| <html lang="en"> |
| <head> |
| <title>Input Section Common - Untitled</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="Untitled"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Input-Section.html#Input-Section" title="Input Section"> |
| <link rel="prev" href="Input-Section-Wildcards.html#Input-Section-Wildcards" title="Input Section Wildcards"> |
| <link rel="next" href="Input-Section-Keep.html#Input-Section-Keep" title="Input Section Keep"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| This file documents the GNU linker LD |
| (Sourcery G++ Lite 2011.03-41) |
| version 2.20.51. |
| |
| Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, |
| 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 |
| or any later version published by the Free Software Foundation; |
| with no Invariant Sections, with no Front-Cover Texts, and with no |
| Back-Cover Texts. A copy of the license is included in the |
| section entitled ``GNU Free Documentation License''.--> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Input-Section-Common"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="Input-Section-Keep.html#Input-Section-Keep">Input Section Keep</a>, |
| Previous: <a rel="previous" accesskey="p" href="Input-Section-Wildcards.html#Input-Section-Wildcards">Input Section Wildcards</a>, |
| Up: <a rel="up" accesskey="u" href="Input-Section.html#Input-Section">Input Section</a> |
| <hr> |
| </div> |
| |
| <h5 class="subsubsection">3.6.4.3 Input Section for Common Symbols</h5> |
| |
| <p><a name="index-common-symbol-placement-406"></a><a name="index-uninitialized-data-placement-407"></a>A special notation is needed for common symbols, because in many object |
| file formats common symbols do not have a particular input section. The |
| linker treats common symbols as though they are in an input section |
| named ‘<samp><span class="samp">COMMON</span></samp>’. |
| |
| <p>You may use file names with the ‘<samp><span class="samp">COMMON</span></samp>’ section just as with any |
| other input sections. You can use this to place common symbols from a |
| particular input file in one section while common symbols from other |
| input files are placed in another section. |
| |
| <p>In most cases, common symbols in input files will be placed in the |
| ‘<samp><span class="samp">.bss</span></samp>’ section in the output file. For example: |
| <pre class="smallexample"> .bss { *(.bss) *(COMMON) } |
| </pre> |
| <p><a name="index-scommon-section-408"></a><a name="index-small-common-symbols-409"></a>Some object file formats have more than one type of common symbol. For |
| example, the MIPS ELF object file format distinguishes standard common |
| symbols and small common symbols. In this case, the linker will use a |
| different special section name for other types of common symbols. In |
| the case of MIPS ELF, the linker uses ‘<samp><span class="samp">COMMON</span></samp>’ for standard common |
| symbols and ‘<samp><span class="samp">.scommon</span></samp>’ for small common symbols. This permits you |
| to map the different types of common symbols into memory at different |
| locations. |
| |
| <p><a name="index-g_t_005bCOMMON_005d-410"></a>You will sometimes see ‘<samp><span class="samp">[COMMON]</span></samp>’ in old linker scripts. This |
| notation is now considered obsolete. It is equivalent to |
| ‘<samp><span class="samp">*(COMMON)</span></samp>’. |
| |
| </body></html> |
| |