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< html >
< body >
< h1 > Domain XML format< / h1 >
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< ul id = "toc" > < / ul >
< p >
This section describes the XML format used to represent domains, there are
variations on the format based on the kind of domains run and the options
used to launch them. For hypervisor specific details consult the
< a href = "drivers.html" > driver docs< / a >
< / p >
< h2 > < a name = "elements" > Element and attribute overview< / a > < / h2 >
< p >
The root element required for all virtual machines is
named < code > domain< / code > . It has two attributes, the
< code > type< / code > specifies the hypervisor used for running
the domain. The allowed values are driver specific, but
include "xen", "kvm", "qemu", "lxc" and "kqemu". The
second attribute is < code > id< / code > which is a unique
integer identifier for the running guest machine. Inactive
machines have no id value.
< / p >
< h3 > < a name = "elementsMetadata" > General metadata< / a > < / h3 >
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< pre >
< domain type='xen' id='3'>
< name> fv0< /name>
< uuid> 4dea22b31d52d8f32516782e98ab3fa0< /uuid>
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< description> Some human readable description< /description>
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...< / pre >
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< dl >
< dt > < code > name< / code > < / dt >
< dd > The content of the < code > name< / code > element provides
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a short name for the virtual machine. This name should
consist only of alpha-numeric characters and is required
to be unique within the scope of a single host. It is
often used to form the filename for storing the persistent
configuration file. < span class = "since" > Since 0.0.1< / span > < / dd >
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< dt > < code > uuid< / code > < / dt >
< dd > The content of the < code > uuid< / code > element provides
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a globally unique identifier for the virtual machine.
The format must be RFC 4122 compliant, eg < code > 3e3fce45-4f53-4fa7-bb32-11f34168b82b< / code > .
If omitted when defining/creating a new machine, a random
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UUID is generated. It is also possible to provide the UUID
via a < a href = "#elementsSysinfo" > < code > sysinfo< / code > < / a >
specification. < span class = "since" > Since 0.0.1, sysinfo
since 0.8.7< / span > < / dd >
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< dt > < code > description< / code > < / dt >
< dd > The content of the < code > description< / code > element provides a
human readable description of the virtual machine. This data is not
used by libvirt in any way, it can contain any information the user
wants. < span class = "since" > Since 0.7.2< / span > < / dd >
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< / dl >
< h3 > < a name = "elementsOS" > Operating system booting< / a > < / h3 >
< p >
There are a number of different ways to boot virtual machines
each with their own pros and cons.
< / p >
< h4 > < a name = "elementsOSBIOS" > BIOS bootloader< / a > < / h4 >
< p >
Booting via the BIOS is available for hypervisors supporting
full virtualization. In this case the BIOS has a boot order
priority (floppy, harddisk, cdrom, network) determining where
to obtain/find the boot image.
< / p >
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< pre >
...
< os>
< type> hvm< /type>
< loader> /usr/lib/xen/boot/hvmloader< /loader>
< boot dev='hd'/>
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< boot dev='cdrom'/>
< bootmenu enable='yes'/>
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< smbios mode='sysinfo'/>
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< /os>
...< / pre >
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< dl >
< dt > < code > type< / code > < / dt >
< dd > The content of the < code > type< / code > element specifies the
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type of operating system to be booted in the virtual machine.
< code > hvm< / code > indicates that the OS is one designed to run
on bare metal, so requires full virtualization. < code > linux< / code >
(badly named!) refers to an OS that supports the Xen 3 hypervisor
guest ABI. There are also two optional attributes, < code > arch< / code >
specifying the CPU architecture to virtualization, and < code > machine< / code >
referring to the machine type. The < a href = "formatcaps.html" > Capabilities XML< / a >
provides details on allowed values for these. < span class = "since" > Since 0.0.1< / span > < / dd >
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< dt > < code > loader< / code > < / dt >
< dd > The optional < code > loader< / code > tag refers to a firmware blob
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used to assist the domain creation process. At this time, it is
only needed by Xen fully virtualized domains. < span class = "since" > Since 0.1.0< / span > < / dd >
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< dt > < code > boot< / code > < / dt >
< dd > The < code > dev< / code > attribute takes one of the values "fd", "hd",
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"cdrom" or "network" and is used to specify the next boot device
to consider. The < code > boot< / code > element can be repeated multiple
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times to setup a priority list of boot devices to try in turn. The
< code > boot< / code > element cannot be used if per-device boot elements
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are used (see < a href = "#elementsDisks" > disks< / a > ,
< a href = "#elementsNICS" > network interfaces< / a > , and
< a href = "#elementsUSB" > USB and PCI devices< / a > sections below).
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< span class = "since" > Since 0.1.3, per-device boot since 0.8.8< / span >
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< / dd >
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< dt > < code > bootmenu< / code > < / dt >
< dd > Whether or not to enable an interactive boot menu prompt on guest
startup. The < code > enable< / code > attribute can be either "yes" or "no".
If not specified, the hypervisor default is used. < span class = "since" >
Since 0.8.3< / span >
< / dd >
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< dt > < code > smbios< / code > < / dt >
< dd > How to populate SMBIOS information visible in the guest.
The < code > mode< / code > attribute must be specified, and is either
"emulate" (let the hypervisor generate all values), "host" (copy
all of Block 0 and Block 1, except for the UUID, from the host's
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SMBIOS values;
the < a href = "html/libvirt-libvirt.html#virConnectGetSysinfo" >
< code > virConnectGetSysinfo< / code > < / a > call can be
used to see what values are copied), or "sysinfo" (use the values in
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the < a href = "#elementsSysinfo" > sysinfo< / a > element). If not
specified, the hypervisor default is used. < span class = "since" >
Since 0.8.7< / span >
< / dd >
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< / dl >
< h4 > < a name = "elementsOSBootloader" > Host bootloader< / a > < / h4 >
< p >
Hypervisors employing paravirtualization do not usually emulate
a BIOS, and instead the host is responsible to kicking off the
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operating system boot. This may use a pseudo-bootloader in the
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host to provide an interface to choose a kernel for the guest.
An example is < code > pygrub< / code > with Xen.
< / p >
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< pre >
...
< bootloader> /usr/bin/pygrub< /bootloader>
< bootloader_args> --append single< /bootloader_args>
...< / pre >
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< dl >
< dt > < code > bootloader< / code > < / dt >
< dd > The content of the < code > bootloader< / code > element provides
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a fully qualified path to the bootloader executable in the
host OS. This bootloader will be run to choose which kernel
to boot. The required output of the bootloader is dependent
on the hypervisor in use. < span class = "since" > Since 0.1.0< / span > < / dd >
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< dt > < code > bootloader_args< / code > < / dt >
< dd > The optional < code > bootloader_args< / code > element allows
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command line arguments to be passed to the bootloader.
< span class = "since" > Since 0.2.3< / span >
< / dd >
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< / dl >
< h4 > < a name = "elementsOSKernel" > Direct kernel boot< / a > < / h4 >
< p >
When installing a new guest OS it is often useful to boot directly
from a kernel and initrd stored in the host OS, allowing command
line arguments to be passed directly to the installer. This capability
is usually available for both para and full virtualized guests.
< / p >
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< pre >
...
< os>
< type> hvm< /type>
< loader> /usr/lib/xen/boot/hvmloader< /loader>
< kernel> /root/f8-i386-vmlinuz< /kernel>
< initrd> /root/f8-i386-initrd< /initrd>
< cmdline> console=ttyS0 ks=http://example.com/f8-i386/os/< /cmdline>
< /os>
...< / pre >
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< dl >
< dt > < code > type< / code > < / dt >
< dd > This element has the same semantics as described earlier in the
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< a href = "#elementsOSBIOS" > BIOS boot section< / a > < / dd >
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< dt > < code > loader< / code > < / dt >
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< dd > This element has the same semantics as described earlier in the
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< a href = "#elementsOSBIOS" > BIOS boot section< / a > < / dd >
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< dt > < code > kernel< / code > < / dt >
< dd > The contents of this element specify the fully-qualified path
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to the kernel image in the host OS.< / dd >
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< dt > < code > initrd< / code > < / dt >
< dd > The contents of this element specify the fully-qualified path
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to the (optional) ramdisk image in the host OS.< / dd >
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< dt > < code > cmdline< / code > < / dt >
< dd > The contents of this element specify arguments to be passed to
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the kernel (or installer) at boottime. This is often used to
specify an alternate primary console (eg serial port), or the
installation media source / kickstart file< / dd >
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< / dl >
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< h3 > < a name = "elementsSysinfo" > SMBIOS System Information< / a > < / h3 >
< p >
Some hypervisors allow control over what system information is
presented to the guest (for example, SMBIOS fields can be
populated by a hypervisor and inspected via
the < code > dmidecode< / code > command in the guest). The
optional < code > sysinfo< / code > element covers all such categories
of information. < span class = "since" > Since 0.8.7< / span >
< / p >
< pre >
...
< os>
< smbios mode='sysinfo'/>
...
< /os>
< sysinfo type='smbios'>
< bios>
< entry name='vendor'> LENOVO< /entry>
< /bios>
< system>
< entry name='manufacturer'> Fedora< /entry>
< entry name='vendor'> Virt-Manager< /entry>
< /system>
< /sysinfo>
...< / pre >
< p >
The < code > sysinfo< / code > element has a mandatory
attribute < code > type< / code > that determine the layout of
sub-elements, with supported values of:
< / p >
< dl >
< dt > < code > smbios< / code > < / dt >
< dd > Sub-elements call out specific SMBIOS values, which will
affect the guest if used in conjunction with
the < code > smbios< / code > sub-element of
the < a href = "#elementsOS" > < code > os< / code > < / a > element. Each
sub-element of < code > sysinfo< / code > names a SMBIOS block, and
within those elements can be a list of < code > entry< / code >
elements that describe a field within the block. The following
blocks and entries are recognized:
< dl >
< dt > < code > bios< / code > < / dt >
< dd >
This is block 0 of SMBIOS, with entry names drawn from
"vendor", "version", "date", and "release".
< / dd >
< dt > < code > system< / code > < / dt >
< dd >
This is block 1 of SMBIOS, with entry names drawn from
"manufacturer", "product", "version", "serial", "uuid",
"sku", and "family". If a "uuid" entry is provided
alongside a
top-level < a href = "#elementsMetadata" > < code > uuid< / code >
element< / a > , the two values must match.
< / dd >
< / dl >
< / dd >
< / dl >
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< h3 > < a name = "elementsResources" > Basic resources< / a > < / h3 >
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< pre >
...
< memory> 524288< /memory>
< currentMemory> 524288< /currentMemory>
< memoryBacking>
< hugepages/>
< /memoryBacking>
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< blkiotune>
< weight> 800< /weight>
< /blkiotune>
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< memtune>
< hard_limit> 1048576< /hard_limit>
< soft_limit> 131072< /soft_limit>
< swap_hard_limit> 2097152< /swap_hard_limit>
< min_guarantee> 65536< /min_guarantee>
< /memtune>
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< vcpu cpuset="1-4,^3,6" current="1"> 2< /vcpu>
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< cputune>
< vcpupin vcpu="0" cpuset="1-4,^2">
< vcpupin vcpu="1" cpuset="0,1">
< vcpupin vcpu="2" cpuset="2,3">
< vcpupin vcpu="3" cpuset="0,4">
< cpushares> 2048< /cpushares>
< /cputune>
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...< / pre >
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< dl >
< dt > < code > memory< / code > < / dt >
< dd > The maximum allocation of memory for the guest at boot time.
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The units for this value are kilobytes (i.e. blocks of 1024 bytes)< / dd >
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< dt > < code > currentMemory< / code > < / dt >
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< dd > The actual allocation of memory for the guest. This value can
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be less than the maximum allocation, to allow for ballooning
up the guests memory on the fly. If this is omitted, it defaults
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to the same value as the < code > memory< / code > element< / dd >
Support configuration of huge pages in guests
Add option to domain XML for
<memoryBacking>
<hugepages/>
</memoryBacking>
* configure.in: Add check for mntent.h
* qemud/libvirtd_qemu.aug, qemud/test_libvirtd_qemu.aug, src/qemu.conf
Add 'hugetlbfs_mount' config parameter
* src/qemu_conf.c, src/qemu_conf.h: Check for -mem-path flag in QEMU,
and pass it when hugepages are requested.
Load hugetlbfs_mount config parameter, search for mount if not given.
* src/qemu_driver.c: Free hugetlbfs_mount/path parameter in driver shutdown.
Create directory for QEMU hugepage usage, chowning if required.
