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Reviewed-by: Peter Krempa <pkrempa@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
348 lines
12 KiB
XML
348 lines
12 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html>
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<html xmlns="http://www.w3.org/1999/xhtml">
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<body>
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<h1>libxl hypervisor driver for Xen</h1>
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<ul id="toc"></ul>
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<p>
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The libvirt libxl driver provides the ability to manage virtual
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machines on any Xen release from 4.6.0 onwards.
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</p>
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<h2><a id="project">Project Links</a></h2>
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<ul>
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<li>
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The <a href="https://www.xenproject.org">Xen</a>
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hypervisor on Linux and Solaris hosts
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</li>
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</ul>
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<h2><a id="prereq">Deployment pre-requisites</a></h2>
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<p>
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The libvirt libxl driver uses Xen's libxl API, also known as
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libxenlight, to implement libvirt's hypervisor driver
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functionality. libxl provides a consolidated interface for
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managing a Xen host and its virtual machines, unlike old
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versions of Xen where applications often had to communicate
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with xend, xenstored, and the hypervisor itself via hypercalls.
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With libxl the only pre-requisit is a properly installed Xen
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host with the libxl toolstack running in a service domain
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(often Domain-0).
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</p>
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<h2><a id="uri">Connections to libxl driver</a></h2>
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<p>
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The libvirt libxl driver is a single-instance privileged driver,
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with a driver name of 'xen'. Some example connection URIs for
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the libxl driver are:
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</p>
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<pre>
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xen:///system (local access, direct)
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xen+unix:///system (local access, via daemon)
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xen://example.com/system (remote access, TLS/x509)
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xen+tcp://example.com/system (remote access, SASl/Kerberos)
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xen+ssh://root@example.com/system (remote access, SSH tunnelled)
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</pre>
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<h2><a id="imex">Import and export of libvirt domain XML configs</a></h2>
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<p>
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The libxl driver currently supports three native
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config formats. The first, known as <code>xen-xm</code>, is the
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original Xen virtual machine config format used by the legacy
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xm/xend toolstack. The second, known as <code>xen-sxpr</code>,
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is also one of the original formats that was used by xend's
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legacy HTTP RPC service (<span class='removed'>removed in 5.6.0</span>)
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</p>
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<p>
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The third format is <code>xen-xl</code>, which is the virtual
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machine config format supported by modern Xen. The <code>xen-xl</code>
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format is described in the xl.cfg(5) man page.
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</p>
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<h3><a id="xmlimport">Converting from XM config files to domain XML</a></h3>
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<p>
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The <code>virsh domxml-from-native</code> provides a way to convert an
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existing set of xl, xm, or sxpr config files to libvirt Domain XML,
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which can then be used by libvirt.
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</p>
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<pre>$ virsh -c xen:///system domxml-from-native xen-xm rhel5.cfg
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<domain type='xen'>
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<name>rhel5pv</name>
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<uuid>8f07fe28-753f-2729-d76d-bdbd892f949a</uuid>
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<memory>2560000</memory>
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<currentMemory>307200</currentMemory>
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<vcpu>4</vcpu>
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<bootloader>/usr/bin/pygrub</bootloader>
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<os>
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<type arch='x86_64' machine='xenpv'>linux</type>
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</os>
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<clock offset='utc'/>
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<on_poweroff>destroy</on_poweroff>
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<on_reboot>restart</on_reboot>
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<on_crash>restart</on_crash>
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<devices>
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<disk type='file' device='disk'>
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<driver name='tap' type='aio'/>
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<source file='/var/lib/xen/images/rhel5pv.img'/>
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<target dev='xvda' bus='xen'/>
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</disk>
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<disk type='file' device='disk'>
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<driver name='tap' type='qcow'/>
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<source file='/root/qcow1-xen.img'/>
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<target dev='xvdd' bus='xen'/>
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</disk>
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<interface type='bridge'>
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<mac address='00:16:3e:60:36:ba'/>
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<source bridge='xenbr0'/>
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</interface>
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<console type='pty'>
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<target port='0'/>
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</console>
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<input type='mouse' bus='xen'/>
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<graphics type='vnc' port='-1' autoport='yes' listen='0.0.0.0'/>
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</devices>
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</domain></pre>
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<h3><a id="xmlexport">Converting from domain XML to XM config files</a></h3>
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<p>
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The <code>virsh domxml-to-native</code> provides a way to convert a
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guest description using libvirt Domain XML into xl, xm, or sxpr config
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format.
