Attachment 101602 Details for Bug 105177 – /doc/en/draft/xen.xml

/doc/en/draft/xen.xml

xen.xml (text/plain), 7.70 KB, created by Jan Kundrát (RETIRED) on 2006-11-10 06:51:47 UTC

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><?xml version='1.0' encoding='UTF-8'?>
>
><!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
>
><guide link="/doc/en/draft/xen.xml" disclaimer="draft">
>
><title>Xen Paravirtualization under Gentoo</title>
>
><author title="Author">
> <mail link="jkt@gentoo.org">Jan KundrÃ¡t</mail>
></author>
>
><abstract>
>This guide shows you how to get Xen up and running on your Gentoo box.
></abstract>
>
>
>
><license/>
>
><version>1</version>
><date>2006-11-10</date>
>
><chapter>
><title>Introduction</title>
><section>
><body>
>
><impo>
>This guide is currently x86-centric as that's the platform I've set up the Xen
>on. It'd be great if someone adds notes about using Xen on different platforms.
></impo>
>
>
>Before we into the installation and configuration of the virtual machine, we
>should explain some basic terms that are quite common in the world of Xen.
>
>
><dl>
> <dt>Domain</dt>
> <dd>An instance of your "virtual computer", running its own kernel and user
> level applications</dd>
> <dt>Dom0</dt>
> <dd>The "primary" domain that is running all the time and is usually
> responsible for things like setting up another domains and other management
> tasks. It's "automatically" launched by the Xen hypervisor during the boot
> process. When the dom0 exists, Xen by default reboots the machine.
> </dd>
> <dt>DomU</dt>
> <dd>"Regular" instances of the unprivileged virtual machines. Each of them can
> be running different kernel version with wildly differing userspace
> environment, even another operating system.
> </dd>
> <dt>Hypervisor</dt>
> <dd>A Xen-supplied software that runs at the "bare metal" of your computer and
> is responsible for low-level tasks like CPU scheduling, memory management and
> dom0 launching upon boot.
> </dd>
></dl>
>
>
>Xen comes with extensive <uri
>link="http://www.cl.cam.ac.uk/research/srg/netos/xen/documentation.html">documetnation</uri>.
>It's a good idea to read through it to get familiar with its internal structure
>as it's out of scope of this guide.
>
>
></body>
></section>
></chapter>
><chapter>
><title>Installing Xen</title>
><section>
><title>Installation of necessary packages</title>
><body>
>
>
>Installing the Xen hypervisor under Gentoo is a breeze, as usually :). The
>following will install both the hypervisor and a userspace management tools:
>
>
><pre caption="Installing the Xen hypervisor">
># emerge app-emulation/xen
></pre>
>
>
>As Xen requires a modified kernel, at least for domain0, you'll have to install
>patched kernel sources, unless you choose to manage them manually. It's
>generally not a good idea, so we suggest just plain old boring installation of 
>the <c>sys-kernel/xen-sources</c> package:
>
>
><pre caption="Installing Xen-patched kernel sources">
># emerge sys-kernel/xen-sources
></pre>
>
></body>
></section>
><section>
><title>Building the Xen-patched kernel</title>
><body>
>
><impo>
>FIXME: add blurb about genkernel stuff
></impo>
>
>
>If you choose to configure and build the kernel yourself (which isn't a bad idea
>at all), you'll notice some differences from the <uri
>link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7#doc_chap3">general
>instructions</uri>. 
>
>
>
>As Xen requires each domain to have its own kernel image loaded into memory, you
>usually want to strip the domU kernels to the bare minimum that's required for a
>proper function. Unlike the dom0 which is generally responsible for tasks like
>I/O to hard drives, networking stuff and graphics output, the domUs don't
>require to worry about your HW devices at all. There's simply no need to include
>a driver for your SCSI controller into domU kernel as it's already handled by
>dom0.
>
>
><note>
>Xen itself supports a delegating of some device directly to the domU instance.
