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<title>PROVIDE - Untitled</title>
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<p>
<a name="PROVIDE"></a>Next:&nbsp;<a rel="next" accesskey="n" href="PROVIDE_005fHIDDEN.html#PROVIDE_005fHIDDEN">PROVIDE_HIDDEN</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="Simple-Assignments.html#Simple-Assignments">Simple Assignments</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="Assignments.html#Assignments">Assignments</a>
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<h4 class="subsection">3.5.2 PROVIDE</h4>
<p><a name="index-PROVIDE-359"></a>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
<span class="samp">etext</span>. However, ANSI C requires that the user be able to use
<span class="samp">etext</span> as a function name without encountering an error. The
<code>PROVIDE</code> keyword may be used to define a symbol, such as
<span class="samp">etext</span>, only if it is referenced but not defined. The syntax is
<code>PROVIDE(</code><var>symbol</var><code> = </code><var>expression</var><code>)</code>.
<p>Here is an example of using <code>PROVIDE</code> to define <span class="samp">etext</span>:
<pre class="smallexample"> SECTIONS
{
.text :
{
*(.text)
_etext = .;
PROVIDE(etext = .);
}
}
</pre>
<p>In this example, if the program defines <span class="samp">_etext</span> (with a leading
underscore), the linker will give a multiple definition error. If, on
the other hand, the program defines <span class="samp">etext</span> (with no leading
underscore), the linker will silently use the definition in the program.
If the program references <span class="samp">etext</span> but does not define it, the
linker will use the definition in the linker script.
</body></html>