1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- Copyright (C) 1988-2021 Free Software Foundation, Inc. 4 5Permission is granted to copy, distribute and/or modify this document 6under the terms of the GNU Free Documentation License, Version 1.3 or 7any later version published by the Free Software Foundation; with the 8Invariant Sections being "Free Software" and "Free Software Needs 9Free Documentation", with the Front-Cover Texts being "A GNU Manual," 10and with the Back-Cover Texts as in (a) below. 11 12(a) The FSF's Back-Cover Text is: "You are free to copy and modify 13this GNU Manual. 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However, sometimes you need to override its 75conclusions. Use these commands to manage <small>GDB</small>’s view of the 76current ABI. 77</p> 78<a name="index-OS-ABI"></a> 79<a name="index-set-osabi"></a> 80<a name="index-show-osabi"></a> 81<a name="index-Newlib-OS-ABI-and-its-influence-on-the-longjmp-handling"></a> 82 83<p>One <small>GDB</small> configuration can debug binaries for multiple operating 84system targets, either via remote debugging or native emulation. 85<small>GDB</small> will autodetect the <em>OS ABI</em> (Operating System ABI) in use, 86but you can override its conclusion using the <code>set osabi</code> command. 87One example where this is useful is in debugging of binaries which use 88an alternate C library (e.g. <small>UCLIBC</small> for <small>GNU</small>/Linux) which does 89not have the same identifying marks that the standard C library for your 90platform provides. 91</p> 92<p>When <small>GDB</small> is debugging the AArch64 architecture, it provides a 93“Newlib” OS ABI. This is useful for handling <code>setjmp</code> and 94<code>longjmp</code> when debugging binaries that use the <small>NEWLIB</small> C library. 95The “Newlib” OS ABI can be selected by <code>set osabi Newlib</code>. 96</p> 97<dl compact="compact"> 98<dt><code>show osabi</code></dt> 99<dd><p>Show the OS ABI currently in use. 100</p> 101</dd> 102<dt><code>set osabi</code></dt> 103<dd><p>With no argument, show the list of registered available OS ABI’s. 104</p> 105</dd> 106<dt><code>set osabi <var>abi</var></code></dt> 107<dd><p>Set the current OS ABI to <var>abi</var>. 108</p></dd> 109</dl> 110 111<a name="index-float-promotion"></a> 112 113<p>Generally, the way that an argument of type <code>float</code> is passed to a 114function depends on whether the function is prototyped. For a prototyped 115(i.e. ANSI/ISO style) function, <code>float</code> arguments are passed unchanged, 116according to the architecture’s convention for <code>float</code>. For unprototyped 117(i.e. K&R style) functions, <code>float</code> arguments are first promoted to type 118<code>double</code> and then passed. 119</p> 120<p>Unfortunately, some forms of debug information do not reliably indicate whether 121a function is prototyped. If <small>GDB</small> calls a function that is not marked 122as prototyped, it consults <kbd>set coerce-float-to-double</kbd>. 123</p> 124<dl compact="compact"> 125<dd><a name="index-set-coerce_002dfloat_002dto_002ddouble"></a> 126</dd> 127<dt><code>set coerce-float-to-double</code></dt> 128<dt><code>set coerce-float-to-double on</code></dt> 129<dd><p>Arguments of type <code>float</code> will be promoted to <code>double</code> when passed 130to an unprototyped function. This is the default setting. 131</p> 132</dd> 133<dt><code>set coerce-float-to-double off</code></dt> 134<dd><p>Arguments of type <code>float</code> will be passed directly to unprototyped 135functions. 136</p> 137<a name="index-show-coerce_002dfloat_002dto_002ddouble"></a> 138</dd> 139<dt><code>show coerce-float-to-double</code></dt> 140<dd><p>Show the current setting of promoting <code>float</code> to <code>double</code>. 141</p></dd> 142</dl> 143 144<a name="index-set-cp_002dabi"></a> 145<a name="index-show-cp_002dabi"></a> 146<p><small>GDB</small> needs to know the ABI used for your program’s C<tt>++</tt> 147objects. The correct C<tt>++</tt> ABI depends on which C<tt>++</tt> compiler was 148used to build your application. <small>GDB</small> only fully supports 149programs with a single C<tt>++</tt> ABI; if your program contains code using 150multiple C<tt>++</tt> ABI’s or if <small>GDB</small> can not identify your 151program’s ABI correctly, you can tell <small>GDB</small> which ABI to use. 152Currently supported ABI’s include “gnu-v2”, for <code>g++</code> versions 153before 3.0, “gnu-v3”, for <code>g++</code> versions 3.0 and later, and 154“hpaCC” for the HP ANSI C<tt>++</tt> compiler. Other C<tt>++</tt> compilers may 155use the “gnu-v2” or “gnu-v3” ABI’s as well. The default setting is 156“auto”. 157</p> 158<dl compact="compact"> 159<dt><code>show cp-abi</code></dt> 160<dd><p>Show the C<tt>++</tt> ABI currently in use. 161</p> 162</dd> 163<dt><code>set cp-abi</code></dt> 164<dd><p>With no argument, show the list of supported C<tt>++</tt> ABI’s. 165</p> 166</dd> 167<dt><code>set cp-abi <var>abi</var></code></dt> 168<dt><code>set cp-abi auto</code></dt> 169<dd><p>Set the current C<tt>++</tt> ABI to <var>abi</var>, or return to automatic detection. 170</p></dd> 171</dl> 172 173<hr> 174<div class="header"> 175<p> 176Next: <a href="Auto_002dloading.html#Auto_002dloading" accesskey="n" rel="next">Auto-loading</a>, Previous: <a href="Numbers.html#Numbers" accesskey="p" rel="previous">Numbers</a>, Up: <a href="Controlling-GDB.html#Controlling-GDB" accesskey="u" rel="up">Controlling GDB</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> 177</div> 178 179 180 181</body> 182</html> 183