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</p>
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<pre>$ virsh -c xen:///system domxml-to-native xen-xm rhel5pv.xml
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name = "rhel5pv"
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uuid = "8f07fe28-753f-2729-d76d-bdbd892f949a"
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maxmem = 2500
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memory = 300
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vcpus = 4
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bootloader = "/usr/bin/pygrub"
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kernel = "/var/lib/xen/boot_kernel.0YK-cS"
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ramdisk = "/var/lib/xen/boot_ramdisk.vWgrxK"
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extra = "ro root=/dev/VolGroup00/LogVol00 rhgb quiet"
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on_poweroff = "destroy"
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on_reboot = "restart"
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on_crash = "restart"
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sdl = 0
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vnc = 1
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vncunused = 1
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vnclisten = "0.0.0.0"
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disk = [ "tap:aio:/var/lib/xen/images/rhel5pv.img,xvda,w", "tap:qcow:/root/qcow1-xen.img,xvdd,w" ]
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vif = [ "mac=00:16:3e:60:36:ba,bridge=virbr0,script=vif-bridge,vifname=vif5.0" ]</pre>
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<h2><a id="xencommand">Pass-through of arbitrary command-line arguments
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to the qemu device model</a></h2>
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<p><span class="since">Since 6.7.0</span>, the Xen driver supports passing
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arbitrary command-line arguments to the qemu device model used by Xen with
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the <code><xen:commandline></code> element under <code>domain</code>.
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In order to use command-line pass-through, an XML namespace request must be
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issued that pulls in <code>http://libvirt.org/schemas/domain/xen/1.0</code>.
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With the namespace in place, it is then possible to add
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<code><xen:arg></code>sub-elements to
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<code><xen:commandline></code> describing each argument passed to
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the device model when starting the domain.
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</p>
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<p>The following example illustrates passing arguments to the QEMU device
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model that define a floppy drive, which Xen does not support through its
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public APIs:
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</p>
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<pre>
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<domain type="xen" xmlns:xen="http://libvirt.org/schemas/domain/xen/1.0">
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...
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<xen:commandline>
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<xen:arg value='-drive'/>
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<xen:arg value='file=/path/to/image,format=raw,if=none,id=drive-fdc0-0-0'/>
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<xen:arg value='-global'/>
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<xen:arg value='isa-fdc.driveA=drive-fdc0-0-0'/>
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</xen:commandline>
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</domain>
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</pre>
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<h2><a id="xmlconfig">Example domain XML config</a></h2>
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<p>
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Below are some example XML configurations for Xen guest domains.
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For full details of the available options, consult the <a href="formatdomain.html">domain XML format</a>
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guide.
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</p>
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<h3>Paravirtualized guest bootloader</h3>
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<p>
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Using a bootloader allows a paravirtualized guest to be booted using
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a kernel stored inside its virtual disk image
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</p>
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<pre><domain type='xen' >
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<name>fc8</name>
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<bootloader>/usr/bin/pygrub</bootloader>
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<os>
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<type>linux</type>
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</os>
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<memory>131072</memory>
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<vcpu>1</vcpu>
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<devices>
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<disk type='file'>
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<source file='/var/lib/xen/images/fc4.img'/>
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<target dev='sda1'/>
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</disk>
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<interface type='bridge'>
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<source bridge='xenbr0'/>
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<mac address='aa:00:00:00:00:11'/>
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<script path='/etc/xen/scripts/vif-bridge'/>
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</interface>
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<console tty='/dev/pts/5'/>
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</devices>
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</domain></pre>
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<h3>Paravirtualized guest direct kernel boot</h3>
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<p>
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For installation of paravirtualized guests it is typical to boot the
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domain using a kernel and initrd stored in the host OS
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</p>
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<pre><domain type='xen' >
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<name>fc8</name>
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<os>
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<type>linux</type>
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<kernel>/var/lib/xen/install/vmlinuz-fedora8-x86_64</kernel>
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<initrd>/var/lib/xen/install/initrd-vmlinuz-fedora8-x86_64</initrd>
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<cmdline> kickstart=http://example.com/myguest.ks </cmdline>
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</os>
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<memory>131072</memory>
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<vcpu>1</vcpu>
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<devices>
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<disk type='file'>
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<source file='/var/lib/xen/images/fc4.img'/>
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<target dev='sda1'/>
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</disk>
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<interface type='bridge'>
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<source bridge='xenbr0'/>
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<mac address='aa:00:00:00:00:11'/>
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<script path='/etc/xen/scripts/vif-bridge'/>
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</interface>
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<graphics type='vnc' port='-1'/>
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<console tty='/dev/pts/5'/>
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</devices>
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</domain></pre>
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<h3>Fullyvirtualized guest BIOS boot</h3>
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<p>
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Fullyvirtualized guests use the emulated BIOS to boot off the primary
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harddisk, CDROM or Network PXE ROM.
