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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To do this, you must write a linker script (see <a href="http://sourceware.org/binutils/docs/ld/Overlay-Description.html#Overlay-Description">Overlay 77Description</a> in <cite>Using ld: the GNU linker</cite>). Unfortunately, 78since linker scripts are specific to a particular host system, target 79architecture, and target memory layout, this manual cannot provide 80portable sample code demonstrating <small>GDB</small>’s overlay support. 81</p> 82<p>However, the <small>GDB</small> source distribution does contain an overlaid 83program, with linker scripts for a few systems, as part of its test 84suite. The program consists of the following files from 85<samp>gdb/testsuite/gdb.base</samp>: 86</p> 87<dl compact="compact"> 88<dt><samp>overlays.c</samp></dt> 89<dd><p>The main program file. 90</p></dd> 91<dt><samp>ovlymgr.c</samp></dt> 92<dd><p>A simple overlay manager, used by <samp>overlays.c</samp>. 93</p></dd> 94<dt><samp>foo.c</samp></dt> 95<dt><samp>bar.c</samp></dt> 96<dt><samp>baz.c</samp></dt> 97<dt><samp>grbx.c</samp></dt> 98<dd><p>Overlay modules, loaded and used by <samp>overlays.c</samp>. 99</p></dd> 100<dt><samp>d10v.ld</samp></dt> 101<dt><samp>m32r.ld</samp></dt> 102<dd><p>Linker scripts for linking the test program on the <code>d10v-elf</code> 103and <code>m32r-elf</code> targets. 104</p></dd> 105</dl> 106 107<p>You can build the test program using the <code>d10v-elf</code> GCC 108cross-compiler like this: 109</p> 110<div class="smallexample"> 111<pre class="smallexample">$ d10v-elf-gcc -g -c overlays.c 112$ d10v-elf-gcc -g -c ovlymgr.c 113$ d10v-elf-gcc -g -c foo.c 114$ d10v-elf-gcc -g -c bar.c 115$ d10v-elf-gcc -g -c baz.c 116$ d10v-elf-gcc -g -c grbx.c 117$ d10v-elf-gcc -g overlays.o ovlymgr.o foo.o bar.o \ 118 baz.o grbx.o -Wl,-Td10v.ld -o overlays 119</pre></div> 120 121<p>The build process is identical for any other architecture, except that 122you must substitute the appropriate compiler and linker script for the 123target system for <code>d10v-elf-gcc</code> and <code>d10v.ld</code>. 124</p> 125 126 127 128 129</body> 130</html> 131