doc/en/xen-guide.xml

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/xen-guide.xml,v 1.13 2012/07/24 12:12:51 swift Exp $ -->

<guide disclaimer="draft">
<title>Configuring Gentoo with Xen</title>

<author title="Author">
  <mail link="swift@gentoo.org">Sven Vermeulen</mail>
</author>
<author title="Editor">
  <mail link="nightmorph"/>
</author>

<abstract>
This guide describes how to start using Xen on your Gentoo system
</abstract>

<!-- The content of this document is licensed under the CC-BY-SA license -->
<!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
<license/>

<version>9</version>
<date>2012-10-07</date>

<chapter>
<title>Introduction</title>
<section>
<body>

<p>
The <uri link="http://www.xen.org/">Xen</uri> technology allows you to run
multiple operating systems on a single physical system, govern resource
consumption and even migrate domains (which are the virtual environments in
which a guest operating system runs) from one Xen-powered system to another. Xen
requires the host operating system to support Xen (which, in this case, will be
a Linux kernel) but guest operating systems can run unmodified <e>if</e> your
hardware supports Intel Virtualization Technology (VT-x) or AMD Virtualization
Technology (SVM). Otherwise your guest operating systems must also support Xen.
</p>

<p>
This guide will talk you through the configuration steps necessary to get Xen up
and running on Gentoo Linux. We will not discuss Xen itself (the Xen project has
<uri link="http://xen.org/support/documentation.html">decent documentation</uri>
available) nor will we talk about specialized setups that might be very
interesting for Xen setups but are not Xen-related (like exporting Portage
through NFS, booting Linux using PXE, etc.)
</p>

</body>
</section>
</chapter>
<chapter>
<title>Preparing Domain0</title>
<section>
<title>Introduction</title>
<body>

<p>
<e>Domain0</e> is the primary domain under Xen, hosting the host operating
system which governs all other domains. In this chapter we will prepare an
existing Gentoo installation to become the host operating system in this domain
and build the Xen-powered kernel so that Gentoo is ready to host other Xen
domains.
</p>

</body>
</section>
<section>
<title>Rebuilding the Gentoo Installation?</title>
<body>

<p>
A dramatic change that might be necessary is to rebuild the entire Gentoo
installation with a different <c>CFLAGS</c> setting. Guest operating systems
running under Xen might otherwise see major performance degradation. If you,
however, are planning on checking out Xen rather than installing it for
production use and are not terribly fond of rebuilding all programs, you can
skip this step. In this case you will notice performance degradation but you
will still be able to use Xen.
</p>

<impo>
It is advised that, if you change your <c>CFLAGS</c> and build your system with
a gcc lower than version 4, you do not have <c>-Os</c> set as it has been
reported to produce broken code.
</impo>

<pre caption="Editing the CFLAGS and rebuild the Gentoo installation">
~# <i>nano -w /etc/portage/make.conf</i>
<comment>(Add -mno-tls-direct-seg-refs ONLY if you have a 32-bit dom0)</comment>
<comment>(You don't need this flag if you have a 64-bit dom0)</comment>
CFLAGS="-O2 -march=pentium4 -pipe <i>-mno-tls-direct-seg-refs</i>"

~# <i>emerge -e world</i>
</pre>

<p>
If you boot your system using an initial ramdisk (initrd) you need to
rebuild the initrd as well (which is best done by running all steps you would do
when you rebuild your kernel).
</p>

</body>
</section>
<section>
<title>Installing Xen</title>
<body>

<p>
Xen actually contains many components, so you'll need to install a few
packages.
</p>

<pre caption="Installing Xen">
~# <i>emerge xen xen-tools gentoo-sources</i>
</pre>