* docs/formatdomain.html.in: Document memoryBacking/hugepages elements
* docs/schemas/domain.rng: Add memoryBacking/hugepages elements to schema
* src/util.c, src/util.h, src/libvirt_private.syms: Add virFileFindMountPoint
helper API
* tests/qemuhelptest.c: Add -mem-path constants
* tests/qemuxml2argvtest.c, tests/qemuxml2xmltest.c: Add tests for hugepage
handling
* tests/qemuxml2argvdata/qemuxml2argv-hugepages.xml,
tests/qemuxml2argvdata/qemuxml2argv-hugepages.args: Data files for
hugepage tests
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< dt > < code > memoryBacking< / code > < / dt >
< dd > The optional < code > memoryBacking< / code > element, may have an
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< code > hugepages< / code > element set within it. This tells the
hypervisor that the guest should have its memory allocated using
hugepages instead of the normal native page size.< / dd >
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< dt > < code > blkiotune< / code > < / dt >
< dd > The optional < code > blkiotune< / code > element provides the ability
to tune Blkio cgroup tunable parameters for the domain. If this is
omitted, it defaults to the OS provided defaults.< / dd >
< dt > < code > weight< / code > < / dt >
< dd > The optional < code > weight< / code > element is the I/O weight of the
guest. The value should be in range [100, 1000].< / dd >
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< dt > < code > memtune< / code > < / dt >
< dd > The optional < code > memtune< / code > element provides details
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regarding the memory tunable parameters for the domain. If this is
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omitted, it defaults to the OS provided defaults. For QEMU/KVM, the
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parameters are applied to the QEMU process as a whole. Thus, when
counting them, one needs to add up guest RAM, guest video RAM, and
some memory overhead of QEMU itself. The last piece is hard to
determine so one needs guess and try.< / dd >
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< dt > < code > hard_limit< / code > < / dt >
< dd > The optional < code > hard_limit< / code > element is the maximum memory
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the guest can use. The units for this value are kilobytes (i.e. blocks
of 1024 bytes)< / dd >
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< dt > < code > soft_limit< / code > < / dt >
< dd > The optional < code > soft_limit< / code > element is the memory limit to
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enforce during memory contention. The units for this value are
kilobytes (i.e. blocks of 1024 bytes)< / dd >
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< dt > < code > swap_hard_limit< / code > < / dt >
< dd > The optional < code > swap_hard_limit< / code > element is the maximum
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memory plus swap the guest can use. The units for this value are
kilobytes (i.e. blocks of 1024 bytes). This has to be more than
hard_limit value provided< / dd >
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< dt > < code > min_guarantee< / code > < / dt >
< dd > The optional < code > min_guarantee< / code > element is the guaranteed
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minimum memory allocation for the guest. The units for this value are
kilobytes (i.e. blocks of 1024 bytes)< / dd >
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< dt > < code > vcpu< / code > < / dt >
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< dd > The content of this element defines the maximum number of virtual
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CPUs allocated for the guest OS, which must be between 1 and
the maximum supported by the hypervisor. < span class = "since" > Since
0.4.4< / span > , this element can contain an optional
< code > cpuset< / code > attribute, which is a comma-separated
list of physical CPU numbers that virtual CPUs can be pinned
to. Each element in that list is either a single CPU number,
a range of CPU numbers, or a caret followed by a CPU number to
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be excluded from a previous range. < span class = "since" > Since
0.8.5< / span > , the optional attribute < code > current< / code > can
be used to specify whether fewer than the maximum number of
virtual CPUs should be enabled.
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< / dd >
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< dt > < code > cputune< / code > < / dt >
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< dd >
The optional < code > cputune< / code > element provides details
regarding the cpu tunable parameters for the domain.
< span class = "since" > Since 0.9.0< / span >
< / dd >
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< dt > < code > vcpupin< / code > < / dt >
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< dd >
The optional < code > vcpupin< / code > element specifies which of host
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physical CPUS the domain VCPU will be pinned to. If this is ommited,
each VCPU pinned to all the physical CPUS by default. It contains two
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required attributes, the attribute < code > vcpu< / code > specifies vcpu id,
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and the attribute < code > cpuset< / code > is same as attribute < code > cpuset< / code >
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of element < code > vcpu< / code > . (NB: Only qemu driver support)
< span class = "since" > Since 0.9.0< / span >
< / dd >
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< dt > < code > shares< / code > < / dt >
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< dd >
The optional < code > shares< / code > element specifies the proportional
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weighted share for the domain. If this is ommited, it defaults to
the OS provided defaults. NB, There is no unit for the value, it's a relative
measure based on the setting of other VM, e.g. A VM configured with value
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2048 will get twice as much CPU time as a VM configured with value 1024.
< span class = "since" > Since 0.9.0< / span >
< / dd >
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< / dl >
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< h3 > < a name = "elementsCPU" > CPU model and topology< / a > < / h3 >
< p >
Requirements for CPU model, its features and topology can be specified
using the following collection of elements.
< span class = "since" > Since 0.7.5< / span >
< / p >
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< pre >
...
< cpu match='exact'>
< model> core2duo< /model>
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< vendor> Intel< /vendor>
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< topology sockets='1' cores='2' threads='1'/>
< feature policy='disable' name='lahf_lm'/>
< /cpu>
...< / pre >
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< p >
In case no restrictions need to be put on CPU model and its features, a
simpler < code > cpu< / code > element can be used.
< span class = "since" > Since 0.7.6< / span >
< / p >
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< pre >
...
< cpu>
< topology sockets='1' cores='2' threads='1'/>
< /cpu>
...< / pre >
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< dl >
< dt > < code > cpu< / code > < / dt >
< dd > The < code > cpu< / code > element is the main container for describing
guest CPU requirements. Its < code > match< / code > attribute specified how
strictly has the virtual CPU provided to the guest match these
requirements. < span class = "since" > Since 0.7.6< / span > the
< code > match< / code > attribute can be omitted if < code > topology< / code >
is the only element within < code > cpu< / code > . Possible values for the
< code > match< / code > attribute are:
< dl >
< dt > < code > minimum< / code > < / dt >
< dd > The specified CPU model and features describes the minimum
requested CPU.< / dd >
< dt > < code > exact< / code > < / dt >
< dd > The virtual CPU provided to the guest will exactly match the
specification< / dd >
< dt > < code > strict< / code > < / dt >
< dd > The guest will not be created unless the host CPU does exactly
match the specification.< / dd >
< / dl >
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< span class = "since" > Since 0.8.5< / span > the < code > match< / code >
attribute can be omitted and will default to < code > exact< / code > .
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< / dd >
< dt > < code > model< / code > < / dt >
< dd > The content of the < code > model< / code > element specifies CPU model
requested by the guest. The list of available CPU models and their
definition can be found in < code > cpu_map.xml< / code > file installed
in libvirt's data directory.< / dd >
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< dt > < code > vendor< / code > < / dt >
< dd > < span class = "since" > Since 0.8.3< / span > the content of the
< code > vendor< / code > element specifies CPU vendor requested by the
guest. If this element is missing, the guest can be run on a CPU
matching given features regardless on its vendor. The list of
supported vendors can be found in < code > cpu_map.xml< / code > .< / dd >
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< dt > < code > topology< / code > < / dt >
< dd > The < code > topology< / code > element specifies requested topology of
virtual CPU provided to the guest. Three non-zero values have to be
given for < code > sockets< / code > , < code > cores< / code > , and
< code > threads< / code > : total number of CPU sockets, number of cores per
socket, and number of threads per core, respectively.< / dd >
< dt > < code > feature< / code > < / dt >
< dd > The < code > cpu< / code > element can contain zero or more
< code > elements< / code > used to fine-tune features provided by the
selected CPU model. The list of known feature names can be found in
the same file as CPU models. The meaning of each < code > feature< / code >
element depends on its < code > policy< / code > attribute, which has to be
set to one of the following values:
< dl >
< dt > < code > force< / code > < / dt >
< dd > The virtual CPU will claim the feature is supported regardless
of it being supported by host CPU.< / dd >
< dt > < code > require< / code > < / dt >
< dd > Guest creation will fail unless the feature is supported by host
CPU.< / dd >
< dt > < code > optional< / code > < / dt >
< dd > The feature will be supported by virtual CPU if and only if it
is supported by host CPU.< / dd >
< dt > < code > disable< / code > < / dt >
< dd > The feature will not be supported by virtual CPU.< / dd >
< dt > < code > forbid< / code > < / dt >
< dd > Guest creation will fail if the feature is supported by host
CPU.< / dd >
< / dl >
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< span class = "since" > Since 0.8.5< / span > the < code > policy< / code >
attribute can be omitted and will default to < code > require< / code > .
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< / dd >
< / dl >
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< h3 > < a name = "elementsLifecycle" > Lifecycle control< / a > < / h3 >
< p >
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It is sometimes necessary to override the default actions taken
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when a guest OS triggers a lifecycle operation. The following
collections of elements allow the actions to be specified. A
common use case is to force a reboot to be treated as a poweroff
when doing the initial OS installation. This allows the VM to be
re-configured for the first post-install bootup.
< / p >
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< pre >
...
< on_poweroff> destroy< /on_poweroff>
< on_reboot> restart< /on_reboot>
< on_crash> restart< /on_crash>
...< / pre >
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< dl >
< dt > < code > on_poweroff< / code > < / dt >
< dd > The content of this element specifies the action to take when
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the guest requests a poweroff.< / dd >
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< dt > < code > on_reboot< / code > < / dt >
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< dd > The content of this element specifies the action to take when
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the guest requests a reboot.< / dd >
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< dt > < code > on_crash< / code > < / dt >
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< dd > The content of this element specifies the action to take when
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the guest crashes.< / dd >
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< / dl >
< p >
Each of these states allow for the same four possible actions.
< / p >
< dl >
< dt > < code > destroy< / code > < / dt >
< dd > The domain will be terminated completely and all resources
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released< / dd >
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< dt > < code > restart< / code > < / dt >
< dd > The domain will be terminated, and then restarted with
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the same configuration< / dd >
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< dt > < code > preserve< / code > < / dt >
< dd > The domain will be terminated, and its resource preserved
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to allow analysis.< / dd >
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< dt > < code > rename-restart< / code > < / dt >
< dd > The domain will be terminated, and then restarted with
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a new name< / dd >
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< / dl >
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< p >
on_crash supports these additional
actions < span class = "since" > since 0.8.4< / span > .
< / p >
< dl >
< dt > < code > coredump-destroy< / code > < / dt >
< dd > The crashed domain's core will be dumped, and then the
domain will be terminated completely and all resources
released< / dd >
< dt > < code > coredump-restart< / code > < / dt >
< dd > The crashed domain's core will be dumped, and then the
domain will be restarted with the same configuration< / dd >
< / dl >
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< h3 > < a name = "elementsFeatures" > Hypervisor features< / a > < / h3 >
< p >
Hypervisors may allow certain CPU / machine features to be
toggled on/off.
< / p >
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< pre >
...
< features>
< pae/>
< acpi/>
< apic/>
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< hap/>
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< /features>
...< / pre >
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< p >
All features are listed within the < code > features< / code >
element, omitting a togglable feature tag turns it off.
The available features can be found by asking
for the < a href = "formatcaps.html" > capabilities XML< / a > ,
but a common set for fully virtualized domains are:
< / p >
< dl >
< dt > < code > pae< / code > < / dt >
< dd > Physical address extension mode allows 32-bit guests
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to address more than 4 GB of memory.< / dd >
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< dt > < code > acpi< / code > < / dt >
< dd > ACPI is useful for power management, for example, with
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KVM guests it is required for graceful shutdown to work.
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< / dd >
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< dt > < code > hap< / code > < / dt >
< dd > Enable use of Hardware Assisted Paging if available in
the hardware.
< / dd >
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< / dl >
< h3 > < a name = "elementsTime" > Time keeping< / a > < / h3 >
< p >
The guest clock is typically initialized from the host clock.
Most operating systems expect the hardware clock to be kept
in UTC, and this is the default. Windows, however, expects
it to be in so called 'localtime'.
< / p >
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< pre >
...
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< clock offset="localtime">
< timer name="rtc" tickpolicy="catchup" track="guest">
< catchup threshold=123 slew=120 limit=10000/>
< /timer>
< timer name="pit" tickpolicy="none"/>
< /clock>
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...< / pre >
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< dl >
< dt > < code > clock< / code > < / dt >
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< dd >
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< p > The < code > offset< / code > attribute takes four possible
values, allowing fine grained control over how the guest
clock is synchronized to the host. NB, not all hypervisors
support all modes.< / p >
< dl >
< dt > < code > utc< / code > < / dt >
< dd >
The guest clock will always be synchronized to UTC when
booted< / dd >
< dt > < code > localtime< / code > < / dt >
< dd >
The guest clock will be synchronized to the host's configured
timezone when booted, if any.
< / dd >
< dt > < code > timezone< / code > < / dt >
< dd >
The guest clock will be synchronized to the requested timezone
using the < code > timezone< / code > attribute.
< span class = "since" > Since 0.7.7< / span >
< / dd >
< dt > < code > variable< / code > < / dt >
< dd >
The guest clock will have an arbitrary offset applied
relative to UTC. The delta relative to UTC is specified
in seconds, using the < code > adjustment< / code > attribute.
The guest is free to adjust the RTC over time an expect
that it will be honoured at next reboot. This is in
contrast to 'utc' mode, where the RTC adjustments are
lost at each reboot. < span class = "since" > Since 0.7.7< / span >
< / dd >
< / dl >
< p >
A < code > clock< / code > may have zero or more
< code > timer< / code > sub-elements. < span class = "since" > Since
0.8.0< / span >
< / p >
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< / dd >
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< dt > < code > timer< / code > < / dt >
< dd >
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< p >
Each timer element requires a < code > name< / code > attribute,
and has other optional attributes that depend on
the < code > name< / code > specified. Various hypervisors
support different combinations of attributes.
