<?xml version="1.0" encoding="iso-8859-1"?>
<!--
     The FreeBSD Documentation Project

     $FreeBSD$
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<chapter id="linuxemu">
  <chapterinfo>
    <authorgroup>
      <author>
	<firstname>Jim</firstname>
	<surname>Mock</surname>
	<contrib>Restructured and parts updated by </contrib>
      </author>
      <!-- 22 Mar 2000 -->
    </authorgroup>
    <authorgroup>
      <author>
	<firstname>Brian N.</firstname>
	<surname>Handy</surname>
	<contrib>Originally contributed by </contrib>
      </author>
      <author>
	<firstname>Rich</firstname>
	<surname>Murphey</surname>
      </author>
    </authorgroup>
  </chapterinfo>

  <title>Linux Binary Compatibility</title>

  <sect1 id="linuxemu-synopsis">
    <title>Synopsis</title>

    <indexterm><primary>Linux binary
	compatibility</primary></indexterm>
    <indexterm>
      <primary>binary compatibility</primary>
      <secondary>Linux</secondary>
    </indexterm>

    <para>FreeBSD provides binary compatibility with several other
      &unix; like operating systems, including Linux.  At this point,
      you may be asking yourself why exactly, does
      FreeBSD need to be able to run Linux binaries?  The answer to
      that question is quite simple.  Many companies and developers
      develop only for Linux, since it is the latest <quote>hot
	thing</quote> in the computing world.  That leaves the rest
      of us FreeBSD users bugging these same companies and developers
      to put out native FreeBSD versions of their applications.  The
      problem is, that most of these companies do not really realize
      how many people would use their product if there were FreeBSD
      versions too, and most continue to only develop for Linux.
      So what is a FreeBSD user to do?  This is where the Linux binary
      compatibility of FreeBSD comes into play.</para>

    <para>In a nutshell, the compatibility allows FreeBSD users to
      run about 90% of all Linux applications without modification.
      This includes applications such as
      <application>&staroffice;</application>, the Linux version of
      <application>&netscape;</application>,
      <application>&adobe;&nbsp;&acrobat;</application>,
      <application>&realplayer;</application>,
      <application>&oracle;</application>,
      <application>&wordperfect;</application>,
      <application>Doom</application>,
      <application>Quake</application>, and more.  It is also reported
      that in some situations, Linux binaries perform better on
      FreeBSD than they do under Linux.</para>

    <para>There are, however, some Linux-specific operating system
      features that are not supported under FreeBSD.  Linux binaries
      will not work on FreeBSD if they overly use &i386; specific
      calls, such as enabling virtual 8086 mode.</para>

    <para>After reading this chapter, you will know:</para>
    <itemizedlist>
      <listitem>
	<para>How to enable Linux binary compatibility on your
	  system.</para>
      </listitem>

      <listitem>
	<para>How to install additional Linux shared
	  libraries.</para>
      </listitem>

      <listitem>
	<para>How to install Linux applications on your FreeBSD
	  system.</para>
      </listitem>

      <listitem>
	<para>The implementation details of Linux compatibility in
	  FreeBSD.</para>
      </listitem>
    </itemizedlist>

    <para>Before reading this chapter, you should:</para>

    <itemizedlist>
      <listitem>
	<para>Know how to install additional third-party
	  software (<xref linkend="ports"/>).</para>
      </listitem>
    </itemizedlist>

  </sect1>

  <sect1 id="linuxemu-lbc-install">
    <title>Installation</title>

    <indexterm><primary>KLD (kernel loadable
	object)</primary></indexterm>

    <para>Linux binary compatibility is not turned on by default.  The
      easiest way to enable this functionality is to load the
      <literal>linux</literal> KLD object (<quote>Kernel LoaDable
      object</quote>).  You can load this module by typing the
      following as <username>root</username>:</para>

    <screen>&prompt.root; <userinput>kldload linux</userinput></screen>

    <para>If you would like Linux compatibility to always be enabled,
      then you should add the following line to
      <filename>/etc/rc.conf</filename>:</para>

    <programlisting>linux_enable="YES"</programlisting>

    <para>The &man.kldstat.8; command can be used to verify that the
      KLD is loaded:</para>

    <screen>&prompt.user; <userinput>kldstat</userinput>
Id Refs Address    Size     Name
 1    2 0xc0100000 16bdb8   kernel
 7    1 0xc24db000 d000     linux.ko</screen>

    <indexterm>
      <primary>kernel options</primary>
      <secondary>COMPAT_LINUX</secondary>
    </indexterm>

    <para>If for some reason you do not want to or cannot load the
      KLD, then you may statically link Linux binary compatibility
      into the kernel by adding <literal>options
	COMPAT_LINUX</literal> to your kernel configuration file.
      Then install your new kernel as described in
      <xref linkend="kernelconfig"/>.</para>

    <sect2>
      <title>Installing Linux Runtime Libraries</title>

      <indexterm>
	<primary>Linux</primary>
	<secondary>installing Linux libraries</secondary>
      </indexterm>

      <para>This can be done one of two ways, either by using the
	<link linkend="linuxemu-libs-port">linux_base</link> port, or
	by installing them <link
	linkend="linuxemu-libs-manually">manually</link>.</para>

    <sect3 id="linuxemu-libs-port">
      <title>Installing Using the linux_base Port</title>

      <indexterm><primary>Ports Collection</primary></indexterm>

      <para>This is by far the easiest method to use when installing
	the runtime libraries.  It is just like installing any other
	port from the <link linkend="ports">Ports
	  Collection</link>:</para>

      <screen>&prompt.root; <userinput>cd /usr/ports/emulators/linux_base-f10</userinput>
&prompt.root; <userinput>make install distclean</userinput></screen>

	<note>
	  <para>On &os; systems prior to &os;&nbsp;8.0, you will have
	    to use the <filename
	      role="package">emulators/linux_base-fc4</filename> port
	    instead of <filename
	      role="package">emulators/linux_base-f10</filename>.</para>
	</note>

	<para>You should now have working Linux binary compatibility.
	  Some programs may complain about incorrect minor versions
	  of the system libraries.  In general, however, this does
	  not seem to be a problem.</para>

	<note><para>There may be multiple versions of the <filename
	    role="package">emulators/linux_base</filename> port
	  available, corresponding to different versions of various
	  Linux distributions.  You should install the port most
	  closely resembling the requirements of the Linux
	  applications you would like to install.</para></note>

