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docs: 

* Convert qemu-doc from Texinfo to rST
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Merge remote-tracking branch 'remotes/pmaydell/tags/pull-docs-20200306' into staging

docs:
 * Convert qemu-doc from Texinfo to rST

# gpg: Signature made Fri 06 Mar 2020 11:08:15 GMT
# gpg:                using RSA key E1A5C593CD419DE28E8315CF3C2525ED14360CDE
# gpg:                issuer "peter.maydell@linaro.org"
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>" [ultimate]
# gpg:                 aka "Peter Maydell <pmaydell@gmail.com>" [ultimate]
# gpg:                 aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>" [ultimate]
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83  15CF 3C25 25ED 1436 0CDE

* remotes/pmaydell/tags/pull-docs-20200306: (33 commits)
  *.hx: Remove all the STEXI/ETEXI blocks
  docs: Remove old texinfo sources
  docs: Stop building qemu-doc
  ui/cocoa.m: Update documentation file and pathname
  docs: Generate qemu.1 manpage with Sphinx
  docs: Split out sections for the manpage into .rst.inc files
  qemu-options.hx: Fix up the autogenerated rST
  qemu-options.hx: Add rST documentation fragments
  scripts/hxtool-conv: Archive script used in qemu-options.hx conversion
  docs: Roll -prom-env and -g target-specific info into qemu-options.hx
  docs: Roll semihosting option information into qemu-options.hx
  doc/scripts/hxtool.py: Strip trailing ':' from DEFHEADING/ARCHHEADING
  hmp-commands-info.hx: Add rST documentation fragments
  hmp-commands.hx: Add rST documentation fragments
  docs/system: convert Texinfo documentation to rST
  docs/system: convert the documentation of deprecated features to rST.
  docs/system: convert managed startup to rST.
  docs/system: Convert security.texi to rST format
  docs/system: Convert qemu-cpu-models.texi to rST
  docs: Create defs.rst.inc as a place to define substitutions
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell 2020-03-06 11:11:54 +00:00
parent 6b02fca713 29f9dff790
commit f4c4357fbf
62 changed files with 9302 additions and 10111 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
.gitignore vendored
View File

@ -46,9 +46,6 @@
!/qapi/qapi-visit-core.c
/qapi/qapi-visit.[ch]
/qapi/qapi-doc.texi
/qemu-doc.html
/qemu-doc.info
/qemu-doc.txt
/qemu-edid
/qemu-img
/qemu-nbd

7
MAINTAINERS
View File

@ -215,6 +215,7 @@ S: Maintained
F: target/mips/
F: default-configs/*mips*
F: disas/*mips*
F: docs/system/cpu-models-mips.rst.inc
F: hw/intc/mips_gic.c
F: hw/mips/
F: hw/misc/mips_*
@ -319,7 +320,7 @@ F: tests/tcg/i386/
F: tests/tcg/x86_64/
F: hw/i386/
F: disas/i386.c
F: docs/qemu-cpu-models.texi
F: docs/system/cpu-models-x86.rst.inc
T: git https://github.com/ehabkost/qemu.git x86-next
Xtensa TCG CPUs
@ -2233,7 +2234,7 @@ M: Stefan Hajnoczi <stefanha@redhat.com>
S: Maintained
F: trace/
F: trace-events
F: qemu-option-trace.texi
F: docs/qemu-option-trace.rst.inc
F: scripts/tracetool.py
F: scripts/tracetool/
F: scripts/qemu-trace-stap*
@ -2803,7 +2804,7 @@ F: contrib/gitdm/*
Incompatible changes
R: libvir-list@redhat.com
F: qemu-deprecated.texi
F: docs/system/deprecated.rst
Build System
------------

47
Makefile
View File

@ -344,7 +344,7 @@ MANUAL_BUILDDIR := docs
endif
ifdef BUILD_DOCS
DOCS=qemu-doc.html qemu-doc.txt qemu.1
DOCS+=$(MANUAL_BUILDDIR)/system/qemu.1
DOCS+=$(MANUAL_BUILDDIR)/tools/qemu-img.1
DOCS+=$(MANUAL_BUILDDIR)/tools/qemu-nbd.8
DOCS+=$(MANUAL_BUILDDIR)/interop/qemu-ga.8
@ -354,7 +354,7 @@ endif
DOCS+=$(MANUAL_BUILDDIR)/system/qemu-block-drivers.7
DOCS+=docs/interop/qemu-qmp-ref.html docs/interop/qemu-qmp-ref.txt docs/interop/qemu-qmp-ref.7
DOCS+=docs/interop/qemu-ga-ref.html docs/interop/qemu-ga-ref.txt docs/interop/qemu-ga-ref.7
DOCS+=docs/qemu-cpu-models.7
DOCS+=$(MANUAL_BUILDDIR)/system/qemu-cpu-models.7
DOCS+=$(MANUAL_BUILDDIR)/index.html
ifdef CONFIG_VIRTFS
DOCS+=$(MANUAL_BUILDDIR)/tools/virtfs-proxy-helper.1
@ -767,10 +767,6 @@ distclean: clean
rm -f $(SUBDIR_DEVICES_MAK)
rm -f po/*.mo tests/qemu-iotests/common.env
rm -f roms/seabios/config.mak roms/vgabios/config.mak
rm -f qemu-doc.info qemu-doc.aux qemu-doc.cp qemu-doc.cps
rm -f qemu-doc.fn qemu-doc.fns qemu-doc.info qemu-doc.ky qemu-doc.kys
rm -f qemu-doc.log qemu-doc.pdf qemu-doc.pg qemu-doc.toc qemu-doc.tp
rm -f qemu-doc.vr qemu-doc.txt
rm -f qemu-plugins-ld.symbols qemu-plugins-ld64.symbols
rm -f config.log
rm -f linux-headers/asm
@ -780,13 +776,13 @@ distclean: clean
rm -f docs/interop/qemu-qmp-ref.txt docs/interop/qemu-ga-ref.txt
rm -f docs/interop/qemu-qmp-ref.pdf docs/interop/qemu-ga-ref.pdf
rm -f docs/interop/qemu-qmp-ref.html docs/interop/qemu-ga-ref.html
rm -f docs/qemu-cpu-models.7
rm -rf .doctrees
$(call clean-manual,devel)
$(call clean-manual,interop)
$(call clean-manual,specs)
$(call clean-manual,system)
$(call clean-manual,tools)
$(call clean-manual,user)
for d in $(TARGET_DIRS); do \
rm -rf $$d || exit 1 ; \
done
@ -845,21 +841,20 @@ install-sphinxdocs: sphinxdocs
$(call install-manual,specs)
$(call install-manual,system)
$(call install-manual,tools)
$(call install-manual,user)
install-doc: $(DOCS) install-sphinxdocs
$(INSTALL_DIR) "$(DESTDIR)$(qemu_docdir)"
$(INSTALL_DATA) $(MANUAL_BUILDDIR)/index.html "$(DESTDIR)$(qemu_docdir)"
$(INSTALL_DATA) qemu-doc.html "$(DESTDIR)$(qemu_docdir)"
$(INSTALL_DATA) qemu-doc.txt "$(DESTDIR)$(qemu_docdir)"
$(INSTALL_DATA) docs/interop/qemu-qmp-ref.html "$(DESTDIR)$(qemu_docdir)"
$(INSTALL_DATA) docs/interop/qemu-qmp-ref.txt "$(DESTDIR)$(qemu_docdir)"
ifdef CONFIG_POSIX
$(INSTALL_DIR) "$(DESTDIR)$(mandir)/man1"
$(INSTALL_DATA) qemu.1 "$(DESTDIR)$(mandir)/man1"
$(INSTALL_DATA) $(MANUAL_BUILDDIR)/system/qemu.1 "$(DESTDIR)$(mandir)/man1"
$(INSTALL_DIR) "$(DESTDIR)$(mandir)/man7"
$(INSTALL_DATA) docs/interop/qemu-qmp-ref.7 "$(DESTDIR)$(mandir)/man7"
$(INSTALL_DATA) $(MANUAL_BUILDDIR)/system/qemu-block-drivers.7 "$(DESTDIR)$(mandir)/man7"
$(INSTALL_DATA) docs/qemu-cpu-models.7 "$(DESTDIR)$(mandir)/man7"
$(INSTALL_DATA) $(MANUAL_BUILDDIR)/system/qemu-cpu-models.7 "$(DESTDIR)$(mandir)/man7"
ifeq ($(CONFIG_TOOLS),y)
$(INSTALL_DATA) $(MANUAL_BUILDDIR)/tools/qemu-img.1 "$(DESTDIR)$(mandir)/man1"
$(INSTALL_DIR) "$(DESTDIR)$(mandir)/man8"
@ -1039,7 +1034,8 @@ sphinxdocs: $(MANUAL_BUILDDIR)/devel/index.html \
$(MANUAL_BUILDDIR)/interop/index.html \
$(MANUAL_BUILDDIR)/specs/index.html \
$(MANUAL_BUILDDIR)/system/index.html \
$(MANUAL_BUILDDIR)/tools/index.html
$(MANUAL_BUILDDIR)/tools/index.html \
$(MANUAL_BUILDDIR)/user/index.html
# Canned command to build a single manual
# Arguments: $1 = manual name, $2 = Sphinx builder ('html' or 'man')
@ -1049,6 +1045,7 @@ sphinxdocs: $(MANUAL_BUILDDIR)/devel/index.html \
build-manual = $(call quiet-command,CONFDIR="$(qemu_confdir)" $(SPHINX_BUILD) $(if $(V),,-q) -W -b $2 -D version=$(VERSION) -D release="$(FULL_VERSION)" -d .doctrees/$1-$2 $(SRC_PATH)/docs/$1 $(MANUAL_BUILDDIR)/$1 ,"SPHINX","$(MANUAL_BUILDDIR)/$1")
# We assume all RST files in the manual's directory are used in it
manual-deps = $(wildcard $(SRC_PATH)/docs/$1/*.rst) \
$(SRC_PATH)/docs/defs.rst.inc \
$(SRC_PATH)/docs/$1/conf.py $(SRC_PATH)/docs/conf.py
# Macro to write out the rule and dependencies for building manpages
# Usage: $(call define-manpage-rule,manualname,manpage1 manpage2...[,extradeps])
@ -1068,15 +1065,18 @@ $(MANUAL_BUILDDIR)/interop/index.html: $(call manual-deps,interop)
$(MANUAL_BUILDDIR)/specs/index.html: $(call manual-deps,specs)
$(call build-manual,specs,html)
$(MANUAL_BUILDDIR)/system/index.html: $(call manual-deps,system)
$(MANUAL_BUILDDIR)/system/index.html: $(call manual-deps,system) $(SRC_PATH)/hmp-commands.hx $(SRC_PATH)/hmp-commands-info.hx $(SRC_PATH)/qemu-options.hx
$(call build-manual,system,html)
$(MANUAL_BUILDDIR)/tools/index.html: $(call manual-deps,tools) $(SRC_PATH)/qemu-img-cmds.hx $(SRC_PATH)/docs/qemu-option-trace.rst.inc
$(call build-manual,tools,html)
$(MANUAL_BUILDDIR)/user/index.html: $(call manual-deps,user)
$(call build-manual,user,html)
$(call define-manpage-rule,interop,qemu-ga.8)
$(call define-manpage-rule,system,qemu-block-drivers.7)
$(call define-manpage-rule,system,qemu.1 qemu-block-drivers.7 qemu-cpu-models.7)
$(call define-manpage-rule,tools,\
qemu-img.1 qemu-nbd.8 qemu-trace-stap.1\
@ -1103,21 +1103,10 @@ docs/interop/qemu-qmp-qapi.texi: qapi/qapi-doc.texi
docs/interop/qemu-ga-qapi.texi: qga/qapi-generated/qga-qapi-doc.texi
@cp -p $< $@
qemu.1: qemu-doc.texi qemu-options.texi qemu-monitor.texi qemu-monitor-info.texi
qemu.1: qemu-option-trace.texi
docs/qemu-cpu-models.7: docs/qemu-cpu-models.texi
html: qemu-doc.html docs/interop/qemu-qmp-ref.html docs/interop/qemu-ga-ref.html sphinxdocs
info: qemu-doc.info docs/interop/qemu-qmp-ref.info docs/interop/qemu-ga-ref.info
pdf: qemu-doc.pdf docs/interop/qemu-qmp-ref.pdf docs/interop/qemu-ga-ref.pdf
txt: qemu-doc.txt docs/interop/qemu-qmp-ref.txt docs/interop/qemu-ga-ref.txt
qemu-doc.html qemu-doc.info qemu-doc.pdf qemu-doc.txt: \
qemu-options.texi \
qemu-tech.texi qemu-option-trace.texi \
qemu-deprecated.texi qemu-monitor.texi \
qemu-monitor-info.texi \
docs/qemu-cpu-models.texi docs/security.texi
html: docs/interop/qemu-qmp-ref.html docs/interop/qemu-ga-ref.html sphinxdocs
info: docs/interop/qemu-qmp-ref.info docs/interop/qemu-ga-ref.info
pdf: docs/interop/qemu-qmp-ref.pdf docs/interop/qemu-ga-ref.pdf
txt: docs/interop/qemu-qmp-ref.txt docs/interop/qemu-ga-ref.txt
docs/interop/qemu-ga-ref.dvi docs/interop/qemu-ga-ref.html \
docs/interop/qemu-ga-ref.info docs/interop/qemu-ga-ref.pdf \

6
docs/conf.py
View File

@ -132,6 +132,12 @@ suppress_warnings = ["ref.option"]
# style document building; our Makefile always sets the variable.
confdir = os.getenv('CONFDIR', "/etc/qemu")
rst_epilog = ".. |CONFDIR| replace:: ``" + confdir + "``\n"
# We slurp in the defs.rst.inc and literally include it into rst_epilog,
# because Sphinx's include:: directive doesn't work with absolute paths
# and there isn't any one single relative path that will work for all
# documents and for both via-make and direct sphinx-build invocation.
with open(os.path.join(qemu_docdir, 'defs.rst.inc')) as f:
rst_epilog += f.read()
# -- Options for HTML output ----------------------------------------------

15
docs/defs.rst.inc Normal file
View File

@ -0,0 +1,15 @@
..
Generally useful rST substitution definitions. This is included for
all rST files as part of the epilogue by docs/conf.py. conf.py
also defines some dynamically generated substitutions like CONFDIR.
Note that |qemu_system| and |qemu_system_x86| are intended to be
used inside a parsed-literal block: the definition must not include
extra literal formatting with ``..``: this works in the HTML output
but the manpages will end up misrendered with following normal text
incorrectly in boldface.
.. |qemu_system| replace:: qemu-system-x86_64
.. |qemu_system_x86| replace:: qemu_system-x86_64
.. |I2C| replace:: I\ :sup:`2`\ C
.. |I2S| replace:: I\ :sup:`2`\ S

2
docs/index.html.in
View File

@ -7,13 +7,13 @@
<body>
<h1>QEMU @@VERSION@@ Documentation</h1>
<ul>
<li><a href="qemu-doc.html">User Documentation</a></li>
<li><a href="qemu-qmp-ref.html">QMP Reference Manual</a></li>
<li><a href="qemu-ga-ref.html">Guest Agent Protocol Reference</a></li>
<li><a href="interop/index.html">System Emulation Management and Interoperability Guide</a></li>
<li><a href="specs/index.html">System Emulation Guest Hardware Specifications</a></li>
<li><a href="system/index.html">System Emulation User's Guide</a></li>
<li><a href="tools/index.html">Tools Guide</a></li>
<li><a href="user/index.html">User Mode Emulation User's Guide</a></li>
</ul>
</body>
</html>

1
docs/index.rst
View File

@ -15,3 +15,4 @@ Welcome to QEMU's documentation!
specs/index
system/index
tools/index
user/index

677
docs/qemu-cpu-models.texi
View File

@ -1,677 +0,0 @@
@c man begin SYNOPSIS
QEMU / KVM CPU model configuration
@c man end
@set qemu_system_x86 qemu-system-x86_64
@c man begin DESCRIPTION
@menu
* recommendations_cpu_models_x86:: Recommendations for KVM CPU model configuration on x86 hosts
* recommendations_cpu_models_MIPS:: Supported CPU model configurations on MIPS hosts
* cpu_model_syntax_apps:: Syntax for configuring CPU models
@end menu
QEMU / KVM virtualization supports two ways to configure CPU models
@table @option
@item Host passthrough
This passes the host CPU model features, model, stepping, exactly to the
guest. Note that KVM may filter out some host CPU model features if they
cannot be supported with virtualization. Live migration is unsafe when
this mode is used as libvirt / QEMU cannot guarantee a stable CPU is
exposed to the guest across hosts. This is the recommended CPU to use,
provided live migration is not required.
@item Named model
QEMU comes with a number of predefined named CPU models, that typically
refer to specific generations of hardware released by Intel and AMD.
These allow the guest VMs to have a degree of isolation from the host CPU,
allowing greater flexibility in live migrating between hosts with differing
hardware.
@end table
In both cases, it is possible to optionally add or remove individual CPU
features, to alter what is presented to the guest by default.
Libvirt supports a third way to configure CPU models known as "Host model".
This uses the QEMU "Named model" feature, automatically picking a CPU model
that is similar the host CPU, and then adding extra features to approximate
the host model as closely as possible. This does not guarantee the CPU family,
stepping, etc will precisely match the host CPU, as they would with "Host
passthrough", but gives much of the benefit of passthrough, while making
live migration safe.
@node recommendations_cpu_models_x86
@subsection Recommendations for KVM CPU model configuration on x86 hosts
The information that follows provides recommendations for configuring
CPU models on x86 hosts. The goals are to maximise performance, while
protecting guest OS against various CPU hardware flaws, and optionally
enabling live migration between hosts with heterogeneous CPU models.
@menu
* preferred_cpu_models_intel_x86:: Preferred CPU models for Intel x86 hosts
* important_cpu_features_intel_x86:: Important CPU features for Intel x86 hosts
* preferred_cpu_models_amd_x86:: Preferred CPU models for AMD x86 hosts
* important_cpu_features_amd_x86:: Important CPU features for AMD x86 hosts
* default_cpu_models_x86:: Default x86 CPU models
* other_non_recommended_cpu_models_x86:: Other non-recommended x86 CPUs
@end menu
@node preferred_cpu_models_intel_x86
@subsubsection Preferred CPU models for Intel x86 hosts
The following CPU models are preferred for use on Intel hosts. Administrators /
applications are recommended to use the CPU model that matches the generation
of the host CPUs in use. In a deployment with a mixture of host CPU models
between machines, if live migration compatibility is required, use the newest
CPU model that is compatible across all desired hosts.
@table @option
@item @code{Skylake-Server}
@item @code{Skylake-Server-IBRS}
Intel Xeon Processor (Skylake, 2016)
@item @code{Skylake-Client}
@item @code{Skylake-Client-IBRS}
Intel Core Processor (Skylake, 2015)
@item @code{Broadwell}
@item @code{Broadwell-IBRS}
@item @code{Broadwell-noTSX}
@item @code{Broadwell-noTSX-IBRS}
Intel Core Processor (Broadwell, 2014)
@item @code{Haswell}
@item @code{Haswell-IBRS}
@item @code{Haswell-noTSX}
@item @code{Haswell-noTSX-IBRS}
Intel Core Processor (Haswell, 2013)
@item @code{IvyBridge}
@item @code{IvyBridge-IBRS}
Intel Xeon E3-12xx v2 (Ivy Bridge, 2012)
@item @code{SandyBridge}
@item @code{SandyBridge-IBRS}
Intel Xeon E312xx (Sandy Bridge, 2011)
@item @code{Westmere}
@item @code{Westmere-IBRS}
Westmere E56xx/L56xx/X56xx (Nehalem-C, 2010)
@item @code{Nehalem}
@item @code{Nehalem-IBRS}
Intel Core i7 9xx (Nehalem Class Core i7, 2008)
@item @code{Penryn}
Intel Core 2 Duo P9xxx (Penryn Class Core 2, 2007)
@item @code{Conroe}
Intel Celeron_4x0 (Conroe/Merom Class Core 2, 2006)
@end table
@node important_cpu_features_intel_x86
@subsubsection Important CPU features for Intel x86 hosts
The following are important CPU features that should be used on Intel x86
hosts, when available in the host CPU. Some of them require explicit
configuration to enable, as they are not included by default in some, or all,
of the named CPU models listed above. In general all of these features are
included if using "Host passthrough" or "Host model".
@table @option
@item @code{pcid}
Recommended to mitigate the cost of the Meltdown (CVE-2017-5754) fix
Included by default in Haswell, Broadwell & Skylake Intel CPU models.
Should be explicitly turned on for Westmere, SandyBridge, and IvyBridge
Intel CPU models. Note that some desktop/mobile Westmere CPUs cannot
support this feature.
@item @code{spec-ctrl}
Required to enable the Spectre v2 (CVE-2017-5715) fix.
Included by default in Intel CPU models with -IBRS suffix.
Must be explicitly turned on for Intel CPU models without -IBRS suffix.
Requires the host CPU microcode to support this feature before it
can be used for guest CPUs.
@item @code{stibp}
Required to enable stronger Spectre v2 (CVE-2017-5715) fixes in some
operating systems.
Must be explicitly turned on for all Intel CPU models.
Requires the host CPU microcode to support this feature before it
can be used for guest CPUs.
@item @code{ssbd}
Required to enable the CVE-2018-3639 fix
Not included by default in any Intel CPU model.
Must be explicitly turned on for all Intel CPU models.
Requires the host CPU microcode to support this feature before it
can be used for guest CPUs.
@item @code{pdpe1gb}
Recommended to allow guest OS to use 1GB size pages
Not included by default in any Intel CPU model.
Should be explicitly turned on for all Intel CPU models.
Note that not all CPU hardware will support this feature.
@item @code{md-clear}
Required to confirm the MDS (CVE-2018-12126, CVE-2018-12127, CVE-2018-12130,
CVE-2019-11091) fixes.
Not included by default in any Intel CPU model.
Must be explicitly turned on for all Intel CPU models.
Requires the host CPU microcode to support this feature before it
can be used for guest CPUs.
@end table
@node preferred_cpu_models_amd_x86
@subsubsection Preferred CPU models for AMD x86 hosts
The following CPU models are preferred for use on Intel hosts. Administrators /
applications are recommended to use the CPU model that matches the generation
of the host CPUs in use. In a deployment with a mixture of host CPU models
between machines, if live migration compatibility is required, use the newest
CPU model that is compatible across all desired hosts.
@table @option
@item @code{EPYC}
@item @code{EPYC-IBPB}
AMD EPYC Processor (2017)
@item @code{Opteron_G5}
AMD Opteron 63xx class CPU (2012)
@item @code{Opteron_G4}
AMD Opteron 62xx class CPU (2011)
@item @code{Opteron_G3}
AMD Opteron 23xx (Gen 3 Class Opteron, 2009)
@item @code{Opteron_G2}
AMD Opteron 22xx (Gen 2 Class Opteron, 2006)
@item @code{Opteron_G1}
AMD Opteron 240 (Gen 1 Class Opteron, 2004)
@end table
@node important_cpu_features_amd_x86
@subsubsection Important CPU features for AMD x86 hosts
The following are important CPU features that should be used on AMD x86
hosts, when available in the host CPU. Some of them require explicit
configuration to enable, as they are not included by default in some, or all,
of the named CPU models listed above. In general all of these features are
included if using "Host passthrough" or "Host model".
@table @option
@item @code{ibpb}
Required to enable the Spectre v2 (CVE-2017-5715) fix.
Included by default in AMD CPU models with -IBPB suffix.
Must be explicitly turned on for AMD CPU models without -IBPB suffix.
Requires the host CPU microcode to support this feature before it
can be used for guest CPUs.
@item @code{stibp}
Required to enable stronger Spectre v2 (CVE-2017-5715) fixes in some
operating systems.
Must be explicitly turned on for all AMD CPU models.
Requires the host CPU microcode to support this feature before it
can be used for guest CPUs.
@item @code{virt-ssbd}
Required to enable the CVE-2018-3639 fix
Not included by default in any AMD CPU model.
Must be explicitly turned on for all AMD CPU models.
This should be provided to guests, even if amd-ssbd is also
provided, for maximum guest compatibility.
Note for some QEMU / libvirt versions, this must be force enabled
when when using "Host model", because this is a virtual feature
that doesn't exist in the physical host CPUs.
@item @code{amd-ssbd}
Required to enable the CVE-2018-3639 fix
Not included by default in any AMD CPU model.
Must be explicitly turned on for all AMD CPU models.
This provides higher performance than virt-ssbd so should be
exposed to guests whenever available in the host. virt-ssbd
should none the less also be exposed for maximum guest
compatibility as some kernels only know about virt-ssbd.
@item @code{amd-no-ssb}
Recommended to indicate the host is not vulnerable CVE-2018-3639
Not included by default in any AMD CPU model.
Future hardware generations of CPU will not be vulnerable to
CVE-2018-3639, and thus the guest should be told not to enable
its mitigations, by exposing amd-no-ssb. This is mutually
exclusive with virt-ssbd and amd-ssbd.
@item @code{pdpe1gb}
Recommended to allow guest OS to use 1GB size pages
Not included by default in any AMD CPU model.
Should be explicitly turned on for all AMD CPU models.
Note that not all CPU hardware will support this feature.
@end table
@node default_cpu_models_x86
@subsubsection Default x86 CPU models
The default QEMU CPU models are designed such that they can run on all hosts.
If an application does not wish to do perform any host compatibility checks
before launching guests, the default is guaranteed to work.
The default CPU models will, however, leave the guest OS vulnerable to various
CPU hardware flaws, so their use is strongly discouraged. Applications should
follow the earlier guidance to setup a better CPU configuration, with host
passthrough recommended if live migration is not needed.
@table @option
@item @code{qemu32}
@item @code{qemu64}
QEMU Virtual CPU version 2.5+ (32 & 64 bit variants)
qemu64 is used for x86_64 guests and qemu32 is used for i686 guests, when no
-cpu argument is given to QEMU, or no <cpu> is provided in libvirt XML.
@end table
@node other_non_recommended_cpu_models_x86
@subsubsection Other non-recommended x86 CPUs
The following CPUs models are compatible with most AMD and Intel x86 hosts, but
their usage is discouraged, as they expose a very limited featureset, which
prevents guests having optimal performance.
@table @option
@item @code{kvm32}
@item @code{kvm64}
Common KVM processor (32 & 64 bit variants)
Legacy models just for historical compatibility with ancient QEMU versions.
@item @code{486}
@item @code{athlon}
@item @code{phenom}
@item @code{coreduo}
@item @code{core2duo}
@item @code{n270}
@item @code{pentium}
@item @code{pentium2}
@item @code{pentium3}
Various very old x86 CPU models, mostly predating the introduction of
hardware assisted virtualization, that should thus not be required for
running virtual machines.
@end table
@node recommendations_cpu_models_MIPS
@subsection Supported CPU model configurations on MIPS hosts
QEMU supports variety of MIPS CPU models:
@menu
* cpu_models_MIPS32:: Supported CPU models for MIPS32 hosts
* cpu_models_MIPS64:: Supported CPU models for MIPS64 hosts
* cpu_models_nanoMIPS:: Supported CPU models for nanoMIPS hosts
* preferred_cpu_models_MIPS:: Preferred CPU models for MIPS hosts
@end menu
@node cpu_models_MIPS32
@subsubsection Supported CPU models for MIPS32 hosts
The following CPU models are supported for use on MIPS32 hosts. Administrators /
applications are recommended to use the CPU model that matches the generation
of the host CPUs in use. In a deployment with a mixture of host CPU models
between machines, if live migration compatibility is required, use the newest
CPU model that is compatible across all desired hosts.
@table @option
@item @code{mips32r6-generic}
MIPS32 Processor (Release 6, 2015)
@item @code{P5600}
MIPS32 Processor (P5600, 2014)
@item @code{M14K}
@item @code{M14Kc}
MIPS32 Processor (M14K, 2009)
@item @code{74Kf}
MIPS32 Processor (74K, 2007)
@item @code{34Kf}
MIPS32 Processor (34K, 2006)
@item @code{24Kc}
@item @code{24KEc}
@item @code{24Kf}
MIPS32 Processor (24K, 2003)
@item @code{4Kc}
@item @code{4Km}
@item @code{4KEcR1}
@item @code{4KEmR1}
@item @code{4KEc}
@item @code{4KEm}
MIPS32 Processor (4K, 1999)
@end table
@node cpu_models_MIPS64
@subsubsection Supported CPU models for MIPS64 hosts
The following CPU models are supported for use on MIPS64 hosts. Administrators /
applications are recommended to use the CPU model that matches the generation
of the host CPUs in use. In a deployment with a mixture of host CPU models
between machines, if live migration compatibility is required, use the newest
CPU model that is compatible across all desired hosts.
@table @option
@item @code{I6400}
MIPS64 Processor (Release 6, 2014)
@item @code{Loongson-2F}
MIPS64 Processor (Loongson 2, 2008)
@item @code{Loongson-2E}
MIPS64 Processor (Loongson 2, 2006)
@item @code{mips64dspr2}
MIPS64 Processor (Release 2, 2006)
@item @code{MIPS64R2-generic}
@item @code{5KEc}
@item @code{5KEf}
MIPS64 Processor (Release 2, 2002)
@item @code{20Kc}
MIPS64 Processor (20K, 2000)
@item @code{5Kc}
@item @code{5Kf}
MIPS64 Processor (5K, 1999)
@item @code{VR5432}
MIPS64 Processor (VR, 1998)
@item @code{R4000}
MIPS64 Processor (MIPS III, 1991)
@end table
@node cpu_models_nanoMIPS
@subsubsection Supported CPU models for nanoMIPS hosts
The following CPU models are supported for use on nanoMIPS hosts. Administrators /
applications are recommended to use the CPU model that matches the generation
of the host CPUs in use. In a deployment with a mixture of host CPU models
between machines, if live migration compatibility is required, use the newest
CPU model that is compatible across all desired hosts.
@table @option
@item @code{I7200}
MIPS I7200 (nanoMIPS, 2018)
@end table
@node preferred_cpu_models_MIPS
@subsubsection Preferred CPU models for MIPS hosts
The following CPU models are preferred for use on different MIPS hosts:
@table @option
@item @code{MIPS III}
R4000
@item @code{MIPS32R2}
34Kf
@item @code{MIPS64R6}
I6400
@item @code{nanoMIPS}
I7200
@end table
@node cpu_model_syntax_apps
@subsection Syntax for configuring CPU models
The example below illustrate the approach to configuring the various
CPU models / features in QEMU and libvirt
@menu
* cpu_model_syntax_qemu:: QEMU command line
* cpu_model_syntax_libvirt:: Libvirt guest XML
@end menu
@node cpu_model_syntax_qemu
@subsubsection QEMU command line
@table @option
@item Host passthrough
@example
$ @value{qemu_system_x86} -cpu host
@end example
With feature customization:
@example
$ @value{qemu_system_x86} -cpu host,-vmx,...
@end example
@item Named CPU models
@example
$ @value{qemu_system_x86} -cpu Westmere
@end example
With feature customization:
@example
$ @value{qemu_system_x86} -cpu Westmere,+pcid,...
@end example
@end table
@node cpu_model_syntax_libvirt
@subsubsection Libvirt guest XML
@table @option
@item Host passthrough
@example
<cpu mode='host-passthrough'/>
@end example
With feature customization:
@example
<cpu mode='host-passthrough'>
<feature name="vmx" policy="disable"/>
...
</cpu>
@end example
@item Host model
@example
<cpu mode='host-model'/>
@end example
With feature customization:
@example
<cpu mode='host-model'>
<feature name="vmx" policy="disable"/>
...
</cpu>
@end example
@item Named model
@example
<cpu mode='custom'>
<model name="Westmere"/>
</cpu>
@end example
With feature customization:
@example
<cpu mode='custom'>
<model name="Westmere"/>
<feature name="pcid" policy="require"/>
...
</cpu>
@end example
@end table
@c man end
@ignore
@setfilename qemu-cpu-models
@settitle QEMU / KVM CPU model configuration
@c man begin SEEALSO
The HTML documentation of QEMU for more precise information and Linux
user mode emulator invocation.
@c man end
@c man begin AUTHOR
Daniel P. Berrange
@c man end
@end ignore

