Editing QEMU (section)

===Accelerator===
KQEMU was a [[Linux kernel]] [[Loadable kernel module|module]], also written by [[Fabrice Bellard]], which notably sped up emulation of x86 or x86-64 guests on platforms with the same CPU architecture. This worked by running [[user mode]] code (and optionally some kernel code) directly on the host computer's CPU, and by using processor and peripheral emulation only for [[kernel mode|kernel-mode]] and [[real mode|real-mode]] code. KQEMU could execute code from many guest operating systems even if the host CPU did not support [[hardware-assisted virtualization]]. KQEMU was initially a [[closed-source]] product available free of charge but starting from version 1.3.0pre10 (February 2007),<ref name="xrH6Q">{{cite web |url=https://lwn.net/Articles/220807/ |title=KQEMU 1.3.0pre10 released - under the GPL [LWN.net&#93; |publisher=Lwn.net |date=February 6, 2007 |access-date=2009-01-03}}</ref> it was [[Software relicensing|relicensed]] under the [[GNU General Public License]]. QEMU versions starting with 0.12.0 ({{as of|2009|08|lc=on}}) support large memory which makes them incompatible with KQEMU.<ref name="KjeBA">{{cite web |first=Anthony |last=Liguori |url=http://lists.gnu.org/archive/html/qemu-devel/2009-08/msg00478.html |title=[Qemu-devel&#93; [PATCH 1/2&#93; Unbreak large mem support by removing kqemu |date=10 August 2009 |access-date=2010-03-11}}</ref> Newer releases of QEMU have completely removed support for KQEMU.

QVM86 was a [[GNU General Public License|GNU GPLv2]] licensed drop-in replacement for the then closed-source KQEMU. The developers of QVM86 ceased development in January 2007.

[[Kernel-based Virtual Machine]] (''KVM'') has mostly taken over as the Linux-based hardware-assisted virtualization solution for use with QEMU following the lack of support for KQEMU and QVM86.{{citation needed|date=May 2014}} QEMU can also use KVM on other architectures like [[ARM architecture|ARM]] and [[MIPS architecture|MIPS]].<ref name="aOKWh">{{cite web |title=QEMU / KVM CPU model configuration |url=https://www.qemu.org/docs/master/system/qemu-cpu-models.html |website=QEMU 5.0.50 (v5.0.0-962-g49ee115552) documentation}}</ref>

Intel's Hardware Accelerated Execution Manager (''HAXM'') is an open-source alternative<ref name="Wsj2a">{{cite web | url = https://lists.nongnu.org/archive/html/qemu-devel/2017-11/msg02504.html | title = HAXM goes open source | date = 2017-11-17 | publisher = QEMU developers | access-date = 2017-01-14 | quote = HAXM is now open source}}</ref> to KVM for x86-based hardware-assisted virtualization on NetBSD, Linux, Windows and macOS using [[Intel VT]]. {{As of | 2013}} Intel mostly solicits its use with QEMU for Android development.<ref name="g4gd5">{{cite web | url = https://software.intel.com/en-us/android/articles/intel-hardware-accelerated-execution-manager | title = Intel Hardware Accelerated Execution Manager<!-- (The URL does not credit any author) | last1 = Haoren | first1 = J. --> | date = 2013-11-27 | publisher = Intel | access-date = 2014-05-12 | quote = The Intel Hardware Accelerated Execution Manager (Intel® HAXM) is a hardware-assisted virtualization engine (hypervisor) that uses Intel Virtualization Technology (Intel® VT) to speed up Android app emulation on a host machine.}}</ref> Starting with version 2.9.0, the official QEMU includes support for HAXM, under the name ''Hax''.<ref name="qemu-inv">{{cite web |title=Invocation |url=https://www.qemu.org/docs/master/system/invocation.html |website=QEMU 5.0.50 (v5.0.0-962-g49ee115552) documentation}}</ref>

QEMU also supports the following accelerators:<ref name="qemu-inv" />
* ''hvf'', Apple's {{Code|Hypervisor.framework}} based on Intel VT.
* ''whpx'', Microsoft's Windows Hypervisor Platform based on Intel VT or AMD-V.
* ''tcg'', QEMU's own [[#Tiny Code Generator|Tiny Code Generator]]. This is the default.