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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | 6ce4ebed87858ecdd79a1091367c6e961055daa9 (patch) | |
| tree | 1c2a6a60531acf791531bbd9c8ac14c23ef8a66c /share/doc/gdb/Auto-Display.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Change-Id: I7303388733328cd98ab9aa3c30236db67f2e9e9c
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diff --git a/share/doc/gdb/Auto-Display.html b/share/doc/gdb/Auto-Display.html new file mode 100644 index 0000000..2e3b701 --- /dev/null +++ b/share/doc/gdb/Auto-Display.html @@ -0,0 +1,196 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 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 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>Debugging with GDB: Auto Display</title> + +<meta name="description" content="Debugging with GDB: Auto Display"> +<meta name="keywords" content="Debugging with GDB: Auto Display"> +<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="Data.html#Data" rel="up" title="Data"> +<link href="Print-Settings.html#Print-Settings" rel="next" title="Print Settings"> +<link href="Memory-Tagging.html#Memory-Tagging" rel="previous" title="Memory Tagging"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +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.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Auto-Display"></a> +<div class="header"> +<p> +Next: <a href="Print-Settings.html#Print-Settings" accesskey="n" rel="next">Print Settings</a>, Previous: <a href="Memory-Tagging.html#Memory-Tagging" accesskey="p" rel="previous">Memory Tagging</a>, Up: <a href="Data.html#Data" accesskey="u" rel="up">Data</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="Automatic-Display"></a> +<h3 class="section">10.8 Automatic Display</h3> +<a name="index-automatic-display"></a> +<a name="index-display-of-expressions"></a> + +<p>If you find that you want to print the value of an expression frequently +(to see how it changes), you might want to add it to the <em>automatic +display list</em> so that <small>GDB</small> prints its value each time your program stops. +Each expression added to the list is given a number to identify it; +to remove an expression from the list, you specify that number. +The automatic display looks like this: +</p> +<div class="smallexample"> +<pre class="smallexample">2: foo = 38 +3: bar[5] = (struct hack *) 0x3804 +</pre></div> + +<p>This display shows item numbers, expressions and their current values. As with +displays you request manually using <code>x</code> or <code>print</code>, you can +specify the output format you prefer; in fact, <code>display</code> decides +whether to use <code>print</code> or <code>x</code> depending your format +specification—it uses <code>x</code> if you specify either the ‘<samp>i</samp>’ +or ‘<samp>s</samp>’ format, or a unit size; otherwise it uses <code>print</code>. +</p> +<dl compact="compact"> +<dd><a name="index-display"></a> +</dd> +<dt><code>display <var>expr</var></code></dt> +<dd><p>Add the expression <var>expr</var> to the list of expressions to display +each time your program stops. See <a href="Expressions.html#Expressions">Expressions</a>. +</p> +<p><code>display</code> does not repeat if you press <tt class="key">RET</tt> again after using it. +</p> +</dd> +<dt><code>display/<var>fmt</var> <var>expr</var></code></dt> +<dd><p>For <var>fmt</var> specifying only a display format and not a size or +count, add the expression <var>expr</var> to the auto-display list but +arrange to display it each time in the specified format <var>fmt</var>. +See <a href="Output-Formats.html#Output-Formats">Output Formats</a>. +</p> +</dd> +<dt><code>display/<var>fmt</var> <var>addr</var></code></dt> +<dd><p>For <var>fmt</var> ‘<samp>i</samp>’ or ‘<samp>s</samp>’, or including a unit-size or a +number of units, add the expression <var>addr</var> as a memory address to +be examined each time your program stops. Examining means in effect +doing ‘<samp>x/<var>fmt</var> <var>addr</var></samp>’. See <a href="Memory.html#Memory">Examining Memory</a>. +</p></dd> +</dl> + +<p>For example, ‘<samp>display/i $pc</samp>’ can be helpful, to see the machine +instruction about to be executed each time execution stops (‘<samp>$pc</samp>’ +is a common name for the program counter; see <a href="Registers.html#Registers">Registers</a>). +</p> +<dl compact="compact"> +<dd><a name="index-delete-display"></a> +<a name="index-undisplay"></a> +</dd> +<dt><code>undisplay <var>dnums</var>…</code></dt> +<dt><code>delete display <var>dnums</var>…</code></dt> +<dd><p>Remove items from the list of expressions to display. Specify the +numbers of the displays that you want affected with the command +argument <var>dnums</var>. It can be a single display number, one of the +numbers shown in the first field of the ‘<samp>info display</samp>’ display; +or it could be a range of display numbers, as in <code>2-4</code>. +</p> +<p><code>undisplay</code> does not repeat if you press <tt class="key">RET</tt> after using it. +(Otherwise you would just get the error ‘<samp>No display number …</samp>’.) +</p> +<a name="index-disable-display"></a> +</dd> +<dt><code>disable display <var>dnums</var>…</code></dt> +<dd><p>Disable the display of item numbers <var>dnums</var>. A disabled display +item is not printed automatically, but is not forgotten. It may be +enabled again later. Specify the numbers of the displays that you +want affected with the command argument <var>dnums</var>. It can be a +single display number, one of the numbers shown in the first field of +the ‘<samp>info display</samp>’ display; or it could be a range of display +numbers, as in <code>2-4</code>. +</p> +<a name="index-enable-display"></a> +</dd> +<dt><code>enable display <var>dnums</var>…</code></dt> +<dd><p>Enable display of item numbers <var>dnums</var>. It becomes effective once +again in auto display of its expression, until you specify otherwise. +Specify the numbers of the displays that you want affected with the +command argument <var>dnums</var>. It can be a single display number, one +of the numbers shown in the first field of the ‘<samp>info display</samp>’ +display; or it could be a range of display numbers, as in <code>2-4</code>. +</p> +</dd> +<dt><code>display</code></dt> +<dd><p>Display the current values of the expressions on the list, just as is +done when your program stops. +</p> +<a name="index-info-display"></a> +</dd> +<dt><code>info display</code></dt> +<dd><p>Print the list of expressions previously set up to display +automatically, each one with its item number, but without showing the +values. This includes disabled expressions, which are marked as such. +It also includes expressions which would not be displayed right now +because they refer to automatic variables not currently available. +</p></dd> +</dl> + +<a name="index-display-disabled-out-of-scope"></a> +<p>If a display expression refers to local variables, then it does not make +sense outside the lexical context for which it was set up. Such an +expression is disabled when execution enters a context where one of its +variables is not defined. For example, if you give the command +<code>display last_char</code> while inside a function with an argument +<code>last_char</code>, <small>GDB</small> displays this argument while your program +continues to stop inside that function. When it stops elsewhere—where +there is no variable <code>last_char</code>—the display is disabled +automatically. The next time your program stops where <code>last_char</code> +is meaningful, you can enable the display expression once again. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="Print-Settings.html#Print-Settings" accesskey="n" rel="next">Print Settings</a>, Previous: <a href="Memory-Tagging.html#Memory-Tagging" accesskey="p" rel="previous">Memory Tagging</a>, Up: <a href="Data.html#Data" accesskey="u" rel="up">Data</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> |