4
docs/specs/ivshmem-spec.txt
View File

@ -38,8 +38,8 @@ There are two basic configurations:
Interrupts are message-signaled (MSI-X). vectors=N configures the
number of vectors to use.
For more details on ivshmem device properties, see The QEMU Emulator
User Documentation (qemu-doc.*).
For more details on ivshmem device properties, see the QEMU Emulator
user documentation.
== The ivshmem PCI device's guest interface ==

10
docs/sphinx/hxtool.py
View File

@ -60,8 +60,9 @@ def parse_defheading(file, lnum, line):
# empty we ignore the directive -- these are used only to add
# blank lines in the plain-text content of the --help output.
#
# Return the heading text
match = re.match(r'DEFHEADING\((.*)\)', line)
# Return the heading text. We strip out any trailing ':' for
# consistency with other headings in the rST documentation.
match = re.match(r'DEFHEADING\((.*?):?\)', line)
if match is None:
serror(file, lnum, "Invalid DEFHEADING line")
return match.group(1)
@ -72,8 +73,9 @@ def parse_archheading(file, lnum, line):
# though note that the 'some string' could be the empty string.
# As with DEFHEADING, empty string ARCHHEADINGs will be ignored.
#
# Return the heading text
match = re.match(r'ARCHHEADING\((.*),.*\)', line)
# Return the heading text. We strip out any trailing ':' for
# consistency with other headings in the rST documentation.
match = re.match(r'ARCHHEADING\((.*?):?,.*\)', line)
if match is None:
serror(file, lnum, "Invalid ARCHHEADING line")
return match.group(1)

79
docs/system/build-platforms.rst Normal file
View File

@ -0,0 +1,79 @@
.. _Supported-build-platforms:
Supported build platforms
=========================
QEMU aims to support building and executing on multiple host OS
platforms. This appendix outlines which platforms are the major build
targets. These platforms are used as the basis for deciding upon the
minimum required versions of 3rd party software QEMU depends on. The
supported platforms are the targets for automated testing performed by
the project when patches are submitted for review, and tested before and
after merge.
If a platform is not listed here, it does not imply that QEMU won't
work. If an unlisted platform has comparable software versions to a
listed platform, there is every expectation that it will work. Bug
reports are welcome for problems encountered on unlisted platforms
unless they are clearly older vintage than what is described here.
Note that when considering software versions shipped in distros as
support targets, QEMU considers only the version number, and assumes the
features in that distro match the upstream release with the same
version. In other words, if a distro backports extra features to the
software in their distro, QEMU upstream code will not add explicit
support for those backports, unless the feature is auto-detectable in a
manner that works for the upstream releases too.
The Repology site https://repology.org is a useful resource to identify
currently shipped versions of software in various operating systems,
though it does not cover all distros listed below.
Linux OS
--------
For distributions with frequent, short-lifetime releases, the project
will aim to support all versions that are not end of life by their
respective vendors. For the purposes of identifying supported software
versions, the project will look at Fedora, Ubuntu, and openSUSE distros.
Other short- lifetime distros will be assumed to ship similar software
versions.
For distributions with long-lifetime releases, the project will aim to
support the most recent major version at all times. Support for the
previous major version will be dropped 2 years after the new major
version is released, or when it reaches "end of life". For the purposes
of identifying supported software versions, the project will look at
RHEL, Debian, Ubuntu LTS, and SLES distros. Other long-lifetime distros
will be assumed to ship similar software versions.
Windows
-------
The project supports building with current versions of the MinGW
toolchain, hosted on Linux.
macOS
-----
The project supports building with the two most recent versions of
macOS, with the current homebrew package set available.
FreeBSD
-------
The project aims to support the all the versions which are not end of
life.
NetBSD
------
The project aims to support the most recent major version at all times.
Support for the previous major version will be dropped 2 years after the
new major version is released.
OpenBSD
-------
The project aims to support the all the versions which are not end of
life.

8
docs/system/conf.py
View File

@ -13,10 +13,16 @@ exec(compile(open(parent_config, "rb").read(), parent_config, 'exec'))
# This slightly misuses the 'description', but is the best way to get
# the manual title to appear in the sidebar.
html_theme_options['description'] = u'System Emulation User''s Guide'
# One entry per manual page. List of tuples
# (source start file, name, description, authors, manual section).
man_pages = [
('qemu-manpage', 'qemu', u'QEMU User Documentation',
['Fabrice Bellard'], 1),
('qemu-block-drivers', 'qemu-block-drivers',
u'QEMU block drivers reference',
['Fabrice Bellard and the QEMU Project developers'], 7)
['Fabrice Bellard and the QEMU Project developers'], 7),
('qemu-cpu-models', 'qemu-cpu-models',
u'QEMU CPU Models',
['The QEMU Project developers'], 7)
]

105
docs/system/cpu-models-mips.rst.inc Normal file
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@ -0,0 +1,105 @@
Supported CPU model configurations on MIPS hosts
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
QEMU supports variety of MIPS CPU models:
Supported CPU models for MIPS32 hosts
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following CPU models are supported for use on MIPS32 hosts.
Administrators / applications are recommended to use the CPU model that
matches the generation of the host CPUs in use. In a deployment with a
mixture of host CPU models between machines, if live migration
compatibility is required, use the newest CPU model that is compatible
across all desired hosts.
``mips32r6-generic``
MIPS32 Processor (Release 6, 2015)
``P5600``
MIPS32 Processor (P5600, 2014)
``M14K``, ``M14Kc``
MIPS32 Processor (M14K, 2009)
``74Kf``
MIPS32 Processor (74K, 2007)
``34Kf``
MIPS32 Processor (34K, 2006)
``24Kc``, ``24KEc``, ``24Kf``
MIPS32 Processor (24K, 2003)
``4Kc``, ``4Km``, ``4KEcR1``, ``4KEmR1``, ``4KEc``, ``4KEm``
MIPS32 Processor (4K, 1999)
Supported CPU models for MIPS64 hosts
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following CPU models are supported for use on MIPS64 hosts.
Administrators / applications are recommended to use the CPU model that
matches the generation of the host CPUs in use. In a deployment with a
mixture of host CPU models between machines, if live migration
compatibility is required, use the newest CPU model that is compatible
across all desired hosts.
``I6400``
MIPS64 Processor (Release 6, 2014)
``Loongson-2F``
MIPS64 Processor (Loongson 2, 2008)
``Loongson-2E``
MIPS64 Processor (Loongson 2, 2006)
``mips64dspr2``
MIPS64 Processor (Release 2, 2006)
``MIPS64R2-generic``, ``5KEc``, ``5KEf``
MIPS64 Processor (Release 2, 2002)
``20Kc``
MIPS64 Processor (20K, 2000
``5Kc``, ``5Kf``
MIPS64 Processor (5K, 1999)
``VR5432``
MIPS64 Processor (VR, 1998)
``R4000``
MIPS64 Processor (MIPS III, 1991)
Supported CPU models for nanoMIPS hosts
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following CPU models are supported for use on nanoMIPS hosts.
Administrators / applications are recommended to use the CPU model that
matches the generation of the host CPUs in use. In a deployment with a
mixture of host CPU models between machines, if live migration
compatibility is required, use the newest CPU model that is compatible
across all desired hosts.
``I7200``
MIPS I7200 (nanoMIPS, 2018)
Preferred CPU models for MIPS hosts
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following CPU models are preferred for use on different MIPS hosts:
``MIPS III``
R4000
``MIPS32R2``
34Kf
``MIPS64R6``
I6400
``nanoMIPS``
I7200

365
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@ -0,0 +1,365 @@
Recommendations for KVM CPU model configuration on x86 hosts
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The information that follows provides recommendations for configuring
CPU models on x86 hosts. The goals are to maximise performance, while
protecting guest OS against various CPU hardware flaws, and optionally
enabling live migration between hosts with heterogeneous CPU models.
Two ways to configure CPU models with QEMU / KVM
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
(1) **Host passthrough**
This passes the host CPU model features, model, stepping, exactly to
the guest. Note that KVM may filter out some host CPU model features
if they cannot be supported with virtualization. Live migration is
unsafe when this mode is used as libvirt / QEMU cannot guarantee a
stable CPU is exposed to the guest across hosts. This is the
recommended CPU to use, provided live migration is not required.
(2) **Named model**
QEMU comes with a number of predefined named CPU models, that
typically refer to specific generations of hardware released by
Intel and AMD. These allow the guest VMs to have a degree of
isolation from the host CPU, allowing greater flexibility in live
migrating between hosts with differing hardware. @end table
In both cases, it is possible to optionally add or remove individual CPU
features, to alter what is presented to the guest by default.
Libvirt supports a third way to configure CPU models known as "Host
model". This uses the QEMU "Named model" feature, automatically picking
a CPU model that is similar the host CPU, and then adding extra features
to approximate the host model as closely as possible. This does not
guarantee the CPU family, stepping, etc will precisely match the host
CPU, as they would with "Host passthrough", but gives much of the
benefit of passthrough, while making live migration safe.
Preferred CPU models for Intel x86 hosts
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following CPU models are preferred for use on Intel hosts.
Administrators / applications are recommended to use the CPU model that
matches the generation of the host CPUs in use. In a deployment with a
mixture of host CPU models between machines, if live migration
compatibility is required, use the newest CPU model that is compatible
across all desired hosts.
``Skylake-Server``, ``Skylake-Server-IBRS``
Intel Xeon Processor (Skylake, 2016)
``Skylake-Client``, ``Skylake-Client-IBRS``
Intel Core Processor (Skylake, 2015)
``Broadwell``, ``Broadwell-IBRS``, ``Broadwell-noTSX``, ``Broadwell-noTSX-IBRS``
Intel Core Processor (Broadwell, 2014)
``Haswell``, ``Haswell-IBRS``, ``Haswell-noTSX``, ``Haswell-noTSX-IBRS``
Intel Core Processor (Haswell, 2013)
``IvyBridge``, ``IvyBridge-IBR``
Intel Xeon E3-12xx v2 (Ivy Bridge, 2012)
``SandyBridge``, ``SandyBridge-IBRS``
Intel Xeon E312xx (Sandy Bridge, 2011)
``Westmere``, ``Westmere-IBRS``
Westmere E56xx/L56xx/X56xx (Nehalem-C, 2010)
``Nehalem``, ``Nehalem-IBRS``
Intel Core i7 9xx (Nehalem Class Core i7, 2008)
``Penryn``
Intel Core 2 Duo P9xxx (Penryn Class Core 2, 2007)
``Conroe``
Intel Celeron_4x0 (Conroe/Merom Class Core 2, 2006)
Important CPU features for Intel x86 hosts
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following are important CPU features that should be used on Intel
x86 hosts, when available in the host CPU. Some of them require explicit
configuration to enable, as they are not included by default in some, or
all, of the named CPU models listed above. In general all of these
features are included if using "Host passthrough" or "Host model".
``pcid``
Recommended to mitigate the cost of the Meltdown (CVE-2017-5754) fix.
Included by default in Haswell, Broadwell & Skylake Intel CPU models.
Should be explicitly turned on for Westmere, SandyBridge, and
IvyBridge Intel CPU models. Note that some desktop/mobile Westmere
CPUs cannot support this feature.
``spec-ctrl``
Required to enable the Spectre v2 (CVE-2017-5715) fix.
Included by default in Intel CPU models with -IBRS suffix.
Must be explicitly turned on for Intel CPU models without -IBRS
suffix.
Requires the host CPU microcode to support this feature before it
can be used for guest CPUs.
``stibp``
Required to enable stronger Spectre v2 (CVE-2017-5715) fixes in some
operating systems.
Must be explicitly turned on for all Intel CPU models.
Requires the host CPU microcode to support this feature before it can
be used for guest CPUs.
``ssbd``
Required to enable the CVE-2018-3639 fix.
Not included by default in any Intel CPU model.
Must be explicitly turned on for all Intel CPU models.
Requires the host CPU microcode to support this feature before it
can be used for guest CPUs.
``pdpe1gb``
Recommended to allow guest OS to use 1GB size pages.
Not included by default in any Intel CPU model.
Should be explicitly turned on for all Intel CPU models.
Note that not all CPU hardware will support this feature.
``md-clear``
Required to confirm the MDS (CVE-2018-12126, CVE-2018-12127,
CVE-2018-12130, CVE-2019-11091) fixes.
Not included by default in any Intel CPU model.
Must be explicitly turned on for all Intel CPU models.
Requires the host CPU microcode to support this feature before it
can be used for guest CPUs.
Preferred CPU models for AMD x86 hosts
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following CPU models are preferred for use on Intel hosts.
Administrators / applications are recommended to use the CPU model that
matches the generation of the host CPUs in use. In a deployment with a
mixture of host CPU models between machines, if live migration
compatibility is required, use the newest CPU model that is compatible
across all desired hosts.
``EPYC``, ``EPYC-IBPB``
AMD EPYC Processor (2017)
``Opteron_G5``
AMD Opteron 63xx class CPU (2012)
``Opteron_G4``
AMD Opteron 62xx class CPU (2011)
``Opteron_G3``
AMD Opteron 23xx (Gen 3 Class Opteron, 2009)
``Opteron_G2``
AMD Opteron 22xx (Gen 2 Class Opteron, 2006)
``Opteron_G1``
AMD Opteron 240 (Gen 1 Class Opteron, 2004)
Important CPU features for AMD x86 hosts
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following are important CPU features that should be used on AMD x86
hosts, when available in the host CPU. Some of them require explicit
configuration to enable, as they are not included by default in some, or
all, of the named CPU models listed above. In general all of these
features are included if using "Host passthrough" or "Host model".
``ibpb``
Required to enable the Spectre v2 (CVE-2017-5715) fix.
Included by default in AMD CPU models with -IBPB suffix.
Must be explicitly turned on for AMD CPU models without -IBPB suffix.
Requires the host CPU microcode to support this feature before it
can be used for guest CPUs.
``stibp``
Required to enable stronger Spectre v2 (CVE-2017-5715) fixes in some
operating systems.
Must be explicitly turned on for all AMD CPU models.
Requires the host CPU microcode to support this feature before it
can be used for guest CPUs.
``virt-ssbd``
Required to enable the CVE-2018-3639 fix
Not included by default in any AMD CPU model.
Must be explicitly turned on for all AMD CPU models.
This should be provided to guests, even if amd-ssbd is also provided,
for maximum guest compatibility.
Note for some QEMU / libvirt versions, this must be force enabled when
when using "Host model", because this is a virtual feature that
doesn't exist in the physical host CPUs.
``amd-ssbd``
Required to enable the CVE-2018-3639 fix
Not included by default in any AMD CPU model.
Must be explicitly turned on for all AMD CPU models.
This provides higher performance than ``virt-ssbd`` so should be
exposed to guests whenever available in the host. ``virt-ssbd`` should
none the less also be exposed for maximum guest compatibility as some
kernels only know about ``virt-ssbd``.
``amd-no-ssb``
Recommended to indicate the host is not vulnerable CVE-2018-3639
Not included by default in any AMD CPU model.
Future hardware generations of CPU will not be vulnerable to
CVE-2018-3639, and thus the guest should be told not to enable
its mitigations, by exposing amd-no-ssb. This is mutually
exclusive with virt-ssbd and amd-ssbd.
``pdpe1gb``
Recommended to allow guest OS to use 1GB size pages
Not included by default in any AMD CPU model.
Should be explicitly turned on for all AMD CPU models.
Note that not all CPU hardware will support this feature.
Default x86 CPU models
^^^^^^^^^^^^^^^^^^^^^^
The default QEMU CPU models are designed such that they can run on all
hosts. If an application does not wish to do perform any host
compatibility checks before launching guests, the default is guaranteed
to work.
The default CPU models will, however, leave the guest OS vulnerable to
various CPU hardware flaws, so their use is strongly discouraged.
Applications should follow the earlier guidance to setup a better CPU
configuration, with host passthrough recommended if live migration is
not needed.
``qemu32``, ``qemu64``
QEMU Virtual CPU version 2.5+ (32 & 64 bit variants)
``qemu64`` is used for x86_64 guests and ``qemu32`` is used for i686
guests, when no ``-cpu`` argument is given to QEMU, or no ``<cpu>`` is
provided in libvirt XML.
Other non-recommended x86 CPUs
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following CPUs models are compatible with most AMD and Intel x86
hosts, but their usage is discouraged, as they expose a very limited
featureset, which prevents guests having optimal performance.
``kvm32``, ``kvm64``
Common KVM processor (32 & 64 bit variants).
Legacy models just for historical compatibility with ancient QEMU
versions.
``486``, ``athlon``, ``phenom``, ``coreduo``, ``core2duo``, ``n270``, ``pentium``, ``pentium2``, ``pentium3``
Various very old x86 CPU models, mostly predating the introduction
of hardware assisted virtualization, that should thus not be
required for running virtual machines.
Syntax for configuring CPU models
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The examples below illustrate the approach to configuring the various
CPU models / features in QEMU and libvirt.
QEMU command line
^^^^^^^^^^^^^^^^^
Host passthrough:
.. parsed-literal::
|qemu_system| -cpu host
Host passthrough with feature customization:
.. parsed-literal::
|qemu_system| -cpu host,-vmx,...
Named CPU models:
.. parsed-literal::
|qemu_system| -cpu Westmere
Named CPU models with feature customization:
.. parsed-literal::
|qemu_system| -cpu Westmere,+pcid,...
Libvirt guest XML
^^^^^^^^^^^^^^^^^
Host passthrough::
<cpu mode='host-passthrough'/>
Host passthrough with feature customization::
<cpu mode='host-passthrough'>
<feature name="vmx" policy="disable"/>
...
</cpu>
Host model::
<cpu mode='host-model'/>
Host model with feature customization::
<cpu mode='host-model'>
<feature name="vmx" policy="disable"/>
...
</cpu>
Named model::
<cpu mode='custom'>
<model name="Westmere"/>
</cpu>
Named model with feature customization::
<cpu mode='custom'>
<model name="Westmere"/>
<feature name="pcid" policy="require"/>
...
</cpu>

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Deprecated features
===================
In general features are intended to be supported indefinitely once
introduced into QEMU. In the event that a feature needs to be removed,
it will be listed in this section. The feature will remain functional
for 2 releases prior to actual removal. Deprecated features may also
generate warnings on the console when QEMU starts up, or if activated
via a monitor command, however, this is not a mandatory requirement.
Prior to the 2.10.0 release there was no official policy on how
long features would be deprecated prior to their removal, nor
any documented list of which features were deprecated. Thus
any features deprecated prior to 2.10.0 will be treated as if
they were first deprecated in the 2.10.0 release.
What follows is a list of all features currently marked as
deprecated.
System emulator command line arguments
--------------------------------------
``-machine enforce-config-section=on|off`` (since 3.1)
''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``enforce-config-section`` parameter is replaced by the
``-global migration.send-configuration={on|off}`` option.
``-no-kvm`` (since 1.3.0)
'''''''''''''''''''''''''
The ``-no-kvm`` argument is now a synonym for setting ``-accel tcg``.
``-usbdevice`` (since 2.10.0)
'''''''''''''''''''''''''''''
The ``-usbdevice DEV`` argument is now a synonym for setting
the ``-device usb-DEV`` argument instead. The deprecated syntax
would automatically enable USB support on the machine type.
If using the new syntax, USB support must be explicitly
enabled via the ``-machine usb=on`` argument.
``-drive file=json:{...{'driver':'file'}}`` (since 3.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''
The 'file' driver for drives is no longer appropriate for character or host
devices and will only accept regular files (S_IFREG). The correct driver
for these file types is 'host_cdrom' or 'host_device' as appropriate.
``-net ...,name=``\ *name* (since 3.1)
''''''''''''''''''''''''''''''''''''''
The ``name`` parameter of the ``-net`` option is a synonym
for the ``id`` parameter, which should now be used instead.
``-smp`` (invalid topologies) (since 3.1)
'''''''''''''''''''''''''''''''''''''''''
CPU topology properties should describe whole machine topology including
possible CPUs.
However, historically it was possible to start QEMU with an incorrect topology
where *n* <= *sockets* * *cores* * *threads* < *maxcpus*,
which could lead to an incorrect topology enumeration by the guest.
Support for invalid topologies will be removed, the user must ensure
topologies described with -smp include all possible cpus, i.e.
*sockets* * *cores* * *threads* = *maxcpus*.
``-vnc acl`` (since 4.0.0)
''''''''''''''''''''''''''
The ``acl`` option to the ``-vnc`` argument has been replaced
by the ``tls-authz`` and ``sasl-authz`` options.
``QEMU_AUDIO_`` environment variables and ``-audio-help`` (since 4.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``-audiodev`` argument is now the preferred way to specify audio
backend settings instead of environment variables. To ease migration to
the new format, the ``-audiodev-help`` option can be used to convert
the current values of the environment variables to ``-audiodev`` options.
Creating sound card devices and vnc without ``audiodev=`` property (since 4.2)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
When not using the deprecated legacy audio config, each sound card
should specify an ``audiodev=`` property. Additionally, when using
vnc, you should specify an ``audiodev=`` propery if you plan to
transmit audio through the VNC protocol.
``-mon ...,control=readline,pretty=on|off`` (since 4.1)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``pretty=on|off`` switch has no effect for HMP monitors, but is
silently ignored. Using the switch with HMP monitors will become an
error in the future.
``-realtime`` (since 4.1)
'''''''''''''''''''''''''
The ``-realtime mlock=on|off`` argument has been replaced by the
``-overcommit mem-lock=on|off`` argument.
``-numa node,mem=``\ *size* (since 4.1)
'''''''''''''''''''''''''''''''''''''''
The parameter ``mem`` of ``-numa node`` is used to assign a part of
guest RAM to a NUMA node. But when using it, it's impossible to manage specified
RAM chunk on the host side (like bind it to a host node, setting bind policy, ...),
so guest end-ups with the fake NUMA configuration with suboptiomal performance.
However since 2014 there is an alternative way to assign RAM to a NUMA node
using parameter ``memdev``, which does the same as ``mem`` and adds
means to actualy manage node RAM on the host side. Use parameter ``memdev``
with *memory-backend-ram* backend as an replacement for parameter ``mem``
to achieve the same fake NUMA effect or a properly configured
*memory-backend-file* backend to actually benefit from NUMA configuration.
In future new machine versions will not accept the option but it will still
work with old machine types. User can check QAPI schema to see if the legacy
option is supported by looking at MachineInfo::numa-mem-supported property.
``-numa`` node (without memory specified) (since 4.1)
'''''''''''''''''''''''''''''''''''''''''''''''''''''
Splitting RAM by default between NUMA nodes has the same issues as ``mem``
parameter described above with the difference that the role of the user plays
QEMU using implicit generic or board specific splitting rule.
Use ``memdev`` with *memory-backend-ram* backend or ``mem`` (if
it's supported by used machine type) to define mapping explictly instead.
``-mem-path`` fallback to RAM (since 4.1)
'''''''''''''''''''''''''''''''''''''''''
Currently if guest RAM allocation from file pointed by ``mem-path``
fails, QEMU falls back to allocating from RAM, which might result
in unpredictable behavior since the backing file specified by the user
is ignored. In the future, users will be responsible for making sure
the backing storage specified with ``-mem-path`` can actually provide
the guest RAM configured with ``-m`` and QEMU will fail to start up if
RAM allocation is unsuccessful.
RISC-V ``-bios`` (since 4.1)
''''''''''''''''''''''''''''
QEMU 4.1 introduced support for the -bios option in QEMU for RISC-V for the
RISC-V virt machine and sifive_u machine.
QEMU 4.1 has no changes to the default behaviour to avoid breakages. This
default will change in a future QEMU release, so please prepare now. All users
of the virt or sifive_u machine must change their command line usage.
QEMU 4.1 has three options, please migrate to one of these three:
1. ``-bios none`` - This is the current default behavior if no -bios option
is included. QEMU will not automatically load any firmware. It is up
to the user to load all the images they need.
2. ``-bios default`` - In a future QEMU release this will become the default
behaviour if no -bios option is specified. This option will load the
default OpenSBI firmware automatically. The firmware is included with
the QEMU release and no user interaction is required. All a user needs
to do is specify the kernel they want to boot with the -kernel option
3. ``-bios <file>`` - Tells QEMU to load the specified file as the firmwrae.
``-tb-size`` option (since 5.0)
'''''''''''''''''''''''''''''''
QEMU 5.0 introduced an alternative syntax to specify the size of the translation
block cache, ``-accel tcg,tb-size=``. The new syntax deprecates the
previously available ``-tb-size`` option.
``-show-cursor`` option (since 5.0)
'''''''''''''''''''''''''''''''''''
Use ``-display sdl,show-cursor=on`` or
``-display gtk,show-cursor=on`` instead.
QEMU Machine Protocol (QMP) commands
------------------------------------
``change`` (since 2.5.0)
''''''''''''''''''''''''
Use ``blockdev-change-medium`` or ``change-vnc-password`` instead.
``migrate_set_downtime`` and ``migrate_set_speed`` (since 2.8.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Use ``migrate-set-parameters`` instead.
``migrate-set-cache-size`` and ``query-migrate-cache-size`` (since 2.11.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Use ``migrate-set-parameters`` and ``query-migrate-parameters`` instead.
``query-block`` result field ``dirty-bitmaps[i].status`` (since 4.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``status`` field of the ``BlockDirtyInfo`` structure, returned by
the query-block command is deprecated. Two new boolean fields,
``recording`` and ``busy`` effectively replace it.
``query-block`` result field ``dirty-bitmaps`` (Since 4.2)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``dirty-bitmaps`` field of the ``BlockInfo`` structure, returned by
the query-block command is itself now deprecated. The ``dirty-bitmaps``
field of the ``BlockDeviceInfo`` struct should be used instead, which is the
type of the ``inserted`` field in query-block replies, as well as the
type of array items in query-named-block-nodes.
Since the ``dirty-bitmaps`` field is optionally present in both the old and
new locations, clients must use introspection to learn where to anticipate
the field if/when it does appear in command output.
``query-cpus`` (since 2.12.0)
'''''''''''''''''''''''''''''
The ``query-cpus`` command is replaced by the ``query-cpus-fast`` command.
``query-cpus-fast`` ``arch`` output member (since 3.0.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``arch`` output member of the ``query-cpus-fast`` command is
replaced by the ``target`` output member.
``cpu-add`` (since 4.0)
'''''''''''''''''''''''
Use ``device_add`` for hotplugging vCPUs instead of ``cpu-add``. See
documentation of ``query-hotpluggable-cpus`` for additional
details.
``query-events`` (since 4.0)
''''''''''''''''''''''''''''
The ``query-events`` command has been superseded by the more powerful
and accurate ``query-qmp-schema`` command.
chardev client socket with ``wait`` option (since 4.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''
Character devices creating sockets in client mode should not specify
the 'wait' field, which is only applicable to sockets in server mode
Human Monitor Protocol (HMP) commands
-------------------------------------
The ``hub_id`` parameter of ``hostfwd_add`` / ``hostfwd_remove`` (since 3.1)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``[hub_id name]`` parameter tuple of the 'hostfwd_add' and
'hostfwd_remove' HMP commands has been replaced by ``netdev_id``.
``cpu-add`` (since 4.0)
'''''''''''''''''''''''
Use ``device_add`` for hotplugging vCPUs instead of ``cpu-add``. See
documentation of ``query-hotpluggable-cpus`` for additional details.
``acl_show``, ``acl_reset``, ``acl_policy``, ``acl_add``, ``acl_remove`` (since 4.0.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``acl_show``, ``acl_reset``, ``acl_policy``, ``acl_add``, and
``acl_remove`` commands are deprecated with no replacement. Authorization
for VNC should be performed using the pluggable QAuthZ objects.
Guest Emulator ISAs
-------------------
RISC-V ISA privledge specification version 1.09.1 (since 4.1)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The RISC-V ISA privledge specification version 1.09.1 has been deprecated.
QEMU supports both the newer version 1.10.0 and the ratified version 1.11.0, these
should be used instead of the 1.09.1 version.
System emulator CPUS
--------------------
RISC-V ISA CPUs (since 4.1)
'''''''''''''''''''''''''''
The RISC-V cpus with the ISA version in the CPU name have been depcreated. The
four CPUs are: ``rv32gcsu-v1.9.1``, ``rv32gcsu-v1.10.0``, ``rv64gcsu-v1.9.1`` and
``rv64gcsu-v1.10.0``. Instead the version can be specified via the CPU ``priv_spec``
option when using the ``rv32`` or ``rv64`` CPUs.
RISC-V ISA CPUs (since 4.1)
'''''''''''''''''''''''''''
The RISC-V no MMU cpus have been depcreated. The two CPUs: ``rv32imacu-nommu`` and
``rv64imacu-nommu`` should no longer be used. Instead the MMU status can be specified
via the CPU ``mmu`` option when using the ``rv32`` or ``rv64`` CPUs.
System emulator devices
-----------------------
``ide-drive`` (since 4.2)
'''''''''''''''''''''''''
The 'ide-drive' device is deprecated. Users should use 'ide-hd' or
'ide-cd' as appropriate to get an IDE hard disk or CD-ROM as needed.
``scsi-disk`` (since 4.2)
'''''''''''''''''''''''''
The 'scsi-disk' device is deprecated. Users should use 'scsi-hd' or
'scsi-cd' as appropriate to get a SCSI hard disk or CD-ROM as needed.
System emulator machines
------------------------
mips ``r4k`` platform (since 5.0)
'''''''''''''''''''''''''''''''''
This machine type is very old and unmaintained. Users should use the ``malta``
machine type instead.
``pc-1.0``, ``pc-1.1``, ``pc-1.2`` and ``pc-1.3`` (since 5.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
These machine types are very old and likely can not be used for live migration
from old QEMU versions anymore. A newer machine type should be used instead.
``spike_v1.9.1`` and ``spike_v1.10`` (since 4.1)
''''''''''''''''''''''''''''''''''''''''''''''''
The version specific Spike machines have been deprecated in favour of the
generic ``spike`` machine. If you need to specify an older version of the RISC-V
spec you can use the ``-cpu rv64gcsu,priv_spec=v1.9.1`` command line argument.
Device options
--------------
Emulated device options
'''''''''''''''''''''''
``-device virtio-blk,scsi=on|off`` (since 5.0.0)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The virtio-blk SCSI passthrough feature is a legacy VIRTIO feature. VIRTIO 1.0
and later do not support it because the virtio-scsi device was introduced for
full SCSI support. Use virtio-scsi instead when SCSI passthrough is required.
Note this also applies to ``-device virtio-blk-pci,scsi=on|off``, which is an
alias.
Block device options
''''''''''''''''''''
``"backing": ""`` (since 2.12.0)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
In order to prevent QEMU from automatically opening an image's backing
chain, use ``"backing": null`` instead.
``rbd`` keyvalue pair encoded filenames: ``""`` (since 3.1.0)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Options for ``rbd`` should be specified according to its runtime options,
like other block drivers. Legacy parsing of keyvalue pair encoded
filenames is useful to open images with the old format for backing files;
These image files should be updated to use the current format.
Example of legacy encoding::
json:{"file.driver":"rbd", "file.filename":"rbd:rbd/name"}
The above, converted to the current supported format::
json:{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"}
Related binaries
----------------
``qemu-img convert -n -o`` (since 4.2.0)
''''''''''''''''''''''''''''''''''''''''
All options specified in ``-o`` are image creation options, so
they have no effect when used with ``-n`` to skip image creation.
Silently ignored options can be confusing, so this combination of
options will be made an error in future versions.
Backwards compatibility
-----------------------
Runnability guarantee of CPU models (since 4.1.0)
'''''''''''''''''''''''''''''''''''''''''''''''''
Previous versions of QEMU never changed existing CPU models in
ways that introduced additional host software or hardware
requirements to the VM. This allowed management software to
safely change the machine type of an existing VM without
introducing new requirements ("runnability guarantee"). This
prevented CPU models from being updated to include CPU
vulnerability mitigations, leaving guests vulnerable in the
default configuration.
The CPU model runnability guarantee won't apply anymore to
existing CPU models. Management software that needs runnability
guarantees must resolve the CPU model aliases using te
``alias-of`` field returned by the ``query-cpu-definitions`` QMP
command.
While those guarantees are kept, the return value of
``query-cpu-definitions`` will have existing CPU model aliases
point to a version that doesn't break runnability guarantees
(specifically, version 1 of those CPU models). In future QEMU
versions, aliases will point to newer CPU model versions
depending on the machine type, so management software must
resolve CPU model aliases before starting a virtual machine.
Recently removed features
=========================
What follows is a record of recently removed, formerly deprecated
features that serves as a record for users who have encountered
trouble after a recent upgrade.
QEMU Machine Protocol (QMP) commands
------------------------------------
``block-dirty-bitmap-add`` "autoload" parameter (since 4.2.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The "autoload" parameter has been ignored since 2.12.0. All bitmaps
are automatically loaded from qcow2 images.
Related binaries
----------------
``qemu-nbd --partition`` (removed in 5.0.0)
'''''''''''''''''''''''''''''''''''''''''''
The ``qemu-nbd --partition $digit`` code (also spelled ``-P``)
could only handle MBR partitions, and never correctly handled logical
partitions beyond partition 5. Exporting a partition can still be
done by utilizing the ``--image-opts`` option with a raw blockdev
using the ``offset`` and ``size`` parameters layered on top of
any other existing blockdev. For example, if partition 1 is 100MiB
long starting at 1MiB, the old command::
qemu-nbd -t -P 1 -f qcow2 file.qcow2
can be rewritten as::
qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.file.driver=file,file.file.filename=file.qcow2