< / p >
< dl >
< dt > < code > name< / code > < / dt >
< dd >
The < code > name< / code > attribute selects which timer is
being modified, and can be one of "platform", "pit",
"rtc", "hpet", or "tsc".
< / dd >
< dt > < code > track< / code > < / dt >
< dd >
The < code > track< / code > attribute specifies what the timer
tracks, and can be "boot", "guest", or "wall".
Only valid for < code > name="rtc"< / code >
or < code > name="platform"< / code > .
< / dd >
< dt > < code > tickpolicy< / code > < / dt >
< dd >
The < code > tickpolicy< / code > attribute determines how
missed ticks in the guest are handled, and can be "delay",
"catchup", "merge", or "discard". If the policy is
"catchup", there can be further details in
the < code > catchup< / code > sub-element.
< dl >
< dt > < code > catchup< / code > < / dt >
< dd >
The < code > catchup< / code > element has three optional
attributes, each a positive integer. The attributes
are < code > threshold< / code > , < code > slew< / code > ,
and < code > limit< / code > .
< / dd >
< / dl >
< / dd >
< dt > < code > frequency< / code > < / dt >
< dd >
The < code > frequency< / code > attribute is an unsigned
integer specifying the frequency at
which < code > name="tsc"< / code > runs.
< / dd >
< dt > < code > mode< / code > < / dt >
< dd >
The < code > mode< / code > attribute controls how
the < code > name="tsc"< / code > timer is managed, and can be
"auto", "native", "emulate", "paravirt", or "smpsafe".
Other timers are always emulated.
< / dd >
< dt > < code > present< / code > < / dt >
< dd >
The < code > present< / code > attribute can be "yes" or "no" to
specify whether a particular timer is available to the guest.
< / dd >
< / dl >
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< / dd >
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< / dl >
< h3 > < a name = "elementsDevices" > Devices< / a > < / h3 >
< p >
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The final set of XML elements are all used to describe devices
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provided to the guest domain. All devices occur as children
of the main < code > devices< / code > element.
< span class = "since" > Since 0.1.3< / span >
< / p >
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< pre >
...
< devices>
< emulator> /usr/lib/xen/bin/qemu-dm< /emulator>
< /devices>
...< / pre >
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< dl >
< dt > < code > emulator< / code > < / dt >
< dd >
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The contents of the < code > emulator< / code > element specify
the fully qualified path to the device model emulator binary.
The < a href = "formatcaps.html" > capabilities XML< / a > specifies
the recommended default emulator to use for each particular
domain type / architecture combination.
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< / dd >
< / dl >
< h4 > < a name = "elementsDisks" > Hard drives, floppy disks, CDROMs< / a > < / h4 >
< p >
Any device that looks like a disk, be it a floppy, harddisk,
cdrom, or paravirtualized driver is specified via the < code > disk< / code >
element.
< / p >
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< pre >
...
< devices>
< disk type='file'>
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< driver name="tap" type="aio" cache="default"/>
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< source file='/var/lib/xen/images/fv0'/>
< target dev='hda' bus='ide'/>
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< boot order='2'/>
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< encryption type='...'>
...
< /encryption>
< shareable/>
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< serial>
...
< /serial>
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< /disk>
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...
< disk type='network'>
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< driver name="qemu" type="raw" io="threads"/>
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< source protocol="sheepdog" name="image_name">
< host name="hostname" port="7000"/>
< /source>
< target dev="hdb" bus="ide"/>
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< boot order='1'/>
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< address type='drive' controller='0' bus='1' unit='0'/>
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< /disk>
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< /devices>
...< / pre >
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< dl >
< dt > < code > disk< / code > < / dt >
< dd > The < code > disk< / code > element is the main container for describing
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disks. The < code > type< / code > attribute is either "file",
"block", "dir", or "network"
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and refers to the underlying source for the disk. The optional
< code > device< / code > attribute indicates how the disk is to be exposed
to the guest OS. Possible values for this attribute are "floppy", "disk"
and "cdrom", defaulting to "disk".
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< span class = "since" > Since 0.0.3; "device" attribute since 0.1.4;
"network" attribute since 0.8.7< / span > < / dd >
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< dt > < code > source< / code > < / dt >
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< dd > If the disk < code > type< / code > is "file", then
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the < code > file< / code > attribute specifies the fully-qualified
path to the file holding the disk. If the disk
< code > type< / code > is "block", then the < code > dev< / code >
attribute specifies the path to the host device to serve as
the disk. If the disk < code > type< / code > is "network", then
the < code > protocol< / code > attribute specifies the protocol to
access to the requested image; possible values are "nbd",
"rbd", and "sheepdog". If the < code > protocol< / code > attribute
is "rbd" or "sheepdog", an additional
attribute < code > name< / code > is mandatory to specify which
image to be used. When the disk < code > type< / code > is
"network", the < code > source< / code > may have zero or
more < code > host< / code > sub-elements used to specify the hosts
to connect.
< span class = "since" > Since 0.0.3< / span > < / dd >
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< dt > < code > target< / code > < / dt >
< dd > The < code > target< / code > element controls the bus / device under which the
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disk is exposed to the guest OS. The < code > dev< / code > attribute indicates
the "logical" device name. The actual device name specified is not guaranteed to map to
the device name in the guest OS. Treat it as a device ordering hint.
The optional < code > bus< / code > attribute specifies the type of disk device
to emulate; possible values are driver specific, with typical values being
"ide", "scsi", "virtio", "xen" or "usb". If omitted, the bus type is
inferred from the style of the device name. eg, a device named 'sda'
will typically be exported using a SCSI bus.
< span class = "since" > Since 0.0.3; < code > bus< / code > attribute since 0.4.3;
2008-08-12 11:28:28 +04:00
"usb" attribute value since after 0.4.4< / span > < / dd >
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< dt > < code > driver< / code > < / dt >
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< dd >
The optional driver element allows specifying further details
related to the hypervisor driver used to provide the disk.
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< span class = "since" > Since 0.1.8< / span >
2010-04-21 18:28:21 +04:00
< ul >
< li >
If the hypervisor supports multiple backend drivers, then
the < code > name< / code > attribute selects the primary
backend driver name, while the optional < code > type< / code >
attribute provides the sub-type. For example, xen
supports a name of "tap", "tap2", "phy", or "file", with a
type of "aio", while qemu only supports a name of "qemu",
but multiple types including "raw", "bochs", "qcow2", and
"qed".
< / li >
< li >
The optional < code > cache< / code > attribute controls the
cache mechanism, possible values are "default", "none",
"writethrough" and "writeback".
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< span class = "since" > Since 0.6.0< / span >
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< / li >
< li >
The optional < code > error_policy< / code > attribute controls
how the hypervisor will behave on an error, possible
values are "stop", "ignore", and "enospace".
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< span class = "since" > Since 0.8.0< / span >
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< / li >
< li >
The optional < code > io< / code > attribute controls specific
policies on I/O; qemu guests support "threads" and
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"native". < span class = "since" > Since 0.8.8< / span >
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< / li >
< / ul >
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< / dd >
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< dt > < code > boot< / code > < / dt >
< dd > Specifies that the disk is bootable. The < code > order< / code >
attribute determines the order in which devices will be tried during
boot sequence. The per-device < code > boot< / code > elements cannot be
used together with general boot elements in
< a href = "#elementsOSBIOS" > BIOS bootloader< / a > section.
< span class = "since" > Since 0.8.8< / span >
< / dd >
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< dt > < code > encryption< / code > < / dt >
< dd > If present, specifies how the volume is encrypted. See
the < a href = "formatstorageencryption.html" > Storage Encryption< / a > page
for more information.
< / dd >
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< dt > < code > shareable< / code > < / dt >
< dd > If present, this indicates the device is expected to be shared
between domains (assuming the hypervisor and OS support this),
which means that caching should be deactivated for that device.
< / dd >
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< dt > < code > serial< / code > < / dt >
< dd > If present, this specify serial number of virtual hard drive.
For example, it may look as < code > < serial> WD-WMAP9A966149< /serial> < / code > .
< span class = "since" > Since 0.7.1< / span >
< / dd >
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< dt > < code > host< / code > < / dt >
< dd > The < code > host< / code > element has two attributes "name" and "port",
which specify the hostname and the port number. The meaning of this
element and the number of the elements depend on the protocol attribute.
< table class = "top_table" >
< tr >
< th > Protocol < / th >
< th > Meaning < / th >
< th > Number of hosts < / th >
< / tr >
< tr >
< td > nbd < / td >
< td > a server running nbd-server < / td >
< td > only one < / td >
< / tr >
< tr >
< td > rbd < / td >
< td > monitor servers of RBD < / td >
< td > one or more < / td >
< / tr >
< tr >
< td > sheepdog < / td >
< td > one of the sheepdog servers (default is localhost:7000) < / td >
< td > zero or one < / td >
< / tr >
< / table >
< / dd >
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< dt > < code > address< / code > < / dt >
< dd > If present, the < code > address< / code > element ties the disk
to a given slot of a controller (the
actual < code > < controller> < / code > device can often be
inferred by libvirt, although it can
be < a href = "#elementsControllers" > explicitly specified< / a > ).
The < code > type< / code > attribute is mandatory, and is typically
"pci" or "drive". For a "pci" controller, additional
attributes for < code > bus< / code > , < code > slot< / code > ,
and < code > function< / code > must be present, as well as an
optional < code > domain< / code > . For a "drive" controller,
additional attributes < code > controller< / code > , < code > bus< / code > ,
and < code > unit< / code > are available, each defaulting to 0.
< / dd >
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< / dl >
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< h4 > < a name = "elementsFilesystems" > Filesystems< / a > < / h4 >
< p >
A directory on the host that can be accessed directly from the guest.
< span class = "since" > since 0.3.3, since 0.8.5 for QEMU/KVM< / span >
< / p >
< pre >
...
< devices>
< filesystem type='template'>
< source name='my-vm-template'/>
< target dir='/'/>
< /filesystem>
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< filesystem type='mount' accessmode='passthrough'>
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< source dir='/export/to/guest'/>
< target dir='/import/from/host'/>
< readonly/>
< /filesystem>
...
< /devices>
...< / pre >
< dl >
< dt > < code > filesystem< / code > < / dt >
< dd >
The filesystem attribute < code > type< / code > specifies the type of the
< code > source< / code > . The possible values are:
< dl >
< dt > < code > type='mount'< / code > < / dt >
< dd >
A host directory to mount in the guest. Used by LXC,
OpenVZ < span class = "since" > (since 0.6.2)< / span >
and QEMU/KVM < span class = "since" > (since 0.8.5)< / span > .
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This is the default < code > type< / code > if one is not specified.
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< / dd >
< dt > < code > type='template'< / code > < / dt >
< dd >
OpenVZ filesystem template. Only used by OpenVZ driver.
< / dd >
< dt > < code > type='file'< / code > < / dt >
< dd >
Currently unused.
< / dd >
< dt > < code > type='block'< / code > < / dt >
< dd >
Currently unused.
< / dd >
< / dl >
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The filesystem block has an optional attribute < code > accessmode< / code >
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which specifies the security mode for accessing the source
< span class = "since" > (since 0.8.5)< / span > . Currently this only works
with < code > type='mount'< / code > for the QEMU/KVM driver. The possible
values are:
< dl >
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< dt > < code > accessmode='passthrough'< / code > < / dt >
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< dd >
The < code > source< / code > is accessed with the permissions of the
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user inside the guest. This is the default < code > accessmode< / code > if
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one is not specified.
< a href = "http://lists.gnu.org/archive/html/qemu-devel/2010-05/msg02673.html" > More info< / a >
< / dd >
2011-05-05 22:56:59 +04:00
< dt > < code > accessmode='mapped'< / code > < / dt >
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< dd >
The < code > source< / code > is accessed with the permissions of the
hypervisor (QEMU process).
< a href = "http://lists.gnu.org/archive/html/qemu-devel/2010-05/msg02673.html" > More info< / a >
< / dd >
2011-05-05 22:56:59 +04:00
< dt > < code > accessmode='squash'< / code > < / dt >
2011-04-29 21:20:28 +04:00
< dd >
Similar to 'passthrough', the exception is that failure of
privileged operations like 'chown' are ignored. This makes a
passthrough-like mode usable for people who run the hypervisor
as non-root.
< a href = "http://lists.gnu.org/archive/html/qemu-devel/2010-09/msg00121.html" > More info< / a >
< / dd >
< / dl >
< / dd >
< dt > < code > source< / code > < / dt >
< dd >
The resource on the host that is being accessed in the guest. The
< code > name< / code > attribute must be used with
< code > type='template'< / code > , and the < code > dir< / code > attribute must
be used with < code > type='mount'< / code >
< / dd >
< dt > < code > target< / code > < / dt >
< dd >
Where the < code > source< / code > can be accessed in the guest. For
most drivers this is an automatic mount point, but for QEMU/KVM
this is merely an arbitrary string tag that is exported to the
guest as a hint for where to mount.
