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docs: update Xen driver information

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Now that the old Xen driver is removed, update the drvxen
page with current information on the libxl drvier and remove
all the old cruft.

Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Jim Fehlig 2018-04-06 13:54:09 -06:00
parent bdb6ba0fad
commit 990dd4b356
1 changed files with 35 additions and 56 deletions
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91
docs/drvxen.html.in
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@ -2,20 +2,20 @@
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<body>
<h1>Xen hypervisor driver</h1>
<h1>libxl hypervisor driver for Xen</h1>
<ul id="toc"></ul>
<p>
The libvirt Xen driver provides the ability to manage virtual machines
on any Xen release from 3.0.1 onwards.
The libvirt libxl driver provides the ability to manage virtual
machines on any Xen release from 4.4.0 onwards.
</p>
<h2><a id="project">Project Links</a></h2>
<ul>
<li>
The <a href="http://www.cl.cam.ac.uk/Research/SRG/netos/xen/index.html">Xen</a>
The <a href="https://www.xenproject.org">Xen</a>
hypervisor on Linux and Solaris hosts
</li>
</ul>
@ -23,54 +23,23 @@
<h2><a id="prereq">Deployment pre-requisites</a></h2>
<p>
The libvirt Xen driver uses a combination of channels to manage Xen
virtual machines.
The libvirt libxl driver uses Xen's libxl API, also known as
libxenlight, to implement libvirt's hypervisor driver
functionality. libxl provides a consolidated interface for
managing a Xen host and its virtual machines, unlike old
versions of Xen where applications often had to communicate
with xend, xenstored, and the hypervisor itself via hypercalls.
With libxl the only pre-requisit is a properly installed Xen
host with the libxl toolstack running in a service domain
(often Domain-0).
</p>
<ul>
<li>
<strong>XenD</strong>: Access to the Xen daemon is a mandatory
requirement for the libvirt Xen driver. It requires that the UNIX
socket interface be enabled in the <code>/etc/xen/xend-config.sxp</code>
configuration file. Specifically the config settings
<code>(xend-unix-server yes)</code>. This path is usually restricted
to only allow the <code>root</code> user access. As an alternative,
the HTTP interface can be used, however, this has significant security
implications.
</li>
<li>
<strong>XenStoreD</strong>: Access to the Xenstore daemon enables
more efficient codepaths for looking up domain information which
lowers the CPU overhead of management.
</li>
<li>
<strong>Hypercalls</strong>: The ability to make direct hypercalls
allows the most efficient codepaths in the driver to be used for
monitoring domain status.
</li>
<li>
<strong>XM config</strong>: When using Xen releases prior to 3.0.4,
there is no inactive domain management in XenD. For such releases,
libvirt will automatically process XM configuration files kept in
the <code>/etc/xen</code> directory. It is important not to place
any other non-config files in this directory.
</li>
<li>
<strong>libxl</strong>: Starting with Xen 4.2, the legacy XenD/xm
toolstack is deprecated in favor of libxl, also commonly called
libxenlight. libvirt supports this new Xen toolstack via the
libxl driver. If XenD is enabled, the legacy xen driver consisting
of the above mentioned channels will be used. If XenD is disabled,
the libxl driver will be used.
</li>
</ul>
<h2><a id="uri">Connections to Xen driver</a></h2>
<h2><a id="uri">Connections to libxl driver</a></h2>
<p>
The libvirt Xen driver is a single-instance privileged driver,
with a driver name of 'xen'. Some example connection URIs for
the libvirt driver are:
The libvirt libxl driver is a single-instance privileged driver,
with a driver name of 'xen'. Some example connection URIs for
the libxl driver are:
</p>
<pre>
@ -83,18 +52,28 @@ xen+ssh://root@example.com/ (remote access, SSH tunnelled)
<h2><a id="imex">Import and export of libvirt domain XML configs</a></h2>
<p>The Xen driver currently supports two native
config formats. The first known as <code>xen-xm</code> is the format
used by the XM tool for files in <code>/etc/xen</code>. The second
known as <code>xen-sxpr</code>, is the format used for interacting
with the XenD's legacy HTTP RPC service.</p>
<p>
The libxl driver currently supports three native
config formats. The first, known as <code>xen-xm</code>, is the
original Xen virtual machine config format used by the legacy
xm/xend toolstack. The second, known as <code>xen-sxpr</code>,
is also one of the original formats that was used by xend's
legacy HTTP RPC service. For compatibility, import and export
of these legacy formats is supported by the libxl driver.
</p>
<p>
The third format is <code>xen-xl</code>, which is the virtual
machine config format supported by modern Xen. The <code>xen-xl</code>
format is described in the xl.cfg(5) man page.
</p>
<h3><a id="xmlimport">Converting from XM config files to domain XML</a></h3>
<p>
The <code>virsh domxml-from-native</code> provides a way to convert an
existing set of XM config files into a guest description using libvirt Domain XML
that can then be used by libvirt.
existing set of xl, xm, or sxpr config files to libvirt Domain XML,
which can then be used by libvirt.
</p>
<pre>$ virsh -c xen:/// domxml-from-native xen-xm rhel5.cfg
@ -139,7 +118,7 @@ xen+ssh://root@example.com/ (remote access, SSH tunnelled)
<p>
The <code>virsh domxml-to-native</code> provides a way to convert a
guest description using libvirt Domain XML, into the XM config file
guest description using libvirt Domain XML into xl, xm, or sxpr config
format.
</p>