<html lang="en">
<head>
<title>s390 Options - 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="S_002f390_002dDependent.html#S_002f390_002dDependent" title="S/390-Dependent">
<link rel="next" href="s390-Characters.html#s390-Characters" title="s390 Characters">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<!--
This file documents the GNU Assembler "as".
Copyright (C) 1991-2015 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="s390-Options"></a>
<p>
Next: <a rel="next" accesskey="n" href="s390-Characters.html#s390-Characters">s390 Characters</a>,
Up: <a rel="up" accesskey="u" href="S_002f390_002dDependent.html#S_002f390_002dDependent">S/390-Dependent</a>
<hr>
</div>
<h4 class="subsection">9.38.1 Options</h4>
<p><a name="index-options-for-s390-1874"></a><a name="index-s390-options-1875"></a>
The following table lists all available s390 specific options:
<a name="index-g_t_0040samp_007b_002dm31_007d-option_002c-s390-1876"></a>
<a name="index-g_t_0040samp_007b_002dm64_007d-option_002c-s390-1877"></a>
<dl><dt><code>-m31 | -m64</code><dd>Select 31- or 64-bit ABI implying a word size of 32- or 64-bit.
<p>These options are only available with the ELF object file format, and
require that the necessary BFD support has been included (on a 31-bit
platform you must add –enable-64-bit-bfd on the call to the configure
script to enable 64-bit usage and use s390x as target platform).
<p><a name="index-g_t_0040samp_007b_002dmesa_007d-option_002c-s390-1878"></a><a name="index-g_t_0040samp_007b_002dmzarch_007d-option_002c-s390-1879"></a><br><dt><code>-mesa | -mzarch</code><dd>Select the architecture mode, either the Enterprise System Architecture
(esa) mode or the z/Architecture mode (zarch).
<p>The 64-bit instructions are only available with the z/Architecture mode.
The combination of ‘<samp><span class="samp">-m64</span></samp>’ and ‘<samp><span class="samp">-mesa</span></samp>’ results in a warning
message.
<p><a name="index-g_t_0040samp_007b_002dmarch_003d_007d-option_002c-s390-1880"></a><br><dt><code>-march=</code><var>CPU</var><dd>This option specifies the target processor. The following processor names
are recognized:
<code>g5</code>,
<code>g6</code>,
<code>z900</code>,
<code>z990</code>,
<code>z9-109</code>,
<code>z9-ec</code>,
<code>z10</code>,
<code>z196</code>,
<code>zEC12</code>, and
<code>z13</code>.
Assembling an instruction that is not supported on the target processor
results in an error message. Do not specify <code>g5</code> or <code>g6</code>
with ‘<samp><span class="samp">-mzarch</span></samp>’.
<p><a name="index-g_t_0040samp_007b_002dmregnames_007d-option_002c-s390-1881"></a><br><dt><code>-mregnames</code><dd>Allow symbolic names for registers.
<p><a name="index-g_t_0040samp_007b_002dmno_002dregnames_007d-option_002c-s390-1882"></a><br><dt><code>-mno-regnames</code><dd>Do not allow symbolic names for registers.
<p><a name="index-g_t_0040samp_007b_002dmwarn_002dareg_002dzero_007d-option_002c-s390-1883"></a><br><dt><code>-mwarn-areg-zero</code><dd>Warn whenever the operand for a base or index register has been specified
but evaluates to zero. This can indicate the misuse of general purpose
register 0 as an address register.
</dl>
</body></html>