< / dd >
< dt > < code > readonly< / code > < / dt >
< dd >
An optional < code > readonly< / code > attribute is available but currently
unused.
< / dd >
< / dl >
2011-01-18 00:33:00 +03:00
< h4 > < a name = "elementsControllers" > Controllers< / a > < / h4 >
< p >
Many devices that have an < code > < address> < / code >
sub-element are designed to work with a controller to manage
related devices. Normally, libvirt can automatically infer such
controllers without requiring explicit XML markup, but sometimes
it is necessary to provide an explicit controller element.
< / p >
< pre >
...
< devices>
< controller type='ide' index='0'/>
< controller type='virtio-serial' index='0' ports='16' vectors='4'/>
< controller type='virtio-serial' index='1'>
< address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/>
< /controller>
...
< /devices>
...< / pre >
< p >
Each controller has a mandatory attribute < code > type< / code > ,
2011-01-06 04:02:20 +03:00
which must be one of "ide", "fdc", "scsi", "sata", "ccid", or
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"virtio-serial", and a mandatory attribute < code > index< / code >
which is the decimal integer describing in which order the bus
controller is encountered (for use in < code > controller< / code >
attributes of < code > < address> < / code > elements). The
"virtio-serial" controller has two additional optional
attributes < code > ports< / code > and < code > vectors< / code > , which
control how many devices can be connected through the
controller. A "scsi" controller has an optional
attribute < code > model< / code > , which is one of "auto",
"buslogic", "lsilogic", "lsias1068", or "vmpvscsi".
< / p >
< p >
For controllers that are themselves devices on a PCI or USB bus,
an optional sub-element < code > < address> < / code > can specify
the exact relationship of the controller to its master bus, with
semantics like any other device's < code > address< / code >
sub-element.
< / p >
2009-01-12 18:09:19 +03:00
< h4 > < a name = "elementsUSB" > USB and PCI devices< / a > < / h4 >
2008-08-12 11:28:28 +04:00
< p >
2009-01-12 18:09:19 +03:00
USB and PCI devices attached to the host can be passed through to the guest using
the < code > hostdev< / code > element. < span class = "since" > since after
0.4.4 for USB and 0.6.0 for PCI (KVM only)< / span > :
2008-08-12 11:28:28 +04:00
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< hostdev mode='subsystem' type='usb'>
< source>
< vendor id='0x1234'/>
< product id='0xbeef'/>
< /source>
2011-02-03 15:06:21 +03:00
< boot order='2'/>
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< /hostdev>
< /devices>
...< / pre >
2009-01-12 18:09:19 +03:00
< p > or:< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
2011-03-01 13:23:20 +03:00
< hostdev mode='subsystem' type='pci' managed='yes'>
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< source>
< address bus='0x06' slot='0x02' function='0x0'/>
< /source>
2011-02-03 15:06:21 +03:00
< boot order='1'/>
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< /hostdev>
< /devices>
...< / pre >
2008-08-12 11:28:28 +04:00
< dl >
< dt > < code > hostdev< / code > < / dt >
< dd > The < code > hostdev< / code > element is the main container for describing
2011-03-01 13:23:20 +03:00
host devices. For usb device passthrough < code > mode< / code > is always
"subsystem" and < code > type< / code > is "usb" for a USB device and "pci"
2011-03-14 10:52:14 +03:00
for a PCI device. When < code > managed< / code > is "yes" for a PCI
2011-03-01 13:23:20 +03:00
device, it is detached from the host before being passed on to
the guest.< / dd >
2008-08-12 11:28:28 +04:00
< dt > < code > source< / code > < / dt >
< dd > The source element describes the device as seen from the host.
The USB device can either be addressed by vendor / product id using the
< code > vendor< / code > and < code > product< / code > elements or by the device's
2009-01-12 18:09:19 +03:00
address on the hosts using the < code > address< / code > element.
PCI devices on the other hand can only be described by their
< code > address< / code > < / dd >
2008-08-12 11:28:28 +04:00
< dt > < code > vendor< / code > , < code > product< / code > < / dt >
< dd > The < code > vendor< / code > and < code > product< / code > elements each have an
< code > id< / code > attribute that specifies the USB vendor and product id.
The ids can be given in decimal, hexadecimal (starting with 0x) or
octal (starting with 0) form.< / dd >
2011-02-03 15:06:21 +03:00
< dt > < code > boot< / code > < / dt >
< dd > Specifies that the device is bootable. The < code > order< / code >
attribute determines the order in which devices will be tried during
boot sequence. The per-device < code > boot< / code > elements cannot be
used together with general boot elements in
< a href = "#elementsOSBIOS" > BIOS bootloader< / a > section.
< span class = "since" > Since 0.8.8< / span > < / dd >
2008-08-12 11:28:28 +04:00
< dt > < code > address< / code > < / dt >
2009-01-12 18:09:19 +03:00
< dd > The < code > address< / code > element for USB devices has a
< code > bus< / code > and < code > device< / code > attribute to specify the
USB bus and device number the device appears at on the host.
The values of these attributes can be given in decimal, hexadecimal
(starting with 0x) or octal (starting with 0) form.
For PCI devices the element carries 3 attributes allowing to designate
the device as can be found with the < code > lspci< / code > or
with < code > virsh nodedev-list< / code > . The
< code > bus< / code > attribute allows the hexadecimal values 0 to ff, the
< code > slot< / code > attribute allows the hexadecimal values 0 to 1f, and
the < code > function< / code > attribute allows the hexadecimal values 0 to
7. There is also an optional < code > domain< / code > attribute for the
PCI domain, with hexadecimal values 0 to ffff, but it is currently
not used by qemu.< / dd >
2008-08-12 11:28:28 +04:00
< / dl >
2011-01-06 04:02:20 +03:00
< h4 > < a name = "elementsSmartcard" > Smartcard devices< / a > < / h4 >
< p >
A virtual smartcard device can be supplied to the guest via the
< code > smartcard< / code > element. A USB smartcard reader device on
the host cannot be used on a guest with simple device
passthrough, since it will then not be available on the host,
possibly locking the host computer when it is "removed".
Therefore, some hypervisors provide a specialized virtual device
that can present a smartcard interface to the guest, with
several modes for describing how credentials are obtained from
the host or even a from a channel created to a third-party
smartcard provider. < span class = "since" > Since 0.8.8< / span >
< / p >
< pre >
...
< devices>
< smartcard mode='host'/>
< smartcard mode='host-certificates'>
< certificate> cert1< /certificate>
< certificate> cert2< /certificate>
< certificate> cert3< /certificate>
< database> /etc/pki/nssdb/< /database>
< /smartcard>
< smartcard mode='passthrough' type='tcp'>
< source mode='bind' host='127.0.0.1' service='2001'/>
< protocol type='raw'/>
< address type='ccid' controller='0' slot='0'/>
< /smartcard>
2011-02-04 05:23:31 +03:00
< smartcard mode='passthrough' type='spicevmc'/>
2011-01-06 04:02:20 +03:00
< /devices>
...
< / pre >
< p >
The < code > < smartcard> < / code > element has a mandatory
attribute < code > mode< / code > . The following modes are supported;
in each mode, the guest sees a device on its USB bus that
behaves like a physical USB CCID (Chip/Smart Card Interface
Device) card.
< / p >
< dl >
< dt > < code > mode='host'< / code > < / dt >
< dd > The simplest operation, where the hypervisor relays all
requests from the guest into direct access to the host's
smartcard via NSS. No other attributes or sub-elements are
required. See below about the use of an
optional < code > < address> < / code > sub-element.< / dd >
< dt > < code > mode='host-certificates'< / code > < / dt >
< dd > Rather than requiring a smartcard to be plugged into the
host, it is possible to provide three NSS certificate names
residing in a database on the host. These certificates can be
generated via the command < code > certutil -d /etc/pki/nssdb -x -t
CT,CT,CT -S -s CN=cert1 -n cert1< / code > , and the resulting three
certificate names must be supplied as the content of each of
three < code > < certificate> < / code > sub-elements. An
additional sub-element < code > < database> < / code > can specify
the absolute path to an alternate directory (matching
the < code > -d< / code > option of the < code > certutil< / code > command
when creating the certificates); if not present, it defaults to
/etc/pki/nssdb.< / dd >
< dt > < code > mode='passthrough'< / code > < / dt >
< dd > Rather than having the hypervisor directly communicate with
the host, it is possible to tunnel all requests through a
secondary character device to a third-party provider (which may
in turn be talking to a smartcard or using three certificate
files). In this mode of operation, an additional
attribute < code > type< / code > is required, matching one of the
supported < a href = "#elementsConsole" > serial device< / a > types, to
2011-02-04 05:23:31 +03:00
describe the host side of the tunnel; < code > type='tcp'< / code >
or < code > type='spicevmc'< / code > (which uses the smartcard
channel of a < a href = "#elementsGraphics" > SPICE graphics
device< / a > ) are typical. Further sub-elements, such
as < code > < source> < / code > , may be required according to the
2011-01-06 04:02:20 +03:00
given type, although a < code > < target> < / code > sub-element
is not required (since the consumer of the character device is
the hypervisor itself, rather than a device visible in the
guest).< / dd >
< / dl >
< p >
Each mode supports an optional
sub-element < code > < address> < / code > , which fine-tunes the
correlation between the smartcard and a ccid bus controller.
If present, the element must have an attribute
of < code > type='ccid'< / code > as well as a < code > bus< / code >
attribute listing the index of the bus that the smartcard
utilizes. An optional < code > slot< / code > attribute lists which
slot within the bus. For now, qemu only supports at most one
smartcard, with an address of bus=0 slot=0.
< / p >
2008-05-08 18:20:07 +04:00
< h4 > < a name = "elementsNICS" > Network interfaces< / a > < / h4 >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< interface type='bridge'>
< source bridge='xenbr0'/>
< mac address='00:16:3e:5d:c7:9e'/>
< script path='vif-bridge'/>
2011-01-12 17:19:34 +03:00
< boot order='1'/>
2010-02-04 17:27:52 +03:00
< /interface>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2011-01-18 00:33:00 +03:00
< p >
There are several possibilities for specifying a network
interface visible to the guest. Each subsection below provides
more details about common setup options. Additionally,
each < code > < interface> < / code > element has an
optional < code > < address> < / code > sub-element that can tie
the interface to a particular pci slot, with
attribute < code > type='pci'< / code > and additional
attributes < code > domain< / code > , < code > bus< / code > , < code > slot< / code > ,
and < code > function< / code > as appropriate.
< / p >
2008-05-08 18:20:07 +04:00
< h5 > < a name = "elementsNICSVirtual" > Virtual network< / a > < / h5 >
< p >
< strong > < em >
This is the recommended config for general guest connectivity on
hosts with dynamic / wireless networking configs
< / em > < / strong >
< / p >
< p >
Provides a virtual network using a bridge device in the host.
Depending on the virtual network configuration, the network may be
totally isolated, NAT'ing to an explicit network device, or NAT'ing to
the default route. DHCP and DNS are provided on the virtual network in
all cases and the IP range can be determined by examining the virtual
network config with '< code > virsh net-dumpxml [networkname]< / code > '.
There is one virtual network called 'default' setup out
of the box which does NAT'ing to the default route and has an IP range of
2011-03-09 02:15:47 +03:00
< code > 192.168.122.0/255.255.255.0< / code > . Each guest will have an
2008-05-08 18:20:07 +04:00
associated tun device created with a name of vnetN, which can also be
2009-11-20 18:25:58 +03:00
overridden with the < target> element (see
< a href = "#elementsNICSTargetOverride" > overriding the target element< / a > ).
2008-05-08 18:20:07 +04:00
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< interface type='network'>
< source network='default'/>
< /interface>
...
< interface type='network'>
< source network='default'/>
< target dev='vnet7'/>
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< mac address="00:11:22:33:44:55"/>
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< /interface>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2009-09-22 14:54:57 +04:00
< h5 > < a name = "elementsNICSBridge" > Bridge to LAN< / a > < / h5 >
2008-05-08 18:20:07 +04:00
< p >
< strong > < em >
This is the recommended config for general guest connectivity on
hosts with static wired networking configs
< / em > < / strong >
< / p >
< p >
Provides a bridge from the VM directly onto the LAN. This assumes
there is a bridge device on the host which has one or more of the hosts
physical NICs enslaved. The guest VM will have an associated tun device
created with a name of vnetN, which can also be overridden with the
2009-11-20 18:25:58 +03:00
< target> element (see
< a href = "#elementsNICSTargetOverride" > overriding the target element< / a > ).
The tun device will be enslaved to the bridge. The IP range / network
configuration is whatever is used on the LAN. This provides the guest VM
full incoming & outgoing net access just like a physical machine.
2008-05-08 18:20:07 +04:00
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< interface type='bridge'>
< source bridge='br0'/>
< /interface>
...