</body>
</section>
<section>
<title>Building the Kernel</title>
<body>

<p>
Next we'll build the Linux kernel with Xen support. This kernel, whose sources
are available at <path>/usr/src/linux</path>, will be our main
running kernel (i.e. the one running domain 0). In the <c>XEN</c> section you'll
find drivers for all kinds of input/output, each driver having a <e>backend</e>
and <e>frontend</e> implementation available. For the domain 0 kernel you need
to select the <e>backend</e> implementation: these are used by the other
domains (who use the <e>frontend</e> drivers) to communicate directly with
the hardware. However, you should be able to configure the kernel to provide
support for both frontend (guest) and backend (host) drivers.
</p>

<p>
If you're wondering about networking: each interface in a domain
has a point-to-point link to an interface on domain 0 (called
<path>vifX.Y</path> where X is the domain number and Y the Yth interface of that
domain), so you can configure your network the way you want (bridging, NAT,
etc.)
</p>

<pre caption="Enabling Xen Support">
Processor type and features  ---&gt;
    [*] Paravirtualized guest support ---&gt;
        [*] Xen guest support
</pre>

<pre caption="Kernel Config">
Bus options (PCI etc.)  ---&gt;
    [*] Xen PCI Frontend

[*] Networking support ---&gt;
    Networking options  ---&gt;
        &lt;*&gt; 802.1d Ethernet Bridging
        [*] Network packet filtering framework (Netfilter) ---&gt;
            [*] Advanced netfilter configuration
                [*] Bridged IP/ARP packets filtering

Device Drivers ---&gt;
    [*] Block devices (NEW) ---&gt;
        &lt;*&gt; Xen block-device backend driver
    [*] Network device support ---&gt;
        &lt;*&gt; Xen backend network device
    Xen driver support ---&gt;
        [*] Xen memory balloon driver (NEW)
        [*]   Scrub pages before returning them to system (NEW)
        &lt;*&gt; Xen /dev/xen/evtchn device (NEW)
        [*] Backend driver support (NEW)
        &lt;*&gt; Xen filesystem (NEW)
        [*]   Create compatibility mount point /proc/xen (NEW)
        [*] Create xen entries under /sys/hypervisor (NEW)
        &lt;M&gt; userspace grant access device driver (NEW)
        &lt;M&gt; user-space grant reference allocator driver (NEW)
        &lt;M&gt; xen platform pci device driver (NEW)
</pre>

<p>
The shown kernel configuration should allow the kernel image to boot both as a
host as well as a guest. However, if you want to, you can slim down the guest
image kernel considerably. Refer to the Xen documentation for more information.
</p>

<p>
Once the kernel is built you'll find the kernel image immediately in the
build directory (not inside <path>arch/</path> or any other directory) called
<path>vmlinuz</path>. Copy it to <path>/boot</path> and then configure your
bootloader to use the Xen hypervisor (one of the components installed
previously) which is stored as <path>/boot/xen.gz</path>. In the bootloader
configuration, add your newly built kernel as the kernel that Xen should
boot. For instance, for GRUB:
</p>

<pre caption="GRUB Configuration for Xen">
title Xen Gentoo Linux 3.5
root (hd0,0)
kernel /boot/xen.gz
module /boot/kernel-3.5.x.y-xen0 root=/dev/sda3
</pre>

<p>
Now reboot your system into Xen and check if you can do whatever you
normally do on your system. If this is the case, you can edit your
bootloader configuration to always boot into Xen.
</p>

<note>
If you wish to start guest domains automatically on boot add <c>xendomains</c>
to the default runlevel as well and create a symlink in
<path>/etc/xen/auto/</path> to the Xen configuration files for the domains
you wish to start.
</note>

</body>
</section>
</chapter>
<chapter>
<title>Creating an Unpriviledged Domain</title>
<section>
<title>Building the Kernel</title>
<body>

<p>
Go to the Xen-powered Linux kernel source and, if necessary, update the
configuration. It is wise to keep as many topics as possible similar to
the main kernel. Then build the kernel
and place the resulting <path>vmlinuz</path> file where you want (we assume this
is <path>/mnt/data/xen/kernel</path>):
</p>

<pre caption="Building the guest kernel">
~# <i>make O=~/build/domU</i>
~# <i>cp ~/build/domU/vmlinuz /mnt/data/xen/kernel/kernel-3.5.x.y-xen</i>
</pre>

