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en_US.ISO8859-1/books/handbook/linuxemu/chapter.xml
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@ -4,25 +4,48 @@
$FreeBSD$
-->
<chapter xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0" xml:id="linuxemu">
<info><title>&linux; Binary Compatibility</title>
<chapter xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
xml:id="linuxemu">
<info>
<title>&linux; Binary Compatibility</title>
<authorgroup>
<author><personname><firstname>Jim</firstname><surname>Mock</surname></personname><contrib>Restructured and parts updated by </contrib></author>
<author>
<personname>
<firstname>Jim</firstname>
<surname>Mock</surname>
</personname>
<contrib>Restructured and parts updated by </contrib>
</author>
<!-- 22 Mar 2000 -->
</authorgroup>
<authorgroup>
<author><personname><firstname>Brian N.</firstname><surname>Handy</surname></personname><contrib>Originally contributed by </contrib></author>
<author><personname><firstname>Rich</firstname><surname>Murphey</surname></personname></author>
<author>
<personname>
<firstname>Brian N.</firstname>
<surname>Handy</surname>
</personname>
<contrib>Originally contributed by </contrib>
</author>
<author>
<personname>
<firstname>Rich</firstname>
<surname>Murphey</surname>
</personname>
</author>
</authorgroup>
</info>
<sect1 xml:id="linuxemu-synopsis">
<title>Synopsis</title>
<indexterm><primary>Linux binary
compatibility</primary></indexterm>
<indexterm>
<primary>Linux binary compatibility</primary>
</indexterm>
<indexterm>
<primary>binary compatibility</primary>
<secondary>Linux</secondary>
@ -43,6 +66,7 @@
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 a &os;
@ -93,12 +117,12 @@
<screen>&prompt.root; <userinput>cd
/usr/ports/emulators/linux_base-f10</userinput> &prompt.root; <userinput>make install distclean</userinput></screen>
<para>Once the port is installed, enable &linux; binary
compatibility by loading the <literal>linux</literal>
module. Type the following as
<systemitem class="username">root</systemitem>:</para>
<para>Once the port is installed, enable &linux; binary
compatibility by loading the <literal>linux</literal> module.
Type the following as
<systemitem class="username">root</systemitem>:</para>
<screen>&prompt.root; <userinput>kldload linux</userinput></screen>
<screen>&prompt.root; <userinput>kldload linux</userinput></screen>
<para>In order for &linux; compatibility to always be enabled at
boot time, add the following line to
@ -120,26 +144,26 @@ Id Refs Address Size Name
</indexterm>
<para>Users who prefer to statically link &linux; binary
compatibility into the kernel should add <literal>options
COMPAT_LINUX</literal> to the custom kernel configuration
file. Compile and install the new kernel as described in <xref linkend="kernelconfig"/>.</para>
compatibility into the kernel should add
<literal>options COMPAT_LINUX</literal> to the custom kernel
configuration file. Compile and install the new kernel as
described in <xref linkend="kernelconfig"/>.</para>
<sect2 xml:id="linuxemu-libs-manually">
<title>Installing Libraries Manually</title>
<para>While using the Ports Collection is recommended, &linux;
libraries can be installed manually. The &linux; shared
libraries required by a program and the runtime linker
should be copied to <filename>/compat/linux</filename>. Any shared
libraries opened by &linux; programs run under &os; will
look in this directory first. For example, if a &linux;
program loads <filename>/lib/libc.so</filename>, &os; 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 to <filename>/compat/linux/lib</filename> rather than
to the paths that the &linux; <command>ld.so</command>
libraries required by a program and the runtime linker should
be copied to <filename>/compat/linux</filename>. Any shared
libraries opened by &linux; programs run under &os; will look
in this directory first. For example, if a &linux; program
loads <filename>/lib/libc.so</filename>, &os; 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 to <filename>/compat/linux/lib</filename> rather
than to the paths that the &linux; <command>ld.so</command>
reports.</para>
<para>Generally, one will need to look for the shared
@ -152,13 +176,16 @@ Id Refs Address Size Name
<sect3>
<title>How to Install Additional Shared Libraries</title>
<indexterm><primary>shared libraries</primary></indexterm>
<indexterm>
<primary>shared libraries</primary>
</indexterm>
<para>If the <literal>linux_base</literal> port is installed
and an application still complains about missing shared
libraries, there are two methods <systemitem class="username">root</systemitem>
can use to determine which shared libraries the &linux;
binaries need.</para>
libraries, there are two methods
<systemitem class="username">root</systemitem> can use to
determine which shared libraries the &linux; binaries
need.</para>
<para>If a &linux; system is available, determine which shared
libraries the application needs, and copy them to the &os;