< interface type='bridge'>
< source bridge='br0'/>
< target dev='vnet7'/>
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< mac address="00:11:22:33:44:55"/>
2010-02-04 17:27:52 +03:00
< /interface>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
< h5 > < a name = "elementsNICSSlirp" > Userspace SLIRP stack< / a > < / h5 >
< p >
Provides a virtual LAN with NAT to the outside world. The virtual
network has DHCP & DNS services and will give the guest VM addresses
starting from < code > 10.0.2.15< / code > . The default router will be
< code > 10.0.2.2< / code > and the DNS server will be < code > 10.0.2.3< / code > .
This networking is the only option for unprivileged users who need their
VMs to have outgoing access.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< interface type='user'/>
...
< interface type='user'>
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< mac address="00:11:22:33:44:55"/>
2010-02-04 17:27:52 +03:00
< /interface>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
< h5 > < a name = "elementsNICSEthernet" > Generic ethernet connection< / a > < / h5 >
< p >
Provides a means for the administrator to execute an arbitrary script
to connect the guest's network to the LAN. The guest will have a tun
device created with a name of vnetN, which can also be overridden with the
< target> element. After creating the tun device a shell script will
be run which is expected to do whatever host network integration is
required. By default this script is called /etc/qemu-ifup but can be
overridden.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< interface type='ethernet'/>
...
< interface type='ethernet'>
< target dev='vnet7'/>
< script path='/etc/qemu-ifup-mynet'/>
< /interface>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2010-02-24 12:29:23 +03:00
< h5 > < a name = "elementsNICSDirect" > Direct attachment to physical interface< / a > < / h5 >
< p >
Provides direct attachment of the virtual machine's NIC to the given
2010-03-26 18:53:32 +03:00
physial interface of the host.
2011-04-02 02:02:10 +04:00
< span class = "since" > Since 0.7.7 (QEMU and KVM only)< / span > < br / >
2010-03-26 18:53:32 +03:00
This setup requires the Linux macvtap
driver to be available. < span class = "since" > (Since Linux 2.6.34.)< / span >
One of the modes 'vepa'
2010-03-05 17:41:38 +03:00
( < a href = "http://www.ieee802.org/1/files/public/docs2009/new-evb-congdon-vepa-modular-0709-v01.pdf" >
2011-03-09 02:15:47 +03:00
'Virtual Ethernet Port Aggregator'< / a > ), 'bridge' or 'private'
2010-02-24 12:29:23 +03:00
can be chosen for the operation mode of the macvtap device, 'vepa'
2010-03-05 17:41:38 +03:00
being the default mode. The individual modes cause the delivery of
packets to behave as follows:
2010-02-24 12:29:23 +03:00
< / p >
2010-03-05 17:41:38 +03:00
< dl >
< dt > < code > vepa< / code > < / dt >
< dd > All VMs' packets are sent to the external bridge. Packets
whose destination is a VM on the same host as where the
packet originates from are sent back to the host by the VEPA
capable bridge (today's bridges are typically not VEPA capable).< / dd >
< dt > < code > bridge< / code > < / dt >
< dd > Packets whose destination is on the same host as where they
originate from are directly delivered to the target macvtap device.
Both origin and destination devices need to be in bridge mode
for direct delivery. If either one of them is in < code > vepa< / code > mode,
2011-04-02 02:02:10 +04:00
a VEPA capable bridge is required.< / dd >
2010-03-05 17:41:38 +03:00
< dt > < code > private< / code > < / dt >
< dd > All packets are sent to the external bridge and will only be
delivered to a target VM on the same host if they are sent through an
external router or gateway and that device sends them back to the
host. This procedure is followed if either the source or destination
device is in < code > private< / code > mode.< / dd >
< / dl >
2010-02-24 12:29:23 +03:00
< pre >
...
< devices>
< interface type='direct'/>
...
< interface type='direct'>
< source dev='eth0' mode='vepa'/>
< /interface>
< /devices>
...< / pre >
2011-03-11 12:47:57 +03:00
< p >
The network access of direct attached virtual machines can be
managed by the hardware switch to which the physical interface
of the host machine is connected to.
2011-03-11 20:08:24 +03:00
< / p >
2011-03-11 12:47:57 +03:00
< p >
The interface can have additional parameters as shown below,
if the switch is conforming to the IEEE 802.1Qbg standard.
The parameters of the virtualport element are documented in more detail
in the IEEE 802.1Qbg standard. The values are network specific and
should be provided by the network administrator. In 802.1Qbg terms,
the Virtual Station Interface (VSI) represents the virtual interface
of a virtual machine.
< / p >
2011-05-02 18:49:03 +04:00
< p >
Please note that IEEE 802.1Qbg requires a non-zero value for the
VLAN ID.
< / p >
2011-03-11 12:47:57 +03:00
< dl >
< dt > < code > managerid< / code > < / dt >
< dd > The VSI Manager ID identifies the database containing the VSI type
and instance definitions. This is an integer value and the
value 0 is reserved.< / dd >
< dt > < code > typeid< / code > < / dt >
< dd > The VSI Type ID identifies a VSI type characterizing the network
access. VSI types are typically managed by network administrator.
This is an integer value.
< / dd >
< dt > < code > typeidversion< / code > < / dt >
< dd > The VSI Type Version allows multiple versions of a VSI Type.
This is an integer value.
< / dd >
< dt > < code > instanceid< / code > < / dt >
< dd > The VSI Instance ID Identifier is generated when a VSI instance
(i.e. a virtual interface of a virtual machine) is created.
This is a globally unique identifier.
< / dd >
< / dl >
< pre >
...
< devices>
< interface type='direct'/>
...
< interface type='direct'>
2011-05-02 18:49:03 +04:00
< source dev='eth0.2' mode='vepa'/>
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< virtualport type="802.1Qbg">
< parameters managerid="11" typeid="1193047" typeidversion="2" instanceid="09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f"/>
< /virtualport>
< /interface>
< /devices>
...< / pre >
2010-02-24 12:29:23 +03:00
2008-05-08 18:20:07 +04:00
< h5 > < a name = "elementsNICSMulticast" > Multicast tunnel< / a > < / h5 >
< p >
A multicast group is setup to represent a virtual network. Any VMs
whose network devices are in the same multicast group can talk to each
other even across hosts. This mode is also available to unprivileged
users. There is no default DNS or DHCP support and no outgoing network
access. To provide outgoing network access, one of the VMs should have a
2nd NIC which is connected to one of the first 4 network types and do the
appropriate routing. The multicast protocol is compatible with that used
by user mode linux guests too. The source address used must be from the
multicast address block.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< interface type='mcast'>
< source address='230.0.0.1' port='5558'/>
< /interface>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
< h5 > < a name = "elementsNICSTCP" > TCP tunnel< / a > < / h5 >
< p >
A TCP client/server architecture provides a virtual network. One VM
provides the server end of the network, all other VMS are configured as
clients. All network traffic is routed between the VMs via the server.
This mode is also available to unprivileged users. There is no default
DNS or DHCP support and no outgoing network access. To provide outgoing
network access, one of the VMs should have a 2nd NIC which is connected
to one of the first 4 network types and do the appropriate routing.< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< interface type='server'>
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< source address='192.168.0.1' port='5558'/>
2010-02-04 17:27:52 +03:00
< /interface>
...
< interface type='client'>
< source address='192.168.0.1' port='5558'/>
< /interface>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2008-10-13 19:25:38 +04:00
< h5 > < a name = "elementsNICSModel" > Setting the NIC model< / a > < / h5 >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< interface type='network'>
< source network='default'/>
< target dev='vnet1'/>
< b > < model type='ne2k_pci'/> < / b >
< /interface>
< /devices>
...< / pre >
2008-10-13 19:25:38 +04:00
< p >
For hypervisors which support this, you can set the model of
emulated network interface card.
< / p >
< p >
The values for < code > type< / code > aren't defined specifically by
libvirt, but by what the underlying hypervisor supports (if
any). For QEMU and KVM you can get a list of supported models
with these commands:
< / p >
< pre >
qemu -net nic,model=? /dev/null
qemu-kvm -net nic,model=? /dev/null
< / pre >
< p >
Typical values for QEMU and KVM include:
ne2k_isa i82551 i82557b i82559er ne2k_pci pcnet rtl8139 e1000 virtio
< / p >
2008-05-08 18:20:07 +04:00
Add txmode attribute to interface XML for virtio backend
This is in response to:
https://bugzilla.redhat.com/show_bug.cgi?id=629662
Explanation
qemu's virtio-net-pci driver allows setting the algorithm used for tx
packets to either "bh" or "timer". This is done by adding ",tx=bh" or
",tx=timer" to the "-device virtio-net-pci" commandline option.
'bh' stands for 'bottom half'; when this is set, packet tx is all done
in an iothread in the bottom half of the driver. (In libvirt, this
option is called the more descriptive "iothread".)
'timer' means that tx work is done in qemu, and if there is more tx
data than can be sent at the present time, a timer is set before qemu
moves on to do other things; when the timer fires, another attempt is
made to send more data. (libvirt retains the name "timer" for this
option.)
The resulting difference, according to the qemu developer who added
the option is:
bh makes tx more asynchronous and reduces latency, but potentially
causes more processor bandwidth contention since the cpu doing the
tx isn't necessarily the cpu where the guest generated the
packets.
Solution
This patch provides a libvirt domain xml knob to change the option on
the qemu commandline, by adding a new attribute "txmode" to the
<driver> element that can be placed inside any <interface> element in
a domain definition. It's use would be something like this:
<interface ...>
...
<model type='virtio'/>
<driver txmode='iothread'/>
...
</interface>
I chose to put this setting as an attribute to <driver> rather than as
a sub-element to <tune> because it is specific to the virtio-net
driver, not something that is generally usable by all network drivers.
(note that this is the same placement as the "driver name=..."
attribute used to choose kernel vs. userland backend for the
virtio-net driver.)
Actually adding the tx=xxx option to the qemu commandline is only done
if the version of qemu being used advertises it in the output of
qemu -device virtio-net-pci,?
If a particular txmode is requested in the XML, and the option isn't
listed in that help output, an UNSUPPORTED_CONFIG error is logged, and
the domain fails to start.
2011-02-03 23:20:01 +03:00
< h5 > < a name = "elementsDriverBackendOptions" > Setting NIC driver-specific options< / a > < / h5 >
< pre >
...
< devices>
< interface type='network'>
< source network='default'/>
< target dev='vnet1'/>
< model type='virtio'/>
2011-03-09 02:35:17 +03:00
< b > < driver name='vhost' txmode='iothread'/> < / b >
Add txmode attribute to interface XML for virtio backend
This is in response to:
https://bugzilla.redhat.com/show_bug.cgi?id=629662
Explanation
qemu's virtio-net-pci driver allows setting the algorithm used for tx
packets to either "bh" or "timer". This is done by adding ",tx=bh" or
",tx=timer" to the "-device virtio-net-pci" commandline option.
'bh' stands for 'bottom half'; when this is set, packet tx is all done
in an iothread in the bottom half of the driver. (In libvirt, this
option is called the more descriptive "iothread".)
'timer' means that tx work is done in qemu, and if there is more tx
data than can be sent at the present time, a timer is set before qemu
moves on to do other things; when the timer fires, another attempt is
made to send more data. (libvirt retains the name "timer" for this
option.)
The resulting difference, according to the qemu developer who added
the option is:
bh makes tx more asynchronous and reduces latency, but potentially
causes more processor bandwidth contention since the cpu doing the
tx isn't necessarily the cpu where the guest generated the
packets.
Solution
This patch provides a libvirt domain xml knob to change the option on
the qemu commandline, by adding a new attribute "txmode" to the
<driver> element that can be placed inside any <interface> element in
a domain definition. It's use would be something like this:
<interface ...>
...
<model type='virtio'/>
<driver txmode='iothread'/>
...
</interface>
I chose to put this setting as an attribute to <driver> rather than as
a sub-element to <tune> because it is specific to the virtio-net
driver, not something that is generally usable by all network drivers.
(note that this is the same placement as the "driver name=..."
attribute used to choose kernel vs. userland backend for the
virtio-net driver.)
Actually adding the tx=xxx option to the qemu commandline is only done
if the version of qemu being used advertises it in the output of
qemu -device virtio-net-pci,?
If a particular txmode is requested in the XML, and the option isn't
listed in that help output, an UNSUPPORTED_CONFIG error is logged, and
the domain fails to start.
2011-02-03 23:20:01 +03:00
< /interface>
< /devices>
...< / pre >
< p >
Some NICs may have tunable driver-specific options. These are
set as attributes of the < code > driver< / code > sub-element of the
interface definition. Currently the following attributes are
available for the < code > "virtio"< / code > NIC driver:
< / p >
< dl >
2011-03-09 02:35:17 +03:00
< dt > < code > name< / code > < / dt >
< dd >
The optional < code > name< / code > attribute forces which type of
backend driver to use. The value can be either 'qemu' (a
user-space backend) or 'vhost' (a kernel backend, which
requires the vhost module to be provided by the kernel); an
attempt to require the vhost driver without kernel support
will be rejected. If this attribute is not present, then the
domain defaults to 'vhost' if present, but silently falls back
to 'qemu' without error.