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In addition to using normal file images for the emulated storage
devices, QEMU can also use networked resources such as iSCSI devices.
These are specified using a special URL syntax.
``iSCSI``
iSCSI support allows QEMU to access iSCSI resources directly and use
as images for the guest storage. Both disk and cdrom images are
supported.
Syntax for specifying iSCSI LUNs is
"iscsi://<target-ip>[:<port>]/<target-iqn>/<lun>"
By default qemu will use the iSCSI initiator-name
'iqn.2008-11.org.linux-kvm[:<name>]' but this can also be set from
the command line or a configuration file.
Since version Qemu 2.4 it is possible to specify a iSCSI request
timeout to detect stalled requests and force a reestablishment of the
session. The timeout is specified in seconds. The default is 0 which
means no timeout. Libiscsi 1.15.0 or greater is required for this
feature.
Example (without authentication):
.. parsed-literal::
|qemu_system| -iscsi initiator-name=iqn.2001-04.com.example:my-initiator \
-cdrom iscsi://192.0.2.1/iqn.2001-04.com.example/2 \
-drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
Example (CHAP username/password via URL):
.. parsed-literal::
|qemu_system| -drive file=iscsi://user%password@192.0.2.1/iqn.2001-04.com.example/1
Example (CHAP username/password via environment variables):
.. parsed-literal::
LIBISCSI_CHAP_USERNAME="user" \
LIBISCSI_CHAP_PASSWORD="password" \
|qemu_system| -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
``NBD``
QEMU supports NBD (Network Block Devices) both using TCP protocol as
well as Unix Domain Sockets. With TCP, the default port is 10809.
Syntax for specifying a NBD device using TCP, in preferred URI form:
"nbd://<server-ip>[:<port>]/[<export>]"
Syntax for specifying a NBD device using Unix Domain Sockets;
remember that '?' is a shell glob character and may need quoting:
"nbd+unix:///[<export>]?socket=<domain-socket>"
Older syntax that is also recognized:
"nbd:<server-ip>:<port>[:exportname=<export>]"
Syntax for specifying a NBD device using Unix Domain Sockets
"nbd:unix:<domain-socket>[:exportname=<export>]"
Example for TCP
.. parsed-literal::
|qemu_system| --drive file=nbd:192.0.2.1:30000
Example for Unix Domain Sockets
.. parsed-literal::
|qemu_system| --drive file=nbd:unix:/tmp/nbd-socket
``SSH``
QEMU supports SSH (Secure Shell) access to remote disks.
Examples:
.. parsed-literal::
|qemu_system| -drive file=ssh://user@host/path/to/disk.img
|qemu_system| -drive file.driver=ssh,file.user=user,file.host=host,file.port=22,file.path=/path/to/disk.img
Currently authentication must be done using ssh-agent. Other
authentication methods may be supported in future.
``Sheepdog``
Sheepdog is a distributed storage system for QEMU. QEMU supports
using either local sheepdog devices or remote networked devices.
Syntax for specifying a sheepdog device
::
sheepdog[+tcp|+unix]://[host:port]/vdiname[?socket=path][#snapid|#tag]
Example
.. parsed-literal::
|qemu_system| --drive file=sheepdog://192.0.2.1:30000/MyVirtualMachine
See also https://sheepdog.github.io/sheepdog/.
``GlusterFS``
GlusterFS is a user space distributed file system. QEMU supports the
use of GlusterFS volumes for hosting VM disk images using TCP, Unix
Domain Sockets and RDMA transport protocols.
Syntax for specifying a VM disk image on GlusterFS volume is
.. parsed-literal::
URI:
gluster[+type]://[host[:port]]/volume/path[?socket=...][,debug=N][,logfile=...]
JSON:
'json:{"driver":"qcow2","file":{"driver":"gluster","volume":"testvol","path":"a.img","debug":N,"logfile":"...",
  "server":[{"type":"tcp","host":"...","port":"..."},
  {"type":"unix","socket":"..."}]}}'
Example
.. parsed-literal::
URI:
|qemu_system| --drive file=gluster://192.0.2.1/testvol/a.img,
  file.debug=9,file.logfile=/var/log/qemu-gluster.log
JSON:
|qemu_system| 'json:{"driver":"qcow2",
  "file":{"driver":"gluster",
  "volume":"testvol","path":"a.img",
  "debug":9,"logfile":"/var/log/qemu-gluster.log",
  "server":[{"type":"tcp","host":"1.2.3.4","port":24007},
  {"type":"unix","socket":"/var/run/glusterd.socket"}]}}'
|qemu_system| -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
  file.debug=9,file.logfile=/var/log/qemu-gluster.log,
  file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
  file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket
See also http://www.gluster.org.
``HTTP/HTTPS/FTP/FTPS``
QEMU supports read-only access to files accessed over http(s) and
ftp(s).
Syntax using a single filename:
::
<protocol>://[<username>[:<password>]@]<host>/<path>
where:
``protocol``
'http', 'https', 'ftp', or 'ftps'.
``username``
Optional username for authentication to the remote server.
``password``
Optional password for authentication to the remote server.
``host``
Address of the remote server.
``path``
Path on the remote server, including any query string.
The following options are also supported:
``url``
The full URL when passing options to the driver explicitly.
``readahead``
The amount of data to read ahead with each range request to the
remote server. This value may optionally have the suffix 'T', 'G',
'M', 'K', 'k' or 'b'. If it does not have a suffix, it will be
assumed to be in bytes. The value must be a multiple of 512 bytes.
It defaults to 256k.
``sslverify``
Whether to verify the remote server's certificate when connecting
over SSL. It can have the value 'on' or 'off'. It defaults to
'on'.
``cookie``
Send this cookie (it can also be a list of cookies separated by
';') with each outgoing request. Only supported when using
protocols such as HTTP which support cookies, otherwise ignored.
``timeout``
Set the timeout in seconds of the CURL connection. This timeout is
the time that CURL waits for a response from the remote server to
get the size of the image to be downloaded. If not set, the
default timeout of 5 seconds is used.
Note that when passing options to qemu explicitly, ``driver`` is the
value of <protocol>.
Example: boot from a remote Fedora 20 live ISO image
.. parsed-literal::
|qemu_system_x86| --drive media=cdrom,file=https://archives.fedoraproject.org/pub/archive/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly
|qemu_system_x86| --drive media=cdrom,file.driver=http,file.url=http://archives.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly
Example: boot from a remote Fedora 20 cloud image using a local
overlay for writes, copy-on-read, and a readahead of 64k
.. parsed-literal::
qemu-img create -f qcow2 -o backing_file='json:{"file.driver":"http",, "file.url":"http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/20/Images/x86_64/Fedora-x86_64-20-20131211.1-sda.qcow2",, "file.readahead":"64k"}' /tmp/Fedora-x86_64-20-20131211.1-sda.qcow2
|qemu_system_x86| -drive file=/tmp/Fedora-x86_64-20-20131211.1-sda.qcow2,copy-on-read=on
Example: boot from an image stored on a VMware vSphere server with a
self-signed certificate using a local overlay for writes, a readahead
of 64k and a timeout of 10 seconds.
.. parsed-literal::
qemu-img create -f qcow2 -o backing_file='json:{"file.driver":"https",, "file.url":"https://user:password@vsphere.example.com/folder/test/test-flat.vmdk?dcPath=Datacenter&dsName=datastore1",, "file.sslverify":"off",, "file.readahead":"64k",, "file.timeout":10}' /tmp/test.qcow2
|qemu_system_x86| -drive file=/tmp/test.qcow2

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.. _gdb_005fusage:
GDB usage
---------
QEMU has a primitive support to work with gdb, so that you can do
'Ctrl-C' while the virtual machine is running and inspect its state.
In order to use gdb, launch QEMU with the '-s' option. It will wait for
a gdb connection:
.. parsed-literal::
|qemu_system| -s -kernel bzImage -hda rootdisk.img -append "root=/dev/hda"
Connected to host network interface: tun0
Waiting gdb connection on port 1234
Then launch gdb on the 'vmlinux' executable::
> gdb vmlinux
In gdb, connect to QEMU::
(gdb) target remote localhost:1234
Then you can use gdb normally. For example, type 'c' to launch the
kernel::
(gdb) c
Here are some useful tips in order to use gdb on system code:
1. Use ``info reg`` to display all the CPU registers.
2. Use ``x/10i $eip`` to display the code at the PC position.
3. Use ``set architecture i8086`` to dump 16 bit code. Then use
``x/10i $cs*16+$eip`` to dump the code at the PC position.
Advanced debugging options:
The default single stepping behavior is step with the IRQs and timer
service routines off. It is set this way because when gdb executes a
single step it expects to advance beyond the current instruction. With
the IRQs and timer service routines on, a single step might jump into
the one of the interrupt or exception vectors instead of executing the
current instruction. This means you may hit the same breakpoint a number
of times before executing the instruction gdb wants to have executed.
Because there are rare circumstances where you want to single step into
an interrupt vector the behavior can be controlled from GDB. There are
three commands you can query and set the single step behavior:
``maintenance packet qqemu.sstepbits``
This will display the MASK bits used to control the single stepping
IE:
::
(gdb) maintenance packet qqemu.sstepbits
sending: "qqemu.sstepbits"
received: "ENABLE=1,NOIRQ=2,NOTIMER=4"
``maintenance packet qqemu.sstep``
This will display the current value of the mask used when single
stepping IE:
::
(gdb) maintenance packet qqemu.sstep
sending: "qqemu.sstep"
received: "0x7"
``maintenance packet Qqemu.sstep=HEX_VALUE``
This will change the single step mask, so if wanted to enable IRQs on
the single step, but not timers, you would use:
::
(gdb) maintenance packet Qqemu.sstep=0x5
sending: "qemu.sstep=0x5"
received: "OK"

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.. _disk_005fimages:
Disk Images
-----------
QEMU supports many disk image formats, including growable disk images
(their size increase as non empty sectors are written), compressed and
encrypted disk images.
.. _disk_005fimages_005fquickstart:
Quick start for disk image creation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You can create a disk image with the command::
qemu-img create myimage.img mysize
where myimage.img is the disk image filename and mysize is its size in
kilobytes. You can add an ``M`` suffix to give the size in megabytes and
a ``G`` suffix for gigabytes.
See the qemu-img invocation documentation for more information.
.. _disk_005fimages_005fsnapshot_005fmode:
Snapshot mode
~~~~~~~~~~~~~
If you use the option ``-snapshot``, all disk images are considered as
read only. When sectors in written, they are written in a temporary file
created in ``/tmp``. You can however force the write back to the raw
disk images by using the ``commit`` monitor command (or C-a s in the
serial console).
.. _vm_005fsnapshots:
VM snapshots
~~~~~~~~~~~~
VM snapshots are snapshots of the complete virtual machine including CPU
state, RAM, device state and the content of all the writable disks. In
order to use VM snapshots, you must have at least one non removable and
writable block device using the ``qcow2`` disk image format. Normally
this device is the first virtual hard drive.
Use the monitor command ``savevm`` to create a new VM snapshot or
replace an existing one. A human readable name can be assigned to each
snapshot in addition to its numerical ID.
Use ``loadvm`` to restore a VM snapshot and ``delvm`` to remove a VM
snapshot. ``info snapshots`` lists the available snapshots with their
associated information::
(qemu) info snapshots
Snapshot devices: hda
Snapshot list (from hda):
ID TAG VM SIZE DATE VM CLOCK
1 start 41M 2006-08-06 12:38:02 00:00:14.954
2 40M 2006-08-06 12:43:29 00:00:18.633
3 msys 40M 2006-08-06 12:44:04 00:00:23.514
A VM snapshot is made of a VM state info (its size is shown in
``info snapshots``) and a snapshot of every writable disk image. The VM
state info is stored in the first ``qcow2`` non removable and writable
block device. The disk image snapshots are stored in every disk image.
The size of a snapshot in a disk image is difficult to evaluate and is
not shown by ``info snapshots`` because the associated disk sectors are
shared among all the snapshots to save disk space (otherwise each
snapshot would need a full copy of all the disk images).
When using the (unrelated) ``-snapshot`` option
(:ref:`disk_005fimages_005fsnapshot_005fmode`),
you can always make VM snapshots, but they are deleted as soon as you
exit QEMU.
VM snapshots currently have the following known limitations:
- They cannot cope with removable devices if they are removed or
inserted after a snapshot is done.
- A few device drivers still have incomplete snapshot support so their
state is not saved or restored properly (in particular USB).
.. include:: qemu-block-drivers.rst.inc

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Contents:
.. toctree::
:maxdepth: 2
:maxdepth: 3
qemu-block-drivers
quickstart
invocation
keys
mux-chardev
monitor
images
net
usb
ivshmem
linuxboot
vnc-security
tls
gdb
managed-startup
targets
security
vfio-ap
deprecated
build-platforms
license

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.. _sec_005finvocation:
Invocation
----------
.. parsed-literal::
|qemu_system| [options] [disk_image]
disk_image is a raw hard disk image for IDE hard disk 0. Some targets do
not need a disk image.
.. hxtool-doc:: qemu-options.hx
Device URL Syntax
~~~~~~~~~~~~~~~~~
.. include:: device-url-syntax.rst.inc

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.. _pcsys_005fivshmem:
Inter-VM Shared Memory device
-----------------------------
On Linux hosts, a shared memory device is available. The basic syntax
is:
.. parsed-literal::
|qemu_system_x86| -device ivshmem-plain,memdev=hostmem
where hostmem names a host memory backend. For a POSIX shared memory
backend, use something like
::
-object memory-backend-file,size=1M,share,mem-path=/dev/shm/ivshmem,id=hostmem
If desired, interrupts can be sent between guest VMs accessing the same
shared memory region. Interrupt support requires using a shared memory
server and using a chardev socket to connect to it. The code for the
shared memory server is qemu.git/contrib/ivshmem-server. An example
syntax when using the shared memory server is:
.. parsed-literal::
# First start the ivshmem server once and for all
ivshmem-server -p pidfile -S path -m shm-name -l shm-size -n vectors
# Then start your qemu instances with matching arguments
|qemu_system_x86| -device ivshmem-doorbell,vectors=vectors,chardev=id
-chardev socket,path=path,id=id
When using the server, the guest will be assigned a VM ID (>=0) that
allows guests using the same server to communicate via interrupts.
Guests can read their VM ID from a device register (see
ivshmem-spec.txt).
Migration with ivshmem
~~~~~~~~~~~~~~~~~~~~~~
With device property ``master=on``, the guest will copy the shared
memory on migration to the destination host. With ``master=off``, the
guest will not be able to migrate with the device attached. In the
latter case, the device should be detached and then reattached after
migration using the PCI hotplug support.
At most one of the devices sharing the same memory can be master. The
master must complete migration before you plug back the other devices.
ivshmem and hugepages
~~~~~~~~~~~~~~~~~~~~~
Instead of specifying the <shm size> using POSIX shm, you may specify a
memory backend that has hugepage support:
.. parsed-literal::
|qemu_system_x86| -object memory-backend-file,size=1G,mem-path=/dev/hugepages/my-shmem-file,share,id=mb1
-device ivshmem-plain,memdev=mb1
ivshmem-server also supports hugepages mount points with the ``-m``
memory path argument.

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.. _pcsys_005fkeys:
Keys in the graphical frontends
-------------------------------
.. include:: keys.rst.inc

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During the graphical emulation, you can use special key combinations to
change modes. The default key mappings are shown below, but if you use
``-alt-grab`` then the modifier is Ctrl-Alt-Shift (instead of Ctrl-Alt)
and if you use ``-ctrl-grab`` then the modifier is the right Ctrl key
(instead of Ctrl-Alt):
Ctrl-Alt-f
Toggle full screen
Ctrl-Alt-+
Enlarge the screen
Ctrl-Alt\--
Shrink the screen
Ctrl-Alt-u
Restore the screen's un-scaled dimensions
Ctrl-Alt-n
Switch to virtual console 'n'. Standard console mappings are:
*1*
Target system display
*2*
Monitor
*3*
Serial port
Ctrl-Alt
Toggle mouse and keyboard grab.
In the virtual consoles, you can use Ctrl-Up, Ctrl-Down, Ctrl-PageUp and
Ctrl-PageDown to move in the back log.

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.. _License:
License
=======
QEMU is a trademark of Fabrice Bellard.
QEMU is released under the `GNU General Public
License <https://www.gnu.org/licenses/gpl-2.0.txt>`__, version 2. Parts
of QEMU have specific licenses, see file
`LICENSE <https://git.qemu.org/?p=qemu.git;a=blob_plain;f=LICENSE>`__.

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.. _direct_005flinux_005fboot:
Direct Linux Boot
-----------------
This section explains how to launch a Linux kernel inside QEMU without
having to make a full bootable image. It is very useful for fast Linux
kernel testing.
The syntax is:
.. parsed-literal::
|qemu_system| -kernel bzImage -hda rootdisk.img -append "root=/dev/hda"
Use ``-kernel`` to provide the Linux kernel image and ``-append`` to
give the kernel command line arguments. The ``-initrd`` option can be
used to provide an INITRD image.
If you do not need graphical output, you can disable it and redirect the
virtual serial port and the QEMU monitor to the console with the
``-nographic`` option. The typical command line is:
.. parsed-literal::
|qemu_system| -kernel bzImage -hda rootdisk.img \
-append "root=/dev/hda console=ttyS0" -nographic
Use Ctrl-a c to switch between the serial console and the monitor (see
:ref:`pcsys_005fkeys`).

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Managed start up options
========================
In system mode emulation, it's possible to create a VM in a paused
state using the ``-S`` command line option. In this state the machine
is completely initialized according to command line options and ready
to execute VM code but VCPU threads are not executing any code. The VM
state in this paused state depends on the way QEMU was started. It
could be in:
- initial state (after reset/power on state)
- with direct kernel loading, the initial state could be amended to execute
code loaded by QEMU in the VM's RAM and with incoming migration
- with incoming migration, initial state will be amended with the migrated
machine state after migration completes
This paused state is typically used by users to query machine state and/or
additionally configure the machine (by hotplugging devices) in runtime before
allowing VM code to run.
However, at the ``-S`` pause point, it's impossible to configure options
that affect initial VM creation (like: ``-smp``/``-m``/``-numa`` ...) or
cold plug devices. The experimental ``--preconfig`` command line option
allows pausing QEMU before the initial VM creation, in a "preconfig" state,
where additional queries and configuration can be performed via QMP
before moving on to the resulting configuration startup. In the
preconfig state, QEMU only allows a limited set of commands over the
QMP monitor, where the commands do not depend on an initialized
machine, including but not limited to:
- ``qmp_capabilities``
- ``query-qmp-schema``
- ``query-commands``
- ``query-status``
- ``x-exit-preconfig``

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.. _pcsys_005fmonitor:
QEMU Monitor
------------
The QEMU monitor is used to give complex commands to the QEMU emulator.
You can use it to:
- Remove or insert removable media images (such as CD-ROM or
floppies).
- Freeze/unfreeze the Virtual Machine (VM) and save or restore its
state from a disk file.
- Inspect the VM state without an external debugger.
Commands
~~~~~~~~
The following commands are available:
.. hxtool-doc:: hmp-commands.hx
.. hxtool-doc:: hmp-commands-info.hx
Integer expressions
~~~~~~~~~~~~~~~~~~~
The monitor understands integers expressions for every integer argument.
You can use register names to get the value of specifics CPU registers
by prefixing them with *$*.

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.. _mux_005fkeys:
Keys in the character backend multiplexer
-----------------------------------------
.. include:: mux-chardev.rst.inc

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During emulation, if you are using a character backend multiplexer
(which is the default if you are using ``-nographic``) then several
commands are available via an escape sequence. These key sequences all
start with an escape character, which is Ctrl-a by default, but can be
changed with ``-echr``. The list below assumes you're using the default.
Ctrl-a h
Print this help
Ctrl-a x
Exit emulator
Ctrl-a s
Save disk data back to file (if -snapshot)
Ctrl-a t
Toggle console timestamps
Ctrl-a b
Send break (magic sysrq in Linux)
Ctrl-a c
Rotate between the frontends connected to the multiplexer (usually
this switches between the monitor and the console)
Ctrl-a Ctrl-a
Send the escape character to the frontend

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.. _pcsys_005fnetwork:
Network emulation
-----------------
QEMU can simulate several network cards (e.g. PCI or ISA cards on the PC
target) and can connect them to a network backend on the host or an
emulated hub. The various host network backends can either be used to
connect the NIC of the guest to a real network (e.g. by using a TAP
devices or the non-privileged user mode network stack), or to other
guest instances running in another QEMU process (e.g. by using the
socket host network backend).
Using TAP network interfaces
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This is the standard way to connect QEMU to a real network. QEMU adds a
virtual network device on your host (called ``tapN``), and you can then
configure it as if it was a real ethernet card.
Linux host
^^^^^^^^^^
As an example, you can download the ``linux-test-xxx.tar.gz`` archive
and copy the script ``qemu-ifup`` in ``/etc`` and configure properly
``sudo`` so that the command ``ifconfig`` contained in ``qemu-ifup`` can
be executed as root. You must verify that your host kernel supports the
TAP network interfaces: the device ``/dev/net/tun`` must be present.
See :ref:`sec_005finvocation` to have examples of command
lines using the TAP network interfaces.
Windows host
^^^^^^^^^^^^
There is a virtual ethernet driver for Windows 2000/XP systems, called
TAP-Win32. But it is not included in standard QEMU for Windows, so you
will need to get it separately. It is part of OpenVPN package, so
download OpenVPN from : https://openvpn.net/.
Using the user mode network stack
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
By using the option ``-net user`` (default configuration if no ``-net``
option is specified), QEMU uses a completely user mode network stack
(you don't need root privilege to use the virtual network). The virtual
network configuration is the following::
guest (10.0.2.15) <------> Firewall/DHCP server <-----> Internet
| (10.0.2.2)
|
----> DNS server (10.0.2.3)
|
----> SMB server (10.0.2.4)
The QEMU VM behaves as if it was behind a firewall which blocks all
incoming connections. You can use a DHCP client to automatically
configure the network in the QEMU VM. The DHCP server assign addresses
to the hosts starting from 10.0.2.15.
In order to check that the user mode network is working, you can ping
the address 10.0.2.2 and verify that you got an address in the range
10.0.2.x from the QEMU virtual DHCP server.
Note that ICMP traffic in general does not work with user mode
networking. ``ping``, aka. ICMP echo, to the local router (10.0.2.2)
shall work, however. If you're using QEMU on Linux >= 3.0, it can use
unprivileged ICMP ping sockets to allow ``ping`` to the Internet. The
host admin has to set the ping_group_range in order to grant access to
those sockets. To allow ping for GID 100 (usually users group)::
echo 100 100 > /proc/sys/net/ipv4/ping_group_range
When using the built-in TFTP server, the router is also the TFTP server.
When using the ``'-netdev user,hostfwd=...'`` option, TCP or UDP
connections can be redirected from the host to the guest. It allows for
example to redirect X11, telnet or SSH connections.
Hubs
~~~~
QEMU can simulate several hubs. A hub can be thought of as a virtual
connection between several network devices. These devices can be for
example QEMU virtual ethernet cards or virtual Host ethernet devices
(TAP devices). You can connect guest NICs or host network backends to
such a hub using the ``-netdev
hubport`` or ``-nic hubport`` options. The legacy ``-net`` option also
connects the given device to the emulated hub with ID 0 (i.e. the
default hub) unless you specify a netdev with ``-net nic,netdev=xxx``
here.
Connecting emulated networks between QEMU instances
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Using the ``-netdev socket`` (or ``-nic socket`` or ``-net socket``)
option, it is possible to create emulated networks that span several
QEMU instances. See the description of the ``-netdev socket`` option in
:ref:`sec_005finvocation` to have a basic
example.

