77 lines
3.9 KiB
HTML
77 lines
3.9 KiB
HTML
<html lang="en">
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<title>Input Section Common - Untitled</title>
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<!--
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This file documents the GNU linker LD
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(GNU Binutils)
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version 2.19.
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Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000,
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2001, 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
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or any later version published by the Free Software Foundation;
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<p>
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<a name="Input-Section-Common"></a>Next: <a rel="next" accesskey="n" href="Input-Section-Keep.html#Input-Section-Keep">Input Section Keep</a>,
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Previous: <a rel="previous" accesskey="p" href="Input-Section-Wildcards.html#Input-Section-Wildcards">Input Section Wildcards</a>,
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<h5 class="subsubsection">3.6.4.3 Input Section for Common Symbols</h5>
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<p><a name="index-common-symbol-placement-376"></a><a name="index-uninitialized-data-placement-377"></a>A special notation is needed for common symbols, because in many object
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file formats common symbols do not have a particular input section. The
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linker treats common symbols as though they are in an input section
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named <span class="samp">COMMON</span>.
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<p>You may use file names with the <span class="samp">COMMON</span> section just as with any
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other input sections. You can use this to place common symbols from a
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particular input file in one section while common symbols from other
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input files are placed in another section.
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<p>In most cases, common symbols in input files will be placed in the
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<span class="samp">.bss</span> section in the output file. For example:
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<pre class="smallexample"> .bss { *(.bss) *(COMMON) }
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</pre>
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<p><a name="index-scommon-section-378"></a><a name="index-small-common-symbols-379"></a>Some object file formats have more than one type of common symbol. For
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example, the MIPS ELF object file format distinguishes standard common
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symbols and small common symbols. In this case, the linker will use a
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different special section name for other types of common symbols. In
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the case of MIPS ELF, the linker uses <span class="samp">COMMON</span> for standard common
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symbols and <span class="samp">.scommon</span> for small common symbols. This permits you
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to map the different types of common symbols into memory at different
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locations.
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<p><a name="index-_005bCOMMON_005d-380"></a>You will sometimes see <span class="samp">[COMMON]</span> in old linker scripts. This
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notation is now considered obsolete. It is equivalent to
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<span class="samp">*(COMMON)</span>.
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</body></html>
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