< span class = "since" > Since 0.8.8 (QEMU and KVM only)< / span >
< / dd >
Add txmode attribute to interface XML for virtio backend
This is in response to:
https://bugzilla.redhat.com/show_bug.cgi?id=629662
Explanation
qemu's virtio-net-pci driver allows setting the algorithm used for tx
packets to either "bh" or "timer". This is done by adding ",tx=bh" or
",tx=timer" to the "-device virtio-net-pci" commandline option.
'bh' stands for 'bottom half'; when this is set, packet tx is all done
in an iothread in the bottom half of the driver. (In libvirt, this
option is called the more descriptive "iothread".)
'timer' means that tx work is done in qemu, and if there is more tx
data than can be sent at the present time, a timer is set before qemu
moves on to do other things; when the timer fires, another attempt is
made to send more data. (libvirt retains the name "timer" for this
option.)
The resulting difference, according to the qemu developer who added
the option is:
bh makes tx more asynchronous and reduces latency, but potentially
causes more processor bandwidth contention since the cpu doing the
tx isn't necessarily the cpu where the guest generated the
packets.
Solution
This patch provides a libvirt domain xml knob to change the option on
the qemu commandline, by adding a new attribute "txmode" to the
<driver> element that can be placed inside any <interface> element in
a domain definition. It's use would be something like this:
<interface ...>
...
<model type='virtio'/>
<driver txmode='iothread'/>
...
</interface>
I chose to put this setting as an attribute to <driver> rather than as
a sub-element to <tune> because it is specific to the virtio-net
driver, not something that is generally usable by all network drivers.
(note that this is the same placement as the "driver name=..."
attribute used to choose kernel vs. userland backend for the
virtio-net driver.)
Actually adding the tx=xxx option to the qemu commandline is only done
if the version of qemu being used advertises it in the output of
qemu -device virtio-net-pci,?
If a particular txmode is requested in the XML, and the option isn't
listed in that help output, an UNSUPPORTED_CONFIG error is logged, and
the domain fails to start.
2011-02-03 23:20:01 +03:00
< dt > < code > txmode< / code > < / dt >
< dd >
The < code > txmode< / code > attribute specifies how to handle
transmission of packets when the transmit buffer is full. The
value can be either 'iothread' or 'timer'.
2011-04-02 02:02:10 +04:00
< span class = "since" > Since 0.8.8 (QEMU and KVM only)< / span > < br / > < br / >
Add txmode attribute to interface XML for virtio backend
This is in response to:
https://bugzilla.redhat.com/show_bug.cgi?id=629662
Explanation
qemu's virtio-net-pci driver allows setting the algorithm used for tx
packets to either "bh" or "timer". This is done by adding ",tx=bh" or
",tx=timer" to the "-device virtio-net-pci" commandline option.
'bh' stands for 'bottom half'; when this is set, packet tx is all done
in an iothread in the bottom half of the driver. (In libvirt, this
option is called the more descriptive "iothread".)
'timer' means that tx work is done in qemu, and if there is more tx
data than can be sent at the present time, a timer is set before qemu
moves on to do other things; when the timer fires, another attempt is
made to send more data. (libvirt retains the name "timer" for this
option.)
The resulting difference, according to the qemu developer who added
the option is:
bh makes tx more asynchronous and reduces latency, but potentially
causes more processor bandwidth contention since the cpu doing the
tx isn't necessarily the cpu where the guest generated the
packets.
Solution
This patch provides a libvirt domain xml knob to change the option on
the qemu commandline, by adding a new attribute "txmode" to the
<driver> element that can be placed inside any <interface> element in
a domain definition. It's use would be something like this:
<interface ...>
...
<model type='virtio'/>
<driver txmode='iothread'/>
...
</interface>
I chose to put this setting as an attribute to <driver> rather than as
a sub-element to <tune> because it is specific to the virtio-net
driver, not something that is generally usable by all network drivers.
(note that this is the same placement as the "driver name=..."
attribute used to choose kernel vs. userland backend for the
virtio-net driver.)
Actually adding the tx=xxx option to the qemu commandline is only done
if the version of qemu being used advertises it in the output of
qemu -device virtio-net-pci,?
If a particular txmode is requested in the XML, and the option isn't
listed in that help output, an UNSUPPORTED_CONFIG error is logged, and
the domain fails to start.
2011-02-03 23:20:01 +03:00
If set to 'iothread', packet tx is all done in an iothread in
the bottom half of the driver (this option translates into
adding "tx=bh" to the qemu commandline -device virtio-net-pci
2011-04-02 02:02:10 +04:00
option).< br / > < br / >
Add txmode attribute to interface XML for virtio backend
This is in response to:
https://bugzilla.redhat.com/show_bug.cgi?id=629662
Explanation
qemu's virtio-net-pci driver allows setting the algorithm used for tx
packets to either "bh" or "timer". This is done by adding ",tx=bh" or
",tx=timer" to the "-device virtio-net-pci" commandline option.
'bh' stands for 'bottom half'; when this is set, packet tx is all done
in an iothread in the bottom half of the driver. (In libvirt, this
option is called the more descriptive "iothread".)
'timer' means that tx work is done in qemu, and if there is more tx
data than can be sent at the present time, a timer is set before qemu
moves on to do other things; when the timer fires, another attempt is
made to send more data. (libvirt retains the name "timer" for this
option.)
The resulting difference, according to the qemu developer who added
the option is:
bh makes tx more asynchronous and reduces latency, but potentially
causes more processor bandwidth contention since the cpu doing the
tx isn't necessarily the cpu where the guest generated the
packets.
Solution
This patch provides a libvirt domain xml knob to change the option on
the qemu commandline, by adding a new attribute "txmode" to the
<driver> element that can be placed inside any <interface> element in
a domain definition. It's use would be something like this:
<interface ...>
...
<model type='virtio'/>
<driver txmode='iothread'/>
...
</interface>
I chose to put this setting as an attribute to <driver> rather than as
a sub-element to <tune> because it is specific to the virtio-net
driver, not something that is generally usable by all network drivers.
(note that this is the same placement as the "driver name=..."
attribute used to choose kernel vs. userland backend for the
virtio-net driver.)
Actually adding the tx=xxx option to the qemu commandline is only done
if the version of qemu being used advertises it in the output of
qemu -device virtio-net-pci,?
If a particular txmode is requested in the XML, and the option isn't
listed in that help output, an UNSUPPORTED_CONFIG error is logged, and
the domain fails to start.
2011-02-03 23:20:01 +03:00
If set to 'timer', tx work is done in qemu, and if there is
more tx data than can be sent at the present time, a timer is
set before qemu moves on to do other things; when the timer
2011-04-02 02:02:10 +04:00
fires, another attempt is made to send more data.< br / > < br / >
Add txmode attribute to interface XML for virtio backend
This is in response to:
https://bugzilla.redhat.com/show_bug.cgi?id=629662
Explanation
qemu's virtio-net-pci driver allows setting the algorithm used for tx
packets to either "bh" or "timer". This is done by adding ",tx=bh" or
",tx=timer" to the "-device virtio-net-pci" commandline option.
'bh' stands for 'bottom half'; when this is set, packet tx is all done
in an iothread in the bottom half of the driver. (In libvirt, this
option is called the more descriptive "iothread".)
'timer' means that tx work is done in qemu, and if there is more tx
data than can be sent at the present time, a timer is set before qemu
moves on to do other things; when the timer fires, another attempt is
made to send more data. (libvirt retains the name "timer" for this
option.)
The resulting difference, according to the qemu developer who added
the option is:
bh makes tx more asynchronous and reduces latency, but potentially
causes more processor bandwidth contention since the cpu doing the
tx isn't necessarily the cpu where the guest generated the
packets.
Solution
This patch provides a libvirt domain xml knob to change the option on
the qemu commandline, by adding a new attribute "txmode" to the
<driver> element that can be placed inside any <interface> element in
a domain definition. It's use would be something like this:
<interface ...>
...
<model type='virtio'/>
<driver txmode='iothread'/>
...
</interface>
I chose to put this setting as an attribute to <driver> rather than as
a sub-element to <tune> because it is specific to the virtio-net
driver, not something that is generally usable by all network drivers.
(note that this is the same placement as the "driver name=..."
attribute used to choose kernel vs. userland backend for the
virtio-net driver.)
Actually adding the tx=xxx option to the qemu commandline is only done
if the version of qemu being used advertises it in the output of
qemu -device virtio-net-pci,?
If a particular txmode is requested in the XML, and the option isn't
listed in that help output, an UNSUPPORTED_CONFIG error is logged, and
the domain fails to start.
2011-02-03 23:20:01 +03:00
The resulting difference, according to the qemu developer who
added the option is: "bh makes tx more asynchronous and reduces
latency, but potentially causes more processor bandwidth
contention since the cpu doing the tx isn't necessarily the
2011-04-02 02:02:10 +04:00
cpu where the guest generated the packets."< br / > < br / >
Add txmode attribute to interface XML for virtio backend
This is in response to:
https://bugzilla.redhat.com/show_bug.cgi?id=629662
Explanation
qemu's virtio-net-pci driver allows setting the algorithm used for tx
packets to either "bh" or "timer". This is done by adding ",tx=bh" or
",tx=timer" to the "-device virtio-net-pci" commandline option.
'bh' stands for 'bottom half'; when this is set, packet tx is all done
in an iothread in the bottom half of the driver. (In libvirt, this
option is called the more descriptive "iothread".)
'timer' means that tx work is done in qemu, and if there is more tx
data than can be sent at the present time, a timer is set before qemu
moves on to do other things; when the timer fires, another attempt is
made to send more data. (libvirt retains the name "timer" for this
option.)
The resulting difference, according to the qemu developer who added
the option is:
bh makes tx more asynchronous and reduces latency, but potentially
causes more processor bandwidth contention since the cpu doing the
tx isn't necessarily the cpu where the guest generated the
packets.
Solution
This patch provides a libvirt domain xml knob to change the option on
the qemu commandline, by adding a new attribute "txmode" to the
<driver> element that can be placed inside any <interface> element in
a domain definition. It's use would be something like this:
<interface ...>
...
<model type='virtio'/>
<driver txmode='iothread'/>
...
</interface>
I chose to put this setting as an attribute to <driver> rather than as
a sub-element to <tune> because it is specific to the virtio-net
driver, not something that is generally usable by all network drivers.
(note that this is the same placement as the "driver name=..."
attribute used to choose kernel vs. userland backend for the
virtio-net driver.)
Actually adding the tx=xxx option to the qemu commandline is only done
if the version of qemu being used advertises it in the output of
qemu -device virtio-net-pci,?
If a particular txmode is requested in the XML, and the option isn't
listed in that help output, an UNSUPPORTED_CONFIG error is logged, and
the domain fails to start.
2011-02-03 23:20:01 +03:00
< b > In general you should leave this option alone, unless you
are very certain you know what you are doing.< / b >
< / dd >
< / dl >
2009-11-20 18:25:58 +03:00
< h5 > < a name = "elementsNICSTargetOverride" > Overriding the target element< / a > < / h5 >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< interface type='network'>
< source network='default'/>
< b > < target dev='vnet1'/> < / b >
< /interface>
< /devices>
...< / pre >
2009-11-20 18:25:58 +03:00
< p >
If no target is specified, certain hypervisors will automatically
generate a name for the created tun device. This name can be manually
specifed, however the name < i > must not start with either 'vnet' or
'vif'< / i > , which are prefixes reserved by libvirt and certain
hypervisors. Manually specified targets using these prefixes will be
ignored.
< / p >
2011-01-12 17:19:34 +03:00
< h5 > < a name = "elementsNICSBoot" > Specifying boot order< / a > < / h5 >
< pre >
...
< devices>
< interface type='network'>
< source network='default'/>
< target dev='vnet1'/>
< b > < boot order='1'/> < / b >
< /interface>
< /devices>
...< / pre >
< p >
For hypervisors which support this, you can set exact NIC which should
be used for network boot. The < code > order< / code > attribute determines
the order in which devices will be tried during boot sequence. The
per-device < code > boot< / code > elements cannot be used together with
general boot elements in
< a href = "#elementsOSBIOS" > BIOS bootloader< / a > section.
< span class = "since" > Since 0.8.8< / span >
< / p >
2008-05-08 18:20:07 +04:00
< h4 > < a name = "elementsInput" > Input devices< / a > < / h4 >
< p >
Input devices allow interaction with the graphical framebuffer in the guest
virtual machine. When enabling the framebuffer, an input device is automatically
provided. It may be possible to add additional devices explicitly, for example,
to provide a graphics tablet for absolute cursor movement.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< input type='mouse' bus='usb'/>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
< dl >
< dt > < code > input< / code > < / dt >
2008-08-08 14:24:14 +04:00
< dd > The < code > input< / code > element has one mandatory attribute, the < code > type< / code >
2009-11-06 18:04:19 +03:00
whose value can be either 'mouse' or 'tablet'. The latter provides absolute
cursor movement, while the former uses relative movement. The optional
< code > bus< / code > attribute can be used to refine the exact device type.
