88 lines
4.3 KiB
HTML
88 lines
4.3 KiB
HTML
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<html lang="en">
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<head>
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<title>Overlay Sample Program - Debugging with GDB</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="Debugging with GDB">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Overlays.html#Overlays" title="Overlays">
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<link rel="prev" href="Automatic-Overlay-Debugging.html#Automatic-Overlay-Debugging" title="Automatic Overlay Debugging">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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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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</head>
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<body>
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<div class="node">
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<a name="Overlay-Sample-Program"></a>
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<p>
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Previous: <a rel="previous" accesskey="p" href="Automatic-Overlay-Debugging.html#Automatic-Overlay-Debugging">Automatic Overlay Debugging</a>,
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Up: <a rel="up" accesskey="u" href="Overlays.html#Overlays">Overlays</a>
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<hr>
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</div>
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<h3 class="section">14.4 Overlay Sample Program</h3>
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<p><a name="index-overlay-example-program-964"></a>
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When linking a program which uses overlays, you must place the overlays
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at their load addresses, while relocating them to run at their mapped
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addresses. To do this, you must write a linker script (see <a href="../ld/Overlay-Description.html#Overlay-Description">Overlay Description</a>). Unfortunately,
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since linker scripts are specific to a particular host system, target
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architecture, and target memory layout, this manual cannot provide
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portable sample code demonstrating <span class="sc">gdb</span>'s overlay support.
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<p>However, the <span class="sc">gdb</span> source distribution does contain an overlaid
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program, with linker scripts for a few systems, as part of its test
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suite. The program consists of the following files from
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<samp><span class="file">gdb/testsuite/gdb.base</span></samp>:
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<dl>
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<dt><samp><span class="file">overlays.c</span></samp><dd>The main program file.
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<br><dt><samp><span class="file">ovlymgr.c</span></samp><dd>A simple overlay manager, used by <samp><span class="file">overlays.c</span></samp>.
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<br><dt><samp><span class="file">foo.c</span></samp><dt><samp><span class="file">bar.c</span></samp><dt><samp><span class="file">baz.c</span></samp><dt><samp><span class="file">grbx.c</span></samp><dd>Overlay modules, loaded and used by <samp><span class="file">overlays.c</span></samp>.
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<br><dt><samp><span class="file">d10v.ld</span></samp><dt><samp><span class="file">m32r.ld</span></samp><dd>Linker scripts for linking the test program on the <code>d10v-elf</code>
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and <code>m32r-elf</code> targets.
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</dl>
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<p>You can build the test program using the <code>d10v-elf</code> GCC
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cross-compiler like this:
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<pre class="smallexample"> $ d10v-elf-gcc -g -c overlays.c
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$ d10v-elf-gcc -g -c ovlymgr.c
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$ d10v-elf-gcc -g -c foo.c
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$ d10v-elf-gcc -g -c bar.c
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$ d10v-elf-gcc -g -c baz.c
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$ d10v-elf-gcc -g -c grbx.c
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$ d10v-elf-gcc -g overlays.o ovlymgr.o foo.o bar.o \
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baz.o grbx.o -Wl,-Td10v.ld -o overlays
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</pre>
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<p>The build process is identical for any other architecture, except that
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you must substitute the appropriate compiler and linker script for the
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target system for <code>d10v-elf-gcc</code> and <code>d10v.ld</code>.
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</body></html>
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