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:orphan:
QEMU block drivers reference
============================
.. |qemu_system| replace:: qemu-system-x86_64
Synopsis
--------
..
We put the 'Synopsis' and 'See also' sections into the manpage, but not
the HTML. This makes the HTML docs read better and means the ToC in
the index has a more useful set of entries. Ideally, the section
headings 'Disk image file formats' would be top-level headings for
the HTML, but sub-headings of the conventional manpage 'Description'
header for the manpage. Unfortunately, due to deficiencies in
the Sphinx 'only' directive, this isn't possible: they must be headers
at the same level as 'Synopsis' and 'See also', otherwise Sphinx's
identification of which header underline style is which gets confused.
QEMU block driver reference manual
.. only:: man
Description
-----------
Synopsis
--------
.. include:: qemu-block-drivers.rst.inc
QEMU block driver reference manual
See also
--------
Disk image file formats
-----------------------
QEMU supports many image file formats that can be used with VMs as well as with
any of the tools (like ``qemu-img``). This includes the preferred formats
raw and qcow2 as well as formats that are supported for compatibility with
older QEMU versions or other hypervisors.
Depending on the image format, different options can be passed to
``qemu-img create`` and ``qemu-img convert`` using the ``-o`` option.
This section describes each format and the options that are supported for it.
.. program:: image-formats
.. option:: raw
Raw disk image format. This format has the advantage of
being simple and easily exportable to all other emulators. If your
file system supports *holes* (for example in ext2 or ext3 on
Linux or NTFS on Windows), then only the written sectors will reserve
space. Use ``qemu-img info`` to know the real size used by the
image or ``ls -ls`` on Unix/Linux.
Supported options:
.. program:: raw
.. option:: preallocation
Preallocation mode (allowed values: ``off``, ``falloc``,
``full``). ``falloc`` mode preallocates space for image by
calling ``posix_fallocate()``. ``full`` mode preallocates space
for image by writing data to underlying storage. This data may or
may not be zero, depending on the storage location.
.. program:: image-formats
.. option:: qcow2
QEMU image format, the most versatile format. Use it to have smaller
images (useful if your filesystem does not supports holes, for example
on Windows), zlib based compression and support of multiple VM
snapshots.
Supported options:
.. program:: qcow2
.. option:: compat
Determines the qcow2 version to use. ``compat=0.10`` uses the
traditional image format that can be read by any QEMU since 0.10.
``compat=1.1`` enables image format extensions that only QEMU 1.1 and
newer understand (this is the default). Amongst others, this includes
zero clusters, which allow efficient copy-on-read for sparse images.
.. option:: backing_file
File name of a base image (see ``create`` subcommand)
.. option:: backing_fmt
Image format of the base image
.. option:: encryption
This option is deprecated and equivalent to ``encrypt.format=aes``
.. option:: encrypt.format
If this is set to ``luks``, it requests that the qcow2 payload (not
qcow2 header) be encrypted using the LUKS format. The passphrase to
use to unlock the LUKS key slot is given by the ``encrypt.key-secret``
parameter. LUKS encryption parameters can be tuned with the other
``encrypt.*`` parameters.
If this is set to ``aes``, the image is encrypted with 128-bit AES-CBC.
The encryption key is given by the ``encrypt.key-secret`` parameter.
This encryption format is considered to be flawed by modern cryptography
standards, suffering from a number of design problems:
- The AES-CBC cipher is used with predictable initialization vectors based
on the sector number. This makes it vulnerable to chosen plaintext attacks
which can reveal the existence of encrypted data.
- The user passphrase is directly used as the encryption key. A poorly
chosen or short passphrase will compromise the security of the encryption.
- In the event of the passphrase being compromised there is no way to
change the passphrase to protect data in any qcow images. The files must
be cloned, using a different encryption passphrase in the new file. The
original file must then be securely erased using a program like shred,
though even this is ineffective with many modern storage technologies.
The use of this is no longer supported in system emulators. Support only
remains in the command line utilities, for the purposes of data liberation
and interoperability with old versions of QEMU. The ``luks`` format
should be used instead.
.. option:: encrypt.key-secret
Provides the ID of a ``secret`` object that contains the passphrase
(``encrypt.format=luks``) or encryption key (``encrypt.format=aes``).
.. option:: encrypt.cipher-alg
Name of the cipher algorithm and key length. Currently defaults
to ``aes-256``. Only used when ``encrypt.format=luks``.
.. option:: encrypt.cipher-mode
Name of the encryption mode to use. Currently defaults to ``xts``.
Only used when ``encrypt.format=luks``.
.. option:: encrypt.ivgen-alg
Name of the initialization vector generator algorithm. Currently defaults
to ``plain64``. Only used when ``encrypt.format=luks``.
.. option:: encrypt.ivgen-hash-alg
Name of the hash algorithm to use with the initialization vector generator
(if required). Defaults to ``sha256``. Only used when ``encrypt.format=luks``.
.. option:: encrypt.hash-alg
Name of the hash algorithm to use for PBKDF algorithm
Defaults to ``sha256``. Only used when ``encrypt.format=luks``.
.. option:: encrypt.iter-time
Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.
Defaults to ``2000``. Only used when ``encrypt.format=luks``.
.. option:: cluster_size
Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster
sizes can improve the image file size whereas larger cluster sizes generally
provide better performance.
.. option:: preallocation
Preallocation mode (allowed values: ``off``, ``metadata``, ``falloc``,
``full``). An image with preallocated metadata is initially larger but can
improve performance when the image needs to grow. ``falloc`` and ``full``
preallocations are like the same options of ``raw`` format, but sets up
metadata also.
.. option:: lazy_refcounts
If this option is set to ``on``, reference count updates are postponed with
the goal of avoiding metadata I/O and improving performance. This is
particularly interesting with :option:`cache=writethrough` which doesn't batch
metadata updates. The tradeoff is that after a host crash, the reference count
tables must be rebuilt, i.e. on the next open an (automatic) ``qemu-img
check -r all`` is required, which may take some time.
This option can only be enabled if ``compat=1.1`` is specified.
.. option:: nocow
If this option is set to ``on``, it will turn off COW of the file. It's only
valid on btrfs, no effect on other file systems.
Btrfs has low performance when hosting a VM image file, even more
when the guest on the VM also using btrfs as file system. Turning off
COW is a way to mitigate this bad performance. Generally there are two
ways to turn off COW on btrfs:
- Disable it by mounting with nodatacow, then all newly created files
will be NOCOW.
- For an empty file, add the NOCOW file attribute. That's what this
option does.
Note: this option is only valid to new or empty files. If there is
an existing file which is COW and has data blocks already, it couldn't
be changed to NOCOW by setting ``nocow=on``. One can issue ``lsattr
filename`` to check if the NOCOW flag is set or not (Capital 'C' is
NOCOW flag).
.. program:: image-formats
.. option:: qed
Old QEMU image format with support for backing files and compact image files
(when your filesystem or transport medium does not support holes).
When converting QED images to qcow2, you might want to consider using the
``lazy_refcounts=on`` option to get a more QED-like behaviour.
Supported options:
.. program:: qed
.. option:: backing_file
File name of a base image (see ``create`` subcommand).
.. option:: backing_fmt
Image file format of backing file (optional). Useful if the format cannot be
autodetected because it has no header, like some vhd/vpc files.
.. option:: cluster_size
Changes the cluster size (must be power-of-2 between 4K and 64K). Smaller
cluster sizes can improve the image file size whereas larger cluster sizes
generally provide better performance.
.. option:: table_size
Changes the number of clusters per L1/L2 table (must be
power-of-2 between 1 and 16). There is normally no need to
change this value but this option can between used for
performance benchmarking.
.. program:: image-formats
.. option:: qcow
Old QEMU image format with support for backing files, compact image files,
encryption and compression.
Supported options:
.. program:: qcow
.. option:: backing_file
File name of a base image (see ``create`` subcommand)
.. option:: encryption
This option is deprecated and equivalent to ``encrypt.format=aes``
.. option:: encrypt.format
If this is set to ``aes``, the image is encrypted with 128-bit AES-CBC.
The encryption key is given by the ``encrypt.key-secret`` parameter.
This encryption format is considered to be flawed by modern cryptography
standards, suffering from a number of design problems enumerated previously
against the ``qcow2`` image format.
The use of this is no longer supported in system emulators. Support only
remains in the command line utilities, for the purposes of data liberation
and interoperability with old versions of QEMU.
Users requiring native encryption should use the ``qcow2`` format
instead with ``encrypt.format=luks``.
.. option:: encrypt.key-secret
Provides the ID of a ``secret`` object that contains the encryption
key (``encrypt.format=aes``).
.. program:: image-formats
.. option:: luks
LUKS v1 encryption format, compatible with Linux dm-crypt/cryptsetup
Supported options:
.. program:: luks
.. option:: key-secret
Provides the ID of a ``secret`` object that contains the passphrase.
.. option:: cipher-alg
Name of the cipher algorithm and key length. Currently defaults
to ``aes-256``.
.. option:: cipher-mode
Name of the encryption mode to use. Currently defaults to ``xts``.
.. option:: ivgen-alg
Name of the initialization vector generator algorithm. Currently defaults
to ``plain64``.
.. option:: ivgen-hash-alg
Name of the hash algorithm to use with the initialization vector generator
(if required). Defaults to ``sha256``.
.. option:: hash-alg
Name of the hash algorithm to use for PBKDF algorithm
Defaults to ``sha256``.
.. option:: iter-time
Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.
Defaults to ``2000``.
.. program:: image-formats
.. option:: vdi
VirtualBox 1.1 compatible image format.
Supported options:
.. program:: vdi
.. option:: static
If this option is set to ``on``, the image is created with metadata
preallocation.
.. program:: image-formats
.. option:: vmdk
VMware 3 and 4 compatible image format.
Supported options:
.. program: vmdk
.. option:: backing_file
File name of a base image (see ``create`` subcommand).
.. option:: compat6
Create a VMDK version 6 image (instead of version 4)
.. option:: hwversion
Specify vmdk virtual hardware version. Compat6 flag cannot be enabled
if hwversion is specified.
.. option:: subformat
Specifies which VMDK subformat to use. Valid options are
``monolithicSparse`` (default),
``monolithicFlat``,
``twoGbMaxExtentSparse``,
``twoGbMaxExtentFlat`` and
``streamOptimized``.
.. program:: image-formats
.. option:: vpc
VirtualPC compatible image format (VHD).
Supported options:
.. program:: vpc
.. option:: subformat
Specifies which VHD subformat to use. Valid options are
``dynamic`` (default) and ``fixed``.
.. program:: image-formats
.. option:: VHDX
Hyper-V compatible image format (VHDX).
Supported options:
.. program:: VHDX
.. option:: subformat
Specifies which VHDX subformat to use. Valid options are
``dynamic`` (default) and ``fixed``.
.. option:: block_state_zero
Force use of payload blocks of type 'ZERO'. Can be set to ``on`` (default)
or ``off``. When set to ``off``, new blocks will be created as
``PAYLOAD_BLOCK_NOT_PRESENT``, which means parsers are free to return
arbitrary data for those blocks. Do not set to ``off`` when using
``qemu-img convert`` with ``subformat=dynamic``.
.. option:: block_size
Block size; min 1 MB, max 256 MB. 0 means auto-calculate based on
image size.
.. option:: log_size
Log size; min 1 MB.
Read-only formats
-----------------
More disk image file formats are supported in a read-only mode.
.. program:: image-formats
.. option:: bochs
Bochs images of ``growing`` type.
.. program:: image-formats
.. option:: cloop
Linux Compressed Loop image, useful only to reuse directly compressed
CD-ROM images present for example in the Knoppix CD-ROMs.
.. program:: image-formats
.. option:: dmg
Apple disk image.
.. program:: image-formats
.. option:: parallels
Parallels disk image format.
Using host drives
-----------------
In addition to disk image files, QEMU can directly access host
devices. We describe here the usage for QEMU version >= 0.8.3.
Linux
'''''
On Linux, you can directly use the host device filename instead of a
disk image filename provided you have enough privileges to access
it. For example, use ``/dev/cdrom`` to access to the CDROM.
CD
You can specify a CDROM device even if no CDROM is loaded. QEMU has
specific code to detect CDROM insertion or removal. CDROM ejection by
the guest OS is supported. Currently only data CDs are supported.
Floppy
You can specify a floppy device even if no floppy is loaded. Floppy
removal is currently not detected accurately (if you change floppy
without doing floppy access while the floppy is not loaded, the guest
OS will think that the same floppy is loaded).
Use of the host's floppy device is deprecated, and support for it will
be removed in a future release.
Hard disks
Hard disks can be used. Normally you must specify the whole disk
(``/dev/hdb`` instead of ``/dev/hdb1``) so that the guest OS can
see it as a partitioned disk. WARNING: unless you know what you do, it
is better to only make READ-ONLY accesses to the hard disk otherwise
you may corrupt your host data (use the ``-snapshot`` command
line option or modify the device permissions accordingly).
Windows
'''''''
CD
The preferred syntax is the drive letter (e.g. ``d:``). The
alternate syntax ``\\.\d:`` is supported. ``/dev/cdrom`` is
supported as an alias to the first CDROM drive.
Currently there is no specific code to handle removable media, so it
is better to use the ``change`` or ``eject`` monitor commands to
change or eject media.
Hard disks
Hard disks can be used with the syntax: ``\\.\PhysicalDriveN``
where *N* is the drive number (0 is the first hard disk).
WARNING: unless you know what you do, it is better to only make
READ-ONLY accesses to the hard disk otherwise you may corrupt your
host data (use the ``-snapshot`` command line so that the
modifications are written in a temporary file).
Mac OS X
''''''''
``/dev/cdrom`` is an alias to the first CDROM.
Currently there is no specific code to handle removable media, so it
is better to use the ``change`` or ``eject`` monitor commands to
change or eject media.
Virtual FAT disk images
-----------------------
QEMU can automatically create a virtual FAT disk image from a
directory tree. In order to use it, just type:
.. parsed-literal::
|qemu_system| linux.img -hdb fat:/my_directory
Then you access access to all the files in the ``/my_directory``
directory without having to copy them in a disk image or to export
them via SAMBA or NFS. The default access is *read-only*.
Floppies can be emulated with the ``:floppy:`` option:
.. parsed-literal::
|qemu_system| linux.img -fda fat:floppy:/my_directory
A read/write support is available for testing (beta stage) with the
``:rw:`` option:
.. parsed-literal::
|qemu_system| linux.img -fda fat:floppy:rw:/my_directory
What you should *never* do:
- use non-ASCII filenames
- use "-snapshot" together with ":rw:"
- expect it to work when loadvm'ing
- write to the FAT directory on the host system while accessing it with the guest system
NBD access
----------
QEMU can access directly to block device exported using the Network Block Device
protocol.
.. parsed-literal::
|qemu_system| linux.img -hdb nbd://my_nbd_server.mydomain.org:1024/
If the NBD server is located on the same host, you can use an unix socket instead
of an inet socket:
.. parsed-literal::
|qemu_system| linux.img -hdb nbd+unix://?socket=/tmp/my_socket
In this case, the block device must be exported using qemu-nbd:
.. parsed-literal::
qemu-nbd --socket=/tmp/my_socket my_disk.qcow2
The use of qemu-nbd allows sharing of a disk between several guests:
.. parsed-literal::
qemu-nbd --socket=/tmp/my_socket --share=2 my_disk.qcow2
and then you can use it with two guests:
.. parsed-literal::
|qemu_system| linux1.img -hdb nbd+unix://?socket=/tmp/my_socket
|qemu_system| linux2.img -hdb nbd+unix://?socket=/tmp/my_socket
If the nbd-server uses named exports (supported since NBD 2.9.18, or with QEMU's
own embedded NBD server), you must specify an export name in the URI:
.. parsed-literal::
|qemu_system| -cdrom nbd://localhost/debian-500-ppc-netinst
|qemu_system| -cdrom nbd://localhost/openSUSE-11.1-ppc-netinst
The URI syntax for NBD is supported since QEMU 1.3. An alternative syntax is
also available. Here are some example of the older syntax:
.. parsed-literal::
|qemu_system| linux.img -hdb nbd:my_nbd_server.mydomain.org:1024
|qemu_system| linux2.img -hdb nbd:unix:/tmp/my_socket
|qemu_system| -cdrom nbd:localhost:10809:exportname=debian-500-ppc-netinst
Sheepdog disk images
--------------------
Sheepdog is a distributed storage system for QEMU. It provides highly
available block level storage volumes that can be attached to
QEMU-based virtual machines.
You can create a Sheepdog disk image with the command:
.. parsed-literal::
qemu-img create sheepdog:///IMAGE SIZE
where *IMAGE* is the Sheepdog image name and *SIZE* is its
size.
To import the existing *FILENAME* to Sheepdog, you can use a
convert command.
.. parsed-literal::
qemu-img convert FILENAME sheepdog:///IMAGE
You can boot from the Sheepdog disk image with the command:
.. parsed-literal::
|qemu_system| sheepdog:///IMAGE
You can also create a snapshot of the Sheepdog image like qcow2.
.. parsed-literal::
qemu-img snapshot -c TAG sheepdog:///IMAGE
where *TAG* is a tag name of the newly created snapshot.
To boot from the Sheepdog snapshot, specify the tag name of the
snapshot.
.. parsed-literal::
|qemu_system| sheepdog:///IMAGE#TAG
You can create a cloned image from the existing snapshot.
.. parsed-literal::
qemu-img create -b sheepdog:///BASE#TAG sheepdog:///IMAGE
where *BASE* is an image name of the source snapshot and *TAG*
is its tag name.
You can use an unix socket instead of an inet socket:
.. parsed-literal::
|qemu_system| sheepdog+unix:///IMAGE?socket=PATH
If the Sheepdog daemon doesn't run on the local host, you need to
specify one of the Sheepdog servers to connect to.
.. parsed-literal::
qemu-img create sheepdog://HOSTNAME:PORT/IMAGE SIZE
|qemu_system| sheepdog://HOSTNAME:PORT/IMAGE
iSCSI LUNs
----------
iSCSI is a popular protocol used to access SCSI devices across a computer
network.
There are two different ways iSCSI devices can be used by QEMU.
The first method is to mount the iSCSI LUN on the host, and make it appear as
any other ordinary SCSI device on the host and then to access this device as a
/dev/sd device from QEMU. How to do this differs between host OSes.
The second method involves using the iSCSI initiator that is built into
QEMU. This provides a mechanism that works the same way regardless of which
host OS you are running QEMU on. This section will describe this second method
of using iSCSI together with QEMU.
In QEMU, iSCSI devices are described using special iSCSI URLs. URL syntax:
::
iscsi://[<username>[%<password>]@]<host>[:<port>]/<target-iqn-name>/<lun>
Username and password are optional and only used if your target is set up
using CHAP authentication for access control.
Alternatively the username and password can also be set via environment
variables to have these not show up in the process list:
::
export LIBISCSI_CHAP_USERNAME=<username>
export LIBISCSI_CHAP_PASSWORD=<password>
iscsi://<host>/<target-iqn-name>/<lun>
Various session related parameters can be set via special options, either
in a configuration file provided via '-readconfig' or directly on the
command line.
If the initiator-name is not specified qemu will use a default name
of 'iqn.2008-11.org.linux-kvm[:<uuid>'] where <uuid> is the UUID of the
virtual machine. If the UUID is not specified qemu will use
'iqn.2008-11.org.linux-kvm[:<name>'] where <name> is the name of the
virtual machine.
Setting a specific initiator name to use when logging in to the target:
::
-iscsi initiator-name=iqn.qemu.test:my-initiator
Controlling which type of header digest to negotiate with the target:
::
-iscsi header-digest=CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
These can also be set via a configuration file:
::
[iscsi]
user = "CHAP username"
password = "CHAP password"
initiator-name = "iqn.qemu.test:my-initiator"
# header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
header-digest = "CRC32C"
Setting the target name allows different options for different targets:
::
[iscsi "iqn.target.name"]
user = "CHAP username"
password = "CHAP password"
initiator-name = "iqn.qemu.test:my-initiator"
# header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
header-digest = "CRC32C"
How to use a configuration file to set iSCSI configuration options:
.. parsed-literal::
cat >iscsi.conf <<EOF
[iscsi]
user = "me"
password = "my password"
initiator-name = "iqn.qemu.test:my-initiator"
header-digest = "CRC32C"
EOF
|qemu_system| -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \\
-readconfig iscsi.conf
How to set up a simple iSCSI target on loopback and access it via QEMU:
this example shows how to set up an iSCSI target with one CDROM and one DISK
using the Linux STGT software target. This target is available on Red Hat based
systems as the package 'scsi-target-utils'.
.. parsed-literal::
tgtd --iscsi portal=127.0.0.1:3260
tgtadm --lld iscsi --op new --mode target --tid 1 -T iqn.qemu.test
tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 1 \\
-b /IMAGES/disk.img --device-type=disk
tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 2 \\
-b /IMAGES/cd.iso --device-type=cd
tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL
|qemu_system| -iscsi initiator-name=iqn.qemu.test:my-initiator \\
-boot d -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \\
-cdrom iscsi://127.0.0.1/iqn.qemu.test/2
GlusterFS disk images
---------------------
GlusterFS is a user space distributed file system.
You can boot from the GlusterFS disk image with the command:
URI:
.. parsed-literal::
|qemu_system| -drive file=gluster[+TYPE]://[HOST}[:PORT]]/VOLUME/PATH
[?socket=...][,file.debug=9][,file.logfile=...]
JSON:
.. parsed-literal::
|qemu_system| 'json:{"driver":"qcow2",
"file":{"driver":"gluster",
"volume":"testvol","path":"a.img","debug":9,"logfile":"...",
"server":[{"type":"tcp","host":"...","port":"..."},
{"type":"unix","socket":"..."}]}}'
*gluster* is the protocol.
*TYPE* specifies the transport type used to connect to gluster
management daemon (glusterd). Valid transport types are
tcp and unix. In the URI form, if a transport type isn't specified,
then tcp type is assumed.
*HOST* specifies the server where the volume file specification for
the given volume resides. This can be either a hostname or an ipv4 address.
If transport type is unix, then *HOST* field should not be specified.
Instead *socket* field needs to be populated with the path to unix domain
socket.
*PORT* is the port number on which glusterd is listening. This is optional
and if not specified, it defaults to port 24007. If the transport type is unix,
then *PORT* should not be specified.
*VOLUME* is the name of the gluster volume which contains the disk image.
*PATH* is the path to the actual disk image that resides on gluster volume.
*debug* is the logging level of the gluster protocol driver. Debug levels
are 0-9, with 9 being the most verbose, and 0 representing no debugging output.
The default level is 4. The current logging levels defined in the gluster source
are 0 - None, 1 - Emergency, 2 - Alert, 3 - Critical, 4 - Error, 5 - Warning,
6 - Notice, 7 - Info, 8 - Debug, 9 - Trace
*logfile* is a commandline option to mention log file path which helps in
logging to the specified file and also help in persisting the gfapi logs. The
default is stderr.
You can create a GlusterFS disk image with the command:
.. parsed-literal::
qemu-img create gluster://HOST/VOLUME/PATH SIZE
Examples
.. parsed-literal::
|qemu_system| -drive file=gluster://1.2.3.4/testvol/a.img
|qemu_system| -drive file=gluster+tcp://1.2.3.4/testvol/a.img
|qemu_system| -drive file=gluster+tcp://1.2.3.4:24007/testvol/dir/a.img
|qemu_system| -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]/testvol/dir/a.img
|qemu_system| -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]:24007/testvol/dir/a.img
|qemu_system| -drive file=gluster+tcp://server.domain.com:24007/testvol/dir/a.img
|qemu_system| -drive file=gluster+unix:///testvol/dir/a.img?socket=/tmp/glusterd.socket
|qemu_system| -drive file=gluster+rdma://1.2.3.4:24007/testvol/a.img
|qemu_system| -drive file=gluster://1.2.3.4/testvol/a.img,file.debug=9,file.logfile=/var/log/qemu-gluster.log
|qemu_system| 'json:{"driver":"qcow2",
"file":{"driver":"gluster",
"volume":"testvol","path":"a.img",
"debug":9,"logfile":"/var/log/qemu-gluster.log",
"server":[{"type":"tcp","host":"1.2.3.4","port":24007},
{"type":"unix","socket":"/var/run/glusterd.socket"}]}}'
|qemu_system| -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
file.debug=9,file.logfile=/var/log/qemu-gluster.log,
file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket
Secure Shell (ssh) disk images
------------------------------
You can access disk images located on a remote ssh server
by using the ssh protocol:
.. parsed-literal::
|qemu_system| -drive file=ssh://[USER@]SERVER[:PORT]/PATH[?host_key_check=HOST_KEY_CHECK]
Alternative syntax using properties:
.. parsed-literal::
|qemu_system| -drive file.driver=ssh[,file.user=USER],file.host=SERVER[,file.port=PORT],file.path=PATH[,file.host_key_check=HOST_KEY_CHECK]
*ssh* is the protocol.
*USER* is the remote user. If not specified, then the local
username is tried.
*SERVER* specifies the remote ssh server. Any ssh server can be
used, but it must implement the sftp-server protocol. Most Unix/Linux
systems should work without requiring any extra configuration.
*PORT* is the port number on which sshd is listening. By default
the standard ssh port (22) is used.
*PATH* is the path to the disk image.
The optional *HOST_KEY_CHECK* parameter controls how the remote
host's key is checked. The default is ``yes`` which means to use
the local ``.ssh/known_hosts`` file. Setting this to ``no``
turns off known-hosts checking. Or you can check that the host key
matches a specific fingerprint:
``host_key_check=md5:78:45:8e:14:57:4f:d5:45:83:0a:0e:f3:49:82:c9:c8``
(``sha1:`` can also be used as a prefix, but note that OpenSSH
tools only use MD5 to print fingerprints).
Currently authentication must be done using ssh-agent. Other
authentication methods may be supported in future.
Note: Many ssh servers do not support an ``fsync``-style operation.
The ssh driver cannot guarantee that disk flush requests are
obeyed, and this causes a risk of disk corruption if the remote
server or network goes down during writes. The driver will
print a warning when ``fsync`` is not supported:
::
warning: ssh server ssh.example.com:22 does not support fsync
With sufficiently new versions of libssh and OpenSSH, ``fsync`` is
supported.
NVMe disk images
----------------
NVM Express (NVMe) storage controllers can be accessed directly by a userspace
driver in QEMU. This bypasses the host kernel file system and block layers
while retaining QEMU block layer functionalities, such as block jobs, I/O
throttling, image formats, etc. Disk I/O performance is typically higher than
with ``-drive file=/dev/sda`` using either thread pool or linux-aio.
The controller will be exclusively used by the QEMU process once started. To be
able to share storage between multiple VMs and other applications on the host,
please use the file based protocols.
Before starting QEMU, bind the host NVMe controller to the host vfio-pci
driver. For example:
.. parsed-literal::
# modprobe vfio-pci
# lspci -n -s 0000:06:0d.0
06:0d.0 0401: 1102:0002 (rev 08)
# echo 0000:06:0d.0 > /sys/bus/pci/devices/0000:06:0d.0/driver/unbind
# echo 1102 0002 > /sys/bus/pci/drivers/vfio-pci/new_id
# |qemu_system| -drive file=nvme://HOST:BUS:SLOT.FUNC/NAMESPACE
Alternative syntax using properties:
.. parsed-literal::
|qemu_system| -drive file.driver=nvme,file.device=HOST:BUS:SLOT.FUNC,file.namespace=NAMESPACE
*HOST*:*BUS*:*SLOT*.\ *FUNC* is the NVMe controller's PCI device
address on the host.
*NAMESPACE* is the NVMe namespace number, starting from 1.
Disk image file locking
-----------------------
By default, QEMU tries to protect image files from unexpected concurrent
access, as long as it's supported by the block protocol driver and host
operating system. If multiple QEMU processes (including QEMU emulators and
utilities) try to open the same image with conflicting accessing modes, all but
the first one will get an error.
This feature is currently supported by the file protocol on Linux with the Open
File Descriptor (OFD) locking API, and can be configured to fall back to POSIX
locking if the POSIX host doesn't support Linux OFD locking.
To explicitly enable image locking, specify "locking=on" in the file protocol
driver options. If OFD locking is not possible, a warning will be printed and
the POSIX locking API will be used. In this case there is a risk that the lock
will get silently lost when doing hot plugging and block jobs, due to the
shortcomings of the POSIX locking API.
QEMU transparently handles lock handover during shared storage migration. For
shared virtual disk images between multiple VMs, the "share-rw" device option
should be used.
By default, the guest has exclusive write access to its disk image. If the
guest can safely share the disk image with other writers the
``-device ...,share-rw=on`` parameter can be used. This is only safe if
the guest is running software, such as a cluster file system, that
coordinates disk accesses to avoid corruption.
Note that share-rw=on only declares the guest's ability to share the disk.
Some QEMU features, such as image file formats, require exclusive write access
to the disk image and this is unaffected by the share-rw=on option.
Alternatively, locking can be fully disabled by "locking=off" block device
option. In the command line, the option is usually in the form of
"file.locking=off" as the protocol driver is normally placed as a "file" child
under a format driver. For example:
::
-blockdev driver=qcow2,file.filename=/path/to/image,file.locking=off,file.driver=file
To check if image locking is active, check the output of the "lslocks" command
on host and see if there are locks held by the QEMU process on the image file.
More than one byte could be locked by the QEMU instance, each byte of which
reflects a particular permission that is acquired or protected by the running
block driver.
.. only:: man
See also
--------
The HTML documentation of QEMU for more precise information and Linux
user mode emulator invocation.
The HTML documentation of QEMU for more precise information and Linux
user mode emulator invocation.

