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Next: <a href="Hash-Tables.html#Hash-Tables" accesskey="n" rel="next">Hash Tables</a>, Previous: <a href="File-Caching.html#File-Caching" accesskey="p" rel="prev">File Caching</a>, Up: <a href="BFD-front-end.html#BFD-front-end" accesskey="u" rel="up">BFD front end</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="BFD-Index.html#BFD-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Linker-Functions-1"></a>
<h3 class="section">2.17 Linker Functions</h3>
<a name="index-Linker"></a>
<p>The linker uses three special entry points in the BFD target
vector.  It is not necessary to write special routines for
these entry points when creating a new BFD back end, since
generic versions are provided.  However, writing them can
speed up linking and make it use significantly less runtime
memory.
</p>
<p>The first routine creates a hash table used by the other
routines.  The second routine adds the symbols from an object
file to the hash table.  The third routine takes all the
object files and links them together to create the output
file.  These routines are designed so that the linker proper
does not need to know anything about the symbols in the object
files that it is linking.  The linker merely arranges the
sections as directed by the linker script and lets BFD handle
the details of symbols and relocs.
</p>
<p>The second routine and third routines are passed a pointer to
a <code>struct bfd_link_info</code> structure (defined in
<code>bfdlink.h</code>) which holds information relevant to the link,
including the linker hash table (which was created by the
first routine) and a set of callback functions to the linker
proper.
</p>
<p>The generic linker routines are in <code>linker.c</code>, and use the
header file <code>genlink.h</code>.  As of this writing, the only back
ends which have implemented versions of these routines are
a.out (in <code>aoutx.h</code>) and ECOFF (in <code>ecoff.c</code>).  The a.out
routines are used as examples throughout this section.
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<tr><td align="left" valign="top">&bull; <a href="Creating-a-Linker-Hash-Table.html#Creating-a-Linker-Hash-Table" accesskey="1">Creating a Linker Hash Table</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
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<tr><td align="left" valign="top">&bull; <a href="Adding-Symbols-to-the-Hash-Table.html#Adding-Symbols-to-the-Hash-Table" accesskey="2">Adding Symbols to the Hash Table</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
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<tr><td align="left" valign="top">&bull; <a href="Performing-the-Final-Link.html#Performing-the-Final-Link" accesskey="3">Performing the Final Link</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
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