network-diskless.html

FreeBSD操作系统的详细使用手册

name="CO-DHCP-FILENAME"><img src="./imagelib/callouts/3.png" hspace="0" vspace="0"
border="0" alt="(3)" /></a>
    option root-path "192.168.4.4:/data/misc/diskless"; <a id="CO-DHCP-ROOT-PATH"
name="CO-DHCP-ROOT-PATH"><img src="./imagelib/callouts/4.png" hspace="0" vspace="0"
border="0" alt="(4)" /></a>
  }
  host corbieres {
    hardware ethernet 00:02:b3:27:62:df;
    fixed-address corbieres.example.com;
    next-server 192.168.4.4;
    filename "pxeboot";
    option root-path "192.168.4.4:/data/misc/diskless";
  }
}
         
</pre>

<div class="CALLOUTLIST">
<dl compact="COMPACT">
<dt><a href="network-diskless.html#CO-DHCP-HOST-NAME"><img
src="./imagelib/callouts/1.png" hspace="0" vspace="0" border="0" alt="(1)" /></a></dt>

<dd>This option tells <b class="APPLICATION">dhcpd</b> to send the value in the <var
class="LITERAL">host</var> declarations as the hostname for the diskless host. An
alternate way would be to add an <var class="LITERAL">option host-name <var
class="REPLACEABLE">margaux</var></var> inside the <var class="LITERAL">host</var>
declarations.</dd>

<dt><a href="network-diskless.html#CO-DHCP-NEXT-SERVER"><img
src="./imagelib/callouts/2.png" hspace="0" vspace="0" border="0" alt="(2)" /></a></dt>

<dd>The <var class="LITERAL">next-server</var> directive designates the <acronym
class="ACRONYM">TFTP</acronym> or <acronym class="ACRONYM">NFS</acronym> server to use
for loading loader or kernel file (the default is to use the same host as the <acronym
class="ACRONYM">DHCP</acronym> server).</dd>

<dt><a href="network-diskless.html#CO-DHCP-FILENAME"><img src="./imagelib/callouts/3.png"
hspace="0" vspace="0" border="0" alt="(3)" /></a></dt>

<dd>The <var class="LITERAL">filename</var> directive defines the file that <b
class="APPLICATION">Etherboot</b> or <acronym class="ACRONYM">PXE</acronym> will load for
the next execution step. It must be specified according to the transfer method used. <b
class="APPLICATION">Etherboot</b> can be compiled to use <acronym
class="ACRONYM">NFS</acronym> or <acronym class="ACRONYM">TFTP</acronym>. The FreeBSD
port configures <acronym class="ACRONYM">NFS</acronym> by default. <acronym
class="ACRONYM">PXE</acronym> uses <acronym class="ACRONYM">TFTP</acronym>, which is why
a relative filename is used here (this may depend on the <acronym
class="ACRONYM">TFTP</acronym> server configuration, but would be fairly typical). Also,
<acronym class="ACRONYM">PXE</acronym> loads <tt class="FILENAME">pxeboot</tt>, not the
kernel. There are other interesting possibilities, like loading <tt
class="FILENAME">pxeboot</tt> from a FreeBSD CD-ROM <tt class="FILENAME">/boot</tt>
directory (as <a href="http://www.FreeBSD.org/cgi/man.cgi?query=pxeboot&sektion=8"><span
class="CITEREFENTRY"><span class="REFENTRYTITLE">pxeboot</span>(8)</span></a> can load a
<tt class="FILENAME">GENERIC</tt> kernel, this makes it possible to use <acronym
class="ACRONYM">PXE</acronym> to boot from a remote CD-ROM).</dd>

<dt><a href="network-diskless.html#CO-DHCP-ROOT-PATH"><img
src="./imagelib/callouts/4.png" hspace="0" vspace="0" border="0" alt="(4)" /></a></dt>

<dd>The <var class="LITERAL">root-path</var> option defines the path to the root
filesystem, in usual <acronym class="ACRONYM">NFS</acronym> notation. When using <acronym
class="ACRONYM">PXE</acronym>, it is possible to leave off the host's IP as long as you
do not enable the kernel option BOOTP. The <acronym class="ACRONYM">NFS</acronym> server
will then be the same as the <acronym class="ACRONYM">TFTP</acronym> one.</dd>
</dl>
</div>
</div>

<div class="SECT3">
<h3 class="SECT3"><a id="AEN37222" name="AEN37222">24.6.2.2 Configuration Using
BOOTP</a></h3>

<p>Here follows an equivalent <b class="APPLICATION">bootpd</b> configuration (reduced to
one client). This would be found in <tt class="FILENAME">/etc/bootptab</tt>.</p>