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Disk image file formats
~~~~~~~~~~~~~~~~~~~~~~~
QEMU supports many image file formats that can be used with VMs as well as with
any of the tools (like ``qemu-img``). This includes the preferred formats
raw and qcow2 as well as formats that are supported for compatibility with
older QEMU versions or other hypervisors.
Depending on the image format, different options can be passed to
``qemu-img create`` and ``qemu-img convert`` using the ``-o`` option.
This section describes each format and the options that are supported for it.
.. program:: image-formats
.. option:: raw
Raw disk image format. This format has the advantage of
being simple and easily exportable to all other emulators. If your
file system supports *holes* (for example in ext2 or ext3 on
Linux or NTFS on Windows), then only the written sectors will reserve
space. Use ``qemu-img info`` to know the real size used by the
image or ``ls -ls`` on Unix/Linux.
Supported options:
.. program:: raw
.. option:: preallocation
Preallocation mode (allowed values: ``off``, ``falloc``,
``full``). ``falloc`` mode preallocates space for image by
calling ``posix_fallocate()``. ``full`` mode preallocates space
for image by writing data to underlying storage. This data may or
may not be zero, depending on the storage location.
.. program:: image-formats
.. option:: qcow2
QEMU image format, the most versatile format. Use it to have smaller
images (useful if your filesystem does not supports holes, for example
on Windows), zlib based compression and support of multiple VM
snapshots.
Supported options:
.. program:: qcow2
.. option:: compat
Determines the qcow2 version to use. ``compat=0.10`` uses the
traditional image format that can be read by any QEMU since 0.10.
``compat=1.1`` enables image format extensions that only QEMU 1.1 and
newer understand (this is the default). Amongst others, this includes
zero clusters, which allow efficient copy-on-read for sparse images.
.. option:: backing_file
File name of a base image (see ``create`` subcommand)
.. option:: backing_fmt
Image format of the base image
.. option:: encryption
This option is deprecated and equivalent to ``encrypt.format=aes``
.. option:: encrypt.format
If this is set to ``luks``, it requests that the qcow2 payload (not
qcow2 header) be encrypted using the LUKS format. The passphrase to
use to unlock the LUKS key slot is given by the ``encrypt.key-secret``
parameter. LUKS encryption parameters can be tuned with the other
``encrypt.*`` parameters.
If this is set to ``aes``, the image is encrypted with 128-bit AES-CBC.
The encryption key is given by the ``encrypt.key-secret`` parameter.
This encryption format is considered to be flawed by modern cryptography
standards, suffering from a number of design problems:
- The AES-CBC cipher is used with predictable initialization vectors based
on the sector number. This makes it vulnerable to chosen plaintext attacks
which can reveal the existence of encrypted data.
- The user passphrase is directly used as the encryption key. A poorly
chosen or short passphrase will compromise the security of the encryption.
- In the event of the passphrase being compromised there is no way to
change the passphrase to protect data in any qcow images. The files must
be cloned, using a different encryption passphrase in the new file. The
original file must then be securely erased using a program like shred,
though even this is ineffective with many modern storage technologies.
The use of this is no longer supported in system emulators. Support only
remains in the command line utilities, for the purposes of data liberation
and interoperability with old versions of QEMU. The ``luks`` format
should be used instead.
.. option:: encrypt.key-secret
Provides the ID of a ``secret`` object that contains the passphrase
(``encrypt.format=luks``) or encryption key (``encrypt.format=aes``).
.. option:: encrypt.cipher-alg
Name of the cipher algorithm and key length. Currently defaults
to ``aes-256``. Only used when ``encrypt.format=luks``.
.. option:: encrypt.cipher-mode
Name of the encryption mode to use. Currently defaults to ``xts``.
Only used when ``encrypt.format=luks``.
.. option:: encrypt.ivgen-alg
Name of the initialization vector generator algorithm. Currently defaults
to ``plain64``. Only used when ``encrypt.format=luks``.
.. option:: encrypt.ivgen-hash-alg
Name of the hash algorithm to use with the initialization vector generator
(if required). Defaults to ``sha256``. Only used when ``encrypt.format=luks``.
.. option:: encrypt.hash-alg
Name of the hash algorithm to use for PBKDF algorithm
Defaults to ``sha256``. Only used when ``encrypt.format=luks``.
.. option:: encrypt.iter-time
Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.
Defaults to ``2000``. Only used when ``encrypt.format=luks``.
.. option:: cluster_size
Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster
sizes can improve the image file size whereas larger cluster sizes generally
provide better performance.
.. option:: preallocation
Preallocation mode (allowed values: ``off``, ``metadata``, ``falloc``,
``full``). An image with preallocated metadata is initially larger but can
improve performance when the image needs to grow. ``falloc`` and ``full``
preallocations are like the same options of ``raw`` format, but sets up
metadata also.
.. option:: lazy_refcounts
If this option is set to ``on``, reference count updates are postponed with
the goal of avoiding metadata I/O and improving performance. This is
particularly interesting with :option:`cache=writethrough` which doesn't batch
metadata updates. The tradeoff is that after a host crash, the reference count
tables must be rebuilt, i.e. on the next open an (automatic) ``qemu-img
check -r all`` is required, which may take some time.
This option can only be enabled if ``compat=1.1`` is specified.
.. option:: nocow
If this option is set to ``on``, it will turn off COW of the file. It's only
valid on btrfs, no effect on other file systems.
Btrfs has low performance when hosting a VM image file, even more
when the guest on the VM also using btrfs as file system. Turning off
COW is a way to mitigate this bad performance. Generally there are two
ways to turn off COW on btrfs:
- Disable it by mounting with nodatacow, then all newly created files
will be NOCOW.
- For an empty file, add the NOCOW file attribute. That's what this
option does.
Note: this option is only valid to new or empty files. If there is
an existing file which is COW and has data blocks already, it couldn't
be changed to NOCOW by setting ``nocow=on``. One can issue ``lsattr
filename`` to check if the NOCOW flag is set or not (Capital 'C' is
NOCOW flag).
.. program:: image-formats
.. option:: qed
Old QEMU image format with support for backing files and compact image files
(when your filesystem or transport medium does not support holes).
When converting QED images to qcow2, you might want to consider using the
``lazy_refcounts=on`` option to get a more QED-like behaviour.
Supported options:
.. program:: qed
.. option:: backing_file
File name of a base image (see ``create`` subcommand).
.. option:: backing_fmt
Image file format of backing file (optional). Useful if the format cannot be
autodetected because it has no header, like some vhd/vpc files.
.. option:: cluster_size
Changes the cluster size (must be power-of-2 between 4K and 64K). Smaller
cluster sizes can improve the image file size whereas larger cluster sizes
generally provide better performance.
.. option:: table_size
Changes the number of clusters per L1/L2 table (must be
power-of-2 between 1 and 16). There is normally no need to
change this value but this option can between used for
performance benchmarking.
.. program:: image-formats
.. option:: qcow
Old QEMU image format with support for backing files, compact image files,
encryption and compression.
Supported options:
.. program:: qcow
.. option:: backing_file
File name of a base image (see ``create`` subcommand)
.. option:: encryption
This option is deprecated and equivalent to ``encrypt.format=aes``
.. option:: encrypt.format
If this is set to ``aes``, the image is encrypted with 128-bit AES-CBC.
The encryption key is given by the ``encrypt.key-secret`` parameter.
This encryption format is considered to be flawed by modern cryptography
standards, suffering from a number of design problems enumerated previously
against the ``qcow2`` image format.
The use of this is no longer supported in system emulators. Support only
remains in the command line utilities, for the purposes of data liberation
and interoperability with old versions of QEMU.
Users requiring native encryption should use the ``qcow2`` format
instead with ``encrypt.format=luks``.
.. option:: encrypt.key-secret
Provides the ID of a ``secret`` object that contains the encryption
key (``encrypt.format=aes``).
.. program:: image-formats
.. option:: luks
LUKS v1 encryption format, compatible with Linux dm-crypt/cryptsetup
Supported options:
.. program:: luks
.. option:: key-secret
Provides the ID of a ``secret`` object that contains the passphrase.
.. option:: cipher-alg
Name of the cipher algorithm and key length. Currently defaults
to ``aes-256``.
.. option:: cipher-mode
Name of the encryption mode to use. Currently defaults to ``xts``.
.. option:: ivgen-alg
Name of the initialization vector generator algorithm. Currently defaults
to ``plain64``.
.. option:: ivgen-hash-alg
Name of the hash algorithm to use with the initialization vector generator
(if required). Defaults to ``sha256``.
.. option:: hash-alg
Name of the hash algorithm to use for PBKDF algorithm
Defaults to ``sha256``.
.. option:: iter-time
Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.
Defaults to ``2000``.
.. program:: image-formats
.. option:: vdi
VirtualBox 1.1 compatible image format.
Supported options:
.. program:: vdi
.. option:: static
If this option is set to ``on``, the image is created with metadata
preallocation.
.. program:: image-formats
.. option:: vmdk
VMware 3 and 4 compatible image format.
Supported options:
.. program: vmdk
.. option:: backing_file
File name of a base image (see ``create`` subcommand).
.. option:: compat6
Create a VMDK version 6 image (instead of version 4)
.. option:: hwversion
Specify vmdk virtual hardware version. Compat6 flag cannot be enabled
if hwversion is specified.
.. option:: subformat
Specifies which VMDK subformat to use. Valid options are
``monolithicSparse`` (default),
``monolithicFlat``,
``twoGbMaxExtentSparse``,
``twoGbMaxExtentFlat`` and
``streamOptimized``.
.. program:: image-formats
.. option:: vpc
VirtualPC compatible image format (VHD).
Supported options:
.. program:: vpc
.. option:: subformat
Specifies which VHD subformat to use. Valid options are
``dynamic`` (default) and ``fixed``.
.. program:: image-formats
.. option:: VHDX
Hyper-V compatible image format (VHDX).
Supported options:
.. program:: VHDX
.. option:: subformat
Specifies which VHDX subformat to use. Valid options are
``dynamic`` (default) and ``fixed``.
.. option:: block_state_zero
Force use of payload blocks of type 'ZERO'. Can be set to ``on`` (default)
or ``off``. When set to ``off``, new blocks will be created as
``PAYLOAD_BLOCK_NOT_PRESENT``, which means parsers are free to return
arbitrary data for those blocks. Do not set to ``off`` when using
``qemu-img convert`` with ``subformat=dynamic``.
.. option:: block_size
Block size; min 1 MB, max 256 MB. 0 means auto-calculate based on
image size.
.. option:: log_size
Log size; min 1 MB.
Read-only formats
~~~~~~~~~~~~~~~~~
More disk image file formats are supported in a read-only mode.
.. program:: image-formats
.. option:: bochs
Bochs images of ``growing`` type.
.. program:: image-formats
.. option:: cloop
Linux Compressed Loop image, useful only to reuse directly compressed
CD-ROM images present for example in the Knoppix CD-ROMs.
.. program:: image-formats
.. option:: dmg
Apple disk image.
.. program:: image-formats
.. option:: parallels
Parallels disk image format.
Using host drives
~~~~~~~~~~~~~~~~~
In addition to disk image files, QEMU can directly access host
devices. We describe here the usage for QEMU version >= 0.8.3.
Linux
^^^^^
On Linux, you can directly use the host device filename instead of a
disk image filename provided you have enough privileges to access
it. For example, use ``/dev/cdrom`` to access to the CDROM.
CD
You can specify a CDROM device even if no CDROM is loaded. QEMU has
specific code to detect CDROM insertion or removal. CDROM ejection by
the guest OS is supported. Currently only data CDs are supported.
Floppy
You can specify a floppy device even if no floppy is loaded. Floppy
removal is currently not detected accurately (if you change floppy
without doing floppy access while the floppy is not loaded, the guest
OS will think that the same floppy is loaded).
Use of the host's floppy device is deprecated, and support for it will
be removed in a future release.
Hard disks
Hard disks can be used. Normally you must specify the whole disk
(``/dev/hdb`` instead of ``/dev/hdb1``) so that the guest OS can
see it as a partitioned disk. WARNING: unless you know what you do, it
is better to only make READ-ONLY accesses to the hard disk otherwise
you may corrupt your host data (use the ``-snapshot`` command
line option or modify the device permissions accordingly).
Windows
^^^^^^^
CD
The preferred syntax is the drive letter (e.g. ``d:``). The
alternate syntax ``\\.\d:`` is supported. ``/dev/cdrom`` is
supported as an alias to the first CDROM drive.
Currently there is no specific code to handle removable media, so it
is better to use the ``change`` or ``eject`` monitor commands to
change or eject media.
Hard disks
Hard disks can be used with the syntax: ``\\.\PhysicalDriveN``
where *N* is the drive number (0 is the first hard disk).
WARNING: unless you know what you do, it is better to only make
READ-ONLY accesses to the hard disk otherwise you may corrupt your
host data (use the ``-snapshot`` command line so that the
modifications are written in a temporary file).
Mac OS X
^^^^^^^^
``/dev/cdrom`` is an alias to the first CDROM.
Currently there is no specific code to handle removable media, so it
is better to use the ``change`` or ``eject`` monitor commands to
change or eject media.
Virtual FAT disk images
~~~~~~~~~~~~~~~~~~~~~~~
QEMU can automatically create a virtual FAT disk image from a
directory tree. In order to use it, just type:
.. parsed-literal::
|qemu_system| linux.img -hdb fat:/my_directory
Then you access access to all the files in the ``/my_directory``
directory without having to copy them in a disk image or to export
them via SAMBA or NFS. The default access is *read-only*.
Floppies can be emulated with the ``:floppy:`` option:
.. parsed-literal::
|qemu_system| linux.img -fda fat:floppy:/my_directory
A read/write support is available for testing (beta stage) with the
``:rw:`` option:
.. parsed-literal::
|qemu_system| linux.img -fda fat:floppy:rw:/my_directory
What you should *never* do:
- use non-ASCII filenames
- use "-snapshot" together with ":rw:"
- expect it to work when loadvm'ing
- write to the FAT directory on the host system while accessing it with the guest system
NBD access
~~~~~~~~~~
QEMU can access directly to block device exported using the Network Block Device
protocol.
.. parsed-literal::
|qemu_system| linux.img -hdb nbd://my_nbd_server.mydomain.org:1024/
If the NBD server is located on the same host, you can use an unix socket instead
of an inet socket:
.. parsed-literal::
|qemu_system| linux.img -hdb nbd+unix://?socket=/tmp/my_socket
In this case, the block device must be exported using qemu-nbd:
.. parsed-literal::
qemu-nbd --socket=/tmp/my_socket my_disk.qcow2
The use of qemu-nbd allows sharing of a disk between several guests:
.. parsed-literal::
qemu-nbd --socket=/tmp/my_socket --share=2 my_disk.qcow2
and then you can use it with two guests:
.. parsed-literal::
|qemu_system| linux1.img -hdb nbd+unix://?socket=/tmp/my_socket
|qemu_system| linux2.img -hdb nbd+unix://?socket=/tmp/my_socket
If the nbd-server uses named exports (supported since NBD 2.9.18, or with QEMU's
own embedded NBD server), you must specify an export name in the URI:
.. parsed-literal::
|qemu_system| -cdrom nbd://localhost/debian-500-ppc-netinst
|qemu_system| -cdrom nbd://localhost/openSUSE-11.1-ppc-netinst
The URI syntax for NBD is supported since QEMU 1.3. An alternative syntax is
also available. Here are some example of the older syntax:
.. parsed-literal::
|qemu_system| linux.img -hdb nbd:my_nbd_server.mydomain.org:1024
|qemu_system| linux2.img -hdb nbd:unix:/tmp/my_socket
|qemu_system| -cdrom nbd:localhost:10809:exportname=debian-500-ppc-netinst
Sheepdog disk images
~~~~~~~~~~~~~~~~~~~~
Sheepdog is a distributed storage system for QEMU. It provides highly
available block level storage volumes that can be attached to
QEMU-based virtual machines.
You can create a Sheepdog disk image with the command:
.. parsed-literal::
qemu-img create sheepdog:///IMAGE SIZE
where *IMAGE* is the Sheepdog image name and *SIZE* is its
size.
To import the existing *FILENAME* to Sheepdog, you can use a
convert command.
.. parsed-literal::
qemu-img convert FILENAME sheepdog:///IMAGE
You can boot from the Sheepdog disk image with the command:
.. parsed-literal::
|qemu_system| sheepdog:///IMAGE
You can also create a snapshot of the Sheepdog image like qcow2.
.. parsed-literal::
qemu-img snapshot -c TAG sheepdog:///IMAGE
where *TAG* is a tag name of the newly created snapshot.
To boot from the Sheepdog snapshot, specify the tag name of the
snapshot.
.. parsed-literal::
|qemu_system| sheepdog:///IMAGE#TAG
You can create a cloned image from the existing snapshot.
.. parsed-literal::
qemu-img create -b sheepdog:///BASE#TAG sheepdog:///IMAGE
where *BASE* is an image name of the source snapshot and *TAG*
is its tag name.
You can use an unix socket instead of an inet socket:
.. parsed-literal::
|qemu_system| sheepdog+unix:///IMAGE?socket=PATH
If the Sheepdog daemon doesn't run on the local host, you need to
specify one of the Sheepdog servers to connect to.
.. parsed-literal::
qemu-img create sheepdog://HOSTNAME:PORT/IMAGE SIZE
|qemu_system| sheepdog://HOSTNAME:PORT/IMAGE
iSCSI LUNs
~~~~~~~~~~
iSCSI is a popular protocol used to access SCSI devices across a computer
network.
There are two different ways iSCSI devices can be used by QEMU.
The first method is to mount the iSCSI LUN on the host, and make it appear as
any other ordinary SCSI device on the host and then to access this device as a
/dev/sd device from QEMU. How to do this differs between host OSes.
The second method involves using the iSCSI initiator that is built into
QEMU. This provides a mechanism that works the same way regardless of which
host OS you are running QEMU on. This section will describe this second method
of using iSCSI together with QEMU.
In QEMU, iSCSI devices are described using special iSCSI URLs. URL syntax:
::
iscsi://[<username>[%<password>]@]<host>[:<port>]/<target-iqn-name>/<lun>
Username and password are optional and only used if your target is set up
using CHAP authentication for access control.
Alternatively the username and password can also be set via environment
variables to have these not show up in the process list:
::
export LIBISCSI_CHAP_USERNAME=<username>
export LIBISCSI_CHAP_PASSWORD=<password>
iscsi://<host>/<target-iqn-name>/<lun>
Various session related parameters can be set via special options, either
in a configuration file provided via '-readconfig' or directly on the
command line.
If the initiator-name is not specified qemu will use a default name
of 'iqn.2008-11.org.linux-kvm[:<uuid>'] where <uuid> is the UUID of the
virtual machine. If the UUID is not specified qemu will use
'iqn.2008-11.org.linux-kvm[:<name>'] where <name> is the name of the
virtual machine.
Setting a specific initiator name to use when logging in to the target:
::
-iscsi initiator-name=iqn.qemu.test:my-initiator
Controlling which type of header digest to negotiate with the target:
::
-iscsi header-digest=CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
These can also be set via a configuration file:
::
[iscsi]
user = "CHAP username"
password = "CHAP password"
initiator-name = "iqn.qemu.test:my-initiator"
# header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
header-digest = "CRC32C"
Setting the target name allows different options for different targets:
::
[iscsi "iqn.target.name"]
user = "CHAP username"
password = "CHAP password"
initiator-name = "iqn.qemu.test:my-initiator"
# header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
header-digest = "CRC32C"
How to use a configuration file to set iSCSI configuration options:
.. parsed-literal::
cat >iscsi.conf <<EOF
[iscsi]
user = "me"
password = "my password"
initiator-name = "iqn.qemu.test:my-initiator"
header-digest = "CRC32C"
EOF
|qemu_system| -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \\
-readconfig iscsi.conf
How to set up a simple iSCSI target on loopback and access it via QEMU:
this example shows how to set up an iSCSI target with one CDROM and one DISK
using the Linux STGT software target. This target is available on Red Hat based
systems as the package 'scsi-target-utils'.
.. parsed-literal::
tgtd --iscsi portal=127.0.0.1:3260
tgtadm --lld iscsi --op new --mode target --tid 1 -T iqn.qemu.test
tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 1 \\
-b /IMAGES/disk.img --device-type=disk
tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 2 \\
-b /IMAGES/cd.iso --device-type=cd
tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL
|qemu_system| -iscsi initiator-name=iqn.qemu.test:my-initiator \\
-boot d -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \\
-cdrom iscsi://127.0.0.1/iqn.qemu.test/2
GlusterFS disk images
~~~~~~~~~~~~~~~~~~~~~
GlusterFS is a user space distributed file system.
You can boot from the GlusterFS disk image with the command:
URI:
.. parsed-literal::
|qemu_system| -drive file=gluster[+TYPE]://[HOST}[:PORT]]/VOLUME/PATH
[?socket=...][,file.debug=9][,file.logfile=...]
JSON:
.. parsed-literal::
|qemu_system| 'json:{"driver":"qcow2",
"file":{"driver":"gluster",
"volume":"testvol","path":"a.img","debug":9,"logfile":"...",
"server":[{"type":"tcp","host":"...","port":"..."},
{"type":"unix","socket":"..."}]}}'
*gluster* is the protocol.
*TYPE* specifies the transport type used to connect to gluster
management daemon (glusterd). Valid transport types are
tcp and unix. In the URI form, if a transport type isn't specified,
then tcp type is assumed.
*HOST* specifies the server where the volume file specification for
the given volume resides. This can be either a hostname or an ipv4 address.
If transport type is unix, then *HOST* field should not be specified.
Instead *socket* field needs to be populated with the path to unix domain
socket.
*PORT* is the port number on which glusterd is listening. This is optional
and if not specified, it defaults to port 24007. If the transport type is unix,
then *PORT* should not be specified.
*VOLUME* is the name of the gluster volume which contains the disk image.
*PATH* is the path to the actual disk image that resides on gluster volume.
*debug* is the logging level of the gluster protocol driver. Debug levels
are 0-9, with 9 being the most verbose, and 0 representing no debugging output.
The default level is 4. The current logging levels defined in the gluster source
are 0 - None, 1 - Emergency, 2 - Alert, 3 - Critical, 4 - Error, 5 - Warning,
6 - Notice, 7 - Info, 8 - Debug, 9 - Trace
*logfile* is a commandline option to mention log file path which helps in
logging to the specified file and also help in persisting the gfapi logs. The
default is stderr.
You can create a GlusterFS disk image with the command:
.. parsed-literal::
qemu-img create gluster://HOST/VOLUME/PATH SIZE
Examples
.. parsed-literal::
|qemu_system| -drive file=gluster://1.2.3.4/testvol/a.img
|qemu_system| -drive file=gluster+tcp://1.2.3.4/testvol/a.img
|qemu_system| -drive file=gluster+tcp://1.2.3.4:24007/testvol/dir/a.img
|qemu_system| -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]/testvol/dir/a.img
|qemu_system| -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]:24007/testvol/dir/a.img
|qemu_system| -drive file=gluster+tcp://server.domain.com:24007/testvol/dir/a.img
|qemu_system| -drive file=gluster+unix:///testvol/dir/a.img?socket=/tmp/glusterd.socket
|qemu_system| -drive file=gluster+rdma://1.2.3.4:24007/testvol/a.img
|qemu_system| -drive file=gluster://1.2.3.4/testvol/a.img,file.debug=9,file.logfile=/var/log/qemu-gluster.log
|qemu_system| 'json:{"driver":"qcow2",
"file":{"driver":"gluster",
"volume":"testvol","path":"a.img",
"debug":9,"logfile":"/var/log/qemu-gluster.log",
"server":[{"type":"tcp","host":"1.2.3.4","port":24007},
{"type":"unix","socket":"/var/run/glusterd.socket"}]}}'
|qemu_system| -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
file.debug=9,file.logfile=/var/log/qemu-gluster.log,
file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket
Secure Shell (ssh) disk images
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You can access disk images located on a remote ssh server
by using the ssh protocol:
.. parsed-literal::
|qemu_system| -drive file=ssh://[USER@]SERVER[:PORT]/PATH[?host_key_check=HOST_KEY_CHECK]
Alternative syntax using properties:
.. parsed-literal::
|qemu_system| -drive file.driver=ssh[,file.user=USER],file.host=SERVER[,file.port=PORT],file.path=PATH[,file.host_key_check=HOST_KEY_CHECK]
*ssh* is the protocol.
*USER* is the remote user. If not specified, then the local
username is tried.
*SERVER* specifies the remote ssh server. Any ssh server can be
used, but it must implement the sftp-server protocol. Most Unix/Linux
systems should work without requiring any extra configuration.
*PORT* is the port number on which sshd is listening. By default
the standard ssh port (22) is used.
*PATH* is the path to the disk image.
The optional *HOST_KEY_CHECK* parameter controls how the remote
host's key is checked. The default is ``yes`` which means to use
the local ``.ssh/known_hosts`` file. Setting this to ``no``
turns off known-hosts checking. Or you can check that the host key
matches a specific fingerprint:
``host_key_check=md5:78:45:8e:14:57:4f:d5:45:83:0a:0e:f3:49:82:c9:c8``
(``sha1:`` can also be used as a prefix, but note that OpenSSH
tools only use MD5 to print fingerprints).
Currently authentication must be done using ssh-agent. Other
authentication methods may be supported in future.
Note: Many ssh servers do not support an ``fsync``-style operation.
The ssh driver cannot guarantee that disk flush requests are
obeyed, and this causes a risk of disk corruption if the remote
server or network goes down during writes. The driver will
print a warning when ``fsync`` is not supported:
::
warning: ssh server ssh.example.com:22 does not support fsync
With sufficiently new versions of libssh and OpenSSH, ``fsync`` is
supported.
NVMe disk images
~~~~~~~~~~~~~~~~
NVM Express (NVMe) storage controllers can be accessed directly by a userspace
driver in QEMU. This bypasses the host kernel file system and block layers
while retaining QEMU block layer functionalities, such as block jobs, I/O
throttling, image formats, etc. Disk I/O performance is typically higher than
with ``-drive file=/dev/sda`` using either thread pool or linux-aio.
The controller will be exclusively used by the QEMU process once started. To be
able to share storage between multiple VMs and other applications on the host,
please use the file based protocols.
Before starting QEMU, bind the host NVMe controller to the host vfio-pci
driver. For example:
.. parsed-literal::
# modprobe vfio-pci
# lspci -n -s 0000:06:0d.0
06:0d.0 0401: 1102:0002 (rev 08)
# echo 0000:06:0d.0 > /sys/bus/pci/devices/0000:06:0d.0/driver/unbind
# echo 1102 0002 > /sys/bus/pci/drivers/vfio-pci/new_id
# |qemu_system| -drive file=nvme://HOST:BUS:SLOT.FUNC/NAMESPACE
Alternative syntax using properties:
.. parsed-literal::
|qemu_system| -drive file.driver=nvme,file.device=HOST:BUS:SLOT.FUNC,file.namespace=NAMESPACE
*HOST*:*BUS*:*SLOT*.\ *FUNC* is the NVMe controller's PCI device
address on the host.
*NAMESPACE* is the NVMe namespace number, starting from 1.
Disk image file locking
~~~~~~~~~~~~~~~~~~~~~~~
By default, QEMU tries to protect image files from unexpected concurrent
access, as long as it's supported by the block protocol driver and host
operating system. If multiple QEMU processes (including QEMU emulators and
utilities) try to open the same image with conflicting accessing modes, all but
the first one will get an error.
This feature is currently supported by the file protocol on Linux with the Open
File Descriptor (OFD) locking API, and can be configured to fall back to POSIX
locking if the POSIX host doesn't support Linux OFD locking.
To explicitly enable image locking, specify "locking=on" in the file protocol
driver options. If OFD locking is not possible, a warning will be printed and
the POSIX locking API will be used. In this case there is a risk that the lock
will get silently lost when doing hot plugging and block jobs, due to the
shortcomings of the POSIX locking API.
QEMU transparently handles lock handover during shared storage migration. For
shared virtual disk images between multiple VMs, the "share-rw" device option
should be used.
By default, the guest has exclusive write access to its disk image. If the
guest can safely share the disk image with other writers the
``-device ...,share-rw=on`` parameter can be used. This is only safe if
the guest is running software, such as a cluster file system, that
coordinates disk accesses to avoid corruption.
Note that share-rw=on only declares the guest's ability to share the disk.
Some QEMU features, such as image file formats, require exclusive write access
to the disk image and this is unaffected by the share-rw=on option.
Alternatively, locking can be fully disabled by "locking=off" block device
option. In the command line, the option is usually in the form of
"file.locking=off" as the protocol driver is normally placed as a "file" child
under a format driver. For example:
::
-blockdev driver=qcow2,file.filename=/path/to/image,file.locking=off,file.driver=file
To check if image locking is active, check the output of the "lslocks" command
on host and see if there are locks held by the QEMU process on the image file.
More than one byte could be locked by the QEMU instance, each byte of which
reflects a particular permission that is acquired or protected by the running
block driver.

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:orphan:
QEMU / KVM CPU model configuration
==================================
Synopsis
''''''''
QEMU CPU Modelling Infrastructure manual
Description
'''''''''''
.. include:: cpu-models-x86.rst.inc
.. include:: cpu-models-mips.rst.inc
See also
''''''''
The HTML documentation of QEMU for more precise information and Linux user mode emulator invocation.

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:orphan:
..
This file is the skeleton for the qemu.1 manpage. It mostly
should simply include the .rst.inc files corresponding to the
parts of the documentation that go in the manpage as well as the
HTML manual.
Title
=====
Synopsis
--------
.. parsed-literal::
|qemu_system| [options] [disk_image]
Description
-----------
.. include:: target-i386-desc.rst.inc
Options
-------
disk_image is a raw hard disk image for IDE hard disk 0. Some targets do
not need a disk image.
.. hxtool-doc:: qemu-options.hx
.. include:: keys.rst.inc
.. include:: mux-chardev.rst.inc
Notes
-----
.. include:: device-url-syntax.rst.inc
See also
--------
The HTML documentation of QEMU for more precise information and Linux
user mode emulator invocation.

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.. _pcsys_005fquickstart:
Quick Start
-----------
Download and uncompress a PC hard disk image with Linux installed (e.g.
``linux.img``) and type:
.. parsed-literal::
|qemu_system| linux.img
Linux should boot and give you a prompt.

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@ -1,19 +1,22 @@
@node Security
@chapter Security
Security
========
@section Overview
Overview
--------
This chapter explains the security requirements that QEMU is designed to meet
and principles for securely deploying QEMU.
@section Security Requirements
Security Requirements
---------------------
QEMU supports many different use cases, some of which have stricter security
requirements than others. The community has agreed on the overall security
requirements that users may depend on. These requirements define what is
considered supported from a security perspective.
@subsection Virtualization Use Case
Virtualization Use Case
'''''''''''''''''''''''
The virtualization use case covers cloud and virtual private server (VPS)
hosting, as well as traditional data center and desktop virtualization. These
@ -23,18 +26,17 @@ safely on the physical CPU at close-to-native speed.
The following entities are untrusted, meaning that they may be buggy or
malicious:
@itemize
@item Guest
@item User-facing interfaces (e.g. VNC, SPICE, WebSocket)
@item Network protocols (e.g. NBD, live migration)
@item User-supplied files (e.g. disk images, kernels, device trees)
@item Passthrough devices (e.g. PCI, USB)
@end itemize
- Guest
- User-facing interfaces (e.g. VNC, SPICE, WebSocket)
- Network protocols (e.g. NBD, live migration)
- User-supplied files (e.g. disk images, kernels, device trees)
- Passthrough devices (e.g. PCI, USB)
Bugs affecting these entities are evaluated on whether they can cause damage in
real-world use cases and treated as security bugs if this is the case.
@subsection Non-virtualization Use Case
Non-virtualization Use Case
'''''''''''''''''''''''''''
The non-virtualization use case covers emulation using the Tiny Code Generator
(TCG). In principle the TCG and device emulation code used in conjunction with
@ -47,12 +49,14 @@ Bugs affecting the non-virtualization use case are not considered security
bugs at this time. Users with non-virtualization use cases must not rely on
QEMU to provide guest isolation or any security guarantees.
@section Architecture
Architecture
------------
This section describes the design principles that ensure the security
requirements are met.
@subsection Guest Isolation
Guest Isolation
'''''''''''''''
Guest isolation is the confinement of guest code to the virtual machine. When
guest code gains control of execution on the host this is called escaping the
@ -71,7 +75,8 @@ malicious guest must not gain control of other guests or access their data.
Disk image files and network traffic must be protected from other guests unless
explicitly shared between them by the user.
@subsection Principle of Least Privilege
Principle of Least Privilege
''''''''''''''''''''''''''''
The principle of least privilege states that each component only has access to
the privileges necessary for its function. In the case of QEMU this means that
@ -84,7 +89,7 @@ the guest.
Following the principle of least privilege immediately fulfills guest isolation
requirements. For example, guest A only has access to its own disk image file
@code{a.img} and not guest B's disk image file @code{b.img}.
``a.img`` and not guest B's disk image file ``b.img``.
In reality certain resources are inaccessible to the guest but must be
available to QEMU to perform its function. For example, host system calls are
@ -95,7 +100,8 @@ New features must be designed to follow the principle of least privilege.
Should this not be possible for technical reasons, the security risk must be
clearly documented so users are aware of the trade-off of enabling the feature.
@subsection Isolation mechanisms
Isolation mechanisms
''''''''''''''''''''
Several isolation mechanisms are available to realize this architecture of
guest isolation and the principle of least privilege. With the exception of
@ -105,46 +111,46 @@ described briefly for Linux here.
The fundamental isolation mechanism is that QEMU processes must run as
unprivileged users. Sometimes it seems more convenient to launch QEMU as
root to give it access to host devices (e.g. @code{/dev/net/tun}) but this poses a
root to give it access to host devices (e.g. ``/dev/net/tun``) but this poses a
huge security risk. File descriptor passing can be used to give an otherwise
unprivileged QEMU process access to host devices without running QEMU as root.
It is also possible to launch QEMU as a non-root user and configure UNIX groups
for access to @code{/dev/kvm}, @code{/dev/net/tun}, and other device nodes.
for access to ``/dev/kvm``, ``/dev/net/tun``, and other device nodes.
Some Linux distros already ship with UNIX groups for these devices by default.
@itemize
@item SELinux and AppArmor make it possible to confine processes beyond the
traditional UNIX process and file permissions model. They restrict the QEMU
process from accessing processes and files on the host system that are not
needed by QEMU.
- SELinux and AppArmor make it possible to confine processes beyond the
traditional UNIX process and file permissions model. They restrict the QEMU
process from accessing processes and files on the host system that are not
needed by QEMU.
@item Resource limits and cgroup controllers provide throughput and utilization
limits on key resources such as CPU time, memory, and I/O bandwidth.
- Resource limits and cgroup controllers provide throughput and utilization
limits on key resources such as CPU time, memory, and I/O bandwidth.
@item Linux namespaces can be used to make process, file system, and other system
resources unavailable to QEMU. A namespaced QEMU process is restricted to only
those resources that were granted to it.
- Linux namespaces can be used to make process, file system, and other system
resources unavailable to QEMU. A namespaced QEMU process is restricted to only
those resources that were granted to it.
@item Linux seccomp is available via the QEMU @option{--sandbox} option. It disables
system calls that are not needed by QEMU, thereby reducing the host kernel
attack surface.
@end itemize
- Linux seccomp is available via the QEMU ``--sandbox`` option. It disables
system calls that are not needed by QEMU, thereby reducing the host kernel
attack surface.
@section Sensitive configurations
Sensitive configurations
------------------------
There are aspects of QEMU that can have security implications which users &
management applications must be aware of.
@subsection Monitor console (QMP and HMP)
Monitor console (QMP and HMP)
'''''''''''''''''''''''''''''
The monitor console (whether used with QMP or HMP) provides an interface
to dynamically control many aspects of QEMU's runtime operation. Many of the
commands exposed will instruct QEMU to access content on the host file system
and/or trigger spawning of external processes.
For example, the @code{migrate} command allows for the spawning of arbitrary
For example, the ``migrate`` command allows for the spawning of arbitrary
processes for the purpose of tunnelling the migration data stream. The
@code{blockdev-add} command instructs QEMU to open arbitrary files, exposing
``blockdev-add`` command instructs QEMU to open arbitrary files, exposing
their content to the guest as a virtual disk.
Unless QEMU is otherwise confined using technologies such as SELinux, AppArmor,

