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132 lines
6.2 KiB
HTML
132 lines
6.2 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2019 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Free Software" and "Free Software Needs
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Free Documentation", with the Front-Cover Texts being "A GNU Manual,"
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and with the Back-Cover Texts as in (a) below.
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(a) The FSF's Back-Cover Text is: "You are free to copy and modify
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this GNU Manual. Buying copies from GNU Press supports the FSF in
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developing GNU and promoting software freedom." -->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Breakpoint-related Warnings (Debugging with GDB)</title>
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<meta name="description" content="Breakpoint-related Warnings (Debugging with GDB)">
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<meta name="keywords" content="Breakpoint-related Warnings (Debugging with GDB)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Breakpoints.html#Breakpoints" rel="up" title="Breakpoints">
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<link href="Continuing-and-Stepping.html#Continuing-and-Stepping" rel="next" title="Continuing and Stepping">
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<link href="Error-in-Breakpoints.html#Error-in-Breakpoints" rel="prev" title="Error in Breakpoints">
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<style type="text/css">
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en">
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<a name="Breakpoint_002drelated-Warnings"></a>
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<div class="header">
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<p>
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Previous: <a href="Error-in-Breakpoints.html#Error-in-Breakpoints" accesskey="p" rel="prev">Error in Breakpoints</a>, Up: <a href="Breakpoints.html#Breakpoints" accesskey="u" rel="up">Breakpoints</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>
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</div>
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<hr>
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<a name="g_t_0060_0060Breakpoint-address-adjusted_002e_002e_002e_0027_0027"></a>
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<h4 class="subsection">5.1.12 “Breakpoint address adjusted...”</h4>
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<a name="index-breakpoint-address-adjusted"></a>
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<p>Some processor architectures place constraints on the addresses at
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which breakpoints may be placed. For architectures thus constrained,
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<small>GDB</small> will attempt to adjust the breakpoint’s address to comply
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with the constraints dictated by the architecture.
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</p>
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<p>One example of such an architecture is the Fujitsu FR-V. The FR-V is
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a VLIW architecture in which a number of RISC-like instructions may be
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bundled together for parallel execution. The FR-V architecture
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constrains the location of a breakpoint instruction within such a
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bundle to the instruction with the lowest address. <small>GDB</small>
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honors this constraint by adjusting a breakpoint’s address to the
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first in the bundle.
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</p>
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<p>It is not uncommon for optimized code to have bundles which contain
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instructions from different source statements, thus it may happen that
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a breakpoint’s address will be adjusted from one source statement to
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another. Since this adjustment may significantly alter <small>GDB</small>’s
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breakpoint related behavior from what the user expects, a warning is
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printed when the breakpoint is first set and also when the breakpoint
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is hit.
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</p>
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<p>A warning like the one below is printed when setting a breakpoint
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that’s been subject to address adjustment:
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</p>
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<div class="smallexample">
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<pre class="smallexample">warning: Breakpoint address adjusted from 0x00010414 to 0x00010410.
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</pre></div>
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<p>Such warnings are printed both for user settable and <small>GDB</small>’s
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internal breakpoints. If you see one of these warnings, you should
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verify that a breakpoint set at the adjusted address will have the
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desired affect. If not, the breakpoint in question may be removed and
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other breakpoints may be set which will have the desired behavior.
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E.g., it may be sufficient to place the breakpoint at a later
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instruction. A conditional breakpoint may also be useful in some
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cases to prevent the breakpoint from triggering too often.
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</p>
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<p><small>GDB</small> will also issue a warning when stopping at one of these
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adjusted breakpoints:
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</p>
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<div class="smallexample">
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<pre class="smallexample">warning: Breakpoint 1 address previously adjusted from 0x00010414
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to 0x00010410.
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</pre></div>
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<p>When this warning is encountered, it may be too late to take remedial
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action except in cases where the breakpoint is hit earlier or more
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frequently than expected.
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</p>
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<hr>
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<div class="header">
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<p>
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Previous: <a href="Error-in-Breakpoints.html#Error-in-Breakpoints" accesskey="p" rel="prev">Error in Breakpoints</a>, Up: <a href="Breakpoints.html#Breakpoints" accesskey="u" rel="up">Breakpoints</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>
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</div>
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</body>
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</html>
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