RTEMS GNU Tools On-Line Library

PROVIDE

3.5.2: PROVIDE

In some cases, it is desirable for a linker script to define a symbol only if it is referenced and is not defined by any object included in the link. For example, traditional linkers defined the symbol `etext'. However, ANSI C requires that the user be able to use `etext' as a function name without encountering an error. The PROVIDE keyword may be used to define a symbol, such as `etext', only if it is referenced but not defined. The syntax is PROVIDE(symbol = expression).

Here is an example of using PROVIDE to define `etext':

SECTIONS
{
  .text :
    {
      *(.text)
      _etext = .;
      PROVIDE(etext = .);
    }
}

In this example, if the program defines `_etext' (with a leading underscore), the linker will give a multiple definition error. If, on the other hand, the program defines `etext' (with no leading underscore), the linker will silently use the definition in the program. If the program references `etext' but does not define it, the linker will use the definition in the linker script.