You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
202 lines
9.3 KiB
HTML
202 lines
9.3 KiB
HTML
4 years ago
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
|
|
<html>
|
||
|
|
<!-- Copyright (C) 1988-2019 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 the
|
||
|
|
Invariant Sections being "Free Software" and "Free Software Needs
|
||
|
|
Free Documentation", with the Front-Cover Texts being "A GNU Manual,"
|
||
|
|
and with the Back-Cover Texts as in (a) below.
|
||
|
|
|
||
|
|
(a) The FSF's Back-Cover Text is: "You are free to copy and modify
|
||
|
|
this GNU Manual. Buying copies from GNU Press supports the FSF in
|
||
|
|
developing GNU and promoting software freedom." -->
|
||
|
|
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
|
||
|
|
<head>
|
||
|
|
<title>Overlay Commands (Debugging with GDB)</title>
|
||
|
|
|
||
|
|
<meta name="description" content="Overlay Commands (Debugging with GDB)">
|
||
|
|
<meta name="keywords" content="Overlay Commands (Debugging with GDB)">
|
||
|
|
<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="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
|
||
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
||
|
|
<link href="Overlays.html#Overlays" rel="up" title="Overlays">
|
||
|
|
<link href="Automatic-Overlay-Debugging.html#Automatic-Overlay-Debugging" rel="next" title="Automatic Overlay Debugging">
|
||
|
|
<link href="How-Overlays-Work.html#How-Overlays-Work" rel="prev" title="How Overlays Work">
|
||
|
|
<style type="text/css">
|
||
|
|
<!--
|
||
|
|
a.summary-letter {text-decoration: none}
|
||
|
|
blockquote.indentedblock {margin-right: 0em}
|
||
|
|
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
|
||
|
|
blockquote.smallquotation {font-size: smaller}
|
||
|
|
div.display {margin-left: 3.2em}
|
||
|
|
div.example {margin-left: 3.2em}
|
||
|
|
div.lisp {margin-left: 3.2em}
|
||
|
|
div.smalldisplay {margin-left: 3.2em}
|
||
|
|
div.smallexample {margin-left: 3.2em}
|
||
|
|
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.nolinebreak {white-space: nowrap}
|
||
|
|
span.roman {font-family: initial; font-weight: normal}
|
||
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
||
|
|
ul.no-bullet {list-style: none}
|
||
|
|
-->
|
||
|
|
</style>
|
||
|
|
|
||
|
|
|
||
|
|
</head>
|
||
|
|
|
||
|
|
<body lang="en">
|
||
|
|
<a name="Overlay-Commands"></a>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Automatic-Overlay-Debugging.html#Automatic-Overlay-Debugging" accesskey="n" rel="next">Automatic Overlay Debugging</a>, Previous: <a href="How-Overlays-Work.html#How-Overlays-Work" accesskey="p" rel="prev">How Overlays Work</a>, Up: <a href="Overlays.html#Overlays" accesskey="u" rel="up">Overlays</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>
|
||
|
|
</div>
|
||
|
|
<hr>
|
||
|
|
<a name="Overlay-Commands-1"></a>
|
||
|
|
<h3 class="section">14.2 Overlay Commands</h3>
|
||
|
|
|
||
|
|
<p>To use <small>GDB</small>’s overlay support, each overlay in your program must
|
||
|
|
correspond to a separate section of the executable file. The section’s
|
||
|
|
virtual memory address and load memory address must be the overlay’s
|
||
|
|
mapped and load addresses. Identifying overlays with sections allows
|
||
|
|
<small>GDB</small> to determine the appropriate address of a function or
|
||
|
|
variable, depending on whether the overlay is mapped or not.
|
||
|
|
</p>
|
||
|
|
<p><small>GDB</small>’s overlay commands all start with the word <code>overlay</code>;
|
||
|
|
you can abbreviate this as <code>ov</code> or <code>ovly</code>. The commands are:
|
||
|
|
</p>
|
||
|
|
<dl compact="compact">
|
||
|
|
<dt><code>overlay off</code></dt>
|
||
|
|
<dd><a name="index-overlay"></a>
|
||
|
|
<p>Disable <small>GDB</small>’s overlay support. When overlay support is
|
||
|
|
disabled, <small>GDB</small> assumes that all functions and variables are
|
||
|
|
always present at their mapped addresses. By default, <small>GDB</small>’s
|
||
|
|
overlay support is disabled.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>overlay manual</code></dt>
|
||
|
|
<dd><a name="index-manual-overlay-debugging"></a>
|
||
|
|
<p>Enable <em>manual</em> overlay debugging. In this mode, <small>GDB</small>
|
||
|
|
relies on you to tell it which overlays are mapped, and which are not,
|
||
|
|
using the <code>overlay map-overlay</code> and <code>overlay unmap-overlay</code>
|
||
|
|
commands described below.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>overlay map-overlay <var>overlay</var></code></dt>
|
||
|
|
<dt><code>overlay map <var>overlay</var></code></dt>
|
||
|
|
<dd><a name="index-map-an-overlay"></a>
|
||
|
|
<p>Tell <small>GDB</small> that <var>overlay</var> is now mapped; <var>overlay</var> must
|
||
|
|
be the name of the object file section containing the overlay. When an
|
||
|
|
overlay is mapped, <small>GDB</small> assumes it can find the overlay’s
|
||
|
|
functions and variables at their mapped addresses. <small>GDB</small> assumes
|
||
|
|
that any other overlays whose mapped ranges overlap that of
|
||
|
|
<var>overlay</var> are now unmapped.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>overlay unmap-overlay <var>overlay</var></code></dt>
|
||
|
|
<dt><code>overlay unmap <var>overlay</var></code></dt>
|
||
|
|
<dd><a name="index-unmap-an-overlay"></a>
|
||
|
|
<p>Tell <small>GDB</small> that <var>overlay</var> is no longer mapped; <var>overlay</var>
|
||
|
|
must be the name of the object file section containing the overlay.
