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| <h4 class="subsection">3.6.3 Output Section Address</h4> |
| |
| <p><a name="index-address_002c-section-394"></a><a name="index-section-address-395"></a>The <var>address</var> is an expression for the VMA (the virtual memory |
| address) of the output section. If you do not provide <var>address</var>, |
| the linker will set it based on <var>region</var> if present, or otherwise |
| based on the current value of the location counter. |
| |
| <p>If you provide <var>address</var>, the address of the output section will be |
| set to precisely that. If you provide neither <var>address</var> nor |
| <var>region</var>, then the address of the output section will be set to the |
| current value of the location counter aligned to the alignment |
| requirements of the output section. The alignment requirement of the |
| output section is the strictest alignment of any input section contained |
| within the output section. |
| |
| <p>For example, |
| <pre class="smallexample"> .text . : { *(.text) } |
| </pre> |
| <p class="noindent">and |
| <pre class="smallexample"> .text : { *(.text) } |
| </pre> |
| <p class="noindent">are subtly different. The first will set the address of the |
| ‘<samp><span class="samp">.text</span></samp>’ output section to the current value of the location |
| counter. The second will set it to the current value of the location |
| counter aligned to the strictest alignment of a ‘<samp><span class="samp">.text</span></samp>’ input |
| section. |
| |
| <p>The <var>address</var> may be an arbitrary expression; <a href="Expressions.html#Expressions">Expressions</a>. |
| For example, if you want to align the section on a 0x10 byte boundary, |
| so that the lowest four bits of the section address are zero, you could |
| do something like this: |
| <pre class="smallexample"> .text ALIGN(0x10) : { *(.text) } |
| </pre> |
| <p class="noindent">This works because <code>ALIGN</code> returns the current location counter |
| aligned upward to the specified value. |
| |
| <p>Specifying <var>address</var> for a section will change the value of the |
| location counter, provided that the section is non-empty. (Empty |
| sections are ignored). |
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