      </sect3>

      <sect3 id="linuxemu-libs-manually">
	<title>Installing Libraries Manually</title>

	<para>If you do not have the <quote>ports</quote> collection
	  installed, you can install the libraries by hand instead.
	  You will need the Linux shared libraries that the program
	  depends on and the runtime linker.  Also, you will need to
	  create a <quote>shadow root</quote> directory,
	  <filename>/compat/linux</filename>, for Linux libraries
	  on your FreeBSD system.  Any shared libraries opened by
	  Linux programs run under FreeBSD will look in this tree
	  first.  So, if a Linux program loads, for example,
	  <filename>/lib/libc.so</filename>, FreeBSD will first try
	  to open <filename>/compat/linux/lib/libc.so</filename>,
	  and if that does not exist, it will then try
	  <filename>/lib/libc.so</filename>.  Shared libraries should
	  be installed in the shadow tree
	  <filename>/compat/linux/lib</filename> rather than the paths
	  that the Linux <command>ld.so</command> reports.</para>

	<para>Generally, you will need to look for the shared
	  libraries that Linux binaries depend on only the first few
	  times that you install a Linux program on your FreeBSD
	  system.  After a while, you will have a sufficient set of
	  Linux shared libraries on your system to be able to run
	  newly imported Linux binaries without any extra work.</para>
      </sect3>

      <sect3>
	<title>How to Install Additional Shared Libraries</title>

	<indexterm><primary>shared libraries</primary></indexterm>

	<para>What if you install the <filename>linux_base</filename>
	  port and your application still complains about missing
	  shared libraries?  How do you know which shared libraries
	  Linux binaries need, and where to get them?  Basically,
	  there are 2 possibilities (when following these instructions
	  you will need to be <username>root</username> on your
	  FreeBSD system).</para>

	<para>If you have access to a Linux system, see what shared
	  libraries the application needs, and copy them to your
	  FreeBSD system.  Look at the following example:</para>

	<informalexample>
	  <para>Let us assume you used FTP to get the Linux binary
	    of <application>Doom</application>, and put it on a Linux
	    system you have access to.  You then can check which
	    shared libraries it needs by running
	    <command>ldd linuxdoom</command>, like so:</para>

	  <screen>&prompt.user; <userinput>ldd linuxdoom</userinput>
libXt.so.3 (DLL Jump 3.1) =&gt; /usr/X11/lib/libXt.so.3.1.0
libX11.so.3 (DLL Jump 3.1) =&gt; /usr/X11/lib/libX11.so.3.1.0
libc.so.4 (DLL Jump 4.5pl26) =&gt; /lib/libc.so.4.6.29</screen>

	  <indexterm><primary>symbolic links</primary></indexterm>
	  <para>You would need to get all the files from the last
	    column, and put them under
	    <filename>/compat/linux</filename>, with the names in
	    the first column as symbolic links pointing to them.
	    This means you eventually have these files on your
	    FreeBSD system:</para>

	  <screen>/compat/linux/usr/X11/lib/libXt.so.3.1.0
/compat/linux/usr/X11/lib/libXt.so.3 -&gt; libXt.so.3.1.0
/compat/linux/usr/X11/lib/libX11.so.3.1.0
/compat/linux/usr/X11/lib/libX11.so.3 -&gt; libX11.so.3.1.0
/compat/linux/lib/libc.so.4.6.29
/compat/linux/lib/libc.so.4 -&gt; libc.so.4.6.29</screen>

	  <blockquote>
	    <note>
	      <para>Note that if you already have a Linux shared
		library with a matching major revision number to the
		first column of the <command>ldd</command> output,
		you will not need to copy the file named in the last
		column to your system, the one you already have should
		work.  It is advisable to copy the shared library
		anyway if it is a newer version, though.  You can
		remove the old one, as long as you make the symbolic
		link point to the new one.  So, if you have these
		libraries on your system:</para>

	      <screen>/compat/linux/lib/libc.so.4.6.27
/compat/linux/lib/libc.so.4 -&gt; libc.so.4.6.27</screen>

	      <para>and you find a new binary that claims to require a
		later version according to the output of
		<command>ldd</command>:</para>

	      <screen>libc.so.4 (DLL Jump 4.5pl26) -&gt; libc.so.4.6.29</screen>

	      <para>If it is only one or two versions out of date
		in the trailing digit then do not worry about copying
		<filename>/lib/libc.so.4.6.29</filename> too, because
		the program should work fine with the slightly older
		version.  However, if you like, you can decide to
		replace the <filename>libc.so</filename> anyway, and
		that should leave you with:</para>

	      <screen>/compat/linux/lib/libc.so.4.6.29
/compat/linux/lib/libc.so.4 -&gt; libc.so.4.6.29</screen>
	    </note>
	  </blockquote>

	  <blockquote>
	    <note>
	      <para>The symbolic link mechanism is
		<emphasis>only</emphasis> needed for Linux binaries.
		The FreeBSD runtime linker takes care of looking for
		matching major revision numbers itself and you do not
		need to worry about it.</para>
	    </note>
	  </blockquote>
	</informalexample>
      </sect3>
    </sect2>

    <sect2>
      <title>Installing Linux ELF Binaries</title>

      <indexterm>
	<primary>Linux</primary>
	<secondary>ELF binaries</secondary>
      </indexterm>

      <para>ELF binaries sometimes require an extra step of
	<quote>branding</quote>.  If you attempt to run an unbranded
	ELF binary, you will get an error message like the
	following:</para>

      <screen>&prompt.user; <userinput>./my-linux-elf-binary</userinput>
ELF binary type not known
Abort</screen>

      <para>To help the FreeBSD kernel distinguish between a FreeBSD
	ELF binary and a Linux binary, use the &man.brandelf.1;
	utility.</para>

      <screen>&prompt.user; <userinput>brandelf -t Linux my-linux-elf-binary</userinput></screen>

      <indexterm><primary>GNU toolchain</primary></indexterm>
      <para>The GNU toolchain now places the appropriate branding
	information into ELF binaries automatically, so this step
	should become increasingly unnecessary in the future.</para>
    </sect2>

    <sect2>
      <title>Installing a Random Linux RPM Based Application</title>

      <para>FreeBSD has its own package database and it is used to
	track all ports (&linux; ports as well).  So the &linux; RPM
	database is not used (not supported).</para>

      <para>However if you need to install a random &linux;
	RPM-based application it can be achieved by:</para>