@ -175,7 +202,9 @@ 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>
<indexterm>
<primary>symbolic links</primary>
</indexterm>
<para>Copy all the files in the last column into
<filename>/compat/linux</filename> on
the &os; system, with the names in the first column as
@ -256,7 +285,9 @@ Abort</screen>
<screen>&prompt.user; <userinput>brandelf -t Linux my-linux-elf-binary</userinput></screen>
<indexterm><primary>GNU toolchain</primary></indexterm>
<indexterm>
<primary>GNU toolchain</primary>
</indexterm>
<para>Since the GNU toolchain places the appropriate branding
information into ELF binaries automatically, this step is
usually not necessary.</para>
@ -271,7 +302,8 @@ Abort</screen>
<para>In order to install a &linux; RPM-based application, first
install the <package>archivers/rpm2cpio</package> package or
port. Once installed, <systemitem class="username">root</systemitem> can use this
port. Once installed,
<systemitem class="username">root</systemitem> can use this
command to install a <filename>.rpm</filename> as
follows:</para>
@ -298,22 +330,24 @@ Abort</screen>
<programlisting>order hosts, bind
multi on</programlisting>
<para>This order specifies that
<filename>/etc/hosts</filename> is searched first and DNS
is searched second. When
<para>This order specifies that <filename>/etc/hosts</filename>
is searched first and DNS is searched second. When
<filename>/compat/linux/etc/host.conf</filename> does not
exist, &linux; applications use
<filename>/etc/host.conf</filename> and complain about the
incompatible &os; syntax. Remove
<literal>bind</literal> if a name server is not configured
using <filename>/etc/resolv.conf</filename>.</para>
incompatible &os; syntax. Remove <literal>bind</literal> if a
name server is not configured using
<filename>/etc/resolv.conf</filename>.</para>
</sect2>
</sect1>
<?ignore While the installer works, the binaries do not. As of Oct 2013, Linux
emulation is 32-bit but the trial version of Mathematica is only
available as 64-bit. This section should be revisited if Linux
<?ignore
While the installer works, the binaries do not. As of Oct 2013,
Linux emulation is 32-bit but the trial version of Mathematica is
only available as 64-bit. This section should be revisited if Linux
emulation gets 64-bit binary support.
<sect1 id="linuxemu-mathematica">
<sect1info>
<authorgroup>
@ -332,11 +366,11 @@ multi on</programlisting>
<secondary><application>Mathematica</application></secondary>
</indexterm>
<para>This section describes the process of installing the
&linux; version of <application>&mathematica; 9.X</application>
onto a &os; system. <application>&mathematica;</application>
is a commercial, computational software program used in
scientific, engineering, and mathematical fields. A 30 day trial version is
<para>This section describes the process of installing the &linux;
version of <application>&mathematica; 9.X</application> onto a
&os; system. <application>&mathematica;</application> is a
commercial, computational software program used in scientific,
engineering, and mathematical fields. A 30 day trial version is
available for download from <ulink
url="http://www.wolfram.com/mathematica/">wolfram.com/mathematica</ulink>.</para>
@ -347,11 +381,11 @@ multi on</programlisting>
<filename role="package">textproc/linux-f10-aspell</filename>
package or port is installed and that the &man.linprocfs.5;
file system is mounted.</para>
<screen>&prompt.root; <userinput>sysctl kern.fallback_elf_brand=3</userinput></screen>
<para>&os; will now assume that unbranded ELF binaries
use the &linux; <acronym>ABI</acronym> which should allow the
<para>&os; will now assume that unbranded ELF binaries use the
&linux; <acronym>ABI</acronym> which should allow the
installer to execute from the CDROM.</para>
<para>The downloaded file will be saved to
@ -375,7 +409,6 @@ Enter the installation directory, or press ENTER to select /usr/local/Wolfram/Ma
Now installing...
***********************
Installation complete.</programlisting>
</sect2>
<sect2>
@ -387,8 +420,7 @@ Installation complete.</programlisting>
fonts to be installed locally. This means that these fonts
need to be copied from the CDROM or from a host with
<application>&mathematica;</application> installed to the
local machine. These fonts are normally stored in
<filename
local machine. These fonts are normally stored in <filename
class="directory">/cdrom/Unix/Files/SystemFiles/Fonts</filename>
on the CDROM, or <filename
class="directory">/usr/local/mathematica/SystemFiles/Fonts</filename>
@ -441,9 +473,9 @@ Installation complete.</programlisting>
-->
<!--
As of October 2013, the trial version is only available in the
Professional and Academic editions (not the Student or Personal
editions) and requires a contact with a product specialist before
As of October 2013, the trial version is only available in the
Professional and Academic editions (not the Student or Personal
editions) and requires a contact with a product specialist before
the evaluation download link is made available.
