68 lines
2.9 KiB
HTML
68 lines
2.9 KiB
HTML
|
<html lang="en">
|
||
|
|
<head>
|
||
|
|
<title>bss - Using as</title>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html">
|
||
|
|
<meta name="description" content="Using as">
|
||
|
|
<meta name="generator" content="makeinfo 4.13">
|
||
|
|
<link title="Top" rel="start" href="index.html#Top">
|
||
|
|
<link rel="up" href="Sections.html#Sections" title="Sections">
|
||
|
|
<link rel="prev" href="Sub_002dSections.html#Sub_002dSections" title="Sub-Sections">
|
||
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
||
|
|
<!--
|
||
|
|
This file documents the GNU Assembler "as".
|
||
|
|
|
||
|
|
Copyright (C) 1991-2019 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''.
|
||
|
|
|
||
|
|
-->
|
||
|
|
<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; }
|
||
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
||
|
|
--></style>
|
||
|
|
</head>
|
||
|
|
<body>
|
||
|
|
<div class="node">
|
||
|
|
<a name="bss"></a>
|
||
|
|
<p>
|
||
|
|
Previous: <a rel="previous" accesskey="p" href="Sub_002dSections.html#Sub_002dSections">Sub-Sections</a>,
|
||
|
|
Up: <a rel="up" accesskey="u" href="Sections.html#Sections">Sections</a>
|
||
|
|
<hr>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
<h3 class="section">4.5 bss Section</h3>
|
||
|
|
|
||
|
|
<p><a name="index-bss-section-208"></a><a name="index-common-variable-storage-209"></a>The bss section is used for local common variable storage.
|
||
|
|
You may allocate address space in the bss section, but you may
|
||
|
|
not dictate data to load into it before your program executes. When
|
||
|
|
your program starts running, all the contents of the bss
|
||
|
|
section are zeroed bytes.
|
||
|
|
|
||
|
|
<p>The <code>.lcomm</code> pseudo-op defines a symbol in the bss section; see
|
||
|
|
<a href="Lcomm.html#Lcomm"><code>.lcomm</code></a>.
|
||
|
|
|
||
|
|
<p>The <code>.comm</code> pseudo-op may be used to declare a common symbol, which is
|
||
|
|
another form of uninitialized symbol; see <a href="Comm.html#Comm"><code>.comm</code></a>.
|
||
|
|
|
||
|
|
<p>When assembling for a target which supports multiple sections, such as ELF or
|
||
|
|
COFF, you may switch into the <code>.bss</code> section and define symbols as usual;
|
||
|
|
see <a href="Section.html#Section"><code>.section</code></a>. You may only assemble zero values into the
|
||
|
|
section. Typically the section will only contain symbol definitions and
|
||
|
|
<code>.skip</code> directives (see <a href="Skip.html#Skip"><code>.skip</code></a>).
|
||
|
|
|
||
|
|
</body></html>
|
||
|
|
|