133 lines
6.4 KiB
HTML
133 lines
6.4 KiB
HTML
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
|
|
<html>
|
||
|
|
<!-- This file documents the GNU Assembler "as".
|
||
|
|
|
||
|
|
Copyright (C) 1991-2016 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 5.2, http://www.gnu.org/software/texinfo/ -->
|
||
|
|
<head>
|
||
|
|
<title>Using as: Symver</title>
|
||
|
|
|
||
|
|
<meta name="description" content="Using as: Symver">
|
||
|
|
<meta name="keywords" content="Using as: Symver">
|
||
|
|
<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="AS-Index.html#AS-Index" rel="index" title="AS Index">
|
||
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
||
|
|
<link href="Pseudo-Ops.html#Pseudo-Ops" rel="up" title="Pseudo Ops">
|
||
|
|
<link href="Tag.html#Tag" rel="next" title="Tag">
|
||
|
|
<link href="SubSection.html#SubSection" rel="prev" title="SubSection">
|
||
|
|
<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="Symver"></a>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Tag.html#Tag" accesskey="n" rel="next">Tag</a>, Previous: <a href="SubSection.html#SubSection" accesskey="p" rel="prev">SubSection</a>, Up: <a href="Pseudo-Ops.html#Pseudo-Ops" accesskey="u" rel="up">Pseudo Ops</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
|
||
|
|
</div>
|
||
|
|
<hr>
|
||
|
|
<a name="g_t_002esymver"></a>
|
||
|
|
<h3 class="section">7.90 <code>.symver</code></h3>
|
||
|
|
<a name="index-symver-directive"></a>
|
||
|
|
<a name="index-symbol-versioning"></a>
|
||
|
|
<a name="index-versions-of-symbols"></a>
|
||
|
|
<p>Use the <code>.symver</code> directive to bind symbols to specific version nodes
|
||
|
|
within a source file. This is only supported on ELF platforms, and is
|
||
|
|
typically used when assembling files to be linked into a shared library.
|
||
|
|
There are cases where it may make sense to use this in objects to be bound
|
||
|
|
into an application itself so as to override a versioned symbol from a
|
||
|
|
shared library.
|
||
|
|
</p>
|
||
|
|
<p>For ELF targets, the <code>.symver</code> directive can be used like this:
|
||
|
|
</p><div class="smallexample">
|
||
|
|
<pre class="smallexample">.symver <var>name</var>, <var>name2@nodename</var>
|
||
|
|
</pre></div>
|
||
|
|
<p>If the symbol <var>name</var> is defined within the file
|
||
|
|
being assembled, the <code>.symver</code> directive effectively creates a symbol
|
||
|
|
alias with the name <var>name2@nodename</var>, and in fact the main reason that we
|
||
|
|
just don’t try and create a regular alias is that the <var>@</var> character isn’t
|
||
|
|
permitted in symbol names. The <var>name2</var> part of the name is the actual name
|
||
|
|
of the symbol by which it will be externally referenced. The name <var>name</var>
|
||
|
|
itself is merely a name of convenience that is used so that it is possible to
|
||
|
|
have definitions for multiple versions of a function within a single source
|
||
|
|
file, and so that the compiler can unambiguously know which version of a
|
||
|
|
function is being mentioned. The <var>nodename</var> portion of the alias should be
|
||
|
|
the name of a node specified in the version script supplied to the linker when
|
||
|
|
building a shared library. If you are attempting to override a versioned
|
||
|
|
symbol from a shared library, then <var>nodename</var> should correspond to the
|
||
|
|
nodename of the symbol you are trying to override.
|
||
|
|
</p>
|
||
|
|
<p>If the symbol <var>name</var> is not defined within the file being assembled, all
|
||
|
|
references to <var>name</var> will be changed to <var>name2@nodename</var>. If no
|
||
|
|
reference to <var>name</var> is made, <var>name2@nodename</var> will be removed from the
|
||
|
|
symbol table.
|
||
|
|
</p>
|
||
|
|
<p>Another usage of the <code>.symver</code> directive is:
|
||
|
|
</p><div class="smallexample">
|
||
|
|
<pre class="smallexample">.symver <var>name</var>, <var>name2@@nodename</var>
|
||
|
|
</pre></div>
|
||
|
|
<p>In this case, the symbol <var>name</var> must exist and be defined within
|
||
|
|
the file being assembled. It is similar to <var>name2@nodename</var>. The
|
||
|
|
difference is <var>name2@@nodename</var> will also be used to resolve
|
||
|
|
references to <var>name2</var> by the linker.
|
||
|
|
</p>
|
||
|
|
<p>The third usage of the <code>.symver</code> directive is:
|
||
|
|
</p><div class="smallexample">
|
||
|
|
<pre class="smallexample">.symver <var>name</var>, <var>name2@@@nodename</var>
|
||
|
|
</pre></div>
|
||
|
|
<p>When <var>name</var> is not defined within the
|
||
|
|
file being assembled, it is treated as <var>name2@nodename</var>. When
|
||
|
|
<var>name</var> is defined within the file being assembled, the symbol
|
||
|
|
name, <var>name</var>, will be changed to <var>name2@@nodename</var>.
|
||
|
|
</p>
|
||
|
|
<hr>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Tag.html#Tag" accesskey="n" rel="next">Tag</a>, Previous: <a href="SubSection.html#SubSection" accesskey="p" rel="prev">SubSection</a>, Up: <a href="Pseudo-Ops.html#Pseudo-Ops" accesskey="u" rel="up">Pseudo Ops</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</body>
|
||
|
|
</html>
|