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</p>
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<pre><domain type='xen' id='3'>
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<name>fv0</name>
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<uuid>4dea22b31d52d8f32516782e98ab3fa0</uuid>
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<os>
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<type>hvm</type>
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<loader>/usr/lib/xen/boot/hvmloader</loader>
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<boot dev='hd'/>
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</os>
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<memory>524288</memory>
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<vcpu>1</vcpu>
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<on_poweroff>destroy</on_poweroff>
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<on_reboot>restart</on_reboot>
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<on_crash>restart</on_crash>
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<features>
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<pae/>
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<acpi/>
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<apic/>
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</features>
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<clock sync="localtime"/>
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<devices>
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<emulator>/usr/lib/xen/bin/qemu-dm</emulator>
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<interface type='bridge'>
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<source bridge='xenbr0'/>
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<mac address='00:16:3e:5d:c7:9e'/>
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<script path='vif-bridge'/>
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</interface>
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<disk type='file'>
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<source file='/var/lib/xen/images/fv0'/>
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<target dev='hda'/>
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</disk>
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<disk type='file' device='cdrom'>
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<source file='/var/lib/xen/images/fc5-x86_64-boot.iso'/>
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<target dev='hdc'/>
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<readonly/>
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</disk>
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<disk type='file' device='floppy'>
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<source file='/root/fd.img'/>
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<target dev='fda'/>
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</disk>
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<graphics type='vnc' port='5904'/>
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</devices>
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</domain></pre>
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<h3>Fullyvirtualized guest direct kernel boot</h3>
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<p>
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With Xen 3.2.0 or later it is possible to bypass the BIOS and directly
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boot a Linux kernel and initrd as a fullyvirtualized domain. This allows
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for complete automation of OS installation, for example using the Anaconda
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kickstart support.
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</p>
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<pre><domain type='xen' id='3'>
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<name>fv0</name>
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<uuid>4dea22b31d52d8f32516782e98ab3fa0</uuid>
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<os>
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<type>hvm</type>
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<loader>/usr/lib/xen/boot/hvmloader</loader>
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<kernel>/var/lib/xen/install/vmlinuz-fedora8-x86_64</kernel>
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<initrd>/var/lib/xen/install/initrd-vmlinuz-fedora8-x86_64</initrd>
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<cmdline> kickstart=http://example.com/myguest.ks </cmdline>
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</os>
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<memory>524288</memory>
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<vcpu>1</vcpu>
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<on_poweroff>destroy</on_poweroff>
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<on_reboot>restart</on_reboot>
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<on_crash>restart</on_crash>
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<features>
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<pae/>
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<acpi/>
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<apic/>
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</features>
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<clock sync="localtime"/>
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<devices>
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<emulator>/usr/lib/xen/bin/qemu-dm</emulator>
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<interface type='bridge'>
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<source bridge='xenbr0'/>
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<mac address='00:16:3e:5d:c7:9e'/>
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<script path='vif-bridge'/>
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</interface>
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<disk type='file'>
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<source file='/var/lib/xen/images/fv0'/>
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<target dev='hda'/>
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</disk>
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<disk type='file' device='cdrom'>
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<source file='/var/lib/xen/images/fc5-x86_64-boot.iso'/>
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<target dev='hdc'/>
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<readonly/>
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</disk>
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<disk type='file' device='floppy'>
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<source file='/root/fd.img'/>
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<target dev='fda'/>
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</disk>
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<graphics type='vnc' port='5904'/>
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</devices>
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</domain></pre>
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</body>
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</html>
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