1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- This file documents the GNU linker LD 4(GNU Toolchain for the A-profile Architecture 10.3-2021.07 (arm-10.29)) 5version 2.36.1. 6 7Copyright (C) 1991-2021 Free Software Foundation, Inc. 8 9Permission is granted to copy, distribute and/or modify this document 10under the terms of the GNU Free Documentation License, Version 1.3 11or any later version published by the Free Software Foundation; 12with no Invariant Sections, with no Front-Cover Texts, and with no 13Back-Cover Texts. A copy of the license is included in the 14section entitled "GNU Free Documentation License". --> 15<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> 16<head> 17<title>LD: PowerPC ELF32</title> 18 19<meta name="description" content="LD: PowerPC ELF32"> 20<meta name="keywords" content="LD: PowerPC ELF32"> 21<meta name="resource-type" content="document"> 22<meta name="distribution" content="global"> 23<meta name="Generator" content="makeinfo"> 24<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 25<link href="index.html#Top" rel="start" title="Top"> 26<link href="LD-Index.html#LD-Index" rel="index" title="LD Index"> 27<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> 28<link href="Machine-Dependent.html#Machine-Dependent" rel="up" title="Machine Dependent"> 29<link href="PowerPC64-ELF64.html#PowerPC64-ELF64" rel="next" title="PowerPC64 ELF64"> 30<link href="Nios-II.html#Nios-II" rel="previous" title="Nios II"> 31<style type="text/css"> 32<!-- 33a.summary-letter {text-decoration: none} 34blockquote.smallquotation {font-size: smaller} 35div.display {margin-left: 3.2em} 36div.example {margin-left: 3.2em} 37div.indentedblock {margin-left: 3.2em} 38div.lisp {margin-left: 3.2em} 39div.smalldisplay {margin-left: 3.2em} 40div.smallexample {margin-left: 3.2em} 41div.smallindentedblock {margin-left: 3.2em; font-size: smaller} 42div.smalllisp {margin-left: 3.2em} 43kbd {font-style:oblique} 44pre.display {font-family: inherit} 45pre.format {font-family: inherit} 46pre.menu-comment {font-family: serif} 47pre.menu-preformatted {font-family: serif} 48pre.smalldisplay {font-family: inherit; font-size: smaller} 49pre.smallexample {font-size: smaller} 50pre.smallformat {font-family: inherit; font-size: smaller} 51pre.smalllisp {font-size: smaller} 52span.nocodebreak {white-space:nowrap} 53span.nolinebreak {white-space:nowrap} 54span.roman {font-family:serif; font-weight:normal} 55span.sansserif {font-family:sans-serif; font-weight:normal} 56ul.no-bullet {list-style: none} 57--> 58</style> 59 60 61</head> 62 63<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> 64<a name="PowerPC-ELF32"></a> 65<div class="header"> 66<p> 67Next: <a href="PowerPC64-ELF64.html#PowerPC64-ELF64" accesskey="n" rel="next">PowerPC64 ELF64</a>, Previous: <a href="Nios-II.html#Nios-II" accesskey="p" rel="previous">Nios II</a>, Up: <a href="Machine-Dependent.html#Machine-Dependent" accesskey="u" rel="up">Machine Dependent</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> 68</div> 69<hr> 70<a name="ld-and-PowerPC-32_002dbit-ELF-Support"></a> 71<h3 class="section">5.11 <code>ld</code> and PowerPC 32-bit ELF Support</h3> 72<a name="index-PowerPC-long-branches"></a> 73<a name="index-_002d_002drelax-on-PowerPC"></a> 74<p>Branches on PowerPC processors are limited to a signed 26-bit 75displacement, which may result in <code>ld</code> giving 76‘<samp>relocation truncated to fit</samp>’ errors with very large programs. 