</body>
</section>
<section>
<title>Creating the Domain Disks</title>
<body>

<p>
For best performance, it is best to dedicate a partition (or logical volume) to
a domain rather than a file based filesystem. However, if you are going to use
Xen primarily for tests using a file based filesystem does have its advantages
(especially regarding maintenance).
</p>

<p>
You can create a file based filesystem using <c>dd</c> and <c>mke2fs</c> (or
any other file system creation tool). For instance, to create a 4 Gbyte ext4
filesystem:
</p>

<pre caption="Creating a file based filesystem">
~# <i>dd if=/dev/zero of=/mnt/data/xen/disks/ext4root.img bs=1M count=4096</i>
~# <i>mkfs.ext4 /mnt/data/xen/disks/ext4root.img</i>
</pre>

</body>
</section>
<section>
<title>Configuring a Domain</title>
<body>

<p>
Next we create a Xen configuration file for a domain. You can store these
configuration files where you want, for instance at
<path>/mnt/data/xen/configs</path>. As an example, we create a configuration
file for a small Gentoo environment which uses the disk image we created
previously:
</p>

<pre caption="Creating a domain configuration file">
~# <i>nano -w /mnt/data/xen/configs/gentoo</i>

kernel = "/mnt/data/xen/kernel/kernel-3.5.x.y-xen"
memory = 512
name   = "gentoo"
<comment>(Map the disk image to the virtual /dev/sda1)</comment>
disk   = ['file:/mnt/data/xen/disks/ext4root.img,sda1,w']
root   = "/dev/sda1 ro"
</pre>

<p>
If you are using a block device (such as an lvm volume or partition) for
the disk use 'phy:' instead of 'file:' and leave off /dev. For example:
</p>

<pre caption="Using a block device">
<comment>(LVM Volume)</comment>
disk = [ 'phy:lvm/xen-guest-root,sda1,w' ]

<comment>(Physical Partition)</comment>
disk = [ 'phy:sdb6,sda1,w' ]
</pre>

<p>
You can find example configuration files in <path>/etc/xen</path>.
</p>

</body>
</section>
<section>
<title>Launching the New Domain</title>
<body>

<p>
Now we're all set and we can launch the new domain. If the disk image contained
an operating system, we could just create and attach the domain using the
<c>xl</c> command:
</p>

<pre caption="Creating and starting a new domain">
~# <i>xl create /mnt/data/xen/configs/gentoo -c</i>
</pre>

<p>
The domain would be booted inside the terminal in which you executed the
command. However, in our case, the disk image is empty so the domain won't boot
up in anything useful. To fix this, you can loop-mount the image and install
Gentoo as you're used to.
</p>

<p>
If you want to disconnect from the domain, press <path>Ctrl+]</path>. You can
always reconnect to the domains' console using <c>xl console gentoo</c>.
However, there is only one console per domain, so only use it when you can't
access the domain otherwise (for instance, through SSH).
</p>

</body>
</section>
</chapter>
<chapter>
<title>Networking on Unpriviledged Domains</title>
<section>
<title>Introduction</title>
<body>

<p>
Xen works best when using a bridged mode network configuration.
This means that your default network interface on
the administrative domain becomes a bridge which accepts connections to the
virtual domains as well as to the IP address your administrative domain has.
</p>

</body>
</section>
<section>
<title>Bridged Interfaces</title>
<body>

<p>
Create a bridge interface by creating a new link to the networking init script
as provided by Gentoo:
</p>

<pre caption="Creating a bridge interface">
# <i>cd /etc/init.d</i>
# <i>ln -s net.lo net.br0</i>
</pre>

<p>
Next, edit <path>/etc/conf.d/net</path> and setup the bridge:
</p>

<pre caption="Enabling the bridge br0 interface">
# <i>nano -w /etc/conf.d/net</i>

bridge_br0="eth0"
config_br0="192.168.1.200 netmask 255.255.255.0 brd 192.168.1.255"
routes_br0="default via 192.168.1.1"
</pre>

