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05dd67417f
Based on a patch originally authored by Daniel De Graaf http://lists.xen.org/archives/html/xen-devel/2012-05/msg00565.html This patch converts the Xen libxl driver to support only Xen >= 4.2. Support for Xen 4.1 libxl is dropped since that version of libxl is designated 'technology preview' only and is incompatible with Xen 4.2 libxl. Additionally, the default toolstack in Xen 4.1 is still xend, for which libvirt has a stable, functional driver. (cherry picked from commitdfa1e1dd53) Conflicts: src/libxl/libxl_conf.c - commit e5e8d5 not backported src/libxl/libxl_driver.c - commit1c04f99not backported
339 lines
12 KiB
HTML
339 lines
12 KiB
HTML
<html>
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<body>
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<h1>Xen hypervisor driver</h1>
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<ul id="toc"></ul>
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<p>
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The libvirt Xen driver provides the ability to manage virtual machines
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on any Xen release from 3.0.1 onwards.
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</p>
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<h2><a name="project">Project Links</a></h2>
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<ul>
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<li>
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The <a href="http://www.cl.cam.ac.uk/Research/SRG/netos/xen/index.html">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 name="prereq">Deployment pre-requisites</a></h2>
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<p>
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The libvirt Xen driver uses a combination of channels to manage Xen
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virtual machines.
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</p>
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<ul>
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<li>
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<strong>XenD</strong>: Access to the Xen daemon is a mandatory
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requirement for the libvirt Xen driver. It requires that the UNIX
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socket interface be enabled in the <code>/etc/xen/xend-config.sxp</code>
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configuration file. Specifically the config settings
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<code>(xend-unix-server yes)</code>. This path is usually restricted
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to only allow the <code>root</code> user access. As an alternative,
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the HTTP interface can be used, however, this has significant security
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implications.
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</li>
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<li>
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<strong>XenStoreD</strong>: Access to the Xenstore daemon enables
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more efficient codepaths for looking up domain information which
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lowers the CPU overhead of management.
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</li>
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<li>
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<strong>Hypercalls</strong>: The ability to make direct hypercalls
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allows the most efficient codepaths in the driver to be used for
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monitoring domain status.
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</li>
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<li>
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<strong>XM config</strong>: When using Xen releases prior to 3.0.4,
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there is no inactive domain management in XenD. For such releases,
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libvirt will automatically process XM configuration files kept in
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the <code>/etc/xen</code> directory. It is important not to place
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any other non-config files in this directory.
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</li>
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<li>
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<strong>libxl</strong>: Starting with Xen 4.2, the legacy XenD/xm
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toolstack is deprecated in favor of libxl, also commonly called
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libxenlight. libvirt supports this new Xen toolstack via the
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libxl driver. If XenD is enabled, the legacy xen driver consisting
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of the above mentioned channels will be used. If XenD is disabled,
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the libxl driver will be used.
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</li>
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</ul>
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<h2><a name="uri">Connections to Xen driver</a></h2>
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<p>
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The libvirt Xen 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 libvirt driver are:
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</p>
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<pre>
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xen:/// (local access, direct)
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xen+unix:/// (local access, via daemon)
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xen://example.com/ (remote access, TLS/x509)
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xen+tcp://example.com/ (remote access, SASl/Kerberos)
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xen+ssh://root@example.com/ (remote access, SSH tunnelled)
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</pre>
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<h2><a name="imex">Import and export of libvirt domain XML configs</a></h2>
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<p>The Xen driver currently supports two native
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config formats. The first known as <code>xen-xm</code> is the format
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used by the XM tool for files in <code>/etc/xen</code>. The second
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known as <code>xen-sxpr</code>, is the format used for interacting
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with the XenD's legacy HTTP RPC service.</p>
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<h3><a name="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 XM config files into a guest description using libvirt Domain XML
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that can then be used by libvirt.
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</p>
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<pre>$ virsh -c xen:/// 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 name="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 the XM config file
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format.
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</p>
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<pre>$ virsh -c xen:/// 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 name="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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