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29 lines
4.8 KiB
HTML
29 lines
4.8 KiB
HTML
<?xml version="1.0" encoding="ISO-8859-1"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /><link rel="SHORTCUT ICON" href="/favicon.ico" /><style type="text/css">
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TD {font-family: Verdana,Arial,Helvetica}
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BODY {font-family: Verdana,Arial,Helvetica; margin-top: 2em; margin-left: 0em; margin-right: 0em}
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H1 {font-family: Verdana,Arial,Helvetica}
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H2 {font-family: Verdana,Arial,Helvetica}
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H3 {font-family: Verdana,Arial,Helvetica}
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A:link, A:visited, A:active { text-decoration: underline }
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</style><title>libvir architecture</title></head><body bgcolor="#8b7765" text="#000000" link="#a06060" vlink="#000000"><table border="0" width="100%" cellpadding="5" cellspacing="0" align="center"><tr><td width="120"><a href="http://www.redhat.com/"><img src="redhat.gif" alt="Red Hat Logo" /></a></td><td><table border="0" width="90%" cellpadding="2" cellspacing="0" align="center" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3" bgcolor="#fffacd"><tr><td align="center"><h1>Libvir the virtualization API</h1><h2>libvir architecture</h2></td></tr></table></td></tr></table></td></tr></table><table border="0" cellpadding="4" cellspacing="0" width="100%" align="center"><tr><td bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td valign="top" width="200" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Main Menu</b></center></td></tr><tr><td bgcolor="#fffacd"><form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="20" value="" /><input name="submit" type="submit" value="Search ..." /></form><ul><li><a href="index.html">Home</a></li><li><a href="news.html">Releases</a></li><li><a href="intro.html">Introduction</a></li><li><a href="architecture.html">libvir architecture</a></li><li><a href="downloads.html">Downloads</a></li><li><a href="FAQ.html">FAQ</a></li><li><a href="bugs.html">Reporting bugs and getting help</a></li><li><a style="font-weight:bold" href="html/index.html">API Menu</a></li><li><a href="ChangeLog.html">Recent Changes</a></li></ul></td></tr></table><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr><tr><td bgcolor="#fffacd"><ul><li><a href="https://www.redhat.com/archives/libvir-list/">Mail archive</a></li><li><a href="http://www.cl.cam.ac.uk/Research/SRG/netos/xen/index.html">Xen project</a></li></ul></td></tr></table></td></tr></table><a href="http://xmlsoft.org/"><img src="Libxml2-Logo-90x34.gif" alt="Made with Libxml2 Logo" /></a></td><td valign="top" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%"><tr><td><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table border="0" cellpadding="3" cellspacing="1" width="100%"><tr><td bgcolor="#fffacd"><p>In a Xen environment, program using libvir have to execute in "Domain 0",
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which is the primary Linux OS loaded on the machine. That OS kernel provides
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most if not all of the actual drivers used by the set of domains. It also
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runs the Xen Store, a database of informations shared by the hypervisor, the
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kernels, the drivers and the xen daemon. Xend, the xen daemon, also runs in
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Domain0 and supervise the control and execution of the sets of domains. The
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hypervisor, drivers, kernels and daemons communicate though a shared system
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bus implemented in the hypervisor. The figure below tries to provide a view
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of this environment: </p><img src="architecture.gif" alt="The Xen architecture" /><p>The library can be initialized in 2 ways depending on the level of
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priviledge of the embedding program. If it runs with root access,
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virConnectOpen() can be used, it will use a read/write connection to the Xen
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Store and use Xen Hypervisor calls when possible. If it runs without root
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access virConnectOpenReadOnly() should be used, it will try to open the
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read-only socket <code>/var/run/xenstored/socket_ro</code> to connect to the
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Xen Store. In this case use of hypervisor calls and write to the Xen Store
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will not be possible, restraining the amount of APIs available and slowing
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down information gathering about domains. We expect libvir will also conmnect
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to the Xend daemon for some of the domain control operations, though this is
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not the case in the 0.0.1 initial version.</p><p><a href="bugs.html">Daniel Veillard</a></p></td></tr></table></td></tr></table></td></tr></table></td></tr></table></td></tr></table></body></html>
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