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78 lines
3.9 KiB
HTML
78 lines
3.9 KiB
HTML
15 years ago
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<html lang="en">
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<head>
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<title>Input Section Common - Untitled</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="Untitled">
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<meta name="generator" content="makeinfo 4.7">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Input-Section.html#Input-Section" title="Input Section">
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<link rel="prev" href="Input-Section-Wildcards.html#Input-Section-Wildcards" title="Input Section Wildcards">
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<link rel="next" href="Input-Section-Keep.html#Input-Section-Keep" title="Input Section Keep">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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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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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.1
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or any later version published by the Free Software Foundation;
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with no Invariant Sections, with no Front-Cover Texts, and with no
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Back-Cover Texts. A copy of the license is included in the
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section entitled ``GNU Free Documentation License''.-->
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<meta http-equiv="Content-Style-Type" content="text/css">
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<style type="text/css"><!--
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pre.display { font-family:inherit }
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pre.format { font-family:inherit }
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pre.smalldisplay { font-family:inherit; font-size:smaller }
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pre.smallformat { font-family:inherit; font-size:smaller }
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pre.smallexample { font-size:smaller }
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pre.smalllisp { font-size:smaller }
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span.sc { font-variant:small-caps }
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span.roman { font-family: serif; font-weight: normal; }
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--></style>
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</head>
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<body>
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<div class="node">
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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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Up: <a rel="up" accesskey="u" href="Input-Section.html#Input-Section">Input Section</a>
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<hr><br>
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</div>
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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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