<p>Please note that <b class="APPLICATION">Etherboot</b> must be compiled with the
non-default option <var class="LITERAL">NO_DHCP_SUPPORT</var> in order to use BOOTP, and
that <acronym class="ACRONYM">PXE</acronym> <span class="emphasis"><i
class="EMPHASIS">needs</i></span> <acronym class="ACRONYM">DHCP</acronym>. The only
obvious advantage of <b class="APPLICATION">bootpd</b> is that it exists in the base
system.</p>

<pre class="PROGRAMLISTING">
.def100:\
  :hn:ht=1:sa=192.168.4.4:vm=rfc1048:\
  :sm=255.255.255.0:\
  :ds=192.168.4.1:\
  :gw=192.168.4.1:\
  :hd="/tftpboot":\
  :bf="/kernel.diskless":\
  :rp="192.168.4.4:/data/misc/diskless":

margaux:ha=0123456789ab:tc=.def100
         
</pre>
</div>

<div class="SECT3">
<h3 class="SECT3"><a id="AEN37238" name="AEN37238">24.6.2.3 Preparing a Boot Program with
<b class="APPLICATION">Etherboot</b></a></h3>

<p><a href="http://etherboot.sourceforge.net" target="_top">Etherboot's Web site</a>
contains <a href="http://etherboot.sourceforge.net/doc/html/userman/t1.html"
target="_top">extensive documentation</a> mainly intended for Linux systems, but
nonetheless containing useful information. The following will just outline how you would
use <b class="APPLICATION">Etherboot</b> on a FreeBSD system.</p>

<p>You must first install the <a
href="http://www.FreeBSD.org/cgi/url.cgi?ports/net/etherboot/pkg-descr"><tt
class="FILENAME">net/etherboot</tt></a> package or port.</p>

<p>You can change the <b class="APPLICATION">Etherboot</b> configuration (i.e. to use
<acronym class="ACRONYM">TFTP</acronym> instead of <acronym
class="ACRONYM">NFS</acronym>) by editing the <tt class="FILENAME">Config</tt> file in
the <b class="APPLICATION">Etherboot</b> source directory.</p>

<p>For our setup, we shall use a boot floppy. For other methods (PROM, or <span
class="TRADEMARK">MS-DOS</span> program), please refer to the <b
class="APPLICATION">Etherboot</b> documentation.</p>

<p>To make a boot floppy, insert a floppy in the drive on the machine where you installed
<b class="APPLICATION">Etherboot</b>, then change your current directory to the <tt
class="FILENAME">src</tt> directory in the <b class="APPLICATION">Etherboot</b> tree and
type:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">gmake bin32/<var
class="REPLACEABLE">devicetype</var>.fd0</kbd>
   
</pre>

<p><var class="REPLACEABLE">devicetype</var> depends on the type of the Ethernet card in
the diskless workstation. Refer to the <tt class="FILENAME">NIC</tt> file in the same
directory to determine the right <var class="REPLACEABLE">devicetype</var>.</p>
</div>

<div class="SECT3">
<h3 class="SECT3"><a id="AEN37270" name="AEN37270">24.6.2.4 Booting with <acronym
class="ACRONYM">PXE</acronym></a></h3>

<p>By default, the <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=pxeboot&sektion=8"><span
class="CITEREFENTRY"><span class="REFENTRYTITLE">pxeboot</span>(8)</span></a> loader
loads the kernel via <acronym class="ACRONYM">NFS</acronym>. It can be compiled to use
<acronym class="ACRONYM">TFTP</acronym> instead by specifying the <var
class="LITERAL">LOADER_TFTP_SUPPORT</var> option in <tt
class="FILENAME">/etc/make.conf</tt>. See the comments in <tt
class="FILENAME">/etc/defaults/make.conf</tt> (or <tt
class="FILENAME">/usr/share/examples/etc/make.conf</tt> for 5.X systems) for
instructions.</p>

<p>There are two other undocumented <tt class="FILENAME">make.conf</tt> options which may
be useful for setting up a serial console diskless machine: <var
class="LITERAL">BOOT_PXELDR_PROBE_KEYBOARD</var>, and <var
class="LITERAL">BOOT_PXELDR_ALWAYS_SERIAL</var> (the latter only exists on
FreeBSD&nbsp;5.X).</p>

<p>To use <acronym class="ACRONYM">PXE</acronym> when the machine starts, you will
usually need to select the <var class="LITERAL">Boot from network</var> option in your
<acronym class="ACRONYM">BIOS</acronym> setup, or type a function key during the PC
initialization.</p>
</div>