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.. _ARM-System-emulator:
ARM System emulator
-------------------
Use the executable ``qemu-system-arm`` to simulate a ARM machine. The
ARM Integrator/CP board is emulated with the following devices:
- ARM926E, ARM1026E, ARM946E, ARM1136 or Cortex-A8 CPU
- Two PL011 UARTs
- SMC 91c111 Ethernet adapter
- PL110 LCD controller
- PL050 KMI with PS/2 keyboard and mouse.
- PL181 MultiMedia Card Interface with SD card.
The ARM Versatile baseboard is emulated with the following devices:
- ARM926E, ARM1136 or Cortex-A8 CPU
- PL190 Vectored Interrupt Controller
- Four PL011 UARTs
- SMC 91c111 Ethernet adapter
- PL110 LCD controller
- PL050 KMI with PS/2 keyboard and mouse.
- PCI host bridge. Note the emulated PCI bridge only provides access
to PCI memory space. It does not provide access to PCI IO space. This
means some devices (eg. ne2k_pci NIC) are not usable, and others (eg.
rtl8139 NIC) are only usable when the guest drivers use the memory
mapped control registers.
- PCI OHCI USB controller.
- LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM
devices.
- PL181 MultiMedia Card Interface with SD card.
Several variants of the ARM RealView baseboard are emulated, including
the EB, PB-A8 and PBX-A9. Due to interactions with the bootloader, only
certain Linux kernel configurations work out of the box on these boards.
Kernels for the PB-A8 board should have CONFIG_REALVIEW_HIGH_PHYS_OFFSET
enabled in the kernel, and expect 512M RAM. Kernels for The PBX-A9 board
should have CONFIG_SPARSEMEM enabled, CONFIG_REALVIEW_HIGH_PHYS_OFFSET
disabled and expect 1024M RAM.
The following devices are emulated:
- ARM926E, ARM1136, ARM11MPCore, Cortex-A8 or Cortex-A9 MPCore CPU
- ARM AMBA Generic/Distributed Interrupt Controller
- Four PL011 UARTs
- SMC 91c111 or SMSC LAN9118 Ethernet adapter
- PL110 LCD controller
- PL050 KMI with PS/2 keyboard and mouse
- PCI host bridge
- PCI OHCI USB controller
- LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM
devices
- PL181 MultiMedia Card Interface with SD card.
The XScale-based clamshell PDA models (\"Spitz\", \"Akita\", \"Borzoi\"
and \"Terrier\") emulation includes the following peripherals:
- Intel PXA270 System-on-chip (ARM V5TE core)
- NAND Flash memory
- IBM/Hitachi DSCM microdrive in a PXA PCMCIA slot - not in \"Akita\"
- On-chip OHCI USB controller
- On-chip LCD controller
- On-chip Real Time Clock
- TI ADS7846 touchscreen controller on SSP bus
- Maxim MAX1111 analog-digital converter on |I2C| bus
- GPIO-connected keyboard controller and LEDs
- Secure Digital card connected to PXA MMC/SD host
- Three on-chip UARTs
- WM8750 audio CODEC on |I2C| and |I2S| busses
The Palm Tungsten|E PDA (codename \"Cheetah\") emulation includes the
following elements:
- Texas Instruments OMAP310 System-on-chip (ARM 925T core)
- ROM and RAM memories (ROM firmware image can be loaded with
-option-rom)
- On-chip LCD controller
- On-chip Real Time Clock
- TI TSC2102i touchscreen controller / analog-digital converter /
Audio CODEC, connected through MicroWire and |I2S| busses
- GPIO-connected matrix keypad
- Secure Digital card connected to OMAP MMC/SD host
- Three on-chip UARTs
Nokia N800 and N810 internet tablets (known also as RX-34 and RX-44 /
48) emulation supports the following elements:
- Texas Instruments OMAP2420 System-on-chip (ARM 1136 core)
- RAM and non-volatile OneNAND Flash memories
- Display connected to EPSON remote framebuffer chip and OMAP on-chip
display controller and a LS041y3 MIPI DBI-C controller
- TI TSC2301 (in N800) and TI TSC2005 (in N810) touchscreen
controllers driven through SPI bus
- National Semiconductor LM8323-controlled qwerty keyboard driven
through |I2C| bus
- Secure Digital card connected to OMAP MMC/SD host
- Three OMAP on-chip UARTs and on-chip STI debugging console
- Mentor Graphics \"Inventra\" dual-role USB controller embedded in a
TI TUSB6010 chip - only USB host mode is supported
- TI TMP105 temperature sensor driven through |I2C| bus
- TI TWL92230C power management companion with an RTC on
|I2C| bus
- Nokia RETU and TAHVO multi-purpose chips with an RTC, connected
through CBUS
The Luminary Micro Stellaris LM3S811EVB emulation includes the following
devices:
- Cortex-M3 CPU core.
- 64k Flash and 8k SRAM.
- Timers, UARTs, ADC and |I2C| interface.
- OSRAM Pictiva 96x16 OLED with SSD0303 controller on
|I2C| bus.
The Luminary Micro Stellaris LM3S6965EVB emulation includes the
following devices:
- Cortex-M3 CPU core.
- 256k Flash and 64k SRAM.
- Timers, UARTs, ADC, |I2C| and SSI interfaces.
- OSRAM Pictiva 128x64 OLED with SSD0323 controller connected via
SSI.
The Freecom MusicPal internet radio emulation includes the following
elements:
- Marvell MV88W8618 ARM core.
- 32 MB RAM, 256 KB SRAM, 8 MB flash.
- Up to 2 16550 UARTs
- MV88W8xx8 Ethernet controller
- MV88W8618 audio controller, WM8750 CODEC and mixer
- 128x64 display with brightness control
- 2 buttons, 2 navigation wheels with button function
The Siemens SX1 models v1 and v2 (default) basic emulation. The
emulation includes the following elements:
- Texas Instruments OMAP310 System-on-chip (ARM 925T core)
- ROM and RAM memories (ROM firmware image can be loaded with
-pflash) V1 1 Flash of 16MB and 1 Flash of 8MB V2 1 Flash of 32MB
- On-chip LCD controller
- On-chip Real Time Clock
- Secure Digital card connected to OMAP MMC/SD host
- Three on-chip UARTs
A Linux 2.6 test image is available on the QEMU web site. More
information is available in the QEMU mailing-list archive.

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The QEMU PC System emulator simulates the following peripherals:
- i440FX host PCI bridge and PIIX3 PCI to ISA bridge
- Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESA
extensions (hardware level, including all non standard modes).
- PS/2 mouse and keyboard
- 2 PCI IDE interfaces with hard disk and CD-ROM support
- Floppy disk
- PCI and ISA network adapters
- Serial ports
- IPMI BMC, either and internal or external one
- Creative SoundBlaster 16 sound card
- ENSONIQ AudioPCI ES1370 sound card
- Intel 82801AA AC97 Audio compatible sound card
- Intel HD Audio Controller and HDA codec
- Adlib (OPL2) - Yamaha YM3812 compatible chip
- Gravis Ultrasound GF1 sound card
- CS4231A compatible sound card
- PCI UHCI, OHCI, EHCI or XHCI USB controller and a virtual USB-1.1
hub.
SMP is supported with up to 255 CPUs.
QEMU uses the PC BIOS from the Seabios project and the Plex86/Bochs LGPL
VGA BIOS.
QEMU uses YM3812 emulation by Tatsuyuki Satoh.
QEMU uses GUS emulation (GUSEMU32 http://www.deinmeister.de/gusemu/) by
Tibor \"TS\" Schütz.
Note that, by default, GUS shares IRQ(7) with parallel ports and so QEMU
must be told to not have parallel ports to have working GUS.
.. parsed-literal::
|qemu_system_x86| dos.img -soundhw gus -parallel none
Alternatively:
.. parsed-literal::
|qemu_system_x86| dos.img -device gus,irq=5
Or some other unclaimed IRQ.
CS4231A is the chip used in Windows Sound System and GUSMAX products

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.. _QEMU-PC-System-emulator:
x86 (PC) System emulator
------------------------
.. _pcsys_005fdevices:
Peripherals
~~~~~~~~~~~
.. include:: target-i386-desc.rst.inc
.. include:: cpu-models-x86.rst.inc
.. _pcsys_005freq:
OS requirements
~~~~~~~~~~~~~~~
On x86_64 hosts, the default set of CPU features enabled by the KVM
accelerator require the host to be running Linux v4.5 or newer. Red Hat
Enterprise Linux 7 is also supported, since the required
functionality was backported.

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.. _ColdFire-System-emulator:
ColdFire System emulator
------------------------
Use the executable ``qemu-system-m68k`` to simulate a ColdFire machine.
The emulator is able to boot a uClinux kernel.
The M5208EVB emulation includes the following devices:
- MCF5208 ColdFire V2 Microprocessor (ISA A+ with EMAC).
- Three Two on-chip UARTs.
- Fast Ethernet Controller (FEC)
The AN5206 emulation includes the following devices:
- MCF5206 ColdFire V2 Microprocessor.
- Two on-chip UARTs.

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.. _MIPS-System-emulator:
MIPS System emulator
--------------------
Four executables cover simulation of 32 and 64-bit MIPS systems in both
endian options, ``qemu-system-mips``, ``qemu-system-mipsel``
``qemu-system-mips64`` and ``qemu-system-mips64el``. Five different
machine types are emulated:
- A generic ISA PC-like machine \"mips\"
- The MIPS Malta prototype board \"malta\"
- An ACER Pica \"pica61\". This machine needs the 64-bit emulator.
- MIPS emulator pseudo board \"mipssim\"
- A MIPS Magnum R4000 machine \"magnum\". This machine needs the
64-bit emulator.
The generic emulation is supported by Debian 'Etch' and is able to
install Debian into a virtual disk image. The following devices are
emulated:
- A range of MIPS CPUs, default is the 24Kf
- PC style serial port
- PC style IDE disk
- NE2000 network card
The Malta emulation supports the following devices:
- Core board with MIPS 24Kf CPU and Galileo system controller
- PIIX4 PCI/USB/SMbus controller
- The Multi-I/O chip's serial device
- PCI network cards (PCnet32 and others)
- Malta FPGA serial device
- Cirrus (default) or any other PCI VGA graphics card
The Boston board emulation supports the following devices:
- Xilinx FPGA, which includes a PCIe root port and an UART
- Intel EG20T PCH connects the I/O peripherals, but only the SATA bus
is emulated
The ACER Pica emulation supports:
- MIPS R4000 CPU
- PC-style IRQ and DMA controllers
- PC Keyboard
- IDE controller
The MIPS Magnum R4000 emulation supports:
- MIPS R4000 CPU
- PC-style IRQ controller
- PC Keyboard
- SCSI controller
- G364 framebuffer
The Fulong 2E emulation supports:
- Loongson 2E CPU
- Bonito64 system controller as North Bridge
- VT82C686 chipset as South Bridge
- RTL8139D as a network card chipset
The mipssim pseudo board emulation provides an environment similar to
what the proprietary MIPS emulator uses for running Linux. It supports:
- A range of MIPS CPUs, default is the 24Kf
- PC style serial port
- MIPSnet network emulation
.. include:: cpu-models-mips.rst.inc
.. _nanoMIPS-System-emulator:
nanoMIPS System emulator
~~~~~~~~~~~~~~~~~~~~~~~~
Executable ``qemu-system-mipsel`` also covers simulation of 32-bit
nanoMIPS system in little endian mode:
- nanoMIPS I7200 CPU
Example of ``qemu-system-mipsel`` usage for nanoMIPS is shown below:
Download ``<disk_image_file>`` from
https://mipsdistros.mips.com/LinuxDistro/nanomips/buildroot/index.html.
Download ``<kernel_image_file>`` from
https://mipsdistros.mips.com/LinuxDistro/nanomips/kernels/v4.15.18-432-gb2eb9a8b07a1-20180627102142/index.html.
Start system emulation of Malta board with nanoMIPS I7200 CPU::
qemu-system-mipsel -cpu I7200 -kernel <kernel_image_file> \
-M malta -serial stdio -m <memory_size> -hda <disk_image_file> \
-append "mem=256m@0x0 rw console=ttyS0 vga=cirrus vesa=0x111 root=/dev/sda"

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.. _PowerPC-System-emulator:
PowerPC System emulator
-----------------------
Use the executable ``qemu-system-ppc`` to simulate a complete 40P (PREP)
or PowerMac PowerPC system.
QEMU emulates the following PowerMac peripherals:
- UniNorth or Grackle PCI Bridge
- PCI VGA compatible card with VESA Bochs Extensions
- 2 PMAC IDE interfaces with hard disk and CD-ROM support
- NE2000 PCI adapters
- Non Volatile RAM
- VIA-CUDA with ADB keyboard and mouse.
QEMU emulates the following 40P (PREP) peripherals:
- PCI Bridge
- PCI VGA compatible card with VESA Bochs Extensions
- 2 IDE interfaces with hard disk and CD-ROM support
- Floppy disk
- PCnet network adapters
- Serial port
- PREP Non Volatile RAM
- PC compatible keyboard and mouse.
Since version 0.9.1, QEMU uses OpenBIOS https://www.openbios.org/ for
the g3beige and mac99 PowerMac and the 40p machines. OpenBIOS is a free
(GPL v2) portable firmware implementation. The goal is to implement a
100% IEEE 1275-1994 (referred to as Open Firmware) compliant firmware.
More information is available at
http://perso.magic.fr/l_indien/qemu-ppc/.

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.. _Sparc32-System-emulator:
Sparc32 System emulator
-----------------------
Use the executable ``qemu-system-sparc`` to simulate the following Sun4m
architecture machines:
- SPARCstation 4
- SPARCstation 5
- SPARCstation 10
- SPARCstation 20
- SPARCserver 600MP
- SPARCstation LX
- SPARCstation Voyager
- SPARCclassic
- SPARCbook
The emulation is somewhat complete. SMP up to 16 CPUs is supported, but
Linux limits the number of usable CPUs to 4.
QEMU emulates the following sun4m peripherals:
- IOMMU
- TCX or cgthree Frame buffer
- Lance (Am7990) Ethernet
- Non Volatile RAM M48T02/M48T08
- Slave I/O: timers, interrupt controllers, Zilog serial ports,
keyboard and power/reset logic
- ESP SCSI controller with hard disk and CD-ROM support
- Floppy drive (not on SS-600MP)
- CS4231 sound device (only on SS-5, not working yet)
The number of peripherals is fixed in the architecture. Maximum memory
size depends on the machine type, for SS-5 it is 256MB and for others
2047MB.
Since version 0.8.2, QEMU uses OpenBIOS https://www.openbios.org/.
OpenBIOS is a free (GPL v2) portable firmware implementation. The goal
is to implement a 100% IEEE 1275-1994 (referred to as Open Firmware)
compliant firmware.
A sample Linux 2.6 series kernel and ram disk image are available on the
QEMU web site. There are still issues with NetBSD and OpenBSD, but most
kernel versions work. Please note that currently older Solaris kernels
don't work probably due to interface issues between OpenBIOS and
Solaris.

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.. _Sparc64-System-emulator:
Sparc64 System emulator
-----------------------
Use the executable ``qemu-system-sparc64`` to simulate a Sun4u
(UltraSPARC PC-like machine), Sun4v (T1 PC-like machine), or generic
Niagara (T1) machine. The Sun4u emulator is mostly complete, being able
to run Linux, NetBSD and OpenBSD in headless (-nographic) mode. The
Sun4v emulator is still a work in progress.
The Niagara T1 emulator makes use of firmware and OS binaries supplied
in the S10image/ directory of the OpenSPARC T1 project
http://download.oracle.com/technetwork/systems/opensparc/OpenSPARCT1_Arch.1.5.tar.bz2
and is able to boot the disk.s10hw2 Solaris image.
::
qemu-system-sparc64 -M niagara -L /path-to/S10image/ \
-nographic -m 256 \
-drive if=pflash,readonly=on,file=/S10image/disk.s10hw2
QEMU emulates the following peripherals:
- UltraSparc IIi APB PCI Bridge
- PCI VGA compatible card with VESA Bochs Extensions
- PS/2 mouse and keyboard
- Non Volatile RAM M48T59
- PC-compatible serial ports
- 2 PCI IDE interfaces with hard disk and CD-ROM support
- Floppy disk

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.. _Xtensa-System-emulator:
Xtensa System emulator
----------------------
Two executables cover simulation of both Xtensa endian options,
``qemu-system-xtensa`` and ``qemu-system-xtensaeb``. Two different
machine types are emulated:
- Xtensa emulator pseudo board \"sim\"
- Avnet LX60/LX110/LX200 board
The sim pseudo board emulation provides an environment similar to one
provided by the proprietary Tensilica ISS. It supports:
- A range of Xtensa CPUs, default is the DC232B
- Console and filesystem access via semihosting calls
The Avnet LX60/LX110/LX200 emulation supports:
- A range of Xtensa CPUs, default is the DC232B
- 16550 UART
- OpenCores 10/100 Mbps Ethernet MAC

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QEMU System Emulator Targets
============================
QEMU is a generic emulator and it emulates many machines. Most of the
options are similar for all machines. Specific information about the
various targets are mentioned in the following sections.
Contents:
.. toctree::
target-i386
target-ppc
target-sparc
target-sparc64
target-mips
target-arm
target-m68k
target-xtensa

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.. _network_005ftls:
TLS setup for network services
------------------------------
Almost all network services in QEMU have the ability to use TLS for
session data encryption, along with x509 certificates for simple client
authentication. What follows is a description of how to generate
certificates suitable for usage with QEMU, and applies to the VNC
server, character devices with the TCP backend, NBD server and client,
and migration server and client.
At a high level, QEMU requires certificates and private keys to be
provided in PEM format. Aside from the core fields, the certificates
should include various extension data sets, including v3 basic
constraints data, key purpose, key usage and subject alt name.
The GnuTLS package includes a command called ``certtool`` which can be
used to easily generate certificates and keys in the required format
with expected data present. Alternatively a certificate management
service may be used.
At a minimum it is necessary to setup a certificate authority, and issue
certificates to each server. If using x509 certificates for
authentication, then each client will also need to be issued a
certificate.
Assuming that the QEMU network services will only ever be exposed to
clients on a private intranet, there is no need to use a commercial
certificate authority to create certificates. A self-signed CA is
sufficient, and in fact likely to be more secure since it removes the
ability of malicious 3rd parties to trick the CA into mis-issuing certs
for impersonating your services. The only likely exception where a
commercial CA might be desirable is if enabling the VNC websockets
server and exposing it directly to remote browser clients. In such a
case it might be useful to use a commercial CA to avoid needing to
install custom CA certs in the web browsers.
The recommendation is for the server to keep its certificates in either
``/etc/pki/qemu`` or for unprivileged users in ``$HOME/.pki/qemu``.
.. _tls_005fgenerate_005fca:
Setup the Certificate Authority
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This step only needs to be performed once per organization /
organizational unit. First the CA needs a private key. This key must be
kept VERY secret and secure. If this key is compromised the entire trust
chain of the certificates issued with it is lost.
::
# certtool --generate-privkey > ca-key.pem
To generate a self-signed certificate requires one core piece of
information, the name of the organization. A template file ``ca.info``
should be populated with the desired data to avoid having to deal with
interactive prompts from certtool::
# cat > ca.info <<EOF
cn = Name of your organization
ca
cert_signing_key
EOF
# certtool --generate-self-signed \
--load-privkey ca-key.pem
--template ca.info \
--outfile ca-cert.pem
The ``ca`` keyword in the template sets the v3 basic constraints
extension to indicate this certificate is for a CA, while
``cert_signing_key`` sets the key usage extension to indicate this will
be used for signing other keys. The generated ``ca-cert.pem`` file
should be copied to all servers and clients wishing to utilize TLS
support in the VNC server. The ``ca-key.pem`` must not be
disclosed/copied anywhere except the host responsible for issuing
certificates.
.. _tls_005fgenerate_005fserver:
Issuing server certificates
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Each server (or host) needs to be issued with a key and certificate.
When connecting the certificate is sent to the client which validates it
against the CA certificate. The core pieces of information for a server
certificate are the hostnames and/or IP addresses that will be used by
clients when connecting. The hostname / IP address that the client
specifies when connecting will be validated against the hostname(s) and
IP address(es) recorded in the server certificate, and if no match is
found the client will close the connection.
Thus it is recommended that the server certificate include both the
fully qualified and unqualified hostnames. If the server will have
permanently assigned IP address(es), and clients are likely to use them
when connecting, they may also be included in the certificate. Both IPv4
and IPv6 addresses are supported. Historically certificates only
included 1 hostname in the ``CN`` field, however, usage of this field
for validation is now deprecated. Instead modern TLS clients will
validate against the Subject Alt Name extension data, which allows for
multiple entries. In the future usage of the ``CN`` field may be
discontinued entirely, so providing SAN extension data is strongly
recommended.
On the host holding the CA, create template files containing the
information for each server, and use it to issue server certificates.
::
# cat > server-hostNNN.info <<EOF
organization = Name of your organization
cn = hostNNN.foo.example.com
dns_name = hostNNN
dns_name = hostNNN.foo.example.com
ip_address = 10.0.1.87
ip_address = 192.8.0.92
ip_address = 2620:0:cafe::87
ip_address = 2001:24::92
tls_www_server
encryption_key
signing_key
EOF
# certtool --generate-privkey > server-hostNNN-key.pem
# certtool --generate-certificate \
--load-ca-certificate ca-cert.pem \
--load-ca-privkey ca-key.pem \
--load-privkey server-hostNNN-key.pem \
--template server-hostNNN.info \
--outfile server-hostNNN-cert.pem
The ``dns_name`` and ``ip_address`` fields in the template are setting
the subject alt name extension data. The ``tls_www_server`` keyword is
the key purpose extension to indicate this certificate is intended for
usage in a web server. Although QEMU network services are not in fact
HTTP servers (except for VNC websockets), setting this key purpose is
still recommended. The ``encryption_key`` and ``signing_key`` keyword is
the key usage extension to indicate this certificate is intended for
usage in the data session.
The ``server-hostNNN-key.pem`` and ``server-hostNNN-cert.pem`` files
should now be securely copied to the server for which they were
generated, and renamed to ``server-key.pem`` and ``server-cert.pem``
when added to the ``/etc/pki/qemu`` directory on the target host. The
``server-key.pem`` file is security sensitive and should be kept
protected with file mode 0600 to prevent disclosure.
.. _tls_005fgenerate_005fclient:
Issuing client certificates
~~~~~~~~~~~~~~~~~~~~~~~~~~~
The QEMU x509 TLS credential setup defaults to enabling client
verification using certificates, providing a simple authentication
mechanism. If this default is used, each client also needs to be issued
a certificate. The client certificate contains enough metadata to
uniquely identify the client with the scope of the certificate
authority. The client certificate would typically include fields for
organization, state, city, building, etc.
Once again on the host holding the CA, create template files containing
the information for each client, and use it to issue client
certificates.
::
# cat > client-hostNNN.info <<EOF
country = GB
state = London
locality = City Of London
organization = Name of your organization
cn = hostNNN.foo.example.com
tls_www_client
encryption_key
signing_key
EOF
# certtool --generate-privkey > client-hostNNN-key.pem
# certtool --generate-certificate \
--load-ca-certificate ca-cert.pem \
--load-ca-privkey ca-key.pem \
--load-privkey client-hostNNN-key.pem \
--template client-hostNNN.info \
--outfile client-hostNNN-cert.pem
The subject alt name extension data is not required for clients, so the
the ``dns_name`` and ``ip_address`` fields are not included. The
``tls_www_client`` keyword is the key purpose extension to indicate this
certificate is intended for usage in a web client. Although QEMU network
clients are not in fact HTTP clients, setting this key purpose is still
recommended. The ``encryption_key`` and ``signing_key`` keyword is the
key usage extension to indicate this certificate is intended for usage
in the data session.
The ``client-hostNNN-key.pem`` and ``client-hostNNN-cert.pem`` files
should now be securely copied to the client for which they were
generated, and renamed to ``client-key.pem`` and ``client-cert.pem``
when added to the ``/etc/pki/qemu`` directory on the target host. The
``client-key.pem`` file is security sensitive and should be kept
protected with file mode 0600 to prevent disclosure.
If a single host is going to be using TLS in both a client and server
role, it is possible to create a single certificate to cover both roles.
This would be quite common for the migration and NBD services, where a
QEMU process will be started by accepting a TLS protected incoming
migration, and later itself be migrated out to another host. To generate
a single certificate, simply include the template data from both the
client and server instructions in one.
::
# cat > both-hostNNN.info <<EOF
country = GB
state = London
locality = City Of London
organization = Name of your organization
cn = hostNNN.foo.example.com
dns_name = hostNNN
dns_name = hostNNN.foo.example.com
ip_address = 10.0.1.87
ip_address = 192.8.0.92
ip_address = 2620:0:cafe::87
ip_address = 2001:24::92
tls_www_server
tls_www_client
encryption_key
signing_key
EOF
# certtool --generate-privkey > both-hostNNN-key.pem
# certtool --generate-certificate \
--load-ca-certificate ca-cert.pem \
--load-ca-privkey ca-key.pem \
--load-privkey both-hostNNN-key.pem \
--template both-hostNNN.info \
--outfile both-hostNNN-cert.pem
When copying the PEM files to the target host, save them twice, once as
``server-cert.pem`` and ``server-key.pem``, and again as
``client-cert.pem`` and ``client-key.pem``.
.. _tls_005fcreds_005fsetup:
TLS x509 credential configuration
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
QEMU has a standard mechanism for loading x509 credentials that will be
used for network services and clients. It requires specifying the
``tls-creds-x509`` class name to the ``--object`` command line argument
for the system emulators. Each set of credentials loaded should be given
a unique string identifier via the ``id`` parameter. A single set of TLS
credentials can be used for multiple network backends, so VNC,
migration, NBD, character devices can all share the same credentials.
Note, however, that credentials for use in a client endpoint must be
loaded separately from those used in a server endpoint.
When specifying the object, the ``dir`` parameters specifies which
directory contains the credential files. This directory is expected to
contain files with the names mentioned previously, ``ca-cert.pem``,
``server-key.pem``, ``server-cert.pem``, ``client-key.pem`` and
``client-cert.pem`` as appropriate. It is also possible to include a set
of pre-generated Diffie-Hellman (DH) parameters in a file
``dh-params.pem``, which can be created using the
``certtool --generate-dh-params`` command. If omitted, QEMU will
dynamically generate DH parameters when loading the credentials.
The ``endpoint`` parameter indicates whether the credentials will be
used for a network client or server, and determines which PEM files are
loaded.
The ``verify`` parameter determines whether x509 certificate validation
should be performed. This defaults to enabled, meaning clients will
always validate the server hostname against the certificate subject alt
name fields and/or CN field. It also means that servers will request
that clients provide a certificate and validate them. Verification
should never be turned off for client endpoints, however, it may be
turned off for server endpoints if an alternative mechanism is used to
authenticate clients. For example, the VNC server can use SASL to
authenticate clients instead.
To load server credentials with client certificate validation enabled
.. parsed-literal::
|qemu_system| -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server
while to load client credentials use
.. parsed-literal::
|qemu_system| -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=client
Network services which support TLS will all have a ``tls-creds``
parameter which expects the ID of the TLS credentials object. For
example with VNC:
.. parsed-literal::
|qemu_system| -vnc 0.0.0.0:0,tls-creds=tls0
.. _tls_005fpsk:
TLS Pre-Shared Keys (PSK)
~~~~~~~~~~~~~~~~~~~~~~~~~
Instead of using certificates, you may also use TLS Pre-Shared Keys
(TLS-PSK). This can be simpler to set up than certificates but is less
scalable.
Use the GnuTLS ``psktool`` program to generate a ``keys.psk`` file
containing one or more usernames and random keys::
mkdir -m 0700 /tmp/keys
psktool -u rich -p /tmp/keys/keys.psk
TLS-enabled servers such as qemu-nbd can use this directory like so::
qemu-nbd \
-t -x / \
--object tls-creds-psk,id=tls0,endpoint=server,dir=/tmp/keys \
--tls-creds tls0 \
image.qcow2
When connecting from a qemu-based client you must specify the directory
containing ``keys.psk`` and an optional username (defaults to "qemu")::
qemu-img info \
--object tls-creds-psk,id=tls0,dir=/tmp/keys,username=rich,endpoint=client \
--image-opts \
file.driver=nbd,file.host=localhost,file.port=10809,file.tls-creds=tls0,file.export=/

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.. _pcsys_005fusb:
USB emulation
-------------
QEMU can emulate a PCI UHCI, OHCI, EHCI or XHCI USB controller. You can
plug virtual USB devices or real host USB devices (only works with
certain host operating systems). QEMU will automatically create and
connect virtual USB hubs as necessary to connect multiple USB devices.
.. _usb_005fdevices:
Connecting USB devices
~~~~~~~~~~~~~~~~~~~~~~
USB devices can be connected with the ``-device usb-...`` command line
option or the ``device_add`` monitor command. Available devices are:
``usb-mouse``
Virtual Mouse. This will override the PS/2 mouse emulation when
activated.
``usb-tablet``
Pointer device that uses absolute coordinates (like a touchscreen).
This means QEMU is able to report the mouse position without having
to grab the mouse. Also overrides the PS/2 mouse emulation when
activated.
``usb-storage,drive=drive_id``
Mass storage device backed by drive_id (see
:ref:`disk_005fimages`)
``usb-uas``
USB attached SCSI device, see
`usb-storage.txt <https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt>`__
for details
``usb-bot``
Bulk-only transport storage device, see
`usb-storage.txt <https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt>`__
for details here, too
``usb-mtp,rootdir=dir``
Media transfer protocol device, using dir as root of the file tree
that is presented to the guest.
``usb-host,hostbus=bus,hostaddr=addr``
Pass through the host device identified by bus and addr
``usb-host,vendorid=vendor,productid=product``
Pass through the host device identified by vendor and product ID
``usb-wacom-tablet``
Virtual Wacom PenPartner tablet. This device is similar to the
``tablet`` above but it can be used with the tslib library because in
addition to touch coordinates it reports touch pressure.
``usb-kbd``
Standard USB keyboard. Will override the PS/2 keyboard (if present).
``usb-serial,chardev=id``
Serial converter. This emulates an FTDI FT232BM chip connected to
host character device id.
``usb-braille,chardev=id``
Braille device. This will use BrlAPI to display the braille output on
a real or fake device referenced by id.
``usb-net[,netdev=id]``
Network adapter that supports CDC ethernet and RNDIS protocols. id
specifies a netdev defined with ``-netdev …,id=id``. For instance,
user-mode networking can be used with
.. parsed-literal::
|qemu_system| [...] -netdev user,id=net0 -device usb-net,netdev=net0
``usb-ccid``
Smartcard reader device
``usb-audio``
USB audio device
.. _host_005fusb_005fdevices:
Using host USB devices on a Linux host
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
WARNING: this is an experimental feature. QEMU will slow down when using
it. USB devices requiring real time streaming (i.e. USB Video Cameras)
are not supported yet.
1. If you use an early Linux 2.4 kernel, verify that no Linux driver is
actually using the USB device. A simple way to do that is simply to
disable the corresponding kernel module by renaming it from
``mydriver.o`` to ``mydriver.o.disabled``.
2. Verify that ``/proc/bus/usb`` is working (most Linux distributions
should enable it by default). You should see something like that:
::
ls /proc/bus/usb
001 devices drivers
3. Since only root can access to the USB devices directly, you can
either launch QEMU as root or change the permissions of the USB
devices you want to use. For testing, the following suffices:
::
chown -R myuid /proc/bus/usb
4. Launch QEMU and do in the monitor:
::
info usbhost
Device 1.2, speed 480 Mb/s
Class 00: USB device 1234:5678, USB DISK
You should see the list of the devices you can use (Never try to use
hubs, it won't work).
5. Add the device in QEMU by using:
::
device_add usb-host,vendorid=0x1234,productid=0x5678
Normally the guest OS should report that a new USB device is plugged.
You can use the option ``-device usb-host,...`` to do the same.
6. Now you can try to use the host USB device in QEMU.
When relaunching QEMU, you may have to unplug and plug again the USB
device to make it work again (this is a bug).