<p>
Finally, install the <e>net-misc/bridge-utils</e> package, and make sure the
<path>net.br0</path> init script is loaded at boot.
</p>

<pre caption="Finishing the bridge setup">
# <i>emerge net-misc/bridge-utils</i>
# <i>rc-update add net.br0 default</i>
</pre>

</body>
</section>
</chapter>
<chapter>
<title>Further Resources</title>
<section>
<title>Xen Documentation</title>
<body>

<ul>
  <li>
    <uri link="http://www.xen.org/support/documentation.html">Official Xen
    documentation</uri>
  </li>
  <li>
    <uri link="http://wiki.xen.org/">Xen Wiki</uri>
  </li>
</ul>

</body>
</section>
<section>
<title>Xen Tools</title>
<body>

<ul>
  <li>
    <uri
    link="http://virt-manager.org/">app-emulation/virt-manager</uri>
    is a graphical tool for administering virtual machines
  </li>
</ul>

</body>
</section>
</chapter>
</guide>
1	<?xml version='1.0' encoding='UTF-8'?>
2	<!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3	<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/xen-guide.xml,v 1.13 2012/07/24 12:12:51 swift Exp $ -->
4
5	<guide disclaimer="draft">
6	<title>Configuring Gentoo with Xen</title>
7
8	<author title="Author">
9	<mail link="swift@gentoo.org">Sven Vermeulen</mail>
10	</author>
11	<author title="Editor">
12	<mail link="nightmorph"/>
13	</author>
14
15	<abstract>
16	This guide describes how to start using Xen on your Gentoo system
17	</abstract>
18
19	<!-- The content of this document is licensed under the CC-BY-SA license -->
20	<!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
21	<license/>
22
23	<version>9</version>
24	<date>2012-10-07</date>
25
26	<chapter>
27	<title>Introduction</title>
28	<section>
29	<body>
30
31	<p>
32	The <uri link="http://www.xen.org/">Xen</uri> technology allows you to run
33	multiple operating systems on a single physical system, govern resource
34	consumption and even migrate domains (which are the virtual environments in
35	which a guest operating system runs) from one Xen-powered system to another. Xen
36	requires the host operating system to support Xen (which, in this case, will be
37	a Linux kernel) but guest operating systems can run unmodified <e>if</e> your
38	hardware supports Intel Virtualization Technology (VT-x) or AMD Virtualization
39	Technology (SVM). Otherwise your guest operating systems must also support Xen.
40	</p>
41
42	<p>
43	This guide will talk you through the configuration steps necessary to get Xen up
44	and running on Gentoo Linux. We will not discuss Xen itself (the Xen project has
45	<uri link="http://xen.org/support/documentation.html">decent documentation</uri>
46	available) nor will we talk about specialized setups that might be very
47	interesting for Xen setups but are not Xen-related (like exporting Portage
48	through NFS, booting Linux using PXE, etc.)
49	</p>
50
51	</body>
52	</section>
53	</chapter>
54	<chapter>
55	<title>Preparing Domain0</title>
56	<section>
57	<title>Introduction</title>
58	<body>
59
60	<p>
61	<e>Domain0</e> is the primary domain under Xen, hosting the host operating
62	system which governs all other domains. In this chapter we will prepare an
63	existing Gentoo installation to become the host operating system in this domain
64	and build the Xen-powered kernel so that Gentoo is ready to host other Xen
65	domains.
66	</p>
67
68	</body>
69	</section>
70	<section>
71	<title>Rebuilding the Gentoo Installation?</title>
72	<body>
73
74	<p>
75	A dramatic change that might be necessary is to rebuild the entire Gentoo
76	installation with a different <c>CFLAGS</c> setting. Guest operating systems
77	running under Xen might otherwise see major performance degradation. If you,
78	however, are planning on checking out Xen rather than installing it for
