96 lines
4.8 KiB
HTML
96 lines
4.8 KiB
HTML
<html lang="en">
|
|
<head>
|
|
<title>Symver - Using as</title>
|
|
<meta http-equiv="Content-Type" content="text/html">
|
|
<meta name="description" content="Using as">
|
|
<meta name="generator" content="makeinfo 4.7">
|
|
<link title="Top" rel="start" href="index.html#Top">
|
|
<link rel="up" href="Pseudo-Ops.html#Pseudo-Ops" title="Pseudo Ops">
|
|
<link rel="prev" href="SubSection.html#SubSection" title="SubSection">
|
|
<link rel="next" href="Tag.html#Tag" title="Tag">
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
|
<!--
|
|
This file documents the GNU Assembler "as".
|
|
|
|
Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,
|
|
2006, 2007 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 1.1
|
|
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''.
|
|
|
|
man end-->
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
|
<style type="text/css"><!--
|
|
pre.display { font-family:inherit }
|
|
pre.format { font-family:inherit }
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
|
pre.smallexample { font-size:smaller }
|
|
pre.smalllisp { font-size:smaller }
|
|
span.sc { font-variant:small-caps }
|
|
span.roman { font-family: serif; font-weight: normal; }
|
|
--></style>
|
|
</head>
|
|
<body>
|
|
<div class="node">
|
|
<p>
|
|
<a name="Symver"></a>Next: <a rel="next" accesskey="n" href="Tag.html#Tag">Tag</a>,
|
|
Previous: <a rel="previous" accesskey="p" href="SubSection.html#SubSection">SubSection</a>,
|
|
Up: <a rel="up" accesskey="u" href="Pseudo-Ops.html#Pseudo-Ops">Pseudo Ops</a>
|
|
<hr><br>
|
|
</div>
|
|
|
|
<h3 class="section">7.107 <code>.symver</code></h3>
|
|
|
|
<p><a name="index-_0040code_007bsymver_007d-directive-474"></a><a name="index-symbol-versioning-475"></a><a name="index-versions-of-symbols-476"></a>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>For ELF targets, the <code>.symver</code> directive can be used like this:
|
|
<pre class="smallexample"> .symver <var>name</var>, <var>name2@nodename</var>
|
|
</pre>
|
|
<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>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>Another usage of the <code>.symver</code> directive is:
|
|
<pre class="smallexample"> .symver <var>name</var>, <var>name2@@nodename</var>
|
|
</pre>
|
|
<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>The third usage of the <code>.symver</code> directive is:
|
|
<pre class="smallexample"> .symver <var>name</var>, <var>name2@@@nodename</var>
|
|
</pre>
|
|
<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>.
|
|
|
|
</body></html>
|
|
|