<sect1 id="linuxemu-maple">
<sect1info>
@ -492,11 +524,10 @@ Installation complete.</programlisting>
<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 the machine for the license
server.</para>
manager by running the <filename>INSTALL_LIC</filename>
install shell script that comes with
<application>&maple;</application>. Specify the primary
hostname for the machine for the license server.</para>
</step>
<step>
@ -504,7 +535,7 @@ Installation complete.</programlisting>
<filename>/usr/local/maple/bin/maple.system.type</filename>
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
@ -524,14 +555,16 @@ Installation complete.</programlisting>
<literal>"FreeBSD"|\</literal>.</para>
<para>This patch instructs <application>&maple;</application>
to recognize &os; 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>
to recognize &os; 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>
<step>
<para>Start the license server.</para>
<para>The following script, installed as
<filename>/usr/local/rtc/rc.d/lmgrd</filename> is a
@ -562,28 +595,31 @@ stop)
esac
exit 0
----- snip ------------</programlisting></step>
----- snip ------------</programlisting>
</step>
<step>
<para>Test that <application>&maple;</application>
starts:</para>
<step><para>Test that
<application>&maple;</application> starts:</para>
<screen>&prompt.user; <userinput>cd /usr/local/maple/bin</userinput>
<screen>&prompt.user; <userinput>cd /usr/local/maple/bin</userinput>
&prompt.user; <userinput>./xmaple</userinput></screen>
<para>Once everything is working, consider writing
Maplesoft to let them know you would like a native &os;
version!</para></step>
</procedure>
<para>Once everything is working, consider writing Maplesoft
to let them know you would like a native &os;
version!</para>
</step>
</procedure>
<sect2>
<title>Common Pitfalls</title>
<sect2>
<title>Common Pitfalls</title>
<itemizedlist>
<listitem><para><command>lmgrd</command> is known to be
picky about the license file and to dump core if there
are any problems. A correct license file should look
like this:</para>
<itemizedlist>
<listitem>
<para><command>lmgrd</command> is known to be picky about
the license file and to dump core if there are any
problems. A correct license file should look like
this:</para>
<programlisting>#
=======================================================
@ -606,23 +642,27 @@ FEATURE Maple maplelmg 2000.0831 permanent 1 XXXXXXXXXXXX \
<para>Editing the license file works as long as the
<quote>FEATURE</quote> line is not edited. That line is
protected by the license key.</para></listitem>
</itemizedlist>
</sect2>
</sect1>
-->
<!--
As of October, 2013, the Linux version of Matlab is only available for 64-bit.
<sect1 id="linuxemu-matlab">
<sect1info>
<authorgroup>
<author>
<firstname>Dan</firstname>
<surname>Pelleg</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect1info>
protected by the license key.</para>
</listitem>
</itemizedlist>
</sect2>
</sect1>
-->
<!--
As of October, 2013, the Linux version of Matlab is only available
for 64-bit.
<sect1 id="linuxemu-matlab">
<sect1info>
<authorgroup>
<author>
<firstname>Dan</firstname>
<surname>Pelleg</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Installing &matlab;</title>
<indexterm>
@ -631,9 +671,9 @@ FEATURE Maple maplelmg 2000.0831 permanent 1 XXXXXXXXXXXX \
</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
&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> which is
described further in <xref linkend="matlab-jre"/>.</para>
@ -790,9 +830,10 @@ exit 0</programlisting>
</procedure>
<tip>
<para>Depending on the version of <filename
role="package">emulators/linux_base</filename>, running
this script may result in errors. To avoid errors, edit
<para>Depending on the version of
<filename role="package">emulators/linux_base</filename>,
running this script may result in errors. To avoid errors,
edit
<filename>/compat/linux/usr/local/matlab/bin/matlab</filename>,
and change the line that says:</para>
@ -818,8 +859,9 @@ exit 0</programlisting>
<programlisting>! $MATLAB/bin/finish.sh</programlisting>
<note><para>The <literal>$MATLAB</literal> is
literal.</para></note>
<note>
<para>The <literal>$MATLAB</literal> is literal.</para>
</note>
<tip>
<para>The same directory contains
@ -827,15 +869,15 @@ exit 0</programlisting>
<filename>finishdlg.m</filename>, which allow the
workspace to be saved before quitting. If either file
is used, insert the line above immediately after the
<literal>save</literal> command.</para></tip>
</step>
<literal>save</literal> command.</para>
</tip>
</step>
<step>
<para>Create
<filename>$MATLAB/bin/finish.sh</filename> which
contains the following:</para>
<step>
<para>Create <filename>$MATLAB/bin/finish.sh</filename>
which contains the following:</para>
<programlisting>#!/compat/linux/bin/sh
<programlisting>#!/compat/linux/bin/sh
(sleep 5; killall -1 matlab_helper) &amp;
exit 0</programlisting>
</step>
@ -857,9 +899,10 @@ exit 0</programlisting>
</sect1>
<sect1 id="linuxemu-oracle">
While the Oracle website is unclear, the installation script is: You
are attempting to install 64-bit Oracle on a 32-bit operating system.