      <screen>&prompt.root; <userinput>cd /compat/linux</userinput>
&prompt.root; <userinput>rpm2cpio -q &lt; /path/to/linux.archive.rpm | cpio -id</userinput></screen>

      <para>Then brandelf installed ELF binaries (not libraries!).
	You will not be able to do a clean uninstall, but it may
	help you to do tests.</para>
    </sect2>

    <sect2>
      <title>Configuring the Hostname Resolver</title>

      <para>If DNS does not work or you get this message:</para>

      <screen>resolv+: "bind" is an invalid keyword resolv+:
"hosts" is an invalid keyword</screen>

      <para>You will need to configure a
	<filename>/compat/linux/etc/host.conf</filename> file
	containing:</para>

      <programlisting>order hosts, bind
multi on</programlisting>

      <para>The order here specifies that
	<filename>/etc/hosts</filename> is searched first and DNS
	is searched second.  When
	<filename>/compat/linux/etc/host.conf</filename> is not
	installed, Linux applications find FreeBSD's
	<filename>/etc/host.conf</filename> and complain about the
	incompatible FreeBSD syntax.  You should remove
	<literal>bind</literal> if you have not configured a name
	server using the <filename>/etc/resolv.conf</filename>
	file.</para>
    </sect2>
  </sect1>

  <sect1 id="linuxemu-mathematica">
    <sect1info>
      <authorgroup>
	<author>
	  <firstname>Boris</firstname>
	  <surname>Hollas</surname>
	  <contrib>Updated for Mathematica 5.X by </contrib>
	</author>
      </authorgroup>
    </sect1info>
    <title>Installing &mathematica;</title>

    <indexterm>
      <primary>applications</primary>
      <secondary><application>Mathematica</application></secondary>
    </indexterm>

    <para>This document describes the process of installing the Linux
      version of <application>&mathematica; 5.X</application> onto
      a FreeBSD system.</para>

    <para>The Linux version of
      <application>&mathematica;</application>
      or <application>&mathematica; for Students</application> can
      be ordered directly from Wolfram at
      <ulink url="http://www.wolfram.com/"></ulink>.</para>

    <sect2>
      <title>Running the &mathematica; Installer</title>

      <para>First, you have to tell &os; that
	<application>&mathematica;</application>'s Linux
	binaries use the Linux ABI.  The easiest way to do so is to
	set the default ELF brand
	to Linux for all unbranded binaries with the command:</para>

      <screen>&prompt.root; <userinput>sysctl kern.fallback_elf_brand=3</userinput></screen>

      <para>This will make &os; assume that unbranded ELF binaries
	use the Linux ABI and so you should be able to run the
	installer straight from the CDROM.</para>

      <para>Now, copy the file <filename>MathInstaller</filename> to
	your hard drive:</para>

      <screen>&prompt.root; <userinput>mount /cdrom</userinput>
&prompt.root; <userinput>cp /cdrom/Unix/Installers/Linux/MathInstaller /localdir/</userinput></screen>

      <para>and in this file, replace <literal>/bin/sh</literal> in
	the first line by <literal>/compat/linux/bin/sh</literal>.
	This makes sure that the installer is executed by the Linux
	version of &man.sh.1;.  Next, replace all occurrences of
	<literal>Linux)</literal> by <literal>FreeBSD)</literal> with
	a text editor or the script below in the next section.  This
	tells the <application>&mathematica;</application> installer,
	who calls <command>uname -s</command> to determine the
	operating system, to treat &os; as a Linux-like operating
	system.  Invoking <command>MathInstaller</command> will now
	install <application>&mathematica;</application>.</para>
    </sect2>

    <sect2>
      <title>Modifying the &mathematica; Executables</title>

      <para>The shell scripts that
	<application>&mathematica;</application> created during
	installation have to be modified before you can use them.
	If you chose <filename
	  class="directory">/usr/local/bin</filename> as the directory
	to place the
	<application>&mathematica;</application> executables in, you
	will find symlinks in this directory to files called
	<filename>math</filename>, <filename>mathematica</filename>,
	<filename>Mathematica</filename>, and
	<filename>MathKernel</filename>.  In each of these, replace
	<literal>Linux)</literal> by <literal>FreeBSD)</literal> with
	a text editor or the following shell script:</para>

      <programlisting>#!/bin/sh
cd /usr/local/bin
for i in math mathematica Mathematica MathKernel
  do sed 's/Linux)/FreeBSD)/g' $i &gt; $i.tmp
  sed 's/\/bin\/sh/\/compat\/linux\/bin\/sh/g' $i.tmp &gt; $i
  rm $i.tmp
  chmod a+x $i
done</programlisting>
    </sect2>

    <sect2>
      <title>Obtaining Your &mathematica; Password</title>

      <indexterm>
	<primary>Ethernet</primary>
	<secondary>MAC address</secondary>
      </indexterm>

      <para>When you start <application>&mathematica;</application>
	for the first time, you will be asked for a password.  If you
	have not yet obtained a password from Wolfram, run the program
	<command>mathinfo</command> in the installation directory to
	obtain your <quote>machine ID</quote>.  This machine ID is
	based solely on the MAC address of your first Ethernet card,
	so you cannot run your copy of
	<application>&mathematica;</application> on different
	machines.</para>

      <para>When you register with Wolfram, either by email, phone
	or fax, you will give them the <quote>machine ID</quote> and
	they will respond with a corresponding password consisting
	of groups of numbers.</para>
    </sect2>

    <sect2>
      <title>Running the &mathematica; Frontend over a Network</title>

      <para><application>&mathematica;</application> uses some special
	fonts to display characters not
	present in any of the standard font sets (integrals, sums,
	Greek letters, etc.).  The X protocol requires these fonts
	to be install <emphasis>locally</emphasis>.  This means you
	will have to copy these fonts from the CDROM or from a host
	with <application>&mathematica;</application> installed to
	your local machine.  These fonts are normally stored in
	<filename>/cdrom/Unix/Files/SystemFiles/Fonts</filename> on
	the CDROM, or
	<filename>/usr/local/mathematica/SystemFiles/Fonts</filename>
	on your hard drive.  The actual fonts are in the
	subdirectories <filename>Type1</filename> and
	<filename>X</filename>.  There are several ways to use them,
	as described below.</para>

