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8b3d9314ae
Signed-off-by: Peter Krempa <pkrempa@redhat.com> Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
198 lines
6.7 KiB
ReStructuredText
198 lines
6.7 KiB
ReStructuredText
.. role:: since
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==============================
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Driver capabilities XML format
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==============================
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.. contents::
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Element and attribute overview
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------------------------------
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As new virtualization engine support gets added to libvirt, and to handle cases
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like QEMU supporting a variety of emulations, a query interface has been added
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in 0.2.1 allowing to list the set of supported virtualization capabilities on
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the host:
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::
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char * virConnectGetCapabilities (virConnectPtr conn);
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The value returned is an XML document listing the virtualization capabilities of
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the host and virtualization engine to which ```conn`` is connected. One can test
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it using ``virsh`` command line tool command '``capabilities``', it dumps the
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XML associated to the current connection.
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As can be seen in the `Examples`_, the capabilities XML
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consists of the ``capabilities`` element which have exactly one ``host`` child
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element to report information on host capabilities, and zero or more ``guest``
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element to express the set of architectures the host can run at the moment.
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Host capabilities
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~~~~~~~~~~~~~~~~~
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The ``<host/>`` element consists of the following child elements:
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``uuid``
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The host UUID.
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``cpu``
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The host CPU architecture and features.
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``power_management``
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whether host is capable of memory suspend, disk hibernation, or hybrid
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suspend.
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``migration_features``
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This element exposes information on the hypervisor's migration capabilities,
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like live migration, supported URI transports, and so on.
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``topology``
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This element embodies the host internal topology. Management applications may
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want to learn this information when orchestrating new guests - e.g. due to
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reduce inter-NUMA node transfers. Note that the ``sockets`` value reported
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here is per-NUMA-node; this is in contrast to the value given in domain
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definitions, which is interpreted as a total number of sockets for the
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domain.
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``secmodel``
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To find out default security labels for different security models you need to
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parse this element. In contrast with the former elements, this is repeated
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for each security model the libvirt daemon currently supports.
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Guest capabilities
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~~~~~~~~~~~~~~~~~~
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While the previous section (`Host capabilities`_) aims at host capabilities,
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this one focuses on capabilities available to a guest using a given hypervisor.
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The ``<guest/>`` element will typically wrap up the following elements:
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``os_type``
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This expresses what kind of operating system the hypervisor is able to run.
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Possible values are:
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``xen``
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for XEN PV
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``linux``
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legacy alias for ``xen``
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``xenpvh``
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for XEN PVH
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``hvm``
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Unmodified operating system
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``exe``
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Container based virtualization
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``arch``
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This element brings some information on supported guest architecture.
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Possible subelements are:
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``wordsize``
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Size of CPU word in bits, for example 64.
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``emulator``
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Emulator (device model) path, for use in
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`emulator <formatdomain.html#elementEmulator>`__ element of domain XML.
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``loader``
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Loader path, for use in `loader <formatdomain.html#elementLoader>`__
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element of domain XML.
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``machine``
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Machine type, for use in
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`machine <formatdomain.html#attributeOSTypeMachine>`__ attribute of
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os/type element in domain XML. For example Xen supports ``xenfv`` for HVM,
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``xenpv`` for PV, or ``xenpvh`` for PVH.
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``domain``
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The ``type`` attribute of this element specifies the type of hypervisor
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required to run the domain. Use in
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`type <formatdomain.html#attributeDomainType>`__ attribute of the domain
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root element.
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``features``
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This optional element encases possible features that can be used with a guest
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of described type. Possible subelements are:
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``pae``
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If present, 32-bit guests can use PAE address space extensions,
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:since:`since 0.4.1`
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``nonpae``
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If present, 32-bit guests can be run without requiring PAE, :since:`since
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0.4.1`
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``ia64_be``
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If present, IA64 guests can be run in big-endian mode, :since:`since
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0.4.1`
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``acpi``
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If this element is present, the ``default`` attribute describes whether
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the hypervisor exposes ACPI to the guest by default, and the ``toggle``
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attribute describes whether the user can override this default.
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:since:`Since 0.4.1`
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``apic``
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If this element is present, the ``default`` attribute describes whether
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the hypervisor exposes APIC to the guest by default, and the ``toggle``
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attribute describes whether the user can override this default.
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:since:`Since 0.4.1`
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``cpuselection``
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If this element is present, the hypervisor supports the ``<cpu>`` element
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within a domain definition for fine-grained control over the CPU presented
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to the guest. :since:`Since 0.7.5`
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``deviceboot``
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If this element is present, the ``<boot order='...'/>`` element can be
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used inside devices, rather than the older boot specification by category.
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:since:`Since 0.8.8`
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``disksnapshot``
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If this element is present, the ``default`` attribute describes whether
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external disk snapshots are supported. If absent, external snapshots may
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still be supported, but it requires attempting the API and checking for an
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error to find out for sure. :since:`Since 1.2.3`
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Examples
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~~~~~~~~
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For example, in the case of a 64-bit machine with hardware virtualization
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capabilities enabled in the chip and BIOS you will see:
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::
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<capabilities>
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<host>
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<cpu>
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<arch>x86_64</arch>
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<features>
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<vmx/>
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</features>
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<model>core2duo</model>
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<vendor>Intel</vendor>
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<topology sockets="1" dies="1" cores="2" threads="1"/>
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<feature name="lahf_lm"/>
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<feature name='xtpr'/>
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...
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</cpu>
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<power_management>
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<suspend_mem/>
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<suspend_disk/>
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<suspend_hybrid/>
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</power_management>
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</host>
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<!-- xen-3.0-x86_64 -->
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<guest>
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<os_type>xen</os_type>
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<arch name="x86_64">
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<wordsize>64</wordsize>
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<domain type="xen"></domain>
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<emulator>/usr/lib64/xen/bin/qemu-dm</emulator>
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</arch>
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<features>
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</features>
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</guest>
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<!-- hvm-3.0-x86_32 -->
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<guest>
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<os_type>hvm</os_type>
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<arch name="i686">
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<wordsize>32</wordsize>
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<domain type="xen"></domain>
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<emulator>/usr/lib/xen/bin/qemu-dm</emulator>
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<machine>pc</machine>
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<machine>isapc</machine>
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<loader>/usr/lib/xen/boot/hvmloader</loader>
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</arch>
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<features>
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<cpuselection/>
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<deviceboot/>
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</features>
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</guest>
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...
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</capabilities>
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