This is not supported and will not work.
While the Oracle website is unclear, the installation script is:
You are attempting to install 64-bit Oracle on a 32-bit operating
system. This is not supported and will not work.
<sect1info>
<authorgroup>
<author>
@ -869,6 +912,7 @@ exit 0</programlisting>
</author>
</authorgroup>
</sect1info>
<title>Installing &oracle;</title>
<indexterm>
@ -890,8 +934,9 @@ exit 0</programlisting>
<para>To run the intelligent agent, install the Red Hat Tcl
package: <filename>tcl-8.0.3-20.i386.rpm</filename>. The
general command for installing RPMs with the <filename
role='package'>archivers/rpm</filename> port is:</para>
general command for installing RPMs with the
<filename role='package'>archivers/rpm</filename> port
is:</para>
<screen>&prompt.root; <userinput>rpm -i --ignoreos --root /compat/linux --dbpath /var/lib/rpm <replaceable>package</replaceable></userinput></screen>
@ -910,7 +955,9 @@ exit 0</programlisting>
<sect3 id="linuxemu-kernel-tuning">
<title>Kernel Tuning</title>
<indexterm><primary>kernel tuning</primary></indexterm>
<indexterm>
<primary>kernel tuning</primary>
</indexterm>
<para>As described in the <application>&oracle;</application>
installation guide, the maximum size of shared memory needs
@ -965,26 +1012,23 @@ options SYSVMSG #SysV interprocess communication</programlisting>
<thead>
<row>
<entry>Variable</entry>
<entry>Value</entry>
</row>
</thead>
<tbody>
<row>
<entry><envar>LD_LIBRARY_PATH</envar></entry>
<entry><literal>$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
@ -1077,22 +1121,22 @@ export PATH</programlisting>
#
# Define variables to be used in this script</programlisting>
<para>If <application>&oracle;</application> is not installed
from CD, patch the source for <filename>root.sh</filename>.
It is called <filename>rthd.sh</filename> and is located in
<filename class="directory">orainst</filename> in the source
tree.</para>
</sect3>
<para>If <application>&oracle;</application> is not installed
from CD, patch the source for <filename>root.sh</filename>.