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.. _vnc_005fsecurity:
VNC security
------------
The VNC server capability provides access to the graphical console of
the guest VM across the network. This has a number of security
considerations depending on the deployment scenarios.
.. _vnc_005fsec_005fnone:
Without passwords
~~~~~~~~~~~~~~~~~
The simplest VNC server setup does not include any form of
authentication. For this setup it is recommended to restrict it to
listen on a UNIX domain socket only. For example
.. parsed-literal::
|qemu_system| [...OPTIONS...] -vnc unix:/home/joebloggs/.qemu-myvm-vnc
This ensures that only users on local box with read/write access to that
path can access the VNC server. To securely access the VNC server from a
remote machine, a combination of netcat+ssh can be used to provide a
secure tunnel.
.. _vnc_005fsec_005fpassword:
With passwords
~~~~~~~~~~~~~~
The VNC protocol has limited support for password based authentication.
Since the protocol limits passwords to 8 characters it should not be
considered to provide high security. The password can be fairly easily
brute-forced by a client making repeat connections. For this reason, a
VNC server using password authentication should be restricted to only
listen on the loopback interface or UNIX domain sockets. Password
authentication is not supported when operating in FIPS 140-2 compliance
mode as it requires the use of the DES cipher. Password authentication
is requested with the ``password`` option, and then once QEMU is running
the password is set with the monitor. Until the monitor is used to set
the password all clients will be rejected.
.. parsed-literal::
|qemu_system| [...OPTIONS...] -vnc :1,password -monitor stdio
(qemu) change vnc password
Password: ********
(qemu)
.. _vnc_005fsec_005fcertificate:
With x509 certificates
~~~~~~~~~~~~~~~~~~~~~~
The QEMU VNC server also implements the VeNCrypt extension allowing use
of TLS for encryption of the session, and x509 certificates for
authentication. The use of x509 certificates is strongly recommended,
because TLS on its own is susceptible to man-in-the-middle attacks.
Basic x509 certificate support provides a secure session, but no
authentication. This allows any client to connect, and provides an
encrypted session.
.. parsed-literal::
|qemu_system| [...OPTIONS...] \
-object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=no \
-vnc :1,tls-creds=tls0 -monitor stdio
In the above example ``/etc/pki/qemu`` should contain at least three
files, ``ca-cert.pem``, ``server-cert.pem`` and ``server-key.pem``.
Unprivileged users will want to use a private directory, for example
``$HOME/.pki/qemu``. NB the ``server-key.pem`` file should be protected
with file mode 0600 to only be readable by the user owning it.
.. _vnc_005fsec_005fcertificate_005fverify:
With x509 certificates and client verification
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Certificates can also provide a means to authenticate the client
connecting. The server will request that the client provide a
certificate, which it will then validate against the CA certificate.
This is a good choice if deploying in an environment with a private
internal certificate authority. It uses the same syntax as previously,
but with ``verify-peer`` set to ``yes`` instead.
.. parsed-literal::
|qemu_system| [...OPTIONS...] \
-object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=yes \
-vnc :1,tls-creds=tls0 -monitor stdio
.. _vnc_005fsec_005fcertificate_005fpw:
With x509 certificates, client verification and passwords
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Finally, the previous method can be combined with VNC password
authentication to provide two layers of authentication for clients.
.. parsed-literal::
|qemu_system| [...OPTIONS...] \
-object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=yes \
-vnc :1,tls-creds=tls0,password -monitor stdio
(qemu) change vnc password
Password: ********
(qemu)
.. _vnc_005fsec_005fsasl:
With SASL authentication
~~~~~~~~~~~~~~~~~~~~~~~~
The SASL authentication method is a VNC extension, that provides an
easily extendable, pluggable authentication method. This allows for
integration with a wide range of authentication mechanisms, such as PAM,
GSSAPI/Kerberos, LDAP, SQL databases, one-time keys and more. The
strength of the authentication depends on the exact mechanism
configured. If the chosen mechanism also provides a SSF layer, then it
will encrypt the datastream as well.
Refer to the later docs on how to choose the exact SASL mechanism used
for authentication, but assuming use of one supporting SSF, then QEMU
can be launched with:
.. parsed-literal::
|qemu_system| [...OPTIONS...] -vnc :1,sasl -monitor stdio
.. _vnc_005fsec_005fcertificate_005fsasl:
With x509 certificates and SASL authentication
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If the desired SASL authentication mechanism does not supported SSF
layers, then it is strongly advised to run it in combination with TLS
and x509 certificates. This provides securely encrypted data stream,
avoiding risk of compromising of the security credentials. This can be
enabled, by combining the 'sasl' option with the aforementioned TLS +
x509 options:
.. parsed-literal::
|qemu_system| [...OPTIONS...] \
-object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=yes \
-vnc :1,tls-creds=tls0,sasl -monitor stdio
.. _vnc_005fsetup_005fsasl:
Configuring SASL mechanisms
~~~~~~~~~~~~~~~~~~~~~~~~~~~
The following documentation assumes use of the Cyrus SASL implementation
on a Linux host, but the principles should apply to any other SASL
implementation or host. When SASL is enabled, the mechanism
configuration will be loaded from system default SASL service config
/etc/sasl2/qemu.conf. If running QEMU as an unprivileged user, an
environment variable SASL_CONF_PATH can be used to make it search
alternate locations for the service config file.
If the TLS option is enabled for VNC, then it will provide session
encryption, otherwise the SASL mechanism will have to provide
encryption. In the latter case the list of possible plugins that can be
used is drastically reduced. In fact only the GSSAPI SASL mechanism
provides an acceptable level of security by modern standards. Previous
versions of QEMU referred to the DIGEST-MD5 mechanism, however, it has
multiple serious flaws described in detail in RFC 6331 and thus should
never be used any more. The SCRAM-SHA-1 mechanism provides a simple
username/password auth facility similar to DIGEST-MD5, but does not
support session encryption, so can only be used in combination with TLS.
When not using TLS the recommended configuration is
::
mech_list: gssapi
keytab: /etc/qemu/krb5.tab
This says to use the 'GSSAPI' mechanism with the Kerberos v5 protocol,
with the server principal stored in /etc/qemu/krb5.tab. For this to work
the administrator of your KDC must generate a Kerberos principal for the
server, with a name of 'qemu/somehost.example.com@EXAMPLE.COM' replacing
'somehost.example.com' with the fully qualified host name of the machine
running QEMU, and 'EXAMPLE.COM' with the Kerberos Realm.
When using TLS, if username+password authentication is desired, then a
reasonable configuration is
::
mech_list: scram-sha-1
sasldb_path: /etc/qemu/passwd.db
The ``saslpasswd2`` program can be used to populate the ``passwd.db``
file with accounts.
Other SASL configurations will be left as an exercise for the reader.
Note that all mechanisms, except GSSAPI, should be combined with use of
TLS to ensure a secure data channel.

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# -*- coding: utf-8 -*-
#
# QEMU documentation build configuration file for the 'user' manual.
#
# This includes the top level conf file and then makes any necessary tweaks.
import sys
import os
qemu_docdir = os.path.abspath("..")
parent_config = os.path.join(qemu_docdir, "conf.py")
exec(compile(open(parent_config, "rb").read(), parent_config, 'exec'))
# This slightly misuses the 'description', but is the best way to get
# the manual title to appear in the sidebar.
html_theme_options['description'] = u'User Mode Emulation User''s Guide'

16
docs/user/index.rst Normal file
View File

@ -0,0 +1,16 @@
.. This is the top level page for the 'user' manual.
QEMU User Mode Emulation User's Guide
=====================================
This manual is the overall guide for users using QEMU
for user-mode emulation. In this mode, QEMU can launch
processes compiled for one CPU on another CPU.
Contents:
.. toctree::
:maxdepth: 2
main

295
docs/user/main.rst Normal file
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@ -0,0 +1,295 @@
QEMU User space emulator
========================
Supported Operating Systems
---------------------------
The following OS are supported in user space emulation:
- Linux (referred as qemu-linux-user)
- BSD (referred as qemu-bsd-user)
Features
--------
QEMU user space emulation has the following notable features:
**System call translation:**
QEMU includes a generic system call translator. This means that the
parameters of the system calls can be converted to fix endianness and
32/64-bit mismatches between hosts and targets. IOCTLs can be
converted too.
**POSIX signal handling:**
QEMU can redirect to the running program all signals coming from the
host (such as ``SIGALRM``), as well as synthesize signals from
virtual CPU exceptions (for example ``SIGFPE`` when the program
executes a division by zero).
QEMU relies on the host kernel to emulate most signal system calls,
for example to emulate the signal mask. On Linux, QEMU supports both
normal and real-time signals.
**Threading:**
On Linux, QEMU can emulate the ``clone`` syscall and create a real
host thread (with a separate virtual CPU) for each emulated thread.
Note that not all targets currently emulate atomic operations
correctly. x86 and ARM use a global lock in order to preserve their
semantics.
QEMU was conceived so that ultimately it can emulate itself. Although it
is not very useful, it is an important test to show the power of the
emulator.
Linux User space emulator
-------------------------
Quick Start
~~~~~~~~~~~
In order to launch a Linux process, QEMU needs the process executable
itself and all the target (x86) dynamic libraries used by it.
- On x86, you can just try to launch any process by using the native
libraries::
qemu-i386 -L / /bin/ls
``-L /`` tells that the x86 dynamic linker must be searched with a
``/`` prefix.
- Since QEMU is also a linux process, you can launch QEMU with QEMU
(NOTE: you can only do that if you compiled QEMU from the sources)::
qemu-i386 -L / qemu-i386 -L / /bin/ls
- On non x86 CPUs, you need first to download at least an x86 glibc
(``qemu-runtime-i386-XXX-.tar.gz`` on the QEMU web page). Ensure that
``LD_LIBRARY_PATH`` is not set::
unset LD_LIBRARY_PATH
Then you can launch the precompiled ``ls`` x86 executable::
qemu-i386 tests/i386/ls
You can look at ``scripts/qemu-binfmt-conf.sh`` so that QEMU is
automatically launched by the Linux kernel when you try to launch x86
executables. It requires the ``binfmt_misc`` module in the Linux
kernel.
- The x86 version of QEMU is also included. You can try weird things
such as::
qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 \
/usr/local/qemu-i386/bin/ls-i386
Wine launch
~~~~~~~~~~~
- Ensure that you have a working QEMU with the x86 glibc distribution
(see previous section). In order to verify it, you must be able to
do::
qemu-i386 /usr/local/qemu-i386/bin/ls-i386
- Download the binary x86 Wine install (``qemu-XXX-i386-wine.tar.gz``
on the QEMU web page).
- Configure Wine on your account. Look at the provided script
``/usr/local/qemu-i386/bin/wine-conf.sh``. Your previous
``${HOME}/.wine`` directory is saved to ``${HOME}/.wine.org``.
- Then you can try the example ``putty.exe``::
qemu-i386 /usr/local/qemu-i386/wine/bin/wine \
/usr/local/qemu-i386/wine/c/Program\ Files/putty.exe
Command line options
~~~~~~~~~~~~~~~~~~~~
::
qemu-i386 [-h] [-d] [-L path] [-s size] [-cpu model] [-g port] [-B offset] [-R size] program [arguments...]
``-h``
Print the help
``-L path``
Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)
``-s size``
Set the x86 stack size in bytes (default=524288)
``-cpu model``
Select CPU model (-cpu help for list and additional feature
selection)
``-E var=value``
Set environment var to value.
``-U var``
Remove var from the environment.
``-B offset``
Offset guest address by the specified number of bytes. This is useful
when the address region required by guest applications is reserved on
the host. This option is currently only supported on some hosts.
``-R size``
Pre-allocate a guest virtual address space of the given size (in
bytes). \"G\", \"M\", and \"k\" suffixes may be used when specifying
the size.
Debug options:
``-d item1,...``
Activate logging of the specified items (use '-d help' for a list of
log items)
``-p pagesize``
Act as if the host page size was 'pagesize' bytes
``-g port``
Wait gdb connection to port
``-singlestep``
Run the emulation in single step mode.
Environment variables:
QEMU_STRACE
Print system calls and arguments similar to the 'strace' program
(NOTE: the actual 'strace' program will not work because the user
space emulator hasn't implemented ptrace). At the moment this is
incomplete. All system calls that don't have a specific argument
format are printed with information for six arguments. Many
flag-style arguments don't have decoders and will show up as numbers.
Other binaries
~~~~~~~~~~~~~~
user mode (Alpha)
``qemu-alpha`` TODO.
user mode (ARM)
``qemu-armeb`` TODO.
user mode (ARM)
``qemu-arm`` is also capable of running ARM \"Angel\" semihosted ELF
binaries (as implemented by the arm-elf and arm-eabi Newlib/GDB
configurations), and arm-uclinux bFLT format binaries.
user mode (ColdFire)
user mode (M68K)
``qemu-m68k`` is capable of running semihosted binaries using the BDM
(m5xxx-ram-hosted.ld) or m68k-sim (sim.ld) syscall interfaces, and
coldfire uClinux bFLT format binaries.
The binary format is detected automatically.
user mode (Cris)
``qemu-cris`` TODO.
user mode (i386)
``qemu-i386`` TODO. ``qemu-x86_64`` TODO.
user mode (Microblaze)
``qemu-microblaze`` TODO.
user mode (MIPS)
``qemu-mips`` executes 32-bit big endian MIPS binaries (MIPS O32 ABI).
``qemu-mipsel`` executes 32-bit little endian MIPS binaries (MIPS O32
ABI).
``qemu-mips64`` executes 64-bit big endian MIPS binaries (MIPS N64 ABI).
``qemu-mips64el`` executes 64-bit little endian MIPS binaries (MIPS N64
ABI).
``qemu-mipsn32`` executes 32-bit big endian MIPS binaries (MIPS N32
ABI).
``qemu-mipsn32el`` executes 32-bit little endian MIPS binaries (MIPS N32
ABI).
user mode (NiosII)
``qemu-nios2`` TODO.
user mode (PowerPC)
``qemu-ppc64abi32`` TODO. ``qemu-ppc64`` TODO. ``qemu-ppc`` TODO.
user mode (SH4)
``qemu-sh4eb`` TODO. ``qemu-sh4`` TODO.
user mode (SPARC)
``qemu-sparc`` can execute Sparc32 binaries (Sparc32 CPU, 32 bit ABI).
``qemu-sparc32plus`` can execute Sparc32 and SPARC32PLUS binaries
(Sparc64 CPU, 32 bit ABI).
``qemu-sparc64`` can execute some Sparc64 (Sparc64 CPU, 64 bit ABI) and
SPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).
BSD User space emulator
-----------------------
BSD Status
~~~~~~~~~~
- target Sparc64 on Sparc64: Some trivial programs work.
Quick Start
~~~~~~~~~~~
In order to launch a BSD process, QEMU needs the process executable
itself and all the target dynamic libraries used by it.
- On Sparc64, you can just try to launch any process by using the
native libraries::
qemu-sparc64 /bin/ls
Command line options
~~~~~~~~~~~~~~~~~~~~
::
qemu-sparc64 [-h] [-d] [-L path] [-s size] [-bsd type] program [arguments...]
``-h``
Print the help
``-L path``
Set the library root path (default=/)
``-s size``
Set the stack size in bytes (default=524288)
``-ignore-environment``
Start with an empty environment. Without this option, the initial
environment is a copy of the caller's environment.
``-E var=value``
Set environment var to value.
``-U var``
Remove var from the environment.
``-bsd type``
Set the type of the emulated BSD Operating system. Valid values are
FreeBSD, NetBSD and OpenBSD (default).
Debug options:
``-d item1,...``
Activate logging of the specified items (use '-d help' for a list of
log items)
``-p pagesize``
Act as if the host page size was 'pagesize' bytes
``-singlestep``
Run the emulation in single step mode.

600
hmp-commands-info.hx
View File

@ -4,14 +4,18 @@ HXCOMM discarded from C version
HXCOMM DEF(command, args, callback, arg_string, help) is used to construct
HXCOMM monitor info commands
HXCOMM HXCOMM can be used for comments, discarded from both texi and C
HXCOMM
HXCOMM In this file, generally SRST fragments should have two extra
HXCOMM spaces of indent, so that the documentation list item for "info foo"
HXCOMM appears inside the documentation list item for the top level
HXCOMM "info" documentation entry. The exception is the first SRST
HXCOMM fragment that defines that top level entry.
STEXI
@table @option
@item info @var{subcommand}
@findex info
Show various information about the system state.
@table @option
ETEXI
SRST
``info`` *subcommand*
Show various information about the system state.
ERST
{
.name = "version",
@ -22,11 +26,10 @@ ETEXI
.flags = "p",
},
STEXI
@item info version
@findex info version
Show the version of QEMU.
ETEXI
SRST
``info version``
Show the version of QEMU.
ERST
{
.name = "network",
@ -36,11 +39,10 @@ ETEXI
.cmd = hmp_info_network,
},
STEXI
@item info network
@findex info network
Show the network state.
ETEXI
SRST
``info network``
Show the network state.
ERST
{
.name = "chardev",
@ -51,11 +53,10 @@ ETEXI
.flags = "p",
},
STEXI
@item info chardev
@findex info chardev
Show the character devices.
ETEXI
SRST
``info chardev``
Show the character devices.
ERST
{
.name = "block",
@ -66,11 +67,10 @@ ETEXI
.cmd = hmp_info_block,
},
STEXI
@item info block
@findex info block
Show info of one block device or all block devices.
ETEXI
SRST
``info block``
Show info of one block device or all block devices.
ERST
{
.name = "blockstats",
@ -80,11 +80,10 @@ ETEXI
.cmd = hmp_info_blockstats,
},
STEXI
@item info blockstats
@findex info blockstats
Show block device statistics.
ETEXI
SRST
``info blockstats``
Show block device statistics.
ERST
{
.name = "block-jobs",
@ -94,11 +93,10 @@ ETEXI
.cmd = hmp_info_block_jobs,
},
STEXI
@item info block-jobs
@findex info block-jobs
Show progress of ongoing block device operations.
ETEXI
SRST
``info block-jobs``
Show progress of ongoing block device operations.
ERST
{
.name = "registers",
@ -108,11 +106,10 @@ ETEXI
.cmd = hmp_info_registers,
},
STEXI
@item info registers
@findex info registers
Show the cpu registers.
ETEXI
SRST
``info registers``
Show the cpu registers.
ERST
#if defined(TARGET_I386)
{
@ -125,11 +122,10 @@ ETEXI
},
#endif
STEXI
@item info lapic
@findex info lapic
Show local APIC state
ETEXI
SRST
``info lapic``
Show local APIC state
ERST
#if defined(TARGET_I386)
{
@ -141,11 +137,10 @@ ETEXI
},
#endif
STEXI
@item info ioapic
@findex info ioapic
Show io APIC state
ETEXI
SRST
``info ioapic``
Show io APIC state
ERST
{
.name = "cpus",
@ -155,11 +150,10 @@ ETEXI
.cmd = hmp_info_cpus,
},
STEXI
@item info cpus
@findex info cpus
Show infos for each CPU.
ETEXI
SRST
``info cpus``
Show infos for each CPU.
ERST
{
.name = "history",
@ -170,11 +164,10 @@ ETEXI
.flags = "p",
},
STEXI
@item info history
@findex info history
Show the command line history.
ETEXI
SRST
``info history``
Show the command line history.
ERST
{
.name = "irq",
@ -184,11 +177,10 @@ ETEXI
.cmd = hmp_info_irq,
},
STEXI
@item info irq
@findex info irq
Show the interrupts statistics (if available).
ETEXI
SRST
``info irq``
Show the interrupts statistics (if available).
ERST
{
.name = "pic",
@ -198,11 +190,10 @@ ETEXI
.cmd = hmp_info_pic,
},
STEXI
@item info pic
@findex info pic
Show PIC state.
ETEXI
SRST
``info pic``
Show PIC state.
ERST
{
.name = "rdma",
@ -212,11 +203,10 @@ ETEXI
.cmd = hmp_info_rdma,
},
STEXI
@item info rdma
@findex info rdma
Show RDMA state.
ETEXI
SRST
``info rdma``
Show RDMA state.
ERST
{
.name = "pci",
@ -226,11 +216,10 @@ ETEXI
.cmd = hmp_info_pci,
},
STEXI
@item info pci
@findex info pci
Show PCI information.
ETEXI
SRST
``info pci``
Show PCI information.
ERST
#if defined(TARGET_I386) || defined(TARGET_SH4) || defined(TARGET_SPARC) || \
defined(TARGET_PPC) || defined(TARGET_XTENSA) || defined(TARGET_M68K)
@ -243,11 +232,10 @@ ETEXI
},
#endif
STEXI
@item info tlb
@findex info tlb
Show virtual to physical memory mappings.
ETEXI
SRST
``info tlb``
Show virtual to physical memory mappings.
ERST
#if defined(TARGET_I386) || defined(TARGET_RISCV)
{
@ -259,11 +247,10 @@ ETEXI
},
#endif
STEXI
@item info mem
@findex info mem
Show the active virtual memory mappings.
ETEXI
SRST
``info mem``
Show the active virtual memory mappings.
ERST
{
.name = "mtree",
@ -275,11 +262,10 @@ ETEXI
.cmd = hmp_info_mtree,
},
STEXI
@item info mtree
@findex info mtree
Show memory tree.
ETEXI
SRST
``info mtree``
Show memory tree.
ERST
#if defined(CONFIG_TCG)
{
@ -291,11 +277,10 @@ ETEXI
},
#endif
STEXI
@item info jit
@findex info jit
Show dynamic compiler info.
ETEXI
SRST
``info jit``
Show dynamic compiler info.
ERST
#if defined(CONFIG_TCG)
{
@ -307,11 +292,10 @@ ETEXI
},
#endif
STEXI
@item info opcount
@findex info opcount
Show dynamic compiler opcode counters
ETEXI
SRST
``info opcount``
Show dynamic compiler opcode counters
ERST
{
.name = "sync-profile",
@ -324,16 +308,20 @@ ETEXI
.cmd = hmp_info_sync_profile,
},
STEXI
@item info sync-profile [-m|-n] [@var{max}]
@findex info sync-profile
Show synchronization profiling info, up to @var{max} entries (default: 10),
sorted by total wait time.
-m: sort by mean wait time
-n: do not coalesce objects with the same call site
When different objects that share the same call site are coalesced, the "Object"
field shows---enclosed in brackets---the number of objects being coalesced.
ETEXI
SRST
``info sync-profile [-m|-n]`` [*max*]
Show synchronization profiling info, up to *max* entries (default: 10),
sorted by total wait time.
``-m``
sort by mean wait time
``-n``
do not coalesce objects with the same call site
When different objects that share the same call site are coalesced,
the "Object" field shows---enclosed in brackets---the number of objects
being coalesced.
ERST
{
.name = "kvm",
@ -343,11 +331,10 @@ ETEXI
.cmd = hmp_info_kvm,
},
STEXI
@item info kvm
@findex info kvm
Show KVM information.
ETEXI
SRST
``info kvm``
Show KVM information.
ERST
{
.name = "numa",
@ -357,11 +344,10 @@ ETEXI
.cmd = hmp_info_numa,
},
STEXI
@item info numa
@findex info numa
Show NUMA information.
ETEXI
SRST
``info numa``
Show NUMA information.
ERST
{
.name = "usb",
@ -371,11 +357,10 @@ ETEXI
.cmd = hmp_info_usb,
},
STEXI
@item info usb
@findex info usb
Show guest USB devices.
ETEXI
SRST
``info usb``
Show guest USB devices.
ERST
{
.name = "usbhost",
@ -385,11 +370,10 @@ ETEXI
.cmd = hmp_info_usbhost,
},
STEXI
@item info usbhost
@findex info usbhost
Show host USB devices.
ETEXI
SRST
``info usbhost``
Show host USB devices.
ERST
{
.name = "profile",
@ -399,11 +383,10 @@ ETEXI
.cmd = hmp_info_profile,
},
STEXI
@item info profile
@findex info profile
Show profiling information.
ETEXI
SRST
``info profile``
Show profiling information.
ERST
{
.name = "capture",
@ -413,11 +396,10 @@ ETEXI
.cmd = hmp_info_capture,
},
STEXI
@item info capture
@findex info capture
Show capture information.
ETEXI
SRST
``info capture``
Show capture information.
ERST
{
.name = "snapshots",
@ -427,11 +409,10 @@ ETEXI
.cmd = hmp_info_snapshots,
},
STEXI
@item info snapshots
@findex info snapshots
Show the currently saved VM snapshots.
ETEXI
SRST
``info snapshots``
Show the currently saved VM snapshots.
ERST
{
.name = "status",
@ -442,11 +423,10 @@ ETEXI
.flags = "p",
},
STEXI
@item info status
@findex info status
Show the current VM status (running|paused).
ETEXI
SRST
``info status``
Show the current VM status (running|paused).
ERST
{
.name = "mice",
@ -456,11 +436,10 @@ ETEXI
.cmd = hmp_info_mice,
},
STEXI
@item info mice
@findex info mice
Show which guest mouse is receiving events.
ETEXI
SRST
``info mice``
Show which guest mouse is receiving events.
ERST
#if defined(CONFIG_VNC)
{
@ -472,11 +451,10 @@ ETEXI
},
#endif
STEXI
@item info vnc
@findex info vnc
Show the vnc server status.
ETEXI
SRST
``info vnc``
Show the vnc server status.
ERST
#if defined(CONFIG_SPICE)
{
@ -488,11 +466,10 @@ ETEXI
},
#endif
STEXI
@item info spice
@findex info spice
Show the spice server status.
ETEXI
SRST
``info spice``
Show the spice server status.
ERST
{
.name = "name",
@ -503,11 +480,10 @@ ETEXI
.flags = "p",
},
STEXI
@item info name
@findex info name
Show the current VM name.
ETEXI
SRST
``info name``
Show the current VM name.
ERST
{
.name = "uuid",
@ -518,11 +494,10 @@ ETEXI
.flags = "p",
},
STEXI
@item info uuid
@findex info uuid
Show the current VM UUID.
ETEXI
SRST
``info uuid``
Show the current VM UUID.
ERST
{
.name = "cpustats",
@ -532,11 +507,10 @@ ETEXI
.cmd = hmp_info_cpustats,
},
STEXI
@item info cpustats
@findex info cpustats
Show CPU statistics.
ETEXI
SRST
``info cpustats``
Show CPU statistics.
ERST
#if defined(CONFIG_SLIRP)
{
@ -548,11 +522,10 @@ ETEXI
},
#endif
STEXI
@item info usernet
@findex info usernet
Show user network stack connection states.
ETEXI
SRST
``info usernet``
Show user network stack connection states.
ERST
{
.name = "migrate",
@ -562,11 +535,10 @@ ETEXI
.cmd = hmp_info_migrate,
},
STEXI
@item info migrate
@findex info migrate
Show migration status.
ETEXI
SRST
``info migrate``
Show migration status.
ERST
{
.name = "migrate_capabilities",
@ -576,11 +548,10 @@ ETEXI
.cmd = hmp_info_migrate_capabilities,
},
STEXI
@item info migrate_capabilities
@findex info migrate_capabilities
Show current migration capabilities.
ETEXI
SRST
``info migrate_capabilities``
Show current migration capabilities.
ERST
{
.name = "migrate_parameters",
@ -590,11 +561,10 @@ ETEXI
.cmd = hmp_info_migrate_parameters,
},
STEXI
@item info migrate_parameters
@findex info migrate_parameters
Show current migration parameters.
ETEXI
SRST
``info migrate_parameters``
Show current migration parameters.
ERST
{
.name = "migrate_cache_size",
@ -604,11 +574,10 @@ ETEXI
.cmd = hmp_info_migrate_cache_size,
},
STEXI
@item info migrate_cache_size
@findex info migrate_cache_size
Show current migration xbzrle cache size.
ETEXI
SRST
``info migrate_cache_size``
Show current migration xbzrle cache size.
ERST
{
.name = "balloon",
@ -618,11 +587,10 @@ ETEXI
.cmd = hmp_info_balloon,
},
STEXI
@item info balloon
@findex info balloon
Show balloon information.
ETEXI
SRST
``info balloon``
Show balloon information.
ERST
{
.name = "qtree",
@ -632,11 +600,10 @@ ETEXI
.cmd = hmp_info_qtree,
},
STEXI
@item info qtree
@findex info qtree
Show device tree.
ETEXI
SRST
``info qtree``
Show device tree.
ERST
{
.name = "qdm",
@ -646,11 +613,10 @@ ETEXI
.cmd = hmp_info_qdm,
},
STEXI
@item info qdm
@findex info qdm
Show qdev device model list.
ETEXI
SRST
``info qdm``
Show qdev device model list.
ERST
{
.name = "qom-tree",
@ -661,11 +627,10 @@ ETEXI
.flags = "p",
},
STEXI
@item info qom-tree
@findex info qom-tree
Show QOM composition tree.
ETEXI
SRST
``info qom-tree``
Show QOM composition tree.
ERST
{
.name = "roms",
@ -675,11 +640,10 @@ ETEXI
.cmd = hmp_info_roms,
},
STEXI
@item info roms
@findex info roms
Show roms.
ETEXI
SRST
``info roms``
Show roms.
ERST
{
.name = "trace-events",
@ -691,11 +655,10 @@ ETEXI
.command_completion = info_trace_events_completion,
},
STEXI
@item info trace-events
@findex info trace-events
Show available trace-events & their state.
ETEXI
SRST
``info trace-events``
Show available trace-events & their state.
ERST
{
.name = "tpm",
@ -705,11 +668,10 @@ ETEXI
.cmd = hmp_info_tpm,
},
STEXI
@item info tpm
@findex info tpm
Show the TPM device.
ETEXI
SRST
``info tpm``
Show the TPM device.
ERST
{
.name = "memdev",
@ -720,11 +682,10 @@ ETEXI
.flags = "p",
},
STEXI
@item info memdev
@findex info memdev
Show memory backends
ETEXI
SRST
``info memdev``
Show memory backends
ERST
{
.name = "memory-devices",
@ -734,11 +695,10 @@ ETEXI
.cmd = hmp_info_memory_devices,
},
STEXI
@item info memory-devices
@findex info memory-devices
Show memory devices.
ETEXI
SRST
``info memory-devices``
Show memory devices.
ERST
{
.name = "iothreads",
@ -749,11 +709,10 @@ ETEXI
.flags = "p",
},
STEXI
@item info iothreads
@findex info iothreads
Show iothread's identifiers.
ETEXI
SRST
``info iothreads``
Show iothread's identifiers.
ERST
{
.name = "rocker",
@ -763,11 +722,10 @@ ETEXI
.cmd = hmp_rocker,
},
STEXI
@item info rocker @var{name}
@findex info rocker
Show rocker switch.
ETEXI
SRST
``info rocker`` *name*
Show rocker switch.
ERST
{
.name = "rocker-ports",
@ -777,11 +735,10 @@ ETEXI
.cmd = hmp_rocker_ports,
},
STEXI
@item info rocker-ports @var{name}-ports
@findex info rocker-ports
Show rocker ports.
ETEXI
SRST
``info rocker-ports`` *name*-ports
Show rocker ports.
ERST
{
.name = "rocker-of-dpa-flows",
@ -791,11 +748,10 @@ ETEXI
.cmd = hmp_rocker_of_dpa_flows,
},
STEXI
@item info rocker-of-dpa-flows @var{name} [@var{tbl_id}]
@findex info rocker-of-dpa-flows
Show rocker OF-DPA flow tables.
ETEXI
SRST
``info rocker-of-dpa-flows`` *name* [*tbl_id*]
Show rocker OF-DPA flow tables.
ERST
{
.name = "rocker-of-dpa-groups",
@ -805,11 +761,10 @@ ETEXI
.cmd = hmp_rocker_of_dpa_groups,
},
STEXI
@item info rocker-of-dpa-groups @var{name} [@var{type}]
@findex info rocker-of-dpa-groups
Show rocker OF-DPA groups.
ETEXI
SRST
``info rocker-of-dpa-groups`` *name* [*type*]
Show rocker OF-DPA groups.
ERST
#if defined(TARGET_S390X)
{
@ -821,11 +776,10 @@ ETEXI
},
#endif
STEXI
@item info skeys @var{address}
@findex info skeys
Display the value of a storage key (s390 only)
ETEXI
SRST
``info skeys`` *address*
Display the value of a storage key (s390 only)
ERST
#if defined(TARGET_S390X)
{
@ -837,11 +791,11 @@ ETEXI
},
#endif
STEXI
@item info cmma @var{address}
@findex info cmma
Display the values of the CMMA storage attributes for a range of pages (s390 only)
ETEXI
SRST
``info cmma`` *address*
Display the values of the CMMA storage attributes for a range of
pages (s390 only)
ERST
{
.name = "dump",
@ -851,11 +805,10 @@ ETEXI
.cmd = hmp_info_dump,
},
STEXI
@item info dump
@findex info dump
Display the latest dump status.
ETEXI
SRST
``info dump``
Display the latest dump status.
ERST
{
.name = "ramblock",
@ -865,11 +818,10 @@ ETEXI
.cmd = hmp_info_ramblock,
},
STEXI
@item info ramblock
@findex info ramblock
Dump all the ramblocks of the system.
ETEXI
SRST
``info ramblock``
Dump all the ramblocks of the system.
ERST
{
.name = "hotpluggable-cpus",
@ -880,11 +832,10 @@ ETEXI
.flags = "p",
},
STEXI
@item info hotpluggable-cpus
@findex info hotpluggable-cpus
Show information about hotpluggable CPUs
ETEXI
SRST
``info hotpluggable-cpus``
Show information about hotpluggable CPUs
ERST
{
.name = "vm-generation-id",
@ -894,11 +845,10 @@ ETEXI
.cmd = hmp_info_vm_generation_id,
},
STEXI
@item info vm-generation-id
@findex info vm-generation-id
Show Virtual Machine Generation ID
ETEXI
SRST
``info vm-generation-id``
Show Virtual Machine Generation ID
ERST
{
.name = "memory_size_summary",
@ -909,12 +859,11 @@ ETEXI
.cmd = hmp_info_memory_size_summary,
},
STEXI
@item info memory_size_summary
@findex info memory_size_summary
Display the amount of initially allocated and present hotpluggable (if
enabled) memory in bytes.
ETEXI
SRST
``info memory_size_summary``
Display the amount of initially allocated and present hotpluggable (if
enabled) memory in bytes.
ERST
#if defined(TARGET_I386)
{
@ -926,16 +875,9 @@ ETEXI
},
#endif
STEXI
@item info sev
@findex info sev
Show SEV information.
ETEXI
SRST
``info sev``
Show SEV information.
ERST
STEXI
@end table
ETEXI
STEXI
@end table
ETEXI