|
||
|
|
When an overlay is unmapped, <small>GDB</small> assumes it can find the
|
||
|
|
overlay’s functions and variables at their load addresses.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>overlay auto</code></dt>
|
||
|
|
<dd><p>Enable <em>automatic</em> overlay debugging. In this mode, <small>GDB</small>
|
||
|
|
consults a data structure the overlay manager maintains in the inferior
|
||
|
|
to see which overlays are mapped. For details, see <a href="Automatic-Overlay-Debugging.html#Automatic-Overlay-Debugging">Automatic Overlay Debugging</a>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>overlay load-target</code></dt>
|
||
|
|
<dt><code>overlay load</code></dt>
|
||
|
|
<dd><a name="index-reloading-the-overlay-table"></a>
|
||
|
|
<p>Re-read the overlay table from the inferior. Normally, <small>GDB</small>
|
||
|
|
re-reads the table <small>GDB</small> automatically each time the inferior
|
||
|
|
stops, so this command should only be necessary if you have changed the
|
||
|
|
overlay mapping yourself using <small>GDB</small>. This command is only
|
||
|
|
useful when using automatic overlay debugging.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>overlay list-overlays</code></dt>
|
||
|
|
<dt><code>overlay list</code></dt>
|
||
|
|
<dd><a name="index-listing-mapped-overlays"></a>
|
||
|
|
<p>Display a list of the overlays currently mapped, along with their mapped
|
||
|
|
addresses, load addresses, and sizes.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<p>Normally, when <small>GDB</small> prints a code address, it includes the name
|
||
|
|
of the function the address falls in:
|
||
|
|
</p>
|
||
|
|
<div class="smallexample">
|
||
|
|
<pre class="smallexample">(gdb) print main
|
||
|
|
$3 = {int ()} 0x11a0 <main>
|
||
|
|
</pre></div>
|
||
|
|
<p>When overlay debugging is enabled, <small>GDB</small> recognizes code in
|
||
|
|
unmapped overlays, and prints the names of unmapped functions with
|
||
|
|
asterisks around them. For example, if <code>foo</code> is a function in an
|
||
|
|
unmapped overlay, <small>GDB</small> prints it this way:
|
||
|
|
</p>
|
||
|
|
<div class="smallexample">
|
||
|
|
<pre class="smallexample">(gdb) overlay list
|
||
|
|
No sections are mapped.
|
||
|
|
(gdb) print foo
|
||
|
|
$5 = {int (int)} 0x100000 <*foo*>
|
||
|
|
</pre></div>
|
||
|
|
<p>When <code>foo</code>’s overlay is mapped, <small>GDB</small> prints the function’s
|
||
|
|
name normally:
|
||
|
|
</p>
|
||
|
|
<div class="smallexample">
|
||
|
|
<pre class="smallexample">(gdb) overlay list
|
||
|
|
Section .ov.foo.text, loaded at 0x100000 - 0x100034,
|
||
|
|
mapped at 0x1016 - 0x104a
|
||
|
|
(gdb) print foo
|
||
|
|
$6 = {int (int)} 0x1016 <foo>
|
||
|
|
</pre></div>
|
||
|
|
|
||
|
|
<p>When overlay debugging is enabled, <small>GDB</small> can find the correct
|
||
|
|
address for functions and variables in an overlay, whether or not the
|
||
|
|
overlay is mapped. This allows most <small>GDB</small> commands, like
|
||
|
|
<code>break</code> and <code>disassemble</code>, to work normally, even on unmapped
|
||
|
|
code. However, <small>GDB</small>’s breakpoint support has some limitations:
|
||
|
|
</p>
|
||
|
|
<ul>
|
||
|
|
<li> <a name="index-breakpoints-in-overlays"></a>
|
||
|
|
<a name="index-overlays_002c-setting-breakpoints-in"></a>
|
||
|
|
You can set breakpoints in functions in unmapped overlays, as long as
|
||
|
|
<small>GDB</small> can write to the overlay at its load address.
|
||
|
|
</li><li> <small>GDB</small> can not set hardware or simulator-based breakpoints in
|
||
|
|
unmapped overlays. However, if you set a breakpoint at the end of your
|
||
|
|
overlay manager (and tell <small>GDB</small> which overlays are now mapped, if
|
||
|
|
you are using manual overlay management), <small>GDB</small> will re-set its
|
||
|
|
breakpoints properly.
|
||
|
|
</li></ul>
|
||
|
|
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Automatic-Overlay-Debugging.html#Automatic-Overlay-Debugging" accesskey="n" rel="next">Automatic Overlay Debugging</a>, Previous: <a href="How-Overlays-Work.html#How-Overlays-Work" accesskey="p" rel="prev">How Overlays Work</a>, Up: <a href="Overlays.html#Overlays" accesskey="u" rel="up">Overlays</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>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</body>
|
||
|
|
</html>
|