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<refentry>
  <refentryinfo>
    <address>
      <email>jcm@jonmasters.org</email>
    </address>
    <author>
      <firstname>Jon</firstname>
      <surname>Masters</surname>
    </author>
    <date>2010-03-01</date>
  </refentryinfo>
  <refmeta>
    <refentrytitle>depmod</refentrytitle>
    <manvolnum>8</manvolnum>
  </refmeta>
  <refnamediv>
    <refname>depmod</refname> <refpurpose>program to generate <filename>modules.dep</filename> and map files.</refpurpose>
  </refnamediv>
  <refsynopsisdiv>
    <cmdsynopsis>
      <command>depmod</command>
      <arg><option>-b <replaceable>basedir</replaceable></option></arg>
      <arg><option>-e</option></arg>
      <arg><option>-F <replaceable>System.map</replaceable></option></arg>
      <arg><option>-n</option></arg>
      <arg><option>-v</option></arg>
      <arg><option><replaceable>version</replaceable></option></arg>
      <arg><option>-A</option></arg>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>depmod</command>
      <arg><option>-e</option></arg>
      <arg><option>-F<replaceable>System.map</replaceable></option></arg>
      <arg><option>-n</option></arg>
      <arg><option>-v</option></arg>
      <arg><option><replaceable>version</replaceable></option></arg>
      <arg rep='repeat'><option><replaceable>filename</replaceable></option></arg>
    </cmdsynopsis>
  </refsynopsisdiv>
  <refsect1>
    <title>DESCRIPTION</title>
    <para>
      Linux kernel modules can provide services (called "symbols") for
      other modules to use (using one of the EXPORT_SYMBOL variants in the
      code).  If a second module uses this symbol, that second module clearly
      depends on the first module.  These dependencies can get quite complex.
    </para>
    <para>
      <command>depmod</command> creates a list of module dependencies
      by reading each module under
      <filename>/lib/modules/</filename><replaceable>version</replaceable> 
      and determining what symbols it exports and what symbols it
      needs.  By default, this list is written to
      <filename>modules.dep</filename>, and a binary hashed version named
      <filename>modules.dep.bin</filename>, in the same directory.  If
      filenames are given on the command line, only those modules are
      examined (which is rarely useful unless all modules are listed).
      <command>depmod</command> also creates a list of symbols provided
      by modules in the file named <filename>modules.symbols</filename>
      and its binary hashed version, <filename>modules.symbols.bin</filename>.
    </para>
    <para>
      If a <replaceable>version</replaceable> is provided, then that
      kernel version's module directory is used rather than the
      current kernel version (as returned by <command>uname -r</command>).
    </para>
    <para>
      <command>depmod</command> will also generate various legacy map
      files in the output directory for use by the older hotplug
      infrastructure. These map files are largely deprecated.
    </para>
  </refsect1>
  <refsect1>
    <title>OPTIONS</title>
    <variablelist>
      <varlistentry>
          <term><option>-a</option> <option>--all</option>
          </term>
          <listitem>
            <para>
              Probe all modules. This option is enabled by default if no
              file names are given in the command-line.
            </para>
          </listitem>
      </varlistentry>
      <varlistentry>
          <term><option>-A</option> <option>--quick</option>
          </term>
          <listitem>
            <para>
              This option scans to see if any modules are newer than the
              <filename>modules.dep</filename> file before any work is done:
              if not, it silently exits rather than regenerating the files.
            </para>
          </listitem>
      </varlistentry>
      <varlistentry>
	  <term><option>-b <replaceable>basedir</replaceable></option> <option>--basedir <replaceable>basedir</replaceable></option>
	  </term>
	  <listitem>
	    <para>
	      If your modules are not currently in the (normal)
	      directory
	      <filename>/lib/modules/</filename><replaceable>version</replaceable>,
	      but in a staging area, you can specify a
	      <replaceable>basedir</replaceable> which is prepended to
	      the directory name.  This
	      <replaceable>basedir</replaceable> is stripped from the
	      resulting <filename>modules.dep</filename> file, so it
	      is ready to be moved into the normal location. Use this option
	      if you are a distribution vendor who needs to pre-generate the
	      meta-data files rather than running depmod again later.
	    </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-C</option> <option>--config <replaceable>file or directory</replaceable></option>
        </term>
        <listitem>
          <para>
            This option overrides the default configuration file at
            <filename>/etc/depmod.conf</filename> (or the 
            <filename>/etc/depmod.d/</filename> directory if that is not found).
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-e</option> <option>--errsyms</option>
        </term>
	  <listitem>
	    <para>
	      When combined with the <option>-F</option> option, this
	      reports any symbols which a module needs which are not
	      supplied by other modules or the kernel.  Normally, any
	      symbols not provided by modules are assumed to be
	      provided by the kernel (which should be true in a
	      perfect world), but this assumption can break espencially
	      when additionally updated third party drivers are not
	      correctly installed or were built incorrectly.
	    </para>
	  </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-F</option> <option>--filesyms <replaceable>System.map</replaceable></option>
        </term>
        <listitem>
          <para>
	    Supplied with the <filename>System.map</filename> produced
	    when the kernel was built, this allows the
	    <option>-e</option> option to report unresolved symbols.
	  </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-h</option> <option>--help</option>
        </term>
        <listitem>
          <para>
            Print the help message and exit.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-n</option> <option>--dry-run</option>
        </term>
        <listitem>
          <para>
	    This sends the resulting modules.dep and the various
	    map files to standard output rather than writing them into
	    the module directory.
	  </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-v</option> <option>--verbose</option>
        </term>
        <listitem>
          <para>
	    In verbose mode, <command>depmod</command> will print (to stdout)
            all the symbols each module depends on and the module's file name
            which provides that symbol.
	  </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-V</option> <option>--version</option>
        </term>
        <listitem>
          <para>
            Show version of program and exit. See below for caveats when
            run on older kernels.
          </para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
  <refsect1>
    <title>COPYRIGHT</title>

    <para>
      This manual page originally Copyright 2002, Rusty Russell,
      IBM Corporation. Maintained by Jon Masters and others.
    </para>
  </refsect1>
  <refsect1>
    <title>SEE ALSO</title>
    <para>
      <citerefentry>
	<refentrytitle>depmod.conf</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>depmod.d</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>modprobe</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>modules.dep</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>
    </para>
  </refsect1>
</refentry>

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