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Diffstat (limited to 'docs')
49 files changed, 4526 insertions, 1702 deletions
diff --git a/docs/conf.py b/docs/conf.py index 7588bf192e..960043cb86 100644 --- a/docs/conf.py +++ b/docs/conf.py @@ -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 ---------------------------------------------- diff --git a/docs/defs.rst.inc b/docs/defs.rst.inc new file mode 100644 index 0000000000..48d05aaf33 --- /dev/null +++ b/docs/defs.rst.inc @@ -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 diff --git a/docs/index.html.in b/docs/index.html.in index cf61b1cf44..cc19aad2ec 100644 --- a/docs/index.html.in +++ b/docs/index.html.in @@ -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> diff --git a/docs/index.rst b/docs/index.rst index acd604fa8a..376dab2885 100644 --- a/docs/index.rst +++ b/docs/index.rst @@ -15,3 +15,4 @@ Welcome to QEMU's documentation! specs/index system/index tools/index + user/index diff --git a/docs/qemu-cpu-models.texi b/docs/qemu-cpu-models.texi deleted file mode 100644 index f88a1def0d..0000000000 --- a/docs/qemu-cpu-models.texi +++ /dev/null @@ -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 diff --git a/docs/specs/ivshmem-spec.txt b/docs/specs/ivshmem-spec.txt index 042f7eae22..1beb3a01ec 100644 --- a/docs/specs/ivshmem-spec.txt +++ b/docs/specs/ivshmem-spec.txt @@ -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 == diff --git a/docs/sphinx/hxtool.py b/docs/sphinx/hxtool.py index 5d6736f300..7dd223fe36 100644 --- a/docs/sphinx/hxtool.py +++ b/docs/sphinx/hxtool.py @@ -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) diff --git a/docs/system/build-platforms.rst b/docs/system/build-platforms.rst new file mode 100644 index 0000000000..c2b92a9698 --- /dev/null +++ b/docs/system/build-platforms.rst @@ -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. diff --git a/docs/system/conf.py b/docs/system/conf.py index 7ca115f5e0..6251849fef 100644 --- a/docs/system/conf.py +++ b/docs/system/conf.py @@ -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) ] diff --git a/docs/system/cpu-models-mips.rst.inc b/docs/system/cpu-models-mips.rst.inc new file mode 100644 index 0000000000..499b5b6fed --- /dev/null +++ b/docs/system/cpu-models-mips.rst.inc @@ -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 + diff --git a/docs/system/cpu-models-x86.rst.inc b/docs/system/cpu-models-x86.rst.inc new file mode 100644 index 0000000000..cbad930c70 --- /dev/null +++ b/docs/system/cpu-models-x86.rst.inc @@ -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> diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst new file mode 100644 index 0000000000..1eaa559079 --- /dev/null +++ b/docs/system/deprecated.rst @@ -0,0 +1,446 @@ +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 diff --git a/docs/system/device-url-syntax.rst.inc b/docs/system/device-url-syntax.rst.inc new file mode 100644 index 0000000000..88d7a372a7 --- /dev/null +++ b/docs/system/device-url-syntax.rst.inc @@ -0,0 +1,228 @@ + +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 diff --git a/docs/system/gdb.rst b/docs/system/gdb.rst new file mode 100644 index 0000000000..639f814b32 --- /dev/null +++ b/docs/system/gdb.rst @@ -0,0 +1,81 @@ +.. _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" diff --git a/docs/system/images.rst b/docs/system/images.rst new file mode 100644 index 0000000000..ff26bf9587 --- /dev/null +++ b/docs/system/images.rst @@ -0,0 +1,85 @@ +.. _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 diff --git a/docs/system/index.rst b/docs/system/index.rst index 1a4b2c82ac..6e5f20fa13 100644 --- a/docs/system/index.rst +++ b/docs/system/index.rst @@ -12,7 +12,25 @@ or Hypervisor.Framework. 