<div class="SECT3">
<h3 class="SECT3"><a id="AEN37291" name="AEN37291">24.6.2.5 Configuring the <acronym
class="ACRONYM">TFTP</acronym> and <acronym class="ACRONYM">NFS</acronym>
Servers</a></h3>

<p>If you are using <acronym class="ACRONYM">PXE</acronym> or <b
class="APPLICATION">Etherboot</b> configured to use <acronym
class="ACRONYM">TFTP</acronym>, you need to enable <b class="APPLICATION">tftpd</b> on
the file server:</p>

<div class="PROCEDURE">
<ol type="1">
<li>
<p>Create a directory from which <b class="APPLICATION">tftpd</b> will serve the files,
e.g. <tt class="FILENAME">/tftpboot</tt>.</p>
</li>

<li>
<p>Add this line to your <tt class="FILENAME">/etc/inetd.conf</tt>:</p>

<pre class="PROGRAMLISTING">
tftp   dgram   udp wait    root    /usr/libexec/tftpd  tftpd -l -s /tftpboot
</pre>

<div class="NOTE">
<blockquote class="NOTE">
<p><b>Note:</b> It appears that at least some <acronym class="ACRONYM">PXE</acronym>
versions want the <acronym class="ACRONYM">TCP</acronym> version of <acronym
class="ACRONYM">TFTP</acronym>. In this case, add a second line, replacing <var
class="LITERAL">dgram udp</var> with <var class="LITERAL">stream tcp</var>.</p>
</blockquote>
</div>
</li>

<li>
<p>Tell <b class="APPLICATION">inetd</b> to reread its configuration file:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd
class="USERINPUT">kill -HUP `cat /var/run/inetd.pid`</kbd>
</pre>
</li>
</ol>
</div>

<p>You can place the <tt class="FILENAME">tftpboot</tt> directory anywhere on the server.
Make sure that the location is set in both <tt class="FILENAME">inetd.conf</tt> and <tt
class="FILENAME">dhcpd.conf</tt>.</p>

<p>In all cases, you also need to enable <acronym class="ACRONYM">NFS</acronym> and
export the appropriate filesystem on the <acronym class="ACRONYM">NFS</acronym>
server.</p>

<div class="PROCEDURE">
<ol type="1">
<li>
<p>Add this to <tt class="FILENAME">/etc/rc.conf</tt>:</p>

<pre class="PROGRAMLISTING">
nfs_server_enable="YES"
</pre>
</li>

<li>
<p>Export the filesystem where the diskless root directory is located by adding the
following to <tt class="FILENAME">/etc/exports</tt> (adjust the volume mount point and
replace <var class="REPLACEABLE">margaux corbieres</var> with the names of the diskless
workstations):</p>

<pre class="PROGRAMLISTING">
<var class="REPLACEABLE">/data/misc</var> -alldirs -ro <var
class="REPLACEABLE">margaux corbieres</var>
</pre>
</li>

<li>
<p>Tell <b class="APPLICATION">mountd</b> to reread its configuration file. If you
actually needed to enable <acronym class="ACRONYM">NFS</acronym> in <tt
class="FILENAME">/etc/rc.conf</tt> at the first step, you probably want to reboot
instead.</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd
class="USERINPUT">kill -HUP `cat /var/run/mountd.pid`</kbd>
</pre>
</li>
</ol>
</div>
</div>

<div class="SECT3">
<h3 class="SECT3"><a id="AEN37355" name="AEN37355">24.6.2.6 Building a Diskless
Kernel</a></h3>

<p>If using <b class="APPLICATION">Etherboot</b>, you need to create a kernel
configuration file for the diskless client with the following options (in addition to the
usual ones):</p>

<pre class="PROGRAMLISTING">
options     BOOTP          # Use BOOTP to obtain IP address/hostname
options     BOOTP_NFSROOT  # NFS mount root filesystem using BOOTP info
   
</pre>

<p>You may also want to use <var class="LITERAL">BOOTP_NFSV3</var>, <var
class="LITERAL">BOOT_COMPAT</var> and <var class="LITERAL">BOOTP_WIRED_TO</var> (refer to
<tt class="FILENAME">LINT</tt> in 4.X or <tt class="FILENAME">NOTES</tt> on 5.X).</p>

<p>These option names are historical and slightly misleading as they actually enable
indifferent use of <acronym class="ACRONYM">DHCP</acronym> and BOOTP inside the kernel
(it is also possible to force strict BOOTP or <acronym class="ACRONYM">DHCP</acronym>