9.5.5.3 Input Section for Common Symbols

A special notation is needed for common symbols, because common symbols do not have a particular input section. The linker treats common symbols as though they are in an input section named COMMON.

File names may be used with the COMMON section just as with any other input sections. This will place common symbols from a particular input file in one section, while common symbols from other input files are placed in another section.

In most cases, common symbols in input files will be placed in the .bss section in the output file. For example:

.bss { *(.bss) *(COMMON) }

If not otherwise specified, common symbols will be assigned to section .bss.