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 diff --git a/docs/system/invocation.rst b/docs/system/invocation.rst new file mode 100644 index 0000000000..4ba38fc23d --- /dev/null +++ b/docs/system/invocation.rst @@ -0,0 +1,18 @@ +.. _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 diff --git a/docs/system/ivshmem.rst b/docs/system/ivshmem.rst new file mode 100644 index 0000000000..b03a48afa3 --- /dev/null +++ b/docs/system/ivshmem.rst @@ -0,0 +1,64 @@ +.. _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. diff --git a/docs/system/keys.rst b/docs/system/keys.rst new file mode 100644 index 0000000000..e596ae6c4e --- /dev/null +++ b/docs/system/keys.rst @@ -0,0 +1,6 @@ +.. _pcsys_005fkeys: + +Keys in the graphical frontends +------------------------------- + +.. include:: keys.rst.inc diff --git a/docs/system/keys.rst.inc b/docs/system/keys.rst.inc new file mode 100644 index 0000000000..bd9b8e5f6f --- /dev/null +++ b/docs/system/keys.rst.inc @@ -0,0 +1,35 @@ +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. diff --git a/docs/system/license.rst b/docs/system/license.rst new file mode 100644 index 0000000000..cde3d2d25d --- /dev/null +++ b/docs/system/license.rst @@ -0,0 +1,11 @@ +.. _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>`__. diff --git a/docs/system/linuxboot.rst b/docs/system/linuxboot.rst new file mode 100644 index 0000000000..228650abc5 --- /dev/null +++ b/docs/system/linuxboot.rst @@ -0,0 +1,30 @@ +.. _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`). diff --git a/docs/system/managed-startup.rst b/docs/system/managed-startup.rst new file mode 100644 index 0000000000..9bcf98ea79 --- /dev/null +++ b/docs/system/managed-startup.rst @@ -0,0 +1,35 @@ +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`` diff --git a/docs/system/monitor.rst b/docs/system/monitor.rst new file mode 100644 index 0000000000..0bcd5da216 --- /dev/null +++ b/docs/system/monitor.rst @@ -0,0 +1,31 @@ +.. _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 *$*. diff --git a/docs/system/mux-chardev.rst b/docs/system/mux-chardev.rst new file mode 100644 index 0000000000..413a6b3446 --- /dev/null +++ b/docs/system/mux-chardev.rst @@ -0,0 +1,6 @@ +.. _mux_005fkeys: + +Keys in the character backend multiplexer +----------------------------------------- + +.. include:: mux-chardev.rst.inc diff --git a/docs/system/mux-chardev.rst.inc b/docs/system/mux-chardev.rst.inc new file mode 100644 index 0000000000..84ea12cbf5 --- /dev/null +++ b/docs/system/mux-chardev.rst.inc @@ -0,0 +1,27 @@ +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 diff --git a/docs/system/net.rst b/docs/system/net.rst new file mode 100644 index 0000000000..4b2640c448 --- /dev/null +++ b/docs/system/net.rst @@ -0,0 +1,100 @@ +.. _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. diff --git a/docs/system/qemu-block-drivers.rst b/docs/system/qemu-block-drivers.rst index 388adbefbf..bd99d4fa8e 100644 --- a/docs/system/qemu-block-drivers.rst +++ b/docs/system/qemu-block-drivers.rst @@ -1,985 +1,20 @@ +:orphan: + QEMU block drivers reference ============================ -.. |qemu_system| replace:: qemu-system-x86_64 - -.. - 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. - -.. only:: man - - Synopsis - -------- - - QEMU block driver reference manual - -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: - -:: +Synopsis +-------- - -blockdev driver=qcow2,file.filename=/path/to/image,file.locking=off,file.driver=file +QEMU block driver reference manual -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. +Description +----------- -.. only:: man +.. include:: qemu-block-drivers.rst.inc - See also - -------- +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. diff --git a/docs/system/qemu-block-drivers.rst.inc b/docs/system/qemu-block-drivers.rst.inc new file mode 100644 index 0000000000..b052a6d14e --- /dev/null +++ b/docs/system/qemu-block-drivers.rst.inc @@ -0,0 +1,954 @@ +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. diff --git a/docs/system/qemu-cpu-models.rst b/docs/system/qemu-cpu-models.rst new file mode 100644 index 0000000000..53d7538c47 --- /dev/null +++ b/docs/system/qemu-cpu-models.rst @@ -0,0 +1,20 @@ +: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. diff --git a/docs/system/qemu-manpage.rst b/docs/system/qemu-manpage.rst new file mode 100644 index 0000000000..e9a25d0680 --- /dev/null +++ b/docs/system/qemu-manpage.rst @@ -0,0 +1,45 @@ +: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. diff --git a/docs/system/quickstart.rst b/docs/system/quickstart.rst new file mode 100644 