operating_System
Monitors	I-Operating_System
(	O
VMMs	O
)	O
which	O
can	O
utilise	O
the	O
KVM	O
interface	O
including	O
kvmtool	O
,	O
crosvm	O
and	O
Firecracker	B-Application
and	O
numerous	O
specialised	O
VMMs	O
build	O
with	O
frameworks	O
such	O
as	O
rust-vmm	O
.	O
</s>
<s>
Internally	O
,	O
KVM	O
uses	O
SeaBIOS	B-Language
as	O
an	O
open	O
source	O
implementation	O
of	O
a	O
16-bit	O
x86	B-Operating_System
BIOS	B-Operating_System
.	O
</s>
<s>
KVM	O
has	O
had	O
support	O
for	O
hot	B-Device
swappable	I-Device
vCPUs	I-Device
,	O
dynamic	O
memory	O
management	O
,	O
and	O
Live	O
Migration	O
since	O
February	O
2007	O
.	O
</s>
<s>
KVM	O
itself	O
emulates	O
very	O
little	O
hardware	O
,	O
instead	O
deferring	O
to	O
a	O
higher	O
level	O
client	O
application	O
such	O
as	O
QEMU	B-Application
,	O
crosvm	O
,	O
or	O
Firecracker	B-Application
for	O
device	O
emulation	O
.	O
</s>
<s>
Virtual	B-Language
Machine	I-Language
Manager	I-Language
supports	O
creating	O
,	O
editing	O
,	O
starting	O
,	O
and	O
stopping	O
KVM-based	O
virtual	O
machines	O
,	O
as	O
well	O
as	O
live	O
or	O
cold	O
drag-and-drop	O
migration	O
of	O
VMs	O
between	O
hosts	O
.	O
</s>
<s>
Proxmox	B-Language
Virtual	I-Language
Environment	I-Language
an	O
open-source	O
virtualization	B-General_Concept
management	O
package	O
including	O
KVM	O
and	O
LXC	B-Application
.	O
</s>
<s>
The	O
kernel-mode	O
component	O
of	O
KVM	O
is	O
a	O
part	O
of	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
itself	O
licensed	O
under	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
,	O
version	O
2	O
.	O
</s>