      <para>The first way is to copy them into one of the existing
	font directories in
	<filename>/usr/X11R6/lib/X11/fonts</filename>.  This will
	require editing the <filename>fonts.dir</filename> file,
	adding the font names to it, and changing the number of fonts
	on the first line.  Alternatively, you should also just be
	able to run &man.mkfontdir.1; in the directory you have copied
	them to.</para>

      <para>The second way to do this is to copy the directories to
	<filename>/usr/X11R6/lib/X11/fonts</filename>:</para>

      <screen>&prompt.root; <userinput>cd /usr/X11R6/lib/X11/fonts</userinput>
&prompt.root; <userinput>mkdir X</userinput>
&prompt.root; <userinput>mkdir MathType1</userinput>
&prompt.root; <userinput>cd /cdrom/Unix/Files/SystemFiles/Fonts</userinput>
&prompt.root; <userinput>cp X/* /usr/X11R6/lib/X11/fonts/X</userinput>
&prompt.root; <userinput>cp Type1/* /usr/X11R6/lib/X11/fonts/MathType1</userinput>
&prompt.root; <userinput>cd /usr/X11R6/lib/X11/fonts/X</userinput>
&prompt.root; <userinput>mkfontdir</userinput>
&prompt.root; <userinput>cd ../MathType1</userinput>
&prompt.root; <userinput>mkfontdir</userinput></screen>

      <para>Now add the new font directories to your font path:</para>

      <screen>&prompt.root; <userinput>xset fp+ /usr/X11R6/lib/X11/fonts/X</userinput>
&prompt.root; <userinput>xset fp+ /usr/X11R6/lib/X11/fonts/MathType1</userinput>
&prompt.root; <userinput>xset fp rehash</userinput></screen>

      <para>If you are using the <application>&xorg;</application>
	server, you can have these font directories loaded
	automatically by adding them to your
	<filename>xorg.conf</filename> file.</para>

      <indexterm><primary>fonts</primary></indexterm>

      <para>If you <emphasis>do not</emphasis> already have a
	directory called
	<filename>/usr/X11R6/lib/X11/fonts/Type1</filename>, you
	can change the name of the <filename>MathType1</filename>
	directory in the example above to
	<filename>Type1</filename>.</para>
    </sect2>
  </sect1>

  <sect1 id="linuxemu-maple">
    <sect1info>
      <authorgroup>
	<author>
	  <firstname>Aaron</firstname>
	  <surname>Kaplan</surname>
<!--	  <address><email>aaron@lo-res.org</email></address>-->
	  <contrib>Contributed by </contrib>
	</author>
      </authorgroup>
      <authorgroup>
	<author>
	  <firstname>Robert</firstname>
	  <surname>Getschmann</surname>
<!--	  <address><email>rob@getschmann.org</email></address>-->
	  <contrib>Thanks to </contrib>
	</author>
      </authorgroup>
    </sect1info>
    <title>Installing &maple;</title>

    <indexterm>
      <primary>applications</primary>
      <secondary><application>Maple</application></secondary>
    </indexterm>

    <para><application>&maple;</application> is a commercial
      mathematics program similar to
      <application>&mathematica;</application>.  You must purchase
      this software from <ulink
	url="http://www.maplesoft.com/"></ulink> and then register
      there for a license file.  To install this software on FreeBSD,
      please follow these simple steps.</para>

    <procedure>
      <step><para>Execute the <filename>INSTALL</filename> shell
	script from the product distribution.  Choose the
	<quote>RedHat</quote> option when prompted by the
	installation program.  A typical installation directory
	might be <filename
	  class="directory">/usr/local/maple</filename>.</para></step>

      <step><para>If you have not done so, order a license for
	<application>&maple;</application> from Maple Waterloo
	Software (<ulink
	  url="http://register.maplesoft.com/"></ulink>) and copy it
	to
	  <filename>/usr/local/maple/license/license.dat</filename>.</para></step>

	<step><para>Install the <application>FLEXlm</application>
	  license manager by running the
	  <filename>INSTALL_LIC</filename> install shell script that
	  comes with <application>&maple;</application>.  Specify the
	  primary hostname for your machine for the license
	  server.</para></step>

	<step><para>Patch the
	  <filename>/usr/local/maple/bin/maple.system.type</filename>
	  file with the following:</para>
	<programlisting>   ----- snip ------------------
*** maple.system.type.orig      Sun Jul  8 16:35:33 2001
--- maple.system.type   Sun Jul  8 16:35:51 2001
***************
*** 72,77 ****
--- 72,78 ----
          # the IBM RS/6000 AIX case
          MAPLE_BIN="bin.IBM_RISC_UNIX"
          ;;
+     "FreeBSD"|\
      "Linux")
          # the Linux/x86 case
        # We have two Linux implementations, one for Red Hat and
   ----- snip end of patch -----</programlisting>

	<para>Please note that after the
	  <literal>"FreeBSD"|\</literal> no other whitespace should
	  be present.</para>

	<para>This patch instructs <application>&maple;</application>
	  to recognize <quote>FreeBSD</quote> as a type of Linux
	  system.  The <filename>bin/maple</filename> shell script
	  calls the <filename>bin/maple.system.type</filename> shell
	  script which in turn calls <command>uname -a</command> to
	  find out the operating system name.  Depending on the OS
	  name it will find out which binaries to use.</para></step>

	<step><para>Start the license server.</para>

	<para>The following script, installed as
	  <filename>/usr/local/rtc/rc.d/lmgrd</filename> is a
	  convenient way to start up <command>lmgrd</command>:</para>

	<programlisting>   ----- snip ------------

#! /bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/X11R6/bin
PATH=${PATH}:/usr/local/maple/bin:/usr/local/maple/FLEXlm/UNIX/LINUX
export PATH

LICENSE_FILE=/usr/local/maple/license/license.dat
LOG=/var/log/lmgrd.log

case "$1" in
start)
	lmgrd -c ${LICENSE_FILE} 2&gt;&gt; ${LOG} 1&gt;&amp;2
	echo -n " lmgrd"
	;;
stop)
	lmgrd -c ${LICENSE_FILE} -x lmdown 2&gt;&gt; ${LOG} 1&gt;&amp;2
	;;
*)
	echo "Usage: `basename $0` {start|stop}" 1&gt;&amp;2
	exit 64
	;;
esac

exit 0
   ----- snip ------------</programlisting></step>


      <step><para>Test-start
	<application>&maple;</application>:</para>

      <screen>&prompt.user; <userinput>cd /usr/local/maple/bin</userinput>
&prompt.user; <userinput>./xmaple</userinput></screen>