79	production use and are not terribly fond of rebuilding all programs, you can
80	skip this step. In this case you will notice performance degradation but you
81	will still be able to use Xen.
82	</p>
83
84	<impo>
85	It is advised that, if you change your <c>CFLAGS</c> and build your system with
86	a gcc lower than version 4, you do not have <c>-Os</c> set as it has been
87	reported to produce broken code.
88	</impo>
89
90	<pre caption="Editing the CFLAGS and rebuild the Gentoo installation">
91	~# <i>nano -w /etc/portage/make.conf</i>
92	<comment>(Add -mno-tls-direct-seg-refs ONLY if you have a 32-bit dom0)</comment>
93	<comment>(You don't need this flag if you have a 64-bit dom0)</comment>
94	CFLAGS="-O2 -march=pentium4 -pipe <i>-mno-tls-direct-seg-refs</i>"
95
96	~# <i>emerge -e world</i>
97	</pre>
98
99	<p>
100	If you boot your system using an initial ramdisk (initrd) you need to
101	rebuild the initrd as well (which is best done by running all steps you would do
102	when you rebuild your kernel).
103	</p>
104
105	</body>
106	</section>
107	<section>
108	<title>Installing Xen</title>
109	<body>
110
111	<p>
112	Xen actually contains many components, so you'll need to install a few
113	packages.
114	</p>
115
116	<pre caption="Installing Xen">
117	~# <i>emerge xen xen-tools gentoo-sources</i>
118	</pre>
119
120	</body>
121	</section>
122	<section>
123	<title>Building the Kernel</title>
124	<body>
125
126	<p>
127	Next we'll build the Linux kernel with Xen support. This kernel, whose sources
128	are available at <path>/usr/src/linux</path>, will be our main
129	running kernel (i.e. the one running domain 0). In the <c>XEN</c> section you'll
130	find drivers for all kinds of input/output, each driver having a <e>backend</e>
131	and <e>frontend</e> implementation available. For the domain 0 kernel you need
132	to select the <e>backend</e> implementation: these are used by the other
133	domains (who use the <e>frontend</e> drivers) to communicate directly with
134	the hardware. However, you should be able to configure the kernel to provide
135	support for both frontend (guest) and backend (host) drivers.
136	</p>
137
138	<p>
139	If you're wondering about networking: each interface in a domain
140	has a point-to-point link to an interface on domain 0 (called
141	<path>vifX.Y</path> where X is the domain number and Y the Yth interface of that
142	domain), so you can configure your network the way you want (bridging, NAT,
143	etc.)
144	</p>
145
146	<pre caption="Enabling Xen Support">
147	Processor type and features --->
148	[*] Paravirtualized guest support --->
149	[*] Xen guest support
150	</pre>
151
152	<pre caption="Kernel Config">
153	Bus options (PCI etc.) --->
154	[*] Xen PCI Frontend
155
156	[*] Networking support --->
157	Networking options --->
158	<*> 802.1d Ethernet Bridging
159	[*] Network packet filtering framework (Netfilter) --->
160	[*] Advanced netfilter configuration
161	[*] Bridged IP/ARP packets filtering
162
163	Device Drivers --->
164	[*] Block devices (NEW) --->
165	<*> Xen block-device backend driver
166	[*] Network device support --->
167	<*> Xen backend network device
168	Xen driver support --->
169	[*] Xen memory balloon driver (NEW)
170	[*] Scrub pages before returning them to system (NEW)
171	<*> Xen /dev/xen/evtchn device (NEW)
172	[*] Backend driver support (NEW)
173	<*> Xen filesystem (NEW)
174	[*] Create compatibility mount point /proc/xen (NEW)
175	[*] Create xen entries under /sys/hypervisor (NEW)
176	<M> userspace grant access device driver (NEW)
177	<M> user-space grant reference allocator driver (NEW)
178	<M> xen platform pci device driver (NEW)
179	</pre>
180
181	<p>
