libvirt/docs/architecture.html

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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="stylesheet" type="text/css" href="libvir.css" /><title>libvir architecture</title></head><body><div id="container"><div id="intro"><div id="adjustments"></div><div id="pageHeader"></div><div id="content2"><h1 class="style1">libvir architecture</h1><p>In a Xen environment, programs using libvir have to execute in "Domain 0",
which is the primary Linux OS loaded on the machine. That OS kernel provides
most if not all of the actual drivers used by the set of domains. It also
runs the Xen Store, a database of informations shared by the hypervisor, the
kernels, the drivers and the xen daemon. Xend, the xen daemon, also runs in
Domain0 and supervise the control and execution of the sets of domains. The
hypervisor, drivers, kernels and daemons communicate though a shared system
bus implemented in the hypervisor. The figure below tries to provide a view
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
priviledge of the embedding program. If it runs with root access,
virConnectOpen() can be used, it will use three different ways to connect to
the Xen infrastructure:</p><ul><li>a connection to the Xen Daemon though an HTTP RPC layer</li>
  <li>a read/write connection to the Xen Store</li>
  <li>use Xen Hypervisor calls</li>
</ul><p> If it runs without root access virConnectOpenReadOnly() should be used,
it will try to open the read-only socket
<code>/var/run/xenstored/socket_ro</code> to connect to the Xen Store and
also try to use the RPC to the Xen daemon. In this case use of hypervisor
calls and write to the Xen Store will not be possible, restraining the amount
of APIs available and slowing down information gathering about domains. </p></div></div><div class="linkList2"><div class="llinks2"><h3 class="links2"><span>main menu</span></h3><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></div><div class="llinks2"><h3 class="links2"><span>related links</span></h3><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><li><form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="12" value="Search..." /><input name="submit" type="submit" value="Go" /></form></li><li><a href="http://xmlsoft.org/"><img src="Libxml2-Logo-90x34.gif" alt="Made with Libxml2 Logo" /></a></li></ul></div></div><div id="bottom"><p class="p1"></p></div></div></body></html>
* docs/*: extended the documentation Daniel 2005-12-09 13:04:05 +00:00			`<?xml version="1.0" encoding="ISO-8859-1"?>`
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* doc//*: mostly finished the revamp in the plane, starts to look good Daniel 2006-01-21 23:34:36 +00:00			`<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /><link rel="stylesheet" type="text/css" href="libvir.css" /><title>libvir architecture</title></head><body><div id="container"><div id="intro"><div id="adjustments"></div><div id="pageHeader"></div><div id="content2"><h1 class="style1">libvir architecture</h1><p>In a Xen environment, programs using libvir have to execute in "Domain 0",`
* docs/architecture.* docs/*: added a section on the architecture and regenerated the docs. Daniel 2005-12-21 16:59:34 +00:00			`which is the primary Linux OS loaded on the machine. That OS kernel provides`
			`most if not all of the actual drivers used by the set of domains. It also`
			`runs the Xen Store, a database of informations shared by the hypervisor, the`
			`kernels, the drivers and the xen daemon. Xend, the xen daemon, also runs in`
			`Domain0 and supervise the control and execution of the sets of domains. The`
			`hypervisor, drivers, kernels and daemons communicate though a shared system`
			`bus implemented in the hypervisor. The figure below tries to provide a view`
* doc/*: started to augment and update the documentation Daniel 2006-01-22 16:27:09 +00:00			`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`
* docs/architecture.* docs/*: added a section on the architecture and regenerated the docs. Daniel 2005-12-21 16:59:34 +00:00			`priviledge of the embedding program. If it runs with root access,`
* doc/*: started to augment and update the documentation Daniel 2006-01-22 16:27:09 +00:00			`virConnectOpen() can be used, it will use three different ways to connect to`
			`the Xen infrastructure:</p><ul><li>a connection to the Xen Daemon though an HTTP RPC layer</li>`
			`<li>a read/write connection to the Xen Store</li>`
			`<li>use Xen Hypervisor calls</li>`
			`</ul><p> If it runs without root access virConnectOpenReadOnly() should be used,`
			`it will try to open the read-only socket`
			`<code>/var/run/xenstored/socket_ro</code> to connect to the Xen Store and`
			`also try to use the RPC to the Xen daemon. In this case use of hypervisor`
			`calls and write to the Xen Store will not be possible, restraining the amount`
			of APIs available and slowing down information gathering about domains. </p></div></div><div class="linkList2"><div class="llinks2"><h3 class="links2"><span>main menu</span></h3><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></div><div class="llinks2"><h3 class="links2"><span>related links</span></h3><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><li><form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="12" value="Search..." /><input name="submit" type="submit" value="Go" /></form></li><li><a href="http://xmlsoft.org/"><img src="Libxml2-Logo-90x34.gif" alt="Made with Libxml2 Logo" /></a></li></ul></div></div><div id="bottom"><p class="p1"></p></div></div></body></html>