	<para>You should be up and running.  Make sure to write
	  Maplesoft to let them know you would like a native FreeBSD
	  version!</para></step>
      </procedure>

      <sect2>
	<title>Common Pitfalls</title>

	<itemizedlist>
	  <listitem><para>The <application>FLEXlm</application>
	    license manager can be a difficult tool to work with.
	    Additional documentation on the subject can be found at
	    <ulink
	      url="http://www.globetrotter.com/"></ulink>.</para></listitem>

	  <listitem><para><command>lmgrd</command> is known to be very
	    picky about the license file and to core dump if there
	    are any problems.  A correct license file should look
	    like this:</para>

	  <programlisting>#
=======================================================
# License File for UNIX Installations ("Pointer File")
# =======================================================
SERVER chillig ANY
#USE_SERVER
VENDOR maplelmg

FEATURE Maple maplelmg 2000.0831 permanent 1 XXXXXXXXXXXX \
         PLATFORMS=i86_r ISSUER="Waterloo Maple Inc." \
         ISSUED=11-may-2000 NOTICE=" Technische Universitat Wien" \
         SN=XXXXXXXXX</programlisting>

	  <note><para>Serial number and key 'X''ed out.
	    <hostid>chillig</hostid> is a hostname.</para></note>

	  <para>Editing the license file works as long as you do not
	    touch the <quote>FEATURE</quote> line (which is protected
	    by the license key).</para></listitem>
	</itemizedlist>
      </sect2>
    </sect1>

    <sect1 id="linuxemu-matlab">
      <sect1info>
	<authorgroup>
	  <author>
	    <firstname>Dan</firstname>
	    <surname>Pelleg</surname>
	    <contrib>Contributed by </contrib>
	  </author>
	<!-- daniel+handbook@pelleg.org -->
	</authorgroup>
      </sect1info>
    <title>Installing &matlab;</title>

    <indexterm>
      <primary>applications</primary>
      <secondary><application>MATLAB</application></secondary>
    </indexterm>

    <para>This document describes the process of installing the Linux
      version of <application>&matlab; version 6.5</application> onto
      a &os; system.  It works quite well, with the exception of the
      <application>&java.virtual.machine;</application> (see
      <xref linkend="matlab-jre"/>).</para>

    <para>The Linux version of <application>&matlab;</application>
      can be ordered directly from The MathWorks at <ulink
	url="http://www.mathworks.com"></ulink>.  Make sure you also
      get the license file or instructions how to create it.  While
      you are there, let them know you would like a native &os;
      version of their software.</para>

    <sect2>
      <title>Installing &matlab;</title>

      <para>To install <application>&matlab;</application>, do the
	following:</para>

      <procedure>
	<step>
	  <para>Insert the installation CD and mount it.
	    Become <username>root</username>, as recommended by the
	    installation script.  To start the installation script
	    type:</para>

	  <screen>&prompt.root; <userinput>/compat/linux/bin/sh /cdrom/install</userinput></screen>

	  <tip>
	    <para>The installer is graphical.  If you get errors about
	      not being able to open a display, type
	      <command>setenv HOME
		~<replaceable>USER</replaceable></command>,
	      where <replaceable>USER</replaceable> is the user you
	      did a &man.su.1; as.</para>
	  </tip>
	</step>

	<step>
	  <para>
	    When asked for the <application>&matlab;</application>
	    root directory, type:
	    <userinput>/compat/linux/usr/local/matlab</userinput>.</para>

	  <tip>
	    <para>For easier typing on the rest of the installation
	      process, type this at your shell prompt:
	      <command>set
		  MATLAB=/compat/linux/usr/local/matlab</command></para>
	  </tip>
	</step>

	<step>
	  <para>Edit the license file as instructed when
	    obtaining the <application>&matlab;</application>
	      license.</para>

	  <tip>
	    <para>You can prepare this file in advance using your
	      favorite editor, and copy it to
	      <filename>$MATLAB/license.dat</filename> before the
	      installer asks you to edit it.</para>
	  </tip>
	</step>

	<step>
	  <para>Complete the installation process.</para>
	</step>
      </procedure>

      <para>At this point your <application>&matlab;</application>
	installation is complete.  The following steps apply
	<quote>glue</quote> to connect it to your &os; system.</para>
    </sect2>

    <sect2>
      <title>License Manager Startup</title>

      <procedure>
	<step>
	  <para>Create symlinks for the license manager
	    scripts:</para>

	  <screen>&prompt.root; <userinput>ln -s $MATLAB/etc/lmboot /usr/local/etc/lmboot_TMW</userinput>
&prompt.root; <userinput>ln -s $MATLAB/etc/lmdown /usr/local/etc/lmdown_TMW</userinput></screen>
	</step>

	<step>
	  <para>Create a startup file at
	    <filename>/usr/local/etc/rc.d/flexlm</filename>.  The
	    example below is a modified version of the distributed
	    <filename>$MATLAB/etc/rc.lm.glnx86</filename>.  The
	    changes are file locations, and startup of the license
	    manager under Linux emulation.</para>

	  <programlisting>#!/bin/sh
case "$1" in
  start)
        if [ -f /usr/local/etc/lmboot_TMW ]; then
              /compat/linux/bin/sh /usr/local/etc/lmboot_TMW -u <replaceable>username</replaceable> &amp;&amp; echo 'MATLAB_lmgrd'
        fi
        ;;
  stop)
	if [ -f /usr/local/etc/lmdown_TMW ]; then
            /compat/linux/bin/sh /usr/local/etc/lmdown_TMW  &gt; /dev/null 2&gt;&amp;1
	fi
        ;;
  *)
	echo "Usage: $0 {start|stop}"
	exit 1
	;;
esac

exit 0</programlisting>

	  <important>
	    <para>The file must be made executable:</para>

	    <screen>&prompt.root; <userinput>chmod +x /usr/local/etc/rc.d/flexlm</userinput></screen>

	    <para>You must also replace
	      <replaceable>username</replaceable> above with the name
	      of a valid user on your system (and not
	      <username>root</username>).</para>
	  </important>
	</step>

	<step>
	  <para>Start the license manager with the command:</para>

	  <screen>&prompt.root; <userinput>service flexlm start</userinput></screen>
	</step>
      </procedure>
    </sect2>

    <sect2 id="matlab-jre">
      <title>Linking the &java; Runtime Environment</title>

      <para>Change the <application>&java;</application> Runtime
	Environment (JRE) link to one working under &os;:</para>

