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128 lines
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<p>
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<a name="Writing-the-symbol-table"></a>Previous: <a rel="previous" accesskey="p" href="Relocating-the-section-contents.html#Relocating-the-section-contents">Relocating the section contents</a>,
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Up: <a rel="up" accesskey="u" href="Performing-the-Final-Link.html#Performing-the-Final-Link">Performing the Final Link</a>
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<h5 class="subsubsection">2.17.3.3 Writing the symbol table</h5>
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<p>The <code>_bfd_final_link</code> function must gather all the symbols
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in the input files and write them out. It must also write out
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all the symbols in the global hash table. This must be
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controlled by the <code>strip</code> and <code>discard</code> fields of the
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<code>bfd_link_info</code> structure.
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<p>The local symbols of the input files will not have been
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entered into the linker hash table. The <code>_bfd_final_link</code>
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routine must consider each input file and include the symbols
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in the output file. It may be convenient to do this when
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looking through the <code>link_order</code> structures, or it may be
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done by stepping through the <code>input_bfds</code> list.
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<p>The <code>_bfd_final_link</code> routine must also traverse the global
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hash table to gather all the externally visible symbols. It
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is possible that most of the externally visible symbols may be
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written out when considering the symbols of each input file,
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but it is still necessary to traverse the hash table since the
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linker script may have defined some symbols that are not in
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any of the input files.
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<p>The <code>strip</code> field of the <code>bfd_link_info</code> structure
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controls which symbols are written out. The possible values
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are listed in <code>bfdlink.h</code>. If the value is <code>strip_some</code>,
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then the <code>keep_hash</code> field of the <code>bfd_link_info</code>
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structure is a hash table of symbols to keep; each symbol
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should be looked up in this hash table, and only symbols which
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are present should be included in the output file.
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<p>If the <code>strip</code> field of the <code>bfd_link_info</code> structure
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permits local symbols to be written out, the <code>discard</code> field
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is used to further controls which local symbols are included
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in the output file. If the value is <code>discard_l</code>, then all
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local symbols which begin with a certain prefix are discarded;
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this is controlled by the <code>bfd_is_local_label_name</code> entry point.
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<p>The a.out backend handles symbols by calling
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<code>aout_link_write_symbols</code> on each input BFD and then
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traversing the global hash table with the function
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<code>aout_link_write_other_symbol</code>. It builds a string table
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while writing out the symbols, which is written to the output
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file at the end of <code>NAME(aout,final_link)</code>.
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<p><a name="index-bfd_005flink_005fsplit_005fsection-1379"></a>
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<h5 class="subsubsection">2.17.3.4 <code>bfd_link_split_section</code></h5>
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<p><strong>Synopsis</strong>
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<pre class="example"> bfd_boolean bfd_link_split_section (bfd *abfd, asection *sec);
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</pre>
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<p><strong>Description</strong><br>
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Return nonzero if <var>sec</var> should be split during a
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reloceatable or final link.
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<pre class="example"> #define bfd_link_split_section(abfd, sec) \
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BFD_SEND (abfd, _bfd_link_split_section, (abfd, sec))
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</pre>
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<p><a name="index-bfd_005fsection_005falready_005flinked-1380"></a>
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<h5 class="subsubsection">2.17.3.5 <code>bfd_section_already_linked</code></h5>
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<p><strong>Synopsis</strong>
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<pre class="example"> void bfd_section_already_linked (bfd *abfd, asection *sec,
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struct bfd_link_info *info);
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</pre>
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<p><strong>Description</strong><br>
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Check if <var>sec</var> has been already linked during a reloceatable
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or final link.
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<pre class="example"> #define bfd_section_already_linked(abfd, sec, info) \
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BFD_SEND (abfd, _section_already_linked, (abfd, sec, info))
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</pre>
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