<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
<html>
|
<!-- This file documents the GNU linker LD
|
(GNU Toolchain for the A-profile Architecture 10.3-2021.07 (arm-10.29))
|
version 2.36.1.
|
|
Copyright (C) 1991-2021 Free Software Foundation, Inc.
|
|
Permission is granted to copy, distribute and/or modify this document
|
under the terms of the GNU Free Documentation License, Version 1.3
|
or any later version published by the Free Software Foundation;
|
with no Invariant Sections, with no Front-Cover Texts, and with no
|
Back-Cover Texts. A copy of the license is included in the
|
section entitled "GNU Free Documentation License". -->
|
<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ -->
|
<head>
|
<title>LD: PowerPC ELF32</title>
|
|
<meta name="description" content="LD: PowerPC ELF32">
|
<meta name="keywords" content="LD: PowerPC ELF32">
|
<meta name="resource-type" content="document">
|
<meta name="distribution" content="global">
|
<meta name="Generator" content="makeinfo">
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
<link href="index.html#Top" rel="start" title="Top">
|
<link href="LD-Index.html#LD-Index" rel="index" title="LD Index">
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
<link href="Machine-Dependent.html#Machine-Dependent" rel="up" title="Machine Dependent">
|
<link href="PowerPC64-ELF64.html#PowerPC64-ELF64" rel="next" title="PowerPC64 ELF64">
|
<link href="Nios-II.html#Nios-II" rel="previous" title="Nios II">
|
<style type="text/css">
|
<!--
|
a.summary-letter {text-decoration: none}
|
blockquote.smallquotation {font-size: smaller}
|
div.display {margin-left: 3.2em}
|
div.example {margin-left: 3.2em}
|
div.indentedblock {margin-left: 3.2em}
|
div.lisp {margin-left: 3.2em}
|
div.smalldisplay {margin-left: 3.2em}
|
div.smallexample {margin-left: 3.2em}
|
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
|
div.smalllisp {margin-left: 3.2em}
|
kbd {font-style:oblique}
|
pre.display {font-family: inherit}
|
pre.format {font-family: inherit}
|
pre.menu-comment {font-family: serif}
|
pre.menu-preformatted {font-family: serif}
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
pre.smallexample {font-size: smaller}
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
pre.smalllisp {font-size: smaller}
|
span.nocodebreak {white-space:nowrap}
|
span.nolinebreak {white-space:nowrap}
|
span.roman {font-family:serif; font-weight:normal}
|
span.sansserif {font-family:sans-serif; font-weight:normal}
|
ul.no-bullet {list-style: none}
|
-->
|
</style>
|
|
|
</head>
|
|
<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
|
<a name="PowerPC-ELF32"></a>
|
<div class="header">
|
<p>
|
Next: <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>
|
</div>
|
<hr>
|
<a name="ld-and-PowerPC-32_002dbit-ELF-Support"></a>
|
<h3 class="section">5.11 <code>ld</code> and PowerPC 32-bit ELF Support</h3>
|
<a name="index-PowerPC-long-branches"></a>
|
<a name="index-_002d_002drelax-on-PowerPC"></a>
|
<p>Branches on PowerPC processors are limited to a signed 26-bit
|
displacement, which may result in <code>ld</code> giving
|
‘<samp>relocation truncated to fit</samp>’ errors with very large programs.
|
‘<samp>--relax</samp>’ enables the generation of trampolines that can access
|
the entire 32-bit address space. These trampolines are inserted at
|
section boundaries, so may not themselves be reachable if an input
|
section exceeds 33M in size. You may combine ‘<samp>-r</samp>’ and
|
‘<samp>--relax</samp>’ to add trampolines in a partial link. In that case
|
both branches to undefined symbols and inter-section branches are also
|
considered potentially out of range, and trampolines inserted.
|
</p>
|
<a name="index-PowerPC-ELF32-options"></a>
|
<dl compact="compact">
|
<dd><a name="index-PowerPC-PLT"></a>
|
<a name="index-_002d_002dbss_002dplt"></a>
|
</dd>
|
<dt><samp>--bss-plt</samp></dt>
|
<dd><p>Current PowerPC GCC accepts a ‘<samp>-msecure-plt</samp>’ option that
|
generates code capable of using a newer PLT and GOT layout that has
|
the security advantage of no executable section ever needing to be
|
writable and no writable section ever being executable. PowerPC
|
<code>ld</code> will generate this layout, including stubs to access the
|
PLT, if all input files (including startup and static libraries) were
|
compiled with ‘<samp>-msecure-plt</samp>’. ‘<samp>--bss-plt</samp>’ forces the old
|
BSS PLT (and GOT layout) which can give slightly better performance.
|
</p>
|
<a name="index-_002d_002dsecure_002dplt"></a>
|
</dd>
|
<dt><samp>--secure-plt</samp></dt>
|
<dd><p><code>ld</code> will use the new PLT and GOT layout if it is linking new
|
‘<samp>-fpic</samp>’ or ‘<samp>-fPIC</samp>’ code, but does not do so automatically
|
when linking non-PIC code. This option requests the new PLT and GOT
|
layout. A warning will be given if some object file requires the old
|
style BSS PLT.
|
</p>
|
<a name="index-PowerPC-GOT"></a>
|
<a name="index-_002d_002dsdata_002dgot"></a>
|
</dd>
|
<dt><samp>--sdata-got</samp></dt>
|
<dd><p>The new secure PLT and GOT are placed differently relative to other
|
sections compared to older BSS PLT and GOT placement. The location of
|
<code>.plt</code> must change because the new secure PLT is an initialized
|
section while the old PLT is uninitialized. The reason for the
|
<code>.got</code> change is more subtle: The new placement allows
|
<code>.got</code> to be read-only in applications linked with
|
‘<samp>-z relro -z now</samp>’. However, this placement means that
|
<code>.sdata</code> cannot always be used in shared libraries, because the
|
PowerPC ABI accesses <code>.sdata</code> in shared libraries from the GOT
|
pointer. ‘<samp>--sdata-got</samp>’ forces the old GOT placement. PowerPC
|
GCC doesn’t use <code>.sdata</code> in shared libraries, so this option is
|
really only useful for other compilers that may do so.
|
</p>
|
<a name="index-PowerPC-stub-symbols"></a>
|
<a name="index-_002d_002demit_002dstub_002dsyms"></a>
|
</dd>
|
<dt><samp>--emit-stub-syms</samp></dt>
|
<dd><p>This option causes <code>ld</code> to label linker stubs with a local
|
symbol that encodes the stub type and destination.
|
</p>
|
<a name="index-PowerPC-TLS-optimization"></a>
|
<a name="index-_002d_002dno_002dtls_002doptimize"></a>
|
</dd>
|
<dt><samp>--no-tls-optimize</samp></dt>
|
<dd><p>PowerPC <code>ld</code> normally performs some optimization of code
|
sequences used to access Thread-Local Storage. Use this option to
|
disable the optimization.
|
</p></dd>
|
</dl>
|
|
|
|
<hr>
|
<div class="header">
|
<p>
|
Next: <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>
|
</div>
|
|
|
|
</body>
|
</html>
|