      <screen>&prompt.root; <userinput>cd $MATLAB/sys/java/jre/glnx86/</userinput>
&prompt.root; <userinput>unlink jre; ln -s ./jre1.1.8 ./jre</userinput></screen>
    </sect2>

    <sect2>
      <title>Creating a &matlab; Startup Script</title>

      <procedure>
	<step>
	  <para>Place the following startup script in
	    <filename>/usr/local/bin/matlab</filename>:</para>

	  <programlisting>#!/bin/sh
/compat/linux/bin/sh /compat/linux/usr/local/matlab/bin/matlab "$@"</programlisting>
	</step>

	<step>
	  <para>Then type the command
	    <command>chmod +x /usr/local/bin/matlab</command>.</para>
	</step>
      </procedure>

      <tip>
	<para>Depending on your version of
	  <filename role="package">emulators/linux_base</filename>,
	  you may run into errors when running this script.  To avoid
	  that, edit the file
	  <filename>/compat/linux/usr/local/matlab/bin/matlab</filename>,
	  and change the line that says:</para>

	<programlisting>if [ `expr "$lscmd" : '.*-&gt;.*'` -ne 0 ]; then</programlisting>

	<para>(in version 13.0.1 it is on line 410) to this
	  line:</para>

	<programlisting>if test -L $newbase; then</programlisting>
      </tip>
    </sect2>

    <sect2>
      <title>Creating a &matlab; Shutdown Script</title>

      <para>The following is needed to solve a problem with &matlab;
	not exiting correctly.</para>

      <procedure>
	<step>
	  <para>Create a file
	    <filename>$MATLAB/toolbox/local/finish.m</filename>, and
	    in it put the single line:</para>

	  <programlisting>! $MATLAB/bin/finish.sh</programlisting>

	  <note><para>The <literal>$MATLAB</literal> is
	    literal.</para></note>

	  <tip>
	    <para>In the same directory, you will find the files
	      <filename>finishsav.m</filename> and
	      <filename>finishdlg.m</filename>, which let you save
	      your workspace before quitting.  If you use either of
	      them, insert the line above immediately after the
	      <literal>save</literal> command.</para></tip>
	  </step>

	  <step>
	    <para>Create a file
	      <filename>$MATLAB/bin/finish.sh</filename>, which will
	      contain the following:</para>

	    <programlisting>#!/compat/linux/bin/sh
(sleep 5; killall -1 matlab_helper) &amp;
exit 0</programlisting>
	</step>

	<step>
	  <para>Make the file executable:</para>

	  <screen>&prompt.root; <userinput>chmod +x $MATLAB/bin/finish.sh</userinput></screen>
	</step>
      </procedure>
    </sect2>

    <sect2 id="matlab-using">
      <title>Using &matlab;</title>

      <para>At this point you are ready to type
	<command>matlab</command> and start using it.</para>
    </sect2>
  </sect1>

  <sect1 id="linuxemu-oracle">
    <sect1info>
      <authorgroup>
	<author>
	  <firstname>Marcel</firstname>
	  <surname>Moolenaar</surname>
	  <contrib>Contributed by </contrib>
	</author>
	<!-- marcel@cup.hp.com -->
      </authorgroup>
    </sect1info>
    <title>Installing &oracle;</title>

    <indexterm>
      <primary>applications</primary>
      <secondary><application>Oracle</application></secondary>
    </indexterm>

    <sect2>
      <title>Preface</title>

      <para>This document describes the process of installing
	<application>&oracle; 8.0.5</application> and
	<application>&oracle; 8.0.5.1 Enterprise Edition</application>
	for Linux onto a FreeBSD machine.</para>
    </sect2>

    <sect2>
      <title>Installing the Linux Environment</title>

      <para>Make sure you have both <filename
	  role='package'>emulators/linux_base</filename> and
	<filename role='package'>devel/linux_devtools</filename>
	from the Ports Collection installed.  If you run into
	difficulties with these ports, you may have to use the
	packages or older versions available in the Ports
	Collection.</para>

      <para>If you want to run the intelligent agent, you will
	also need to install the Red Hat Tcl package:
	<filename>tcl-8.0.3-20.i386.rpm</filename>.  The general
	command for installing packages with the official
	<application>RPM</application> port (<filename
	  role='package'>archivers/rpm</filename>) is:</para>

      <screen>&prompt.root; <userinput>rpm -i --ignoreos --root /compat/linux --dbpath /var/lib/rpm <replaceable>package</replaceable></userinput></screen>

      <para>Installation of the <replaceable>package</replaceable>
	should not generate any errors.</para>
    </sect2>

    <sect2>
      <title>Creating the &oracle; Environment</title>

      <para>Before you can install
	<application>&oracle;</application>, you need to set up a
	proper environment.  This document only describes what to do
	<emphasis>specially</emphasis> to run
	<application>&oracle;</application> for Linux on FreeBSD, not
	what has been described in the
	<application>&oracle;</application> installation guide.</para>

      <sect3 id="linuxemu-kernel-tuning">
	<title>Kernel Tuning</title>

	<indexterm><primary>kernel tuning</primary></indexterm>

	<para>As described in the <application>&oracle;</application>
	  installation guide, you need to set the maximum size of
	  shared memory.  Do not use <literal>SHMMAX</literal> under
	  FreeBSD. <literal>SHMMAX</literal> is merely calculated
	  out of <literal>SHMMAXPGS</literal> and
	  <literal>PGSIZE</literal>.  Therefore define
	  <literal>SHMMAXPGS</literal>.  All other options can be
	  used as described in the guide.  For example:</para>

	<programlisting>options SHMMAXPGS=10000
options SHMMNI=100
options SHMSEG=10
options SEMMNS=200
options SEMMNI=70
options SEMMSL=61</programlisting>

	<para>Set these options to suit your intended use of
	  <application>&oracle;</application>.</para>

	<para>Also, make sure you have the following options in your
	  kernel configuration file:</para>

	<programlisting>options SYSVSHM #SysV shared memory
options SYSVSEM #SysV semaphores
options SYSVMSG #SysV interprocess communication</programlisting>
      </sect3>

      <sect3 id="linuxemu-oracle-account">

	<title>&oracle; Account</title>

	<para>Create an <username>oracle</username> account just as
	  you would create any other account.  The
	  <username>oracle</username> account is special only that
	  you need to give it a Linux shell.  Add
	  <literal>/compat/linux/bin/bash</literal> to
	  <filename>/etc/shells</filename> and set the shell for
	  the <username>oracle</username> account to
	  <filename>/compat/linux/bin/bash</filename>.</para>
      </sect3>