It takes values "xen" (paravirtualized), "ps2" and "usb".< / dd >
2008-05-08 18:20:07 +04:00
< / dl >
2011-01-18 00:33:00 +03:00
< p >
The < code > input< / code > element has an optional
sub-element < code > < address> < / code > which can tie the
device to a particular PCI slot.
< / p >
2008-05-08 18:20:07 +04:00
< h4 > < a name = "elementsGraphics" > Graphical framebuffers< / a > < / h4 >
< p >
A graphics device allows for graphical interaction with the
guest OS. A guest will typically have either a framebuffer
or a text console configured to allow interaction with the
admin.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< graphics type='sdl' display=':0.0'/>
< graphics type='vnc' port='5904'/>
< graphics type='rdp' autoport='yes' multiUser='yes' />
< graphics type='desktop' fullscreen='yes'/>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
< dl >
< dt > < code > graphics< / code > < / dt >
< dd > The < code > graphics< / code > element has a mandatory < code > type< / code >
2009-09-22 12:32:14 +04:00
attribute which takes the value "sdl", "vnc", "rdp" or "desktop":
< dl >
< dt > < code > "sdl"< / code > < / dt >
< dd >
This displays a window on the host desktop, it can take 3 optional arguments:
a < code > display< / code > attribute for the display to use, an < code > xauth< / code >
attribute for the authentication identifier, and an optional < code > fullscreen< / code >
attribute accepting values 'yes' or 'no'.
< / dd >
< dt > < code > "vnc"< / code > < / dt >
< dd >
Starts a VNC server. The < code > port< / code > attribute specifies the TCP
port number (with -1 as legacy syntax indicating that it should be
auto-allocated). The < code > autoport< / code > attribute is the new
preferred syntax for indicating autoallocation of the TCP port to use.
The < code > listen< / code > attribute is an IP address for the server to
listen on. The < code > passwd< / code > attribute provides a VNC password
in clear text. The < code > keymap< / code > attribute specifies the keymap
2010-04-08 16:43:23 +04:00
to use. It is possible to set a limit on the validity of the password
be giving an timestamp < code > passwdValidTo='2010-04-09T15:51:00'< / code >
2011-04-02 02:02:10 +04:00
assumed to be in UTC. NB, this may not be supported by all hypervisors.< br / >
< br / >
2011-01-08 00:03:07 +03:00
Rather than using listen/port, QEMU supports a < code > socket< / code >
attribute for listening on a unix domain socket path.
< span class = "since" > Since 0.8.8< / span >
2009-08-14 13:54:14 +04:00
< / dd >
< dt > < code > "spice"< / code > < / dt >
< dd >
2011-02-04 21:16:35 +03:00
< p >
2009-08-14 13:54:14 +04:00
Starts a SPICE server. The < code > port< / code > attribute specifies the TCP
port number (with -1 as legacy syntax indicating that it should be
auto-allocated), while < code > tlsPort< / code > gives an alternative
secure port number. The < code > autoport< / code > attribute is the new
preferred syntax for indicating autoallocation of both port numbers.
The < code > listen< / code > attribute is an IP address for the server to
listen on. The < code > passwd< / code > attribute provides a SPICE password
in clear text. The < code > keymap< / code > attribute specifies the keymap
2010-04-08 16:43:23 +04:00
to use. It is possible to set a limit on the validity of the password
be giving an timestamp < code > passwdValidTo='2010-04-09T15:51:00'< / code >
assumed to be in UTC. NB, this may not be supported by all hypervisors.
2011-03-17 19:04:35 +03:00
< span class = "since" > "spice" since 0.8.6< / span > .
2011-02-04 21:16:35 +03:00
< / p >
< p >
2010-04-09 20:56:00 +04:00
When SPICE has both a normal and TLS secured TCP port configured, it
can be desirable to restrict what channels can be run on each port.
This is achieved by adding one or more < channel> elements inside
the main < graphics> element. Valid channel names include
2011-02-04 05:23:31 +03:00
< code > main< / code > , < code > display< / code > , < code > inputs< / code > ,
< code > cursor< / code > , < code > playback< / code > , < code > record< / code > ;
and < span class = "since" > since 0.8.8< / span > : < code > smartcard< / code > .
2011-02-04 21:16:35 +03:00
< / p >
< pre >
2010-04-09 20:56:00 +04:00
< graphics type='spice' port='-1' tlsPort='-1' autoport='yes'>
< channel name='main' mode='secure'/>
< channel name='record' mode='insecure'/>
2011-04-14 12:44:20 +04:00
< image compression='auto_glz'/>
2010-04-09 20:56:00 +04:00
< /graphics> < / pre >
2011-04-14 12:44:20 +04:00
< p >
Spice supports variable compression settings for audio,
images and streaming, < span class = "since" > since
0.9.1< / span > . These settings are accessible via
the < code > compression< / code > attribute in all following
elements: < code > image< / code > to set image compression
(accepts < code > auto_glz< / code > , < code > auto_lz< / code > ,
< code > quic< / code > , < code > glz< / code > , < code > lz< / code > ,
< code > off< / code > ), < code > jpeg< / code > for JPEG
compression for images over wan
(accepts < code > auto< / code > , < code > never< / code > ,
< code > always< / code > ), < code > zlib< / code > for configuring
wan image compression (accepts < code > auto< / code > ,
< code > never< / code > , < code > always< / code > )
and < code > playback< / code > for enabling audio stream
compression (accepts < code > on< / code > or < code > off< / code > ).
< / p >
2009-09-22 12:32:14 +04:00
< / dd >
< dt > < code > "rdp"< / code > < / dt >
< dd >
Starts a RDP server. The < code > port< / code > attribute
specifies the TCP port number (with -1 as legacy syntax indicating
that it should be auto-allocated). The < code > autoport< / code > attribute
is the new preferred syntax for indicating autoallocation of the TCP
port to use. The < code > replaceUser< / code > attribute is a boolean deciding
whether multiple simultaneous connections to the VM are permitted.
The < code > multiUser< / code > whether the existing connection must be dropped
and a new connection must be established by the VRDP server, when a new
client connects in single connection mode.
< / dd >
< dt > < code > "desktop"< / code > < / dt >
< dd >
This value is reserved for VirtualBox domains for the moment. It displays
a window on the host desktop, similarly to "sdl", but using the VirtualBox
viewer. Just like "sdl", it accepts the optional attributes < code > display< / code >
and < code > fullscreen< / code > .
< / dd >
< / dl >
< / dd >
< / dl >
< h4 > < a name = "elementsVideo" > Video devices< / a > < / h4 >
< p >
A video device.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< video>
< model type='vga' vram='8192' heads='1'>
< acceleration accel3d='yes' accel3d='yes'/>
< /model>
< /video>
< /devices>
...< / pre >
2009-09-22 12:32:14 +04:00
< dl >
< dt > < code > video< / code > < / dt >
2009-12-13 20:25:17 +03:00
< dd >
The < code > video< / code > element is the a container for describing
video devices.
< / dd >
2009-09-22 12:32:14 +04:00
2009-12-13 20:25:17 +03:00
< dt > < code > model< / code > < / dt >
< dd >
The < code > model< / code > element has a mandatory < code > type< / code >
2011-03-17 19:04:35 +03:00
attribute which takes the value "vga", "cirrus", "vmvga", "xen",
"vbox", or "qxl" (< span class = "since" > since 0.8.6< / span > )
depending on the hypervisor features available.
2009-12-13 20:25:17 +03:00
You can also provide the amount of video memory in kilobytes using
< code > vram< / code > and the number of screen with < code > heads< / code > .
< / dd >
< dt > < code > acceleration< / code > < / dt >
< dd >
If acceleration should be enabled (if supported) using the
< code > accel3d< / code > and < code > accel2d< / code > attributes in the
< code > acceleration< / code > element.
< / dd >
2011-01-18 00:33:00 +03:00
< dt > < code > address< / code > < / dt >
< dd >
The optional < code > address< / code > sub-element can be used to
tie the video device to a particular PCI slot.
< / dd >
2008-05-08 18:20:07 +04:00
< / dl >
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< h4 > < a name = "elementsConsole" > Consoles, serial, parallel & channel devices< / a > < / h4 >
2008-05-08 18:20:07 +04:00
< p >
A character device provides a way to interact with the virtual machine.
2009-11-09 17:38:20 +03:00
Paravirtualized consoles, serial ports, parallel ports and channels are
all classed as character devices and so represented using the same syntax.
2008-05-08 18:20:07 +04:00
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< parallel type='pty'>
< source path='/dev/pts/2'/>
< target port='0'/>
< /parallel>
< serial type='pty'>
< source path='/dev/pts/3'/>
< target port='0'/>
< /serial>
< console type='pty'>
< source path='/dev/pts/4'/>
< target port='0'/>
< /console>
< channel type='unix'>
< source mode='bind' path='/tmp/guestfwd'/>
< target type='guestfwd' address='10.0.2.1' port='4600'/>
< /channel>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2009-11-09 17:35:21 +03:00
< p >
In each of these directives, the top-level element name (parallel, serial,
console, channel) describes how the device is presented to the guest. The
guest interface is configured by the < code > target< / code > element.
< / p >
2008-05-08 18:20:07 +04:00
2009-11-09 17:35:21 +03:00
< p >
The interface presented to the host is given in the < code > type< / code >
attribute of the top-level element. The host interface is
configured by the < code > source< / code > element.
< / p >
2011-01-18 00:33:00 +03:00
< p >
Each character device element has an optional
sub-element < code > < address> < / code > which can tie the
device to a
particular < a href = "#elementsControllers" > controller< / a > or PCI
slot.
< / p >
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< h5 > < a name = "elementsCharGuestInterface" > Guest interface< / a > < / h5 >
< p >
A character device presents itself to the guest as one of the following
types.
< / p >
< h6 > < a name = "elementCharParallel" > Parallel port< / a > < / h6 >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< parallel type='pty'>
< source path='/dev/pts/2'/>
< target port='0'/>
< /parallel>
< /devices>
...< / pre >
2009-11-09 17:35:21 +03:00
< p >
< code > target< / code > can have a < code > port< / code > attribute, which
2011-04-10 17:03:42 +04:00
specifies the port number. Ports are numbered starting from 0. There are
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usually 0, 1 or 2 parallel ports.
< / p >
< h6 > < a name = "elementCharSerial" > Serial port< / a > < / h6 >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type='pty'>
< source path='/dev/pts/3'/>
< target port='0'/>
< /serial>
< /devices>
...< / pre >
2009-11-09 17:35:21 +03:00
< p >
< code > target< / code > can have a < code > port< / code > attribute, which
2011-04-10 17:03:42 +04:00
specifies the port number. Ports are numbered starting from 0. There are
2009-11-09 17:35:21 +03:00
usually 0, 1 or 2 serial ports.
< / p >
< h6 > < a name = "elementCharConsole" > Console< / a > < / h6 >
< p >
This represents the primary console. This can be the paravirtualized
2010-07-14 21:02:04 +04:00
console with Xen guests, virtio console for QEMU/KVM, or duplicates
the primary serial port for fully virtualized guests without a
paravirtualized console.
< / p >
< p >
A virtio console device is exposed in the
guest as /dev/hvc[0-7] (for more information, see
< a href = "http://fedoraproject.org/wiki/Features/VirtioSerial" > http://fedoraproject.org/wiki/Features/VirtioSerial< / a > )
< span class = "since" > Since 0.8.3< / span >
2009-11-09 17:35:21 +03:00
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< console type='pty'>
< source path='/dev/pts/4'/>
< target port='0'/>
< /console>
2010-07-14 21:02:04 +04:00
< !-- KVM virtio console -->
< console type='pty'>
< source path='/dev/pts/5'/>
< target type='virtio' port='0'/>
< /console>
2010-02-04 17:27:52 +03:00
< /devices>
...< / pre >
2009-11-09 17:35:21 +03:00
< p >
If the console is presented as a serial port, the < code > target< / code >
element has the same attributes as for a serial port. There is usually
only 1 console.
< / p >
2009-11-09 17:38:20 +03:00
< h6 > < a name = "elementCharChannel" > Channel< / a > < / h6 >
< p >
This represents a private communication channel between the host and the
guest.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< channel type='unix'>
< source mode='bind' path='/tmp/guestfwd'/>
< target type='guestfwd' address='10.0.2.1' port='4600'/>
< /channel>
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< !-- KVM virtio channel -->
< channel type='pty'>
< target type='virtio' name='arbitrary.virtio.serial.port.name'/>
< /channel>
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< channel type='spicevmc'>
< target type='virtio' name='com.redhat.spice.0'/>
< /channel>
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< /devices>
...< / pre >
2009-11-09 17:38:20 +03:00
< p >
This can be implemented in a variety of ways. The specific type of
channel is given in the < code > type< / code > attribute of the
< code > target< / code > element. Different channel types have different
< code > target< / code > attributes.
< / p >
< dl >
< dt > < code > guestfwd< / code > < / dt >
< dd > TCP traffic sent by the guest to a given IP address and port is
forwarded to the channel device on the host. The < code > target< / code >
element must have < code > address< / code > and < code > port< / code > attributes.
