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| <a name="Input-Section-for-Common-Symbols"></a> |
| <h4 class="subsubsection">3.6.4.3 Input Section for Common Symbols</h4> |
| <a name="index-common-symbol-placement"></a> |
| <a name="index-uninitialized-data-placement"></a> |
| <p>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>COMMON</samp>’. |
| </p> |
| <p>You may use file names with the ‘<samp>COMMON</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> |
| <p>In most cases, common symbols in input files will be placed in the |
| ‘<samp>.bss</samp>’ section in the output file. For example: |
| </p><div class="smallexample"> |
| <pre class="smallexample">.bss { *(.bss) *(COMMON) } |
| </pre></div> |
| |
| <a name="index-scommon-section"></a> |
| <a name="index-small-common-symbols"></a> |
| <p>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>COMMON</samp>’ for standard common |
| symbols and ‘<samp>.scommon</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-_005bCOMMON_005d"></a> |
| <p>You will sometimes see ‘<samp>[COMMON]</samp>’ in old linker scripts. This |
| notation is now considered obsolete. It is equivalent to |
| ‘<samp>*(COMMON)</samp>’. |
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