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| <title>LD: Input Section Wildcards</title> |
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| <a name="Input-Section-Wildcards"></a> |
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| Next: <a href="Input-Section-Common.html#Input-Section-Common" accesskey="n" rel="next">Input Section Common</a>, Previous: <a href="Input-Section-Basics.html#Input-Section-Basics" accesskey="p" rel="prev">Input Section Basics</a>, Up: <a href="Input-Section.html#Input-Section" accesskey="u" rel="up">Input Section</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p> |
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| <hr> |
| <a name="Input-Section-Wildcard-Patterns"></a> |
| <h4 class="subsubsection">3.6.4.2 Input Section Wildcard Patterns</h4> |
| <a name="index-input-section-wildcards"></a> |
| <a name="index-wildcard-file-name-patterns"></a> |
| <a name="index-file-name-wildcard-patterns"></a> |
| <a name="index-section-name-wildcard-patterns"></a> |
| <p>In an input section description, either the file name or the section |
| name or both may be wildcard patterns. |
| </p> |
| <p>The file name of ‘<samp>*</samp>’ seen in many examples is a simple wildcard |
| pattern for the file name. |
| </p> |
| <p>The wildcard patterns are like those used by the Unix shell. |
| </p> |
| <dl compact="compact"> |
| <dt>‘<samp>*</samp>’</dt> |
| <dd><p>matches any number of characters |
| </p></dd> |
| <dt>‘<samp>?</samp>’</dt> |
| <dd><p>matches any single character |
| </p></dd> |
| <dt>‘<samp>[<var>chars</var>]</samp>’</dt> |
| <dd><p>matches a single instance of any of the <var>chars</var>; the ‘<samp>-</samp>’ |
| character may be used to specify a range of characters, as in |
| ‘<samp>[a-z]</samp>’ to match any lower case letter |
| </p></dd> |
| <dt>‘<samp>\</samp>’</dt> |
| <dd><p>quotes the following character |
| </p></dd> |
| </dl> |
| |
| <p>When a file name is matched with a wildcard, the wildcard characters |
| will not match a ‘<samp>/</samp>’ character (used to separate directory names on |
| Unix). A pattern consisting of a single ‘<samp>*</samp>’ character is an |
| exception; it will always match any file name, whether it contains a |
| ‘<samp>/</samp>’ or not. In a section name, the wildcard characters will match |
| a ‘<samp>/</samp>’ character. |
| </p> |
| <p>File name wildcard patterns only match files which are explicitly |
| specified on the command line or in an <code>INPUT</code> command. The linker |
| does not search directories to expand wildcards. |
| </p> |
| <p>If a file name matches more than one wildcard pattern, or if a file name |
| appears explicitly and is also matched by a wildcard pattern, the linker |
| will use the first match in the linker script. For example, this |
| sequence of input section descriptions is probably in error, because the |
| <samp>data.o</samp> rule will not be used: |
| </p><div class="smallexample"> |
| <pre class="smallexample">.data : { *(.data) } |
| .data1 : { data.o(.data) } |
| </pre></div> |
| |
| <a name="index-SORT_005fBY_005fNAME"></a> |
| <p>Normally, the linker will place files and sections matched by wildcards |
| in the order in which they are seen during the link. You can change |
| this by using the <code>SORT_BY_NAME</code> keyword, which appears before a wildcard |
| pattern in parentheses (e.g., <code>SORT_BY_NAME(.text*)</code>). When the |
| <code>SORT_BY_NAME</code> keyword is used, the linker will sort the files or sections |
| into ascending order by name before placing them in the output file. |
| </p> |
| <a name="index-SORT_005fBY_005fALIGNMENT"></a> |
| <p><code>SORT_BY_ALIGNMENT</code> is very similar to <code>SORT_BY_NAME</code>. The |
| difference is <code>SORT_BY_ALIGNMENT</code> will sort sections into |
| descending order by alignment before placing them in the output file. |
| Larger alignments are placed before smaller alignments in order to |
| reduce the amount of padding necessary. |
| </p> |
| <a name="index-SORT_005fBY_005fINIT_005fPRIORITY"></a> |