index 0000000000..3a3acab5e7 --- /dev/null +++ b/docs/system/quickstart.rst @@ -0,0 +1,13 @@ +.. _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. diff --git a/docs/security.texi b/docs/system/security.rst index 0d6b30edfc..f2092c8768 100644 --- a/docs/security.texi +++ b/docs/system/security.rst @@ -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, diff --git a/docs/system/target-arm.rst b/docs/system/target-arm.rst new file mode 100644 index 0000000000..d2a3b44ce8 --- /dev/null +++ b/docs/system/target-arm.rst @@ -0,0 +1,217 @@ +.. _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. diff --git a/docs/system/target-i386-desc.rst.inc b/docs/system/target-i386-desc.rst.inc new file mode 100644 index 0000000000..47a169e0ae --- /dev/null +++ b/docs/system/target-i386-desc.rst.inc @@ -0,0 +1,62 @@ +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 diff --git a/docs/system/target-i386.rst b/docs/system/target-i386.rst new file mode 100644 index 0000000000..51be03d881 --- /dev/null +++ b/docs/system/target-i386.rst @@ -0,0 +1,23 @@ +.. _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. diff --git a/docs/system/target-m68k.rst b/docs/system/target-m68k.rst new file mode 100644 index 0000000000..d28d3b92e5 --- /dev/null +++ b/docs/system/target-m68k.rst @@ -0,0 +1,21 @@ +.. _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. diff --git a/docs/system/target-mips.rst b/docs/system/target-mips.rst new file mode 100644 index 0000000000..2736fd0509 --- /dev/null +++ b/docs/system/target-mips.rst @@ -0,0 +1,120 @@ +.. _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" diff --git a/docs/system/target-ppc.rst b/docs/system/target-ppc.rst new file mode 100644 index 0000000000..a2f04c533c --- /dev/null +++ b/docs/system/target-ppc.rst @@ -0,0 +1,47 @@ +.. _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/. diff --git a/docs/system/target-sparc.rst b/docs/system/target-sparc.rst new file mode 100644 index 0000000000..b55f8d09e9 --- /dev/null +++ b/docs/system/target-sparc.rst @@ -0,0 +1,62 @@ +.. _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. diff --git a/docs/system/target-sparc64.rst b/docs/system/target-sparc64.rst new file mode 100644 index 0000000000..97e334b930 --- /dev/null +++ b/docs/system/target-sparc64.rst @@ -0,0 +1,37 @@ +.. _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 diff --git a/docs/system/target-xtensa.rst b/docs/system/target-xtensa.rst new file mode 100644 index 0000000000..8d703ad769 --- /dev/null +++ b/docs/system/target-xtensa.rst @@ -0,0 +1,27 @@ +.. _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 diff --git a/docs/system/targets.rst b/docs/system/targets.rst new file mode 100644 index 0000000000..eba3111247 --- /dev/null +++ b/docs/system/targets.rst @@ -0,0 +1,19 @@ +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 diff --git a/docs/system/tls.rst b/docs/system/tls.rst new file mode 100644 index 0000000000..dc2b94257f --- /dev/null +++ b/docs/system/tls.rst @@ -0,0 +1,328 @@ +.. _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=/ diff --git a/docs/system/usb.rst b/docs/system/usb.rst new file mode 100644 index 0000000000..ddfa828d74 --- /dev/null +++ b/docs/system/usb.rst @@ -0,0 +1,137 @@ +.. _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). diff --git a/docs/system/vnc-security.rst b/docs/system/vnc-security.rst new file mode 100644 index 0000000000..b237b07330 --- /dev/null +++ b/docs/system/vnc-security.rst @@ -0,0 +1,202 @@ +.. _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. diff --git a/docs/user/conf.py b/docs/user/conf.py new file mode 100644 index 0000000000..4b09aedd45 --- /dev/null +++ b/docs/user/conf.py @@ -0,0 +1,15 @@ +# -*- 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' diff --git a/docs/user/index.rst b/docs/user/index.rst new file mode 100644 index 0000000000..e030dadf65 --- /dev/null +++ b/docs/user/index.rst @@ -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 diff --git a/docs/user/main.rst b/docs/user/main.rst new file mode 100644 index 0000000000..ca69f7727d --- /dev/null +++ b/docs/user/main.rst @@ -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. |