It is called <filename>rthd.sh</filename> and is located in
<filename class="directory">orainst</filename> in the source
tree.</para>
</sect3>
<sect3 id="linuxemu-patch-tcl">
<title>Patching <filename>genclntsh</filename></title>
<sect3 id="linuxemu-patch-tcl">
<title>Patching <filename>genclntsh</filename></title>
<para>The script <command>genclntsh</command> is used to
create a single shared client library when building the
demos. Apply the following patch to comment out the
definition of <envar>PATH</envar>:</para>
<para>The script <command>genclntsh</command> is used to create
a single shared client library 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
<programlisting>*** bin/genclntsh.orig Wed Sep 30 07:37:19 1998
--- bin/genclntsh Tue Dec 22 15:36:49 1998
***************
*** 32,38 ****
@ -1120,7 +1164,7 @@ export PATH</programlisting>
running on &linux;.</para>
</sect2>
</sect1>
?>
?>
<sect1 xml:id="linuxemu-advanced">
<title>Advanced Topics</title>
@ -1132,9 +1176,9 @@ export PATH</programlisting>
<indexterm><primary>execution class loader</primary></indexterm>
<para>&os; has an abstraction called an <quote>execution class
loader</quote>. This is a wedge into the &man.execve.2;
system call.</para>
<para>&os; has an abstraction called an
<quote>execution class loader</quote>. This is a wedge into the
&man.execve.2; system call.</para>
<para>Historically, the &unix; loader examined the magic number
(generally the first 4 or 8 bytes of the file) to see if it was
@ -1144,8 +1188,8 @@ export PATH</programlisting>
<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. The
assumption was a default of <quote>whatever the current shell
is</quote>.</para>
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>, it
@ -1155,9 +1199,13 @@ export PATH</programlisting>
a fallback to the <literal>#!</literal> loader for running shell
interpreters or shell scripts.</para>
<indexterm><primary>ELF</primary></indexterm>
<indexterm>
<primary>ELF</primary>
</indexterm>
<indexterm><primary>Solaris</primary></indexterm>
<indexterm>
<primary>Solaris</primary>
</indexterm>
<para>For the &linux; <acronym>ABI</acronym> support, &os; sees
the magic number as an ELF binary. The ELF loader looks for a
@ -1171,65 +1219,63 @@ export PATH</programlisting>
<screen>&prompt.root; <userinput>brandelf -t Linux file</userinput></screen>
<indexterm>
<primary>ELF</primary>
<secondary>branding</secondary>
</indexterm>
<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 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>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 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>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 &os;, system call entry points.</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
&os;, system call entry points.</para>
<para>&linux; mode dynamically <emphasis>reroots</emphasis>
lookups. This is, in effect, equivalent to the
<option>union</option> option to file system mounts. First,
an attempt is made to lookup the file in <filename
class="directory">/compat/linux/<replaceable>original-path</replaceable></filename>.
If that fails, the lookup is done in
<filename
class="directory">/<replaceable>original-path</replaceable></filename>.
This makes sure that binaries that require other binaries can
run. For example, the &linux; toolchain can all run under
&linux; <acronym>ABI</acronym> support. It also means that
the &linux; binaries can load and execute &os; binaries, if
there are no corresponding &linux; binaries present, and that
a &man.uname.1; command can be placed in the
<filename>/compat/linux</filename> directory
tree to ensure that the &linux; binaries can not tell they are
not running on &linux;.</para>
<para>&linux; mode dynamically <emphasis>reroots</emphasis>
lookups. This is, in effect, equivalent to the
<option>union</option> option to file system mounts. First, an
attempt is made to lookup the file in <filename
class="directory">/compat/linux/<replaceable>original-path</replaceable></filename>.
If that fails, the lookup is done in <filename
class="directory">/<replaceable>original-path</replaceable></filename>.
This makes sure that binaries that require other binaries can
run. For example, the &linux; toolchain can all run under
&linux; <acronym>ABI</acronym> support. It also means that the
&linux; binaries can load and execute &os; binaries, if there
are no corresponding &linux; binaries present, and that a
&man.uname.1; command can be placed in the
<filename>/compat/linux</filename> directory tree to ensure that
the &linux; binaries can not tell they are not running on
&linux;.</para>
<para>In effect, there is a &linux; kernel in the &os; kernel.
The various underlying functions that implement all of the
services provided by the kernel are identical to both the
&os; system call table entries, and the &linux; system call
table entries: file system operations, virtual memory
operations, signal delivery, and System V IPC. The only
difference is that &os; binaries get the &os;
<emphasis>glue</emphasis> functions, and &linux; binaries get
the &linux; <emphasis>glue</emphasis> functions. The &os;
<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>In effect, there is a &linux; kernel in the &os; kernel.
The various underlying functions that implement all of the
services provided by the kernel are identical to both the &os;
system call table entries, and the &linux; system call table
entries: file system operations, virtual memory operations,
signal delivery, and System V IPC. The only difference is that
&os; binaries get the &os; <emphasis>glue</emphasis> functions,
and &linux; binaries get the &linux; <emphasis>glue</emphasis>
functions. The &os; <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>Technically, this is not really emulation, it is an
<acronym>ABI</acronym> implementation. It is sometimes called
<quote>&linux; emulation</quote> because the implementation
was done at a time when there was no other word to describe
what was going on. Saying that &os; ran &linux; binaries was
not true, since the code was not compiled in.</para>
</sect1>
</chapter>
<para>Technically, this is not really emulation, it is an
<acronym>ABI</acronym> implementation. It is sometimes called
<quote>&linux; emulation</quote> because the implementation was
done at a time when there was no other word to describe what was
going on. Saying that &os; ran &linux; binaries was not true,
since the code was not compiled in.</para>
</sect1>
</chapter>