>You can, for example, have a domain with a dedicated NIC or another one handling
>a TV-capture card. Such setups, usually called Driver Domains, are out of
>scope of this guide, so you should better consult the <uri
>link="http://wiki.xensource.com/xenwiki/DriverDomain">Xen wiki page</uri> and/or
>the official documentation.
></note>
>
>
>As we have installed only one kernel source package, we'll have to create a
>directory where the different kernels are to be built. Let's start with the
>dom0. Please substitute <c>2.6.16.28</c> with the version of <c>xen-sources</c>
>you've installed earlier.
>
>
><pre caption="Preparing the build environment">
># mkdir -p ~/xen-build/2.6.16.28-dom0
></pre>
>
>
>Now you should configure the kernel for dom0. Please note that there are some
>differences from the general kernel config and don't forget to customize the
>examples according to your needs, especially with regard to kernel versions and
>file paths.
>
>
><pre caption="Configuring the dom0 kernel">
># cd /usr/src/linux-2.6.16.28-xen
># make O=~/xen-build/2.6.16.28-dom0 menuconfig
></pre>
>
>
>Here are the most importand Xen-related settings that should take care about:
>
>
><pre caption="dom0 configuration">
>General setup ---&gt;
> Local version - append to kernel release
> <comment>(It's a good idea to set it to "-dom0" in order to distinguish between the dom0 and domU kernel images)</comment>
>
>Processor type and features ---&gt;
> Subarchitecture Type
> (<comment>Set to "Xen-compatible"</comment>)
>
>XEN ---&gt;
> [*] Privileged Guest (domain 0)
> &lt;*&gt; PCI device backend driver
> &lt;*&gt; Block-device backend driver
> <comment>(You usually want your domUs to be able to access some kind of storage :) )</comment>
> &lt;*&gt; Network-device backend driver
> &lt;*&gt; Network-device loopback driver
> &lt; &gt; TPM-device backend driver
> &lt; &gt; Block-device frontend driver
> &lt; &gt; Network-device frontend driver
> &lt; &gt; Block device tap driver
> &lt; &gt; TPM-device frontend driver
> [*] Scrub memory before freeing it to Xen
> [*] Disable serial port drivers
> &lt;*&gt; Export Xen attributes in sysfs
>
><comment>FIXME: add a blurb about various config options and their meaning</comment>
></pre>
>
>
>Now thaty you've configured your dom0 kernel, it's time to build it. Standard
><c>make</c> suggestions like <c>-j3</c> when on a two-way SMP systems apply here
>as well.
>
>
><pre caption="Building a dom0 kernel">
># make O=~/xen-build/2.6.16.28-dom0
>
><comment>(Only if you've included module support:)</comment>
># make O=~/xen-build/2.6.16.28-dom0 modules modules_install
></pre>
>
>
>Now let's install your dom0 kernel image to the <path>/boot</path> directory and 
>ask your favourite bootloader to use the new image instead of an old and 
>not-so-sexy virtualization-unaware Linux kernel.
>
>
><pre caption="Installing the required images into /boot">
># cp ~/xen-build/2.6.16.28-dom0/vmlinuz /boot/linux-2.6.16.28-xen0-vmlinuz
></pre>
>
><note>
>FIXME: when you use LILO, you're screwed as I haven't worked with it. Just go
>and search the web, I'm sure you'll find a manual about how to set it up.
></note>
>
><pre caption="Editting the /boot/grub/grub.conf">
><comment>(Please make sure you include the correct names of the Xen and kernel images:)</comment>
>
># Example Xen settings for Grub
>title=Xen-3.0.2, Linux 2.6.16.28
>kernel /boot/xen-3.0.2.gz dom0_mem=64M
>module /boot/linux-2.6.16.28-xen0-vmlinuz &lt;&lt;your-regular-kernel-options-go-here&gt;&gt;
></pre>
>
>
>After you've double-checked that everything at least seems to be okay
>and/or that you have console access to the box being Xenized, try to reboot it.
>If it comes back up, chances are that you can proceed with the real joy,
>creating virtual domains.
>
>
></body>
></section>
><section>
><title>Ttroubleshooting</title>
><body>
>
>TODO
>
></body>
></section>
></chapter>
></guide>

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