123 lines
5.6 KiB
HTML
123 lines
5.6 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- This file documents the GNU linker LD
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(Linaro_Binutils-2017.02)
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version 2.27.0.
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Copyright (C) 1991-2016 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 1.3
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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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<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>LD: Environment</title>
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<meta name="description" content="LD: Environment">
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<meta name="keywords" content="LD: Environment">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="LD-Index.html#LD-Index" rel="index" title="LD Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Invocation.html#Invocation" rel="up" title="Invocation">
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<link href="Scripts.html#Scripts" rel="next" title="Scripts">
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<link href="Options.html#Options" rel="prev" title="Options">
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<style type="text/css">
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<!--
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a.summary-letter {text-decoration: none}
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blockquote.smallquotation {font-size: smaller}
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div.display {margin-left: 3.2em}
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div.example {margin-left: 3.2em}
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div.indentedblock {margin-left: 3.2em}
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div.lisp {margin-left: 3.2em}
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div.smalldisplay {margin-left: 3.2em}
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div.smallexample {margin-left: 3.2em}
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div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
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div.smalllisp {margin-left: 3.2em}
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kbd {font-style:oblique}
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pre.display {font-family: inherit}
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pre.format {font-family: inherit}
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pre.menu-comment {font-family: serif}
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pre.menu-preformatted {font-family: serif}
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pre.smalldisplay {font-family: inherit; font-size: smaller}
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pre.smallexample {font-size: smaller}
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pre.smallformat {font-family: inherit; font-size: smaller}
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pre.smalllisp {font-size: smaller}
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span.nocodebreak {white-space:nowrap}
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span.nolinebreak {white-space:nowrap}
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span.roman {font-family:serif; font-weight:normal}
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span.sansserif {font-family:sans-serif; font-weight:normal}
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Environment"></a>
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<div class="header">
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<p>
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Previous: <a href="Options.html#Options" accesskey="p" rel="prev">Options</a>, Up: <a href="Invocation.html#Invocation" accesskey="u" rel="up">Invocation</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Environment-Variables"></a>
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<h3 class="section">2.2 Environment Variables</h3>
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<p>You can change the behaviour of <code>ld</code> with the environment variables
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<code>GNUTARGET</code>,
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<code>LDEMULATION</code> and <code>COLLECT_NO_DEMANGLE</code>.
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</p>
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<a name="index-GNUTARGET"></a>
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<a name="index-default-input-format"></a>
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<p><code>GNUTARGET</code> determines the input-file object format if you don’t
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use ‘<samp>-b</samp>’ (or its synonym ‘<samp>--format</samp>’). Its value should be one
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of the BFD names for an input format (see <a href="BFD.html#BFD">BFD</a>). If there is no
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<code>GNUTARGET</code> in the environment, <code>ld</code> uses the natural format
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of the target. If <code>GNUTARGET</code> is set to <code>default</code> then BFD
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attempts to discover the input format by examining binary input files;
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this method often succeeds, but there are potential ambiguities, since
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there is no method of ensuring that the magic number used to specify
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object-file formats is unique. However, the configuration procedure for
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BFD on each system places the conventional format for that system first
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in the search-list, so ambiguities are resolved in favor of convention.
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</p>
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<a name="index-LDEMULATION"></a>
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<a name="index-default-emulation"></a>
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<a name="index-emulation_002c-default"></a>
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<p><code>LDEMULATION</code> determines the default emulation if you don’t use the
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‘<samp>-m</samp>’ option. The emulation can affect various aspects of linker
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behaviour, particularly the default linker script. You can list the
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available emulations with the ‘<samp>--verbose</samp>’ or ‘<samp>-V</samp>’ options. If
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the ‘<samp>-m</samp>’ option is not used, and the <code>LDEMULATION</code> environment
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variable is not defined, the default emulation depends upon how the
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linker was configured.
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</p>
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<a name="index-COLLECT_005fNO_005fDEMANGLE"></a>
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<a name="index-demangling_002c-default"></a>
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<p>Normally, the linker will default to demangling symbols. However, if
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<code>COLLECT_NO_DEMANGLE</code> is set in the environment, then it will
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default to not demangling symbols. This environment variable is used in
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a similar fashion by the <code>gcc</code> linker wrapper program. The default
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may be overridden by the ‘<samp>--demangle</samp>’ and ‘<samp>--no-demangle</samp>’
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options.
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</p>
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<hr>
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<div class="header">
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<p>
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Previous: <a href="Options.html#Options" accesskey="p" rel="prev">Options</a>, Up: <a href="Invocation.html#Invocation" accesskey="u" rel="up">Invocation</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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