1<html lang="en"> 2<head> 3<title>Miscellaneous Commands - Untitled</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Untitled"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="Simple-Commands.html#Simple-Commands" title="Simple Commands"> 9<link rel="prev" href="REGION_005fALIAS.html#REGION_005fALIAS" title="REGION_ALIAS"> 10<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 11<!-- 12This file documents the GNU linker LD 13(Sourcery CodeBench Lite 2011.09-69) 14version 2.21.53. 15 16Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 172001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc. 18 19Permission is granted to copy, distribute and/or modify this document 20under the terms of the GNU Free Documentation License, Version 1.3 21or any later version published by the Free Software Foundation; 22with no Invariant Sections, with no Front-Cover Texts, and with no 23Back-Cover Texts. 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If it is zero, then exit the linker 54with an error code, and print <var>message</var>. 55 56 <br><dt><code>EXTERN(</code><var>symbol</var> <var>symbol</var><code> ...)</code><dd><a name="index-EXTERN-381"></a><a name="index-undefined-symbol-in-linker-script-382"></a>Force <var>symbol</var> to be entered in the output file as an undefined 57symbol. Doing this may, for example, trigger linking of additional 58modules from standard libraries. You may list several <var>symbol</var>s for 59each <code>EXTERN</code>, and you may use <code>EXTERN</code> multiple times. This 60command has the same effect as the ‘<samp><span class="samp">-u</span></samp>’ command-line option. 61 62 <br><dt><code>FORCE_COMMON_ALLOCATION</code><dd><a name="index-FORCE_005fCOMMON_005fALLOCATION-383"></a><a name="index-common-allocation-in-linker-script-384"></a>This command has the same effect as the ‘<samp><span class="samp">-d</span></samp>’ command-line option: 63to make <samp><span class="command">ld</span></samp> assign space to common symbols even if a relocatable 64output file is specified (‘<samp><span class="samp">-r</span></samp>’). 65 66 <br><dt><code>INHIBIT_COMMON_ALLOCATION</code><dd><a name="index-INHIBIT_005fCOMMON_005fALLOCATION-385"></a><a name="index-common-allocation-in-linker-script-386"></a>This command has the same effect as the ‘<samp><span class="samp">--no-define-common</span></samp>’ 67command-line option: to make <code>ld</code> omit the assignment of addresses 68to common symbols even for a non-relocatable output file. 69 70 <br><dt><code>INSERT [ AFTER | BEFORE ] </code><var>output_section</var><dd><a name="index-INSERT-387"></a><a name="index-insert-user-script-into-default-script-388"></a>This command is typically used in a script specified by ‘<samp><span class="samp">-T</span></samp>’ to 71augment the default <code>SECTIONS</code> with, for example, overlays. It 72inserts all prior linker script statements after (or before) 73<var>output_section</var>, and also causes ‘<samp><span class="samp">-T</span></samp>’ to not override the 74default linker script. The exact insertion point is as for orphan 75sections. See <a href="Location-Counter.html#Location-Counter">Location Counter</a>. The insertion happens after the 76linker has mapped input sections to output sections. Prior to the 77insertion, since ‘<samp><span class="samp">-T</span></samp>’ scripts are parsed before the default 78linker script, statements in the ‘<samp><span class="samp">-T</span></samp>’ script occur before the 79default linker script statements in the internal linker representation 80of the script. In particular, input section assignments will be made 81to ‘<samp><span class="samp">-T</span></samp>’ output sections before those in the default script. Here 82is an example of how a ‘<samp><span class="samp">-T</span></samp>’ script using <code>INSERT</code> might look: 83 84 <pre class="smallexample"> SECTIONS 85 { 86 OVERLAY : 87 { 88 .ov1 { ov1*(.text) } 89 .ov2 { ov2*(.text) } 90 } 91 } 92 INSERT AFTER .text; 93</pre> 94 <br><dt><code>NOCROSSREFS(</code><var>section</var> <var>section</var><code> ...)</code><dd><a name="index-NOCROSSREFS_0028_0040var_007bsections_007d_0029-389"></a><a name="index-cross-references-390"></a>This command may be used to tell <samp><span class="command">ld</span></samp> to issue an error about any 95references among certain output sections. 96 97 <p>In certain types of programs, particularly on embedded systems when 98using overlays, when one section is loaded into memory, another section 99will not be. Any direct references between the two sections would be 100errors. For example, it would be an error if code in one section called 101a function defined in the other section. 102 103 <p>The <code>NOCROSSREFS</code> command takes a list of output section names. If 104<samp><span class="command">ld</span></samp> detects any cross references between the sections, it reports 105an error and returns a non-zero exit status. Note that the 106<code>NOCROSSREFS</code> command uses output section names, not input section 107names. 108 109 <br><dt><code>OUTPUT_ARCH(</code><var>bfdarch</var><code>)</code><dd><a name="index-OUTPUT_005fARCH_0028_0040var_007bbfdarch_007d_0029-391"></a><a name="index-machine-architecture-392"></a><a name="index-architecture-393"></a>Specify a particular output machine architecture. The argument is one 110of the names used by the BFD library (see <a href="BFD.html#BFD">BFD</a>). You can see the 111architecture of an object file by using the <code>objdump</code> program with 112the ‘<samp><span class="samp">-f</span></samp>’ option. 113 114 <br><dt><code>LD_FEATURE(</code><var>string</var><code>)</code><dd><a name="index-LD_005fFEATURE_0028_0040var_007bstring_007d_0029-394"></a>This command may be used to modify <samp><span class="command">ld</span></samp> behavior. If 115<var>string</var> is <code>"SANE_EXPR"</code> then absolute symbols and numbers 116in a script are simply treated as numbers everywhere. 117See <a href="Expression-Section.html#Expression-Section">Expression Section</a>. 118</dl> 119 120 </body></html> 121 122