182	The shown kernel configuration should allow the kernel image to boot both as a
183	host as well as a guest. However, if you want to, you can slim down the guest
184	image kernel considerably. Refer to the Xen documentation for more information.
185	</p>
186
187	<p>
188	Once the kernel is built you'll find the kernel image immediately in the
189	build directory (not inside <path>arch/</path> or any other directory) called
190	<path>vmlinuz</path>. Copy it to <path>/boot</path> and then configure your
191	bootloader to use the Xen hypervisor (one of the components installed
192	previously) which is stored as <path>/boot/xen.gz</path>. In the bootloader
193	configuration, add your newly built kernel as the kernel that Xen should
194	boot. For instance, for GRUB:
195	</p>
196
197	<pre caption="GRUB Configuration for Xen">
198	title Xen Gentoo Linux 3.5
199	root (hd0,0)
200	kernel /boot/xen.gz
201	module /boot/kernel-3.5.x.y-xen0 root=/dev/sda3
202	</pre>
203
204	<p>
205	Now reboot your system into Xen and check if you can do whatever you
206	normally do on your system. If this is the case, you can edit your
207	bootloader configuration to always boot into Xen.
208	</p>
209
210	<note>
211	If you wish to start guest domains automatically on boot add <c>xendomains</c>
212	to the default runlevel as well and create a symlink in
213	<path>/etc/xen/auto/</path> to the Xen configuration files for the domains
214	you wish to start.
215	</note>
216
217	</body>
218	</section>
219	</chapter>
220	<chapter>
221	<title>Creating an Unpriviledged Domain</title>
222	<section>
223	<title>Building the Kernel</title>
224	<body>
225
226	<p>
227	Go to the Xen-powered Linux kernel source and, if necessary, update the
228	configuration. It is wise to keep as many topics as possible similar to
229	the main kernel. Then build the kernel
230	and place the resulting <path>vmlinuz</path> file where you want (we assume this
231	is <path>/mnt/data/xen/kernel</path>):
232	</p>
233
234	<pre caption="Building the guest kernel">
235	~# <i>make O=~/build/domU</i>
236	~# <i>cp ~/build/domU/vmlinuz /mnt/data/xen/kernel/kernel-3.5.x.y-xen</i>
237	</pre>
238
239	</body>
240	</section>
241	<section>
242	<title>Creating the Domain Disks</title>
243	<body>
244
245	<p>
246	For best performance, it is best to dedicate a partition (or logical volume) to
247	a domain rather than a file based filesystem. However, if you are going to use
248	Xen primarily for tests using a file based filesystem does have its advantages
249	(especially regarding maintenance).
250	</p>
251
252	<p>
253	You can create a file based filesystem using <c>dd</c> and <c>mke2fs</c> (or
254	any other file system creation tool). For instance, to create a 4 Gbyte ext4
255	filesystem:
256	</p>
257
258	<pre caption="Creating a file based filesystem">
259	~# <i>dd if=/dev/zero of=/mnt/data/xen/disks/ext4root.img bs=1M count=4096</i>
260	~# <i>mkfs.ext4 /mnt/data/xen/disks/ext4root.img</i>
261	</pre>
262
263	</body>
264	</section>
265	<section>
266	<title>Configuring a Domain</title>
267	<body>
268
269	<p>
270	Next we create a Xen configuration file for a domain. You can store these
271	configuration files where you want, for instance at
272	<path>/mnt/data/xen/configs</path>. As an example, we create a configuration
273	file for a small Gentoo environment which uses the disk image we created
274	previously:
275	</p>
276
277	<pre caption="Creating a domain configuration file">
278	~# <i>nano -w /mnt/data/xen/configs/gentoo</i>
279
280	kernel = "/mnt/data/xen/kernel/kernel-3.5.x.y-xen"
281	memory = 512
282	name = "gentoo"
283	<comment>(Map the disk image to the virtual /dev/sda1)</comment>
284	disk = ['file:/mnt/data/xen/disks/ext4root.img,sda1,w']
