88 lines
4 KiB
HTML
88 lines
4 KiB
HTML
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<html lang="en">
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<head>
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<title>Output Section Address - Untitled</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="Untitled">
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<meta name="generator" content="makeinfo 4.7">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="SECTIONS.html#SECTIONS" title="SECTIONS">
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<link rel="prev" href="Output-Section-Name.html#Output-Section-Name" title="Output Section Name">
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<link rel="next" href="Input-Section.html#Input-Section" title="Input Section">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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This file documents the GNU linker LD
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(GNU Binutils)
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version 2.19.
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Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000,
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2001, 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.1
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or any later version published by the Free Software Foundation;
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with no Invariant Sections, with no Front-Cover Texts, and with no
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Back-Cover Texts. A copy of the license is included in the
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section entitled ``GNU Free Documentation License''.-->
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<meta http-equiv="Content-Style-Type" content="text/css">
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<style type="text/css"><!--
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pre.display { font-family:inherit }
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pre.format { font-family:inherit }
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pre.smalldisplay { font-family:inherit; font-size:smaller }
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pre.smallformat { font-family:inherit; font-size:smaller }
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pre.smallexample { font-size:smaller }
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pre.smalllisp { font-size:smaller }
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span.sc { font-variant:small-caps }
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span.roman { font-family: serif; font-weight: normal; }
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--></style>
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</head>
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<body>
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<div class="node">
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<p>
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<a name="Output-Section-Address"></a>Next: <a rel="next" accesskey="n" href="Input-Section.html#Input-Section">Input Section</a>,
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Previous: <a rel="previous" accesskey="p" href="Output-Section-Name.html#Output-Section-Name">Output Section Name</a>,
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Up: <a rel="up" accesskey="u" href="SECTIONS.html#SECTIONS">SECTIONS</a>
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<hr><br>
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</div>
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<h4 class="subsection">3.6.3 Output Section Address</h4>
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<p><a name="index-address_002c-section-364"></a><a name="index-section-address-365"></a>The <var>address</var> is an expression for the VMA (the virtual memory
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address) of the output section. If you do not provide <var>address</var>,
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the linker will set it based on <var>region</var> if present, or otherwise
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based on the current value of the location counter.
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<p>If you provide <var>address</var>, the address of the output section will be
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set to precisely that. If you provide neither <var>address</var> nor
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<var>region</var>, then the address of the output section will be set to the
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current value of the location counter aligned to the alignment
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requirements of the output section. The alignment requirement of the
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output section is the strictest alignment of any input section contained
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within the output section.
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<p>For example,
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<pre class="smallexample"> .text . : { *(.text) }
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</pre>
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<p class="noindent">and
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<pre class="smallexample"> .text : { *(.text) }
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</pre>
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<p class="noindent">are subtly different. The first will set the address of the
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<span class="samp">.text</span> output section to the current value of the location
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counter. The second will set it to the current value of the location
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counter aligned to the strictest alignment of a <span class="samp">.text</span> input
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section.
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<p>The <var>address</var> may be an arbitrary expression; <a href="Expressions.html#Expressions">Expressions</a>.
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For example, if you want to align the section on a 0x10 byte boundary,
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so that the lowest four bits of the section address are zero, you could
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do something like this:
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<pre class="smallexample"> .text ALIGN(0x10) : { *(.text) }
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</pre>
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<p class="noindent">This works because <code>ALIGN</code> returns the current location counter
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aligned upward to the specified value.
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<p>Specifying <var>address</var> for a section will change the value of the
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location counter.
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</body></html>
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