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@node Deprecated features
@appendix Deprecated features
In general features are intended to be supported indefinitely once
introduced into QEMU. In the event that a feature needs to be removed,
it will be listed in this appendix. The feature will remain functional
for 2 releases prior to actual removal. Deprecated features may also
generate warnings on the console when QEMU starts up, or if activated
via a monitor command, however, this is not a mandatory requirement.
Prior to the 2.10.0 release there was no official policy on how
long features would be deprecated prior to their removal, nor
any documented list of which features were deprecated. Thus
any features deprecated prior to 2.10.0 will be treated as if
they were first deprecated in the 2.10.0 release.
What follows is a list of all features currently marked as
deprecated.
@section System emulator command line arguments
@subsection -machine enforce-config-section=on|off (since 3.1)
The @option{enforce-config-section} parameter is replaced by the
@option{-global migration.send-configuration=@var{on|off}} option.
@subsection -no-kvm (since 1.3.0)
The ``-no-kvm'' argument is now a synonym for setting ``-accel tcg''.
@subsection -usbdevice (since 2.10.0)
The ``-usbdevice DEV'' argument is now a synonym for setting
the ``-device usb-DEV'' argument instead. The deprecated syntax
would automatically enable USB support on the machine type.
If using the new syntax, USB support must be explicitly
enabled via the ``-machine usb=on'' argument.
@subsection -drive file=json:@{...@{'driver':'file'@}@} (since 3.0)
The 'file' driver for drives is no longer appropriate for character or host
devices and will only accept regular files (S_IFREG). The correct driver
for these file types is 'host_cdrom' or 'host_device' as appropriate.
@subsection -net ...,name=@var{name} (since 3.1)
The @option{name} parameter of the @option{-net} option is a synonym
for the @option{id} parameter, which should now be used instead.
@subsection -smp (invalid topologies) (since 3.1)
CPU topology properties should describe whole machine topology including
possible CPUs.
However, historically it was possible to start QEMU with an incorrect topology
where @math{@var{n} <= @var{sockets} * @var{cores} * @var{threads} < @var{maxcpus}},
which could lead to an incorrect topology enumeration by the guest.
Support for invalid topologies will be removed, the user must ensure
topologies described with -smp include all possible cpus, i.e.
@math{@var{sockets} * @var{cores} * @var{threads} = @var{maxcpus}}.
@subsection -vnc acl (since 4.0.0)
The @code{acl} option to the @code{-vnc} argument has been replaced
by the @code{tls-authz} and @code{sasl-authz} options.
@subsection QEMU_AUDIO_ environment variables and -audio-help (since 4.0)
The ``-audiodev'' argument is now the preferred way to specify audio
backend settings instead of environment variables. To ease migration to
the new format, the ``-audiodev-help'' option can be used to convert
the current values of the environment variables to ``-audiodev'' options.
@subsection Creating sound card devices and vnc without audiodev= property (since 4.2)
When not using the deprecated legacy audio config, each sound card
should specify an @code{audiodev=} property. Additionally, when using
vnc, you should specify an @code{audiodev=} propery if you plan to
transmit audio through the VNC protocol.
@subsection -mon ...,control=readline,pretty=on|off (since 4.1)
The @code{pretty=on|off} switch has no effect for HMP monitors, but is
silently ignored. Using the switch with HMP monitors will become an
error in the future.
@subsection -realtime (since 4.1)
The @code{-realtime mlock=on|off} argument has been replaced by the
@code{-overcommit mem-lock=on|off} argument.
@subsection -numa node,mem=@var{size} (since 4.1)
The parameter @option{mem} of @option{-numa node} is used to assign a part of
guest RAM to a NUMA node. But when using it, it's impossible to manage specified
RAM chunk on the host side (like bind it to a host node, setting bind policy, ...),
so guest end-ups with the fake NUMA configuration with suboptiomal performance.
However since 2014 there is an alternative way to assign RAM to a NUMA node
using parameter @option{memdev}, which does the same as @option{mem} and adds
means to actualy manage node RAM on the host side. Use parameter @option{memdev}
with @var{memory-backend-ram} backend as an replacement for parameter @option{mem}
to achieve the same fake NUMA effect or a properly configured
@var{memory-backend-file} backend to actually benefit from NUMA configuration.
In future new machine versions will not accept the option but it will still
work with old machine types. User can check QAPI schema to see if the legacy
option is supported by looking at MachineInfo::numa-mem-supported property.
@subsection -numa node (without memory specified) (since 4.1)
Splitting RAM by default between NUMA nodes has the same issues as @option{mem}
parameter described above with the difference that the role of the user plays
QEMU using implicit generic or board specific splitting rule.
Use @option{memdev} with @var{memory-backend-ram} backend or @option{mem} (if
it's supported by used machine type) to define mapping explictly instead.
@subsection RISC-V -bios (since 4.1)
QEMU 4.1 introduced support for the -bios option in QEMU for RISC-V for the
RISC-V virt machine and sifive_u machine.
QEMU 4.1 has no changes to the default behaviour to avoid breakages. This
default will change in a future QEMU release, so please prepare now. All users
of the virt or sifive_u machine must change their command line usage.
QEMU 4.1 has three options, please migrate to one of these three:
1. ``-bios none`` - This is the current default behavior if no -bios option
is included. QEMU will not automatically load any firmware. It is up
to the user to load all the images they need.
2. ``-bios default`` - In a future QEMU release this will become the default
behaviour if no -bios option is specified. This option will load the
default OpenSBI firmware automatically. The firmware is included with
the QEMU release and no user interaction is required. All a user needs
to do is specify the kernel they want to boot with the -kernel option
3. ``-bios <file>`` - Tells QEMU to load the specified file as the firmwrae.
@subsection -tb-size option (since 5.0)
QEMU 5.0 introduced an alternative syntax to specify the size of the translation
block cache, @option{-accel tcg,tb-size=}. The new syntax deprecates the
previously available @option{-tb-size} option.
@subsection -show-cursor option (since 5.0)
Use @option{-display sdl,show-cursor=on} or
@option{-display gtk,show-cursor=on} instead.
@section QEMU Machine Protocol (QMP) commands
@subsection change (since 2.5.0)
Use ``blockdev-change-medium'' or ``change-vnc-password'' instead.
@subsection migrate_set_downtime and migrate_set_speed (since 2.8.0)
Use ``migrate-set-parameters'' instead.
@subsection migrate-set-cache-size and query-migrate-cache-size (since 2.11.0)
Use ``migrate-set-parameters'' and ``query-migrate-parameters'' instead.
@subsection query-block result field dirty-bitmaps[i].status (since 4.0)
The ``status'' field of the ``BlockDirtyInfo'' structure, returned by
the query-block command is deprecated. Two new boolean fields,
``recording'' and ``busy'' effectively replace it.
@subsection query-block result field dirty-bitmaps (Since 4.2)
The ``dirty-bitmaps`` field of the ``BlockInfo`` structure, returned by
the query-block command is itself now deprecated. The ``dirty-bitmaps``
field of the ``BlockDeviceInfo`` struct should be used instead, which is the
type of the ``inserted`` field in query-block replies, as well as the
type of array items in query-named-block-nodes.
Since the ``dirty-bitmaps`` field is optionally present in both the old and
new locations, clients must use introspection to learn where to anticipate
the field if/when it does appear in command output.
@subsection query-cpus (since 2.12.0)
The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command.
@subsection query-cpus-fast "arch" output member (since 3.0.0)
The ``arch'' output member of the ``query-cpus-fast'' command is
replaced by the ``target'' output member.
@subsection cpu-add (since 4.0)
Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''. See
documentation of ``query-hotpluggable-cpus'' for additional
details.
@subsection query-events (since 4.0)
The ``query-events'' command has been superseded by the more powerful
and accurate ``query-qmp-schema'' command.
@subsection chardev client socket with 'wait' option (since 4.0)
Character devices creating sockets in client mode should not specify
the 'wait' field, which is only applicable to sockets in server mode
@section Human Monitor Protocol (HMP) commands
@subsection The hub_id parameter of 'hostfwd_add' / 'hostfwd_remove' (since 3.1)
The @option{[hub_id name]} parameter tuple of the 'hostfwd_add' and
'hostfwd_remove' HMP commands has been replaced by @option{netdev_id}.
@subsection cpu-add (since 4.0)
Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''. See
documentation of ``query-hotpluggable-cpus'' for additional details.
@subsection acl_show, acl_reset, acl_policy, acl_add, acl_remove (since 4.0.0)
The ``acl_show'', ``acl_reset'', ``acl_policy'', ``acl_add'', and
``acl_remove'' commands are deprecated with no replacement. Authorization
for VNC should be performed using the pluggable QAuthZ objects.
@section Guest Emulator ISAs
@subsection RISC-V ISA privledge specification version 1.09.1 (since 4.1)
The RISC-V ISA privledge specification version 1.09.1 has been deprecated.
QEMU supports both the newer version 1.10.0 and the ratified version 1.11.0, these
should be used instead of the 1.09.1 version.
@section System emulator CPUS
@subsection RISC-V ISA CPUs (since 4.1)
The RISC-V cpus with the ISA version in the CPU name have been depcreated. The
four CPUs are: ``rv32gcsu-v1.9.1``, ``rv32gcsu-v1.10.0``, ``rv64gcsu-v1.9.1`` and
``rv64gcsu-v1.10.0``. Instead the version can be specified via the CPU ``priv_spec``
option when using the ``rv32`` or ``rv64`` CPUs.
@subsection RISC-V ISA CPUs (since 4.1)
The RISC-V no MMU cpus have been depcreated. The two CPUs: ``rv32imacu-nommu`` and
``rv64imacu-nommu`` should no longer be used. Instead the MMU status can be specified
via the CPU ``mmu`` option when using the ``rv32`` or ``rv64`` CPUs.
@section System emulator devices
@subsection ide-drive (since 4.2)
The 'ide-drive' device is deprecated. Users should use 'ide-hd' or
'ide-cd' as appropriate to get an IDE hard disk or CD-ROM as needed.
@subsection scsi-disk (since 4.2)
The 'scsi-disk' device is deprecated. Users should use 'scsi-hd' or
'scsi-cd' as appropriate to get a SCSI hard disk or CD-ROM as needed.
@section System emulator machines
@subsection mips r4k platform (since 5.0)
This machine type is very old and unmaintained. Users should use the 'malta'
machine type instead.
@subsection pc-1.0, pc-1.1, pc-1.2 and pc-1.3 (since 5.0)
These machine types are very old and likely can not be used for live migration
from old QEMU versions anymore. A newer machine type should be used instead.
@subsection spike_v1.9.1 and spike_v1.10 (since 4.1)
The version specific Spike machines have been deprecated in favour of the
generic ``spike`` machine. If you need to specify an older version of the RISC-V
spec you can use the ``-cpu rv64gcsu,priv_spec=v1.9.1`` command line argument.
@section Device options
@subsection Emulated device options
@subsubsection -device virtio-blk,scsi=on|off (since 5.0.0)
The virtio-blk SCSI passthrough feature is a legacy VIRTIO feature. VIRTIO 1.0
and later do not support it because the virtio-scsi device was introduced for
full SCSI support. Use virtio-scsi instead when SCSI passthrough is required.
Note this also applies to ``-device virtio-blk-pci,scsi=on|off'', which is an
alias.
@subsection Block device options
@subsubsection "backing": "" (since 2.12.0)
In order to prevent QEMU from automatically opening an image's backing
chain, use ``"backing": null'' instead.
@subsubsection rbd keyvalue pair encoded filenames: "" (since 3.1.0)
Options for ``rbd'' should be specified according to its runtime options,
like other block drivers. Legacy parsing of keyvalue pair encoded
filenames is useful to open images with the old format for backing files;
These image files should be updated to use the current format.
Example of legacy encoding:
@code{json:@{"file.driver":"rbd", "file.filename":"rbd:rbd/name"@}}
The above, converted to the current supported format:
@code{json:@{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"@}}
@section Related binaries
@subsection qemu-img convert -n -o (since 4.2.0)
All options specified in @option{-o} are image creation options, so
they have no effect when used with @option{-n} to skip image creation.
Silently ignored options can be confusing, so this combination of
options will be made an error in future versions.
@section Backwards compatibility
@subsection Runnability guarantee of CPU models (since 4.1.0)
Previous versions of QEMU never changed existing CPU models in
ways that introduced additional host software or hardware
requirements to the VM. This allowed management software to
safely change the machine type of an existing VM without
introducing new requirements ("runnability guarantee"). This
prevented CPU models from being updated to include CPU
vulnerability mitigations, leaving guests vulnerable in the
default configuration.
The CPU model runnability guarantee won't apply anymore to
existing CPU models. Management software that needs runnability
guarantees must resolve the CPU model aliases using te
``alias-of'' field returned by the ``query-cpu-definitions'' QMP
command.
While those guarantees are kept, the return value of
``query-cpu-definitions'' will have existing CPU model aliases
point to a version that doesn't break runnability guarantees
(specifically, version 1 of those CPU models). In future QEMU
versions, aliases will point to newer CPU model versions
depending on the machine type, so management software must
resolve CPU model aliases before starting a virtual machine.
@node Recently removed features
@appendix Recently removed features
What follows is a record of recently removed, formerly deprecated
features that serves as a record for users who have encountered
trouble after a recent upgrade.
@section QEMU Machine Protocol (QMP) commands
@subsection block-dirty-bitmap-add "autoload" parameter (since 4.2.0)
The "autoload" parameter has been ignored since 2.12.0. All bitmaps
are automatically loaded from qcow2 images.
@section Related binaries
@subsection qemu-nbd --partition (removed in 5.0.0)
The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
could only handle MBR partitions, and never correctly handled logical
partitions beyond partition 5. Exporting a partition can still be
done by utilizing the @option{--image-opts} option with a raw blockdev
using the @code{offset} and @code{size} parameters layered on top of
any other existing blockdev. For example, if partition 1 is 100MiB
long starting at 1MiB, the old command:
@code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
can be rewritten as:
@code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.file.driver=file,file.file.filename=file.qcow2}

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@c The contents of this file must be kept in sync with qemu-option-trace.rst.inc
@c until all the users of the texi file have been converted to rst and
@c the texi file can be removed.
Specify tracing options.
@table @option
@item [enable=]@var{pattern}
Immediately enable events matching @var{pattern}
(either event name or a globbing pattern). This option is only
available if QEMU has been compiled with the @var{simple}, @var{log}
or @var{ftrace} tracing backend. To specify multiple events or patterns,
specify the @option{-trace} option multiple times.
Use @code{-trace help} to print a list of names of trace points.
@item events=@var{file}
Immediately enable events listed in @var{file}.
The file must contain one event name (as listed in the @file{trace-events-all}
file) per line; globbing patterns are accepted too. This option is only
available if QEMU has been compiled with the @var{simple}, @var{log} or
@var{ftrace} tracing backend.
@item file=@var{file}
Log output traces to @var{file}.
This option is only available if QEMU has been compiled with
the @var{simple} tracing backend.
@end table

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@node Implementation notes
@appendix Implementation notes
@menu
* CPU emulation::
* Managed start up options::
@end menu
@node CPU emulation
@section CPU emulation
@menu
* x86:: x86 and x86-64 emulation
* ARM:: ARM emulation
* MIPS:: MIPS emulation
* PPC:: PowerPC emulation
* SPARC:: Sparc32 and Sparc64 emulation
* Xtensa:: Xtensa emulation
@end menu
@node x86
@subsection x86 and x86-64 emulation
QEMU x86 target features:
@itemize
@item The virtual x86 CPU supports 16 bit and 32 bit addressing with segmentation.
LDT/GDT and IDT are emulated. VM86 mode is also supported to run
DOSEMU. There is some support for MMX/3DNow!, SSE, SSE2, SSE3, SSSE3,
and SSE4 as well as x86-64 SVM.
@item Support of host page sizes bigger than 4KB in user mode emulation.
@item QEMU can emulate itself on x86.
@item An extensive Linux x86 CPU test program is included @file{tests/test-i386}.
It can be used to test other x86 virtual CPUs.
@end itemize
Current QEMU limitations:
@itemize
@item Limited x86-64 support.
@item IPC syscalls are missing.
@item The x86 segment limits and access rights are not tested at every
memory access (yet). Hopefully, very few OSes seem to rely on that for
normal use.
@end itemize
@node ARM
@subsection ARM emulation
@itemize
@item Full ARM 7 user emulation.
@item NWFPE FPU support included in user Linux emulation.
@item Can run most ARM Linux binaries.
@end itemize
@node MIPS
@subsection MIPS emulation
@itemize
@item The system emulation allows full MIPS32/MIPS64 Release 2 emulation,
including privileged instructions, FPU and MMU, in both little and big
endian modes.
@item The Linux userland emulation can run many 32 bit MIPS Linux binaries.
@end itemize
Current QEMU limitations:
@itemize
@item Self-modifying code is not always handled correctly.
@item 64 bit userland emulation is not implemented.
@item The system emulation is not complete enough to run real firmware.
@item The watchpoint debug facility is not implemented.
@end itemize
@node PPC
@subsection PowerPC emulation
@itemize
@item Full PowerPC 32 bit emulation, including privileged instructions,
FPU and MMU.
@item Can run most PowerPC Linux binaries.
@end itemize
@node SPARC
@subsection Sparc32 and Sparc64 emulation
@itemize
@item Full SPARC V8 emulation, including privileged
instructions, FPU and MMU. SPARC V9 emulation includes most privileged
and VIS instructions, FPU and I/D MMU. Alignment is fully enforced.
@item Can run most 32-bit SPARC Linux binaries, SPARC32PLUS Linux binaries and
some 64-bit SPARC Linux binaries.
@end itemize
Current QEMU limitations:
@itemize
@item IPC syscalls are missing.
@item Floating point exception support is buggy.
@item Atomic instructions are not correctly implemented.
@item There are still some problems with Sparc64 emulators.
@end itemize
@node Xtensa
@subsection Xtensa emulation
@itemize
@item Core Xtensa ISA emulation, including most options: code density,
loop, extended L32R, 16- and 32-bit multiplication, 32-bit division,
MAC16, miscellaneous operations, boolean, FP coprocessor, coprocessor
context, debug, multiprocessor synchronization,
conditional store, exceptions, relocatable vectors, unaligned exception,
interrupts (including high priority and timer), hardware alignment,
region protection, region translation, MMU, windowed registers, thread
pointer, processor ID.
@item Not implemented options: data/instruction cache (including cache
prefetch and locking), XLMI, processor interface. Also options not
covered by the core ISA (e.g. FLIX, wide branches) are not implemented.
@item Can run most Xtensa Linux binaries.
@item New core configuration that requires no additional instructions
may be created from overlay with minimal amount of hand-written code.
@end itemize
@node Managed start up options
@section Managed start up options
In system mode emulation, it's possible to create a VM in a paused state using
the -S command line option. In this state the machine is completely initialized
according to command line options and ready to execute VM code but VCPU threads
are not executing any code. The VM state in this paused state depends on the way
QEMU was started. It could be in:
@table @asis
@item initial state (after reset/power on state)
@item with direct kernel loading, the initial state could be amended to execute
code loaded by QEMU in the VM's RAM and with incoming migration
@item with incoming migration, initial state will by amended with the migrated
machine state after migration completes.
@end table
This paused state is typically used by users to query machine state and/or
additionally configure the machine (by hotplugging devices) in runtime before
allowing VM code to run.
However, at the -S pause point, it's impossible to configure options that affect
initial VM creation (like: -smp/-m/-numa ...) or cold plug devices. The
experimental --preconfig command line option allows pausing QEMU
before the initial VM creation, in a ``preconfig'' state, where additional
queries and configuration can be performed via QMP before moving on to
the resulting configuration startup. In the preconfig state, QEMU only allows
a limited set of commands over the QMP monitor, where the commands do not
depend on an initialized machine, including but not limited to:
@table @asis
@item qmp_capabilities
@item query-qmp-schema
@item query-commands
@item query-status
@item x-exit-preconfig
@end table

137
scripts/hxtool-conv.pl Executable file
View File

@ -0,0 +1,137 @@
#!/usr/bin/perl -w
#
# Script to convert .hx file STEXI/ETEXI blocks to SRST/ERST
#
# Copyright (C) 2020 Linaro
#
# This work is licensed under the terms of the GNU GPL, version 2 or
# (at your option) any later version. See the COPYING file in the
# top-level directory.
# This script was only ever intended as a one-off conversion operation.
# Please excuse the places where it is a bit hacky.
# Some manual intervention after the conversion is expected, as are
# some warnings from makeinfo.
# Warning: this script is not idempotent: don't try to run it on
# a .hx file that already has SRST/ERST sections.
# Expected usage:
# scripts/hxtool-conv.pl file.hx > file.hx.new
use utf8;
my $reading_texi = 0;
my $texiblock = '';
my @tables = ();
sub update_tables($) {
my ($texi) = @_;
# Update our list of open table directives: every @table
# line in the texi fragment is added to the list, and every
# @end table line means we remove an entry from the list.
# If this fragment had a completely self contained table with
# both the @table and @end table lines, this will be a no-op.
foreach (split(/\n/, $texi)) {
push @tables, $_ if /^\@table/;
pop @tables if /^\@end table/;
}
}
sub only_table_directives($) {
# Return true if every line in the fragment is a start or end table directive
my ($texi) = @_;
foreach (split(/\n/, $texi)) {
return 0 unless /^\@table/ or /^\@end table/;
}
return 1;
}
sub output_rstblock($) {
# Write the output to /tmp/frag.texi, wrapped in whatever current @table
# lines we need.
my ($texi) = @_;
# As a special case, if this fragment is only table directives and
# nothing else, update our set of open table directives but otherwise
# ignore it. This avoids emitting an empty SRST/ERST block.
if (only_table_directives($texi)) {
update_tables($texi);
return;
}
open(my $fragfh, '>', '/tmp/frag.texi');
# First output the currently active set of open table directives
print $fragfh join("\n", @tables);
# Next, update our list of open table directives.
# We need to do this before we emit the closing table directives
# so that we emit the right number if this fragment had an
# unbalanced set of directives.
update_tables($texi);
# Then emit the texi fragment itself.
print $fragfh "\n$texi\n";
# Finally, add the necessary closing table directives.
print $fragfh "\@end table\n" x scalar @tables;
close $fragfh;
# Now invoke makeinfo/pandoc on it and slurp the results into a string
open(my $fh, '-|', "makeinfo --force -o - --docbook "
. "-D 'qemu_system_x86 QEMU_SYSTEM_X86_MACRO' "
. "-D 'qemu_system QEMU_SYSTEM_MACRO' /tmp/frag.texi "
. " | pandoc -f docbook -t rst")
or die "can't start makeinfo/pandoc: $!";
binmode $fh, ':encoding(utf8)';
print "SRST\n";
# Slurp the whole thing into a string so we can do multiline
# string matches on it.
my $rst = do {
local $/ = undef;
<$fh>;
};
$rst =~ s/^- − /- /gm;
$rst =~ s/“/"/gm;
$rst =~ s/”/"/gm;
$rst =~ s/‘/'/gm;
$rst =~ s/’/'/gm;
$rst =~ s/QEMU_SYSTEM_MACRO/|qemu_system|/g;
$rst =~ s/QEMU_SYSTEM_X86_MACRO/|qemu_system_x86|/g;
$rst =~ s/(?=::\n\n +\|qemu)/.. parsed-literal/g;
$rst =~ s/:\n\n::$/::/gm;
# Fix up the invalid reference format makeinfo/pandoc emit:
# `Some string here <#anchorname>`__
# should be:
# :ref:`anchorname`
$rst =~ s/\`[^<`]+\<\#([^>]+)\>\`__/:ref:`$1`/gm;
print $rst;
close $fh or die "error on close: $!";
print "ERST\n";
}
# Read the whole .hx input file.
while (<>) {
# Always print the current line
print;
if (/STEXI/) {
$reading_texi = 1;
$texiblock = '';
next;
}
if (/ETEXI/) {
$reading_texi = 0;
# dump RST version of block
output_rstblock($texiblock);
next;
}
if ($reading_texi) {
# Accumulate the texi into a string
# but drop findex entries as they will confuse makeinfo
next if /^\@findex/;
$texiblock .= $_;
}
}
die "Unexpectedly still in texi block at EOF" if $reading_texi;

36
scripts/texi2pod.pl
View File

@ -143,6 +143,24 @@ while(<$inf>) {
next;
};
# Single line command handlers.
/^\@include\s+(.+)$/ and do {
push @instack, $inf;
$inf = gensym();
$file = postprocess($1);
# Try cwd and $ibase, then explicit -I paths.
$done = 0;
foreach $path ("", $ibase, @ipath) {
$mypath = $file;
$mypath = $path . "/" . $mypath if ($path ne "");
open($inf, "<" . $mypath) and ($done = 1, last);
}
die "cannot find $file" if !$done;
next;
};
next unless $output;
# Discard comments. (Can't do it above, because then we'd never see
@ -242,24 +260,6 @@ while(<$inf>) {
s/>/&GT;/g;
}
# Single line command handlers.
/^\@include\s+(.+)$/ and do {
push @instack, $inf;
$inf = gensym();
$file = postprocess($1);
# Try cwd and $ibase, then explicit -I paths.
$done = 0;
foreach $path ("", $ibase, @ipath) {
$mypath = $file;
$mypath = $path . "/" . $mypath if ($path ne "");
open($inf, "<" . $mypath) and ($done = 1, last);
}
die "cannot find $file" if !$done;
next;
};
/^\@(?:section|unnumbered|unnumberedsec|center)\s+(.+)$/
and $_ = "\n=head2 $1\n";
/^\@subsection\s+(.+)$/

4
ui/cocoa.m
View File

@ -1174,7 +1174,7 @@ QemuCocoaView *cocoaView;
- (void) openDocumentation: (NSString *) filename
{
/* Where to look for local files */
NSString *path_array[] = {@"../share/doc/qemu/", @"../doc/qemu/", @"../"};
NSString *path_array[] = {@"../share/doc/qemu/", @"../doc/qemu/", @"../docs/"};
NSString *full_file_path;
/* iterate thru the possible paths until the file is found */
@ -1198,7 +1198,7 @@ QemuCocoaView *cocoaView;
{
COCOA_DEBUG("QemuCocoaAppController: showQEMUDoc\n");
[self openDocumentation: @"qemu-doc.html"];
[self openDocumentation: @"index.html"];
}
/* Stretches video to fit host monitor size */