77‘<samp>--relax</samp>’ enables the generation of trampolines that can access 78the entire 32-bit address space. These trampolines are inserted at 79section boundaries, so may not themselves be reachable if an input 80section exceeds 33M in size. You may combine ‘<samp>-r</samp>’ and 81‘<samp>--relax</samp>’ to add trampolines in a partial link. In that case 82both branches to undefined symbols and inter-section branches are also 83considered potentially out of range, and trampolines inserted. 84</p> 85<a name="index-PowerPC-ELF32-options"></a> 86<dl compact="compact"> 87<dd><a name="index-PowerPC-PLT"></a> 88<a name="index-_002d_002dbss_002dplt"></a> 89</dd> 90<dt><samp>--bss-plt</samp></dt> 91<dd><p>Current PowerPC GCC accepts a ‘<samp>-msecure-plt</samp>’ option that 92generates code capable of using a newer PLT and GOT layout that has 93the security advantage of no executable section ever needing to be 94writable and no writable section ever being executable. PowerPC 95<code>ld</code> will generate this layout, including stubs to access the 96PLT, if all input files (including startup and static libraries) were 97compiled with ‘<samp>-msecure-plt</samp>’. ‘<samp>--bss-plt</samp>’ forces the old 98BSS PLT (and GOT layout) which can give slightly better performance. 99</p> 100<a name="index-_002d_002dsecure_002dplt"></a> 101</dd> 102<dt><samp>--secure-plt</samp></dt> 103<dd><p><code>ld</code> will use the new PLT and GOT layout if it is linking new 104‘<samp>-fpic</samp>’ or ‘<samp>-fPIC</samp>’ code, but does not do so automatically 105when linking non-PIC code. This option requests the new PLT and GOT 106layout. A warning will be given if some object file requires the old 107style BSS PLT. 108</p> 109<a name="index-PowerPC-GOT"></a> 110<a name="index-_002d_002dsdata_002dgot"></a> 111</dd> 112<dt><samp>--sdata-got</samp></dt> 113<dd><p>The new secure PLT and GOT are placed differently relative to other 114sections compared to older BSS PLT and GOT placement. The location of 115<code>.plt</code> must change because the new secure PLT is an initialized 116section while the old PLT is uninitialized. The reason for the 117<code>.got</code> change is more subtle: The new placement allows 118<code>.got</code> to be read-only in applications linked with 119‘<samp>-z relro -z now</samp>’. However, this placement means that 120<code>.sdata</code> cannot always be used in shared libraries, because the 121PowerPC ABI accesses <code>.sdata</code> in shared libraries from the GOT 122pointer. ‘<samp>--sdata-got</samp>’ forces the old GOT placement. PowerPC 123GCC doesn’t use <code>.sdata</code> in shared libraries, so this option is 124really only useful for other compilers that may do so. 125</p> 126<a name="index-PowerPC-stub-symbols"></a> 127<a name="index-_002d_002demit_002dstub_002dsyms"></a> 128</dd> 129<dt><samp>--emit-stub-syms</samp></dt> 130<dd><p>This option causes <code>ld</code> to label linker stubs with a local 131symbol that encodes the stub type and destination. 132</p> 133<a name="index-PowerPC-TLS-optimization"></a> 134<a name="index-_002d_002dno_002dtls_002doptimize"></a> 135</dd> 136<dt><samp>--no-tls-optimize</samp></dt> 137<dd><p>PowerPC <code>ld</code> normally performs some optimization of code 138sequences used to access Thread-Local Storage. Use this option to 139disable the optimization. 140</p></dd> 141</dl> 142 143 144 145<hr> 146<div class="header"> 147<p> 148Next: <a href="PowerPC64-ELF64.html#PowerPC64-ELF64" accesskey="n" rel="next">PowerPC64 ELF64</a>, Previous: <a href="Nios-II.html#Nios-II" accesskey="p" rel="previous">Nios II</a>, Up: <a href="Machine-Dependent.html#Machine-Dependent" accesskey="u" rel="up">Machine Dependent</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> 149</div> 150 151 152 153</body> 154</html> 155