285	root = "/dev/sda1 ro"
286	</pre>
287
288	<p>
289	If you are using a block device (such as an lvm volume or partition) for
290	the disk use 'phy:' instead of 'file:' and leave off /dev. For example:
291	</p>
292
293	<pre caption="Using a block device">
294	<comment>(LVM Volume)</comment>
295	disk = [ 'phy:lvm/xen-guest-root,sda1,w' ]
296
297	<comment>(Physical Partition)</comment>
298	disk = [ 'phy:sdb6,sda1,w' ]
299	</pre>
300
301	<p>
302	You can find example configuration files in <path>/etc/xen</path>.
303	</p>
304
305	</body>
306	</section>
307	<section>
308	<title>Launching the New Domain</title>
309	<body>
310
311	<p>
312	Now we're all set and we can launch the new domain. If the disk image contained
313	an operating system, we could just create and attach the domain using the
314	<c>xl</c> command:
315	</p>
316
317	<pre caption="Creating and starting a new domain">
318	~# <i>xl create /mnt/data/xen/configs/gentoo -c</i>
319	</pre>
320
321	<p>
322	The domain would be booted inside the terminal in which you executed the
323	command. However, in our case, the disk image is empty so the domain won't boot
324	up in anything useful. To fix this, you can loop-mount the image and install
325	Gentoo as you're used to.
326	</p>
327
328	<p>
329	If you want to disconnect from the domain, press <path>Ctrl+]</path>. You can
330	always reconnect to the domains' console using <c>xl console gentoo</c>.
331	However, there is only one console per domain, so only use it when you can't
332	access the domain otherwise (for instance, through SSH).
333	</p>
334
335	</body>
336	</section>
337	</chapter>
338	<chapter>
339	<title>Networking on Unpriviledged Domains</title>
340	<section>
341	<title>Introduction</title>
342	<body>
343
344	<p>
345	Xen works best when using a bridged mode network configuration.
346	This means that your default network interface on
347	the administrative domain becomes a bridge which accepts connections to the
348	virtual domains as well as to the IP address your administrative domain has.
349	</p>
350
351	</body>
352	</section>
353	<section>
354	<title>Bridged Interfaces</title>
355	<body>
356
357	<p>
358	Create a bridge interface by creating a new link to the networking init script
359	as provided by Gentoo:
360	</p>
361
362	<pre caption="Creating a bridge interface">
363	# <i>cd /etc/init.d</i>
364	# <i>ln -s net.lo net.br0</i>
365	</pre>
366
367	<p>
368	Next, edit <path>/etc/conf.d/net</path> and setup the bridge:
369	</p>
370
371	<pre caption="Enabling the bridge br0 interface">
372	# <i>nano -w /etc/conf.d/net</i>
373
374	bridge_br0="eth0"
375	config_br0="192.168.1.200 netmask 255.255.255.0 brd 192.168.1.255"
376	routes_br0="default via 192.168.1.1"
377	</pre>
378
379	<p>
380	Finally, install the <e>net-misc/bridge-utils</e> package, and make sure the
381	<path>net.br0</path> init script is loaded at boot.
382	</p>
383
384	<pre caption="Finishing the bridge setup">
385	# <i>emerge net-misc/bridge-utils</i>
386	# <i>rc-update add net.br0 default</i>
387	</pre>
388
389	</body>
390	</section>
391	</chapter>
392	<chapter>
393	<title>Further Resources</title>
394	<section>
395	<title>Xen Documentation</title>
396	<body>
397
398	<ul>
399	<li>
400	<uri link="http://www.xen.org/support/documentation.html">Official Xen
401	documentation</uri>
402	</li>
403	<li>
404	<uri link="http://wiki.xen.org/">Xen Wiki</uri>
405	</li>
406	</ul>
407
408	</body>
409	</section>
410	<section>
411	<title>Xen Tools</title>
412	<body>
413
414	<ul>
415	<li>
416	<uri
417	link="http://virt-manager.org/">app-emulation/virt-manager</uri>
418	is a graphical tool for administering virtual machines
419	</li>
420	</ul>
421
422	</body>
423	</section>
424	</chapter>
425	</guide>