      <sect3 id="linuxemu-environment">
	<title>Environment</title>

	<para>Besides the normal <application>&oracle;</application>
	  variables, such as <envar>ORACLE_HOME</envar> and
	  <envar>ORACLE_SID</envar> you must set the following
	  environment variables:</para>

	<informaltable frame="none" pgwide="1">
	  <tgroup cols="2">
	    <colspec colwidth="1*"/>
	    <colspec colwidth="2*"/>
	    <thead>
	      <row>
		<entry>Variable</entry>

		<entry>Value</entry>
	      </row>
	    </thead>
	    <tbody>
	      <row>
		<entry><envar>LD_LIBRARY_PATH</envar></entry>

		<entry><literal>$ORACLE_HOME/lib</literal></entry>
	      </row>

	      <row>
		<entry><envar>CLASSPATH</envar></entry>

		<entry><literal>$ORACLE_HOME/jdbc/lib/classes111.zip</literal></entry>
	      </row>

	      <row>
		<entry><envar>PATH</envar></entry>

		<entry><literal>/compat/linux/bin
		    /compat/linux/sbin
		    /compat/linux/usr/bin
		    /compat/linux/usr/sbin
		    /bin
		    /sbin
		    /usr/bin
		    /usr/sbin
		    /usr/local/bin
		  $ORACLE_HOME/bin</literal></entry>
	      </row>
	    </tbody>
	  </tgroup>
	</informaltable>

	<para>It is advised to set all the environment variables in
	  <filename>.profile</filename>.  A complete example
	  is:</para>

	<programlisting>ORACLE_BASE=/oracle; export ORACLE_BASE
ORACLE_HOME=/oracle; export ORACLE_HOME
LD_LIBRARY_PATH=$ORACLE_HOME/lib
export LD_LIBRARY_PATH
ORACLE_SID=ORCL; export ORACLE_SID
ORACLE_TERM=386x; export ORACLE_TERM
CLASSPATH=$ORACLE_HOME/jdbc/lib/classes111.zip
export CLASSPATH
PATH=/compat/linux/bin:/compat/linux/sbin:/compat/linux/usr/bin
PATH=$PATH:/compat/linux/usr/sbin:/bin:/sbin:/usr/bin:/usr/sbin
PATH=$PATH:/usr/local/bin:$ORACLE_HOME/bin
export PATH</programlisting>
      </sect3>
    </sect2>

    <sect2>
      <title>Installing &oracle;</title>

      <para>Due to a slight inconsistency in the Linux emulator,
	you need to create a directory named
	<filename>.oracle</filename> in <filename>/var/tmp</filename>
	before you start the installer.  Let it be owned by the
	<username>oracle</username> user.  You should be able to
	install <application>&oracle;</application> without any
	problems.  If you have problems, check your
	<application>&oracle;</application> distribution and/or
	configuration first!  After you have installed
	<application>&oracle;</application>, apply the patches
	described in the next two subsections.</para>

      <para>A frequent problem is that the TCP protocol adapter is
	not installed right.  As a consequence, you cannot start any
	TCP listeners.  The following actions help solve this
	problem:</para>

      <screen>&prompt.root; <userinput>cd $ORACLE_HOME/network/lib</userinput>
&prompt.root; <userinput>make -f ins_network.mk ntcontab.o</userinput>
&prompt.root; <userinput>cd $ORACLE_HOME/lib</userinput>
&prompt.root; <userinput>ar r libnetwork.a ntcontab.o</userinput>
&prompt.root; <userinput>cd $ORACLE_HOME/network/lib</userinput>
&prompt.root; <userinput>make -f ins_network.mk install</userinput></screen>

      <para>Do not forget to run <filename>root.sh</filename>
	again!</para>

    <sect3 id="linuxemu-patch-root">
      <title>Patching root.sh</title>

      <para>When installing <application>&oracle;</application>,
	some actions, which need to be performed as
	<username>root</username>, are recorded in a shell script
	called <filename>root.sh</filename>.  This script is
	written in the <filename>orainst</filename> directory.
	Apply the following patch to <filename>root.sh</filename>,
	to have it use to proper location of
	<command>chown</command> or alternatively run the script
	under a Linux native shell.</para>

      <programlisting>*** orainst/root.sh.orig Tue Oct 6 21:57:33 1998
--- orainst/root.sh Mon Dec 28 15:58:53 1998
***************
*** 31,37 ****
# This is the default value for CHOWN
# It will redefined later in this script for those ports
# which have it conditionally defined in ss_install.h
! CHOWN=/bin/chown
#
# Define variables to be used in this script
--- 31,37 ----
# This is the default value for CHOWN
# It will redefined later in this script for those ports
# which have it conditionally defined in ss_install.h
! CHOWN=/usr/sbin/chown
#
# Define variables to be used in this script</programlisting>

	<para>When you do not install
	  <application>&oracle;</application> from CD, you can patch
	  the source for <filename>root.sh</filename>.  It is called
	  <filename>rthd.sh</filename> and is located in the
	  <filename>orainst</filename> directory in the source
	  tree.</para>
      </sect3>

      <sect3 id="linuxemu-patch-tcl">
	<title>Patching genclntsh</title>

	<para>The script <command>genclntsh</command> is used to
	  create a single shared client library.  It is used when
	  building the demos.  Apply the following patch to comment
	  out the definition of <envar>PATH</envar>:</para>

	<programlisting>*** bin/genclntsh.orig Wed Sep 30 07:37:19 1998
--- bin/genclntsh Tue Dec 22 15:36:49 1998
***************
*** 32,38 ****
#
# Explicit path to ensure that we're using the correct commands
#PATH=/usr/bin:/usr/ccs/bin export PATH
! PATH=/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin export PATH
#
# each product MUST provide a $PRODUCT/admin/shrept.lst
--- 32,38 ----
#
# Explicit path to ensure that we're using the correct commands
#PATH=/usr/bin:/usr/ccs/bin export PATH
! #PATH=/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin export PATH
#
# each product MUST provide a $PRODUCT/admin/shrept.lst</programlisting>
      </sect3>
    </sect2>

    <sect2>
      <title>Running &oracle;</title>

      <para>When you have followed the instructions, you should be
	able to run <application>&oracle;</application> as if it was
	run on Linux itself.</para>
    </sect2>
  </sect1>