| <p><code>SORT_BY_INIT_PRIORITY</code> is very similar to <code>SORT_BY_NAME</code>. The |
| difference is <code>SORT_BY_INIT_PRIORITY</code> will sort sections into |
| ascending order by numerical value of the GCC init_priority attribute |
| encoded in the section name before placing them in the output file. |
| </p> |
| <a name="index-SORT"></a> |
| <p><code>SORT</code> is an alias for <code>SORT_BY_NAME</code>. |
| </p> |
| <p>When there are nested section sorting commands in linker script, there |
| can be at most 1 level of nesting for section sorting commands. |
| </p> |
| <ol> |
| <li> <code>SORT_BY_NAME</code> (<code>SORT_BY_ALIGNMENT</code> (wildcard section pattern)). |
| It will sort the input sections by name first, then by alignment if two |
| sections have the same name. |
| </li><li> <code>SORT_BY_ALIGNMENT</code> (<code>SORT_BY_NAME</code> (wildcard section pattern)). |
| It will sort the input sections by alignment first, then by name if two |
| sections have the same alignment. |
| </li><li> <code>SORT_BY_NAME</code> (<code>SORT_BY_NAME</code> (wildcard section pattern)) is |
| treated the same as <code>SORT_BY_NAME</code> (wildcard section pattern). |
| </li><li> <code>SORT_BY_ALIGNMENT</code> (<code>SORT_BY_ALIGNMENT</code> (wildcard section pattern)) |
| is treated the same as <code>SORT_BY_ALIGNMENT</code> (wildcard section pattern). |
| </li><li> All other nested section sorting commands are invalid. |
| </li></ol> |
| |
| <p>When both command line section sorting option and linker script |
| section sorting command are used, section sorting command always |
| takes precedence over the command line option. |
| </p> |
| <p>If the section sorting command in linker script isn’t nested, the |
| command line option will make the section sorting command to be |
| treated as nested sorting command. |
| </p> |
| <ol> |
| <li> <code>SORT_BY_NAME</code> (wildcard section pattern ) with |
| <samp>--sort-sections alignment</samp> is equivalent to |
| <code>SORT_BY_NAME</code> (<code>SORT_BY_ALIGNMENT</code> (wildcard section pattern)). |
| </li><li> <code>SORT_BY_ALIGNMENT</code> (wildcard section pattern) with |
| <samp>--sort-section name</samp> is equivalent to |
| <code>SORT_BY_ALIGNMENT</code> (<code>SORT_BY_NAME</code> (wildcard section pattern)). |
| </li></ol> |
| |
| <p>If the section sorting command in linker script is nested, the |
| command line option will be ignored. |
| </p> |
| <a name="index-SORT_005fNONE"></a> |
| <p><code>SORT_NONE</code> disables section sorting by ignoring the command line |
| section sorting option. |
| </p> |
| <p>If you ever get confused about where input sections are going, use the |
| ‘<samp>-M</samp>’ linker option to generate a map file. The map file shows |
| precisely how input sections are mapped to output sections. |
| </p> |
| <p>This example shows how wildcard patterns might be used to partition |
| files. This linker script directs the linker to place all ‘<samp>.text</samp>’ |
| sections in ‘<samp>.text</samp>’ and all ‘<samp>.bss</samp>’ sections in ‘<samp>.bss</samp>’. |
| The linker will place the ‘<samp>.data</samp>’ section from all files beginning |
| with an upper case character in ‘<samp>.DATA</samp>’; for all other files, the |
| linker will place the ‘<samp>.data</samp>’ section in ‘<samp>.data</samp>’. |
| </p><div class="smallexample"> |
| <pre class="smallexample">SECTIONS { |
| .text : { *(.text) } |
| .DATA : { [A-Z]*(.data) } |
| .data : { *(.data) } |
| .bss : { *(.bss) } |
| } |
| </pre></div> |
| |
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| Next: <a href="Input-Section-Common.html#Input-Section-Common" accesskey="n" rel="next">Input Section Common</a>, Previous: <a href="Input-Section-Basics.html#Input-Section-Basics" accesskey="p" rel="prev">Input Section Basics</a>, Up: <a href="Input-Section.html#Input-Section" accesskey="u" rel="up">Input Section</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p> |
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