< span class = "since" > Since 0.7.3< / span > < / dd >
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< dt > < code > virtio< / code > < / dt >
< dd > Paravirtualized virtio channel. Channel is exposed in the guest under
2011-01-18 00:33:00 +03:00
/dev/vport*, and if the optional element < code > name< / code > is specified,
2010-07-14 23:07:59 +04:00
/dev/virtio-ports/$name (for more info, please see
2011-01-18 00:33:00 +03:00
< a href = "http://fedoraproject.org/wiki/Features/VirtioSerial" > http://fedoraproject.org/wiki/Features/VirtioSerial< / a > ). The
optional element < code > address< / code > can tie the channel to a
particular < code > type='virtio-serial'< / code > controller.
2010-07-14 23:07:59 +04:00
< span class = "since" > Since 0.7.7< / span > < / dd >
2011-02-03 07:09:44 +03:00
< dt > < code > spicevmc< / code > < / dt >
< dd > Paravirtualized SPICE channel. The domain must also have a
SPICE server as a < a href = "#elementsGraphics" > graphics
device< / a > , at which point the host piggy-backs messages
across the < code > main< / code > channel. The < code > target< / code >
element must be present, with
attribute < code > type='virtio'< / code > ; an optional
attribute < code > name< / code > controls how the guest will have
access to the channel, and defaults
to < code > name='com.redhat.spice.0'< / code > . The
optional < code > address< / code > element can tie the channel to a
particular < code > type='virtio-serial'< / code > controller.
< span class = "since" > Since 0.8.8< / span > < / dd >
2009-11-09 17:38:20 +03:00
< / dl >
2009-11-09 17:35:21 +03:00
< h5 > < a name = "elementsCharHostInterface" > Host interface< / a > < / h5 >
< p >
A character device presents itself to the host as one of the following
types.
< / p >
2008-05-08 18:20:07 +04:00
2009-11-09 17:35:21 +03:00
< h6 > < a name = "elementsCharSTDIO" > Domain logfile< / a > < / h6 >
2008-05-08 18:20:07 +04:00
< p >
This disables all input on the character device, and sends output
into the virtual machine's logfile
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< console type='stdio'>
< target port='1'>
< /console>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2009-11-09 17:35:21 +03:00
< h6 > < a name = "elementsCharFle" > Device logfile< / a > < / h6 >
2008-05-08 18:20:07 +04:00
< p >
A file is opened and all data sent to the character
device is written to the file.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type="file">
< source path="/var/log/vm/vm-serial.log"/>
< target port="1"/>
< /serial>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2009-11-09 17:35:21 +03:00
< h6 > < a name = "elementsCharVC" > Virtual console< / a > < / h6 >
2008-05-08 18:20:07 +04:00
< p >
Connects the character device to the graphical framebuffer in
a virtual console. This is typically accessed via a special
hotkey sequence such as "ctrl+alt+3"
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type='vc'>
< target port="1"/>
< /serial>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2009-11-09 17:35:21 +03:00
< h6 > < a name = "elementsCharNull" > Null device< / a > < / h6 >
2008-05-08 18:20:07 +04:00
< p >
Connects the character device to the void. No data is ever
provided to the input. All data written is discarded.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type='null'>
< target port="1"/>
< /serial>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2009-11-09 17:35:21 +03:00
< h6 > < a name = "elementsCharPTY" > Pseudo TTY< / a > < / h6 >
2008-05-08 18:20:07 +04:00
< p >
A Pseudo TTY is allocated using /dev/ptmx. A suitable client
such as 'virsh console' can connect to interact with the
serial port locally.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type="pty">
< source path="/dev/pts/3"/>
< target port="1"/>
< /serial>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
< p >
NB special case if < console type='pty'> , then the TTY
2008-08-08 14:24:14 +04:00
path is also duplicated as an attribute tty='/dev/pts/3'
2008-05-08 18:20:07 +04:00
on the top level < console> tag. This provides compat
with existing syntax for < console> tags.
< / p >
2009-11-09 17:35:21 +03:00
< h6 > < a name = "elementsCharHost" > Host device proxy< / a > < / h6 >
2008-05-08 18:20:07 +04:00
< p >
The character device is passed through to the underlying
physical character device. The device types must match,
eg the emulated serial port should only be connected to
2008-08-08 14:24:14 +04:00
a host serial port - don't connect a serial port to a parallel
2008-05-08 18:20:07 +04:00
port.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type="dev">
< source path="/dev/ttyS0"/>
< target port="1"/>
< /serial>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2009-11-09 17:35:21 +03:00
< h6 > < a name = "elementsCharPipe" > Named pipe< / a > < / h6 >
2009-07-09 01:59:23 +04:00
< p >
The character device writes output to a named pipe. See pipe(7) for
more info.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type="pipe">
< source path="/tmp/mypipe"/>
< target port="1"/>
< /serial>
< /devices>
...< / pre >
2009-07-09 01:59:23 +04:00
2009-11-09 17:35:21 +03:00
< h6 > < a name = "elementsCharTCP" > TCP client/server< / a > < / h6 >
2008-05-08 18:20:07 +04:00
< p >
The character device acts as a TCP client connecting to a
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remote server.
2008-05-08 18:20:07 +04:00
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type="tcp">
< source mode="connect" host="0.0.0.0" service="2445"/>
< protocol type="raw"/>
< target port="1"/>
< /serial>
< /devices>
...< / pre >
2009-07-25 00:16:51 +04:00
< p >
Or as a TCP server waiting for a client connection.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type="tcp">
< source mode="bind" host="127.0.0.1" service="2445"/>
< protocol type="raw"/>
< target port="1"/>
< /serial>
< /devices>
...< / pre >
2009-07-25 00:16:51 +04:00
< p >
2010-09-30 01:04:19 +04:00
Alternatively you can use < code > telnet< / code > instead of < code > raw< / code > TCP.
< span class = "since" > Since 0.8.5< / span > you can also use < code > telnets< / code >
(secure telnet) and < code > tls< / code > .
2011-04-02 02:02:10 +04:00
< / p >
2009-07-25 00:16:51 +04:00
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type="tcp">
< source mode="connect" host="0.0.0.0" service="2445"/>
< protocol type="telnet"/>
< target port="1"/>
< /serial>
...
< serial type="tcp">
< source mode="bind" host="127.0.0.1" service="2445"/>
< protocol type="telnet"/>
< target port="1"/>
< /serial>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2009-11-09 17:35:21 +03:00
< h6 > < a name = "elementsCharUDP" > UDP network console< / a > < / h6 >
2008-05-08 18:20:07 +04:00
< p >
The character device acts as a UDP netconsole service,
sending and receiving packets. This is a lossy service.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type="udp">
< source mode="bind" host="0.0.0.0" service="2445"/>
< source mode="connect" host="0.0.0.0" service="2445"/>
< target port="1"/>
< /serial>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2009-11-09 17:35:21 +03:00
< h6 > < a name = "elementsCharUNIX" > UNIX domain socket client/server< / a > < / h6 >
2008-05-08 18:20:07 +04:00
< p >
The character device acts as a UNIX domain socket server,
accepting connections from local clients.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< serial type="unix">
< source mode="bind" path="/tmp/foo"/>
< target port="1"/>
< /serial>
< /devices>
...< / pre >
2008-05-08 18:20:07 +04:00
2009-05-19 17:18:00 +04:00
< h4 > < a name = "elementsSound" > Sound devices< / a > < / h4 >
< p >
A virtual sound card can be attached to the host via the
< code > sound< / code > element. < span class = "since" > Since 0.4.3< / span >
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< sound model='es1370'/>
< /devices>
...< / pre >
2009-05-19 17:18:00 +04:00
< dl >
< dt > < code > sound< / code > < / dt >
< dd >
The < code > sound< / code > element has one mandatory attribute,
< code > model< / code > , which specifies what real sound device is emulated.
Valid values are specific to the underlying hypervisor, though typical
2011-01-13 17:15:11 +03:00
choices are 'es1370', 'sb16', 'ac97', and 'ich6'
(< span class = "since" >
'ac97' only since 0.6.0, 'ich6' only since 0.8.8< / span > )
2009-05-19 17:18:00 +04:00
< / dd >
< / dl >
2011-01-18 00:33:00 +03:00
< p >
Each < code > sound< / code > element has an optional
sub-element < code > < address> < / code > which can tie the
device to a particular PCI slot.
< / p >
2009-10-21 16:26:38 +04:00
< h4 > < a name = "elementsWatchdog" > Watchdog device< / a > < / h4 >
< p >
A virtual hardware watchdog device can be added to the guest via
the < code > watchdog< / code > element.
< span class = "since" > Since 0.7.3, QEMU and KVM only< / span >
< / p >
< p >
The watchdog device requires an additional driver and management
daemon in the guest. Just enabling the watchdog in the libvirt
configuration does not do anything useful on its own.
< / p >
< p >
Currently libvirt does not support notification when the
watchdog fires. This feature is planned for a future version of
libvirt.
< / p >
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< watchdog model='i6300esb'/>
< /devices>
...< / pre >
2009-10-21 16:26:38 +04:00
2010-02-04 17:27:52 +03:00
< pre >
...
< devices>
< watchdog model='i6300esb' action='poweroff'/>
< /devices>
< /domain> < / pre >
2009-10-21 16:26:38 +04:00
< dl >
< dt > < code > model< / code > < / dt >
< dd >
2009-11-06 18:04:19 +03:00
< p >
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The required < code > model< / code > attribute specifies what real
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watchdog device is emulated. Valid values are specific to the
underlying hypervisor.
< / p >
< p >
QEMU and KVM support:
< / p >
< ul >
< li > 'i6300esb' — the recommended device,
emulating a PCI Intel 6300ESB < / li >
< li > 'ib700' — emulating an ISA iBase IB700 < / li >
< / ul >
2009-10-21 16:26:38 +04:00
< / dd >
< dt > < code > action< / code > < / dt >
< dd >
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< p >
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The optional < code > action< / code > attribute describes what
2009-11-06 18:04:19 +03:00
action to take when the watchdog expires. Valid values are
specific to the underlying hypervisor.
< / p >
< p >
QEMU and KVM support:
< / p >
< ul >
< li > 'reset' — default, forcefully reset the guest< / li >
< li > 'shutdown' — gracefully shutdown the guest
(not recommended) < / li >
< li > 'poweroff' — forcefully power off the guest< / li >
< li > 'pause' — pause the guest< / li >
< li > 'none' — do nothing< / li >
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< li > 'dump' — automatically dump the guest
< span class = "since" > Since 0.8.7< / span > < / li >
2009-11-06 18:04:19 +03:00
< / ul >
< p >
2010-12-10 08:52:11 +03:00
Note 1: the 'shutdown' action requires that the guest
2009-11-06 18:04:19 +03:00
is responsive to ACPI signals. In the sort of situations
where the watchdog has expired, guests are usually unable
to respond to ACPI signals. Therefore using 'shutdown'
is not recommended.
< / p >
2010-12-10 08:52:11 +03:00
< p >
Note 2: the directory to save dump files can be configured
by < code > auto_dump_path< / code > in file /etc/libvirt/qemu.conf.
< / p >
2009-10-21 16:26:38 +04:00
< / dd >
< / dl >
2010-07-21 14:53:56 +04:00
< h4 > < a name = "elementsMemBalloon" > Memory balloon device< / a > < / h4 >
< p >
A virtual memory balloon device is added to all Xen and KVM/QEMU
guests. It will be seen as < code > memballoon< / code > element.
It will be automatically added when appropriate, so there is no
need to explicitly add this element in the guest XML unless a
specific PCI slot needs to be assigned.
< span class = "since" > Since 0.8.3, Xen, QEMU and KVM only< / span >
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Additionally, < span class = "since" > since 0.8.4< / span > , if the
memballoon device needs to be explicitly disabled,
< code > model='none'< / code > may be used.
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< / p >
< p >
Example automatically added device with KVM
< / p >
< pre >
...
< devices>
< memballoon model='virtio'/>
< /devices>
...< / pre >
< p >
Example manually added device with static PCI slot 2 requested
< / p >
< pre >
...
< devices>
< watchdog model='virtio'/>
< address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
< /devices>
< /domain> < / pre >
< dl >
< dt > < code > model< / code > < / dt >
< dd >
< p >
The required < code > model< / code > attribute specifies what type
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of balloon device is provided. Valid values are specific to
the virtualization platform
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< / p >
< ul >
< li > 'virtio' — default with QEMU/KVM< / li >
< li > 'xen' — default with Xen< / li >
< / ul >
< / dd >
< / dl >
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< h2 > < a name = "examples" > Example configs< / a > < / h2 >
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< p >
Example configurations for each driver are provide on the
driver specific pages listed below
< / p >
< ul >
< li > < a href = "drvxen.html#xmlconfig" > Xen examples< / a > < / li >
< li > < a href = "drvqemu.html#xmlconfig" > QEMU/KVM examples< / a > < / li >
< / ul >
< / body >
< / html >