  <sect1 id="linuxemu-advanced">
    <title>Advanced Topics</title>

    <para>If you are curious as to how the Linux binary compatibility
      works, this is the section you want to read.  Most of what
      follows is based heavily on an email written to &a.chat; by
      Terry Lambert <email>tlambert@primenet.com</email> (Message ID:
      <literal>&lt;199906020108.SAA07001@usr09.primenet.com&gt;</literal>).</para>

    <sect2>
      <title>How Does It Work?</title>

      <indexterm><primary>execution class loader</primary></indexterm>

      <para>FreeBSD has an abstraction called an <quote>execution
	  class loader</quote>.  This is a wedge into the
	&man.execve.2; system call.</para>

      <para>What happens is that FreeBSD has a list of loaders,
	instead of a single loader with a fallback to the
	<literal>#!</literal> loader for running any shell
	interpreters or shell scripts.</para>

      <para>Historically, the only loader on the &unix; platform
	examined the magic number (generally the first 4 or 8 bytes
	of the file) to see if it was a binary known to the system,
	and if so, invoked the binary loader.</para>

      <para>If it was not the binary type for the system, the
	&man.execve.2; call returned a failure, and the shell
	attempted to start executing it as shell commands.</para>

      <para>The assumption was a default of <quote>whatever the
	  current shell is</quote>.</para>

      <para>Later, a hack was made for &man.sh.1; to examine the
	first two characters, and if they were <literal>:\n</literal>,
	then it invoked the &man.csh.1; shell instead (we believe SCO
	first made this hack).</para>

      <para>What FreeBSD does now is go through a list of loaders,
	with a generic <literal>#!</literal> loader that knows about
	interpreters as the characters which follow to the next
	whitespace next to last, followed by a fallback to
	<filename>/bin/sh</filename>.</para>
      <indexterm><primary>ELF</primary></indexterm>

      <para>For the Linux ABI support, FreeBSD sees the magic number
	as an ELF binary (it makes no distinction between FreeBSD,
	&solaris;, Linux, or any other OS which has an ELF image type,
	at this point).</para>
      <indexterm><primary>Solaris</primary></indexterm>

      <para>The ELF loader looks for a specialized
	<emphasis>brand</emphasis>, which is a comment section in
	the ELF image, and which is not present on SVR4/&solaris;
	ELF binaries.</para>

      <para>For Linux binaries to function, they must be
	<emphasis>branded</emphasis> as type <literal>Linux</literal>
	from &man.brandelf.1;:</para>

      <screen>&prompt.root; <userinput>brandelf -t Linux file</userinput></screen>

      <para>When this is done, the ELF loader will see the
	<literal>Linux</literal> brand on the file.</para>
      <indexterm>
	<primary>ELF</primary>
	<secondary>branding</secondary>
      </indexterm>

      <para>When the ELF loader sees the <literal>Linux</literal>
	brand, the loader replaces a pointer in the
	<literal>proc</literal> structure.  All system calls are
	indexed through this pointer (in a traditional &unix; system,
	this would be the <literal>sysent[]</literal> structure array,
	containing the system calls).  In addition, the process is
	flagged for special handling of the trap vector for the signal
	trampoline code, and several other (minor) fix-ups that are
	handled by the Linux kernel module.</para>

      <para>The Linux system call vector contains, among other
	things, a list of <literal>sysent[]</literal> entries whose
	addresses reside in the kernel module.</para>

      <para>When a system call is called by the Linux binary, the
	trap code dereferences the system call function pointer off
	the <literal>proc</literal> structure, and gets the Linux,
	not the FreeBSD, system call entry points.</para>

      <para>In addition, the Linux mode dynamically
	<emphasis>reroots</emphasis> lookups; this is, in effect,
	what the <option>union</option> option to file system mounts
	(<emphasis>not</emphasis> the <literal>unionfs</literal>
	file system type!) does.  First, an attempt is made to lookup
	the file in the
	<filename>/compat/linux/<replaceable>original-path</replaceable></filename>
	directory, <emphasis>then</emphasis> only if that fails, the
	lookup is done in the
	<filename>/<replaceable>original-path</replaceable></filename>
	directory.  This makes sure that binaries that require other
	binaries can run (e.g., the Linux toolchain can all run under
	Linux ABI support).  It also means that the Linux binaries
	can load and execute FreeBSD binaries, if there are no
	corresponding Linux binaries present, and that you could place
	a &man.uname.1; command in the
	<filename>/compat/linux</filename> directory tree to ensure
	that the Linux binaries could not tell they were not running
	on Linux.</para>

      <para>In effect, there is a Linux kernel in the FreeBSD kernel;
	the various underlying functions that implement all of the
	services provided by the kernel are identical to both the
	FreeBSD system call table entries, and the Linux system call
	table entries: file system operations, virtual memory
	operations, signal delivery, System V IPC, etc&hellip;  The
	only difference is that FreeBSD binaries get the FreeBSD
	<emphasis>glue</emphasis> functions, and Linux binaries get
	the Linux <emphasis>glue</emphasis> functions (most older OS's
	only had their own <emphasis>glue</emphasis> functions:
	addresses of functions in a static global
	<literal>sysent[]</literal> structure array, instead of
	addresses of functions dereferenced off a dynamically
	initialized pointer in the <literal>proc</literal> structure
	of the process making the call).</para>

      <para>Which one is the native FreeBSD ABI?  It does not matter.
	Basically the only difference is that (currently; this could
	easily be changed in a future release, and probably will be
	after this) the FreeBSD <emphasis>glue</emphasis> functions
	are statically linked into the kernel, and the Linux
	<emphasis>glue</emphasis> functions can be statically linked,
	or they can be accessed via a kernel module.</para>

      <para>Yeah, but is this really emulation?  No.  It is an ABI
	implementation, not an emulation.  There is no emulator (or
	simulator, to cut off the next question) involved.</para>

      <para>So why is it sometimes called <quote>Linux
	  emulation</quote>?  To make it hard to sell FreeBSD!
	Really, it is because the historical implementation was done
	at a time when there was really no word other than that to
	describe what was going on; saying that FreeBSD ran Linux
	binaries was not true, if you did not compile the code in or
	load a module, and there needed to be a word to describe what
	was being loaded&mdash;hence <quote>the Linux
	  emulator</quote>.</para>
    </sect2>
  </sect1>
</chapter>