mingw/info/gdb/Overlay-Sample-Program.html

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  12 Node:<a name="Overlay%20Sample%20Program">Overlay Sample Program</a>,
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  18 <h3 class="section">Overlay Sample Program</h3>
  19
  20    <p>When linking a program which uses overlays, you must place the overlays
  21 at their load addresses, while relocating them to run at their mapped
  22 addresses.  To do this, you must write a linker script (see <a href="../ld.info/Overlay-Description.html#Overlay%20Description">Overlay Description</a>).  Unfortunately,
  23 since linker scripts are specific to a particular host system, target
  24 architecture, and target memory layout, this manual cannot provide
  25 portable sample code demonstrating GDB's overlay support.
  26
  27    <p>However, the GDB source distribution does contain an overlaid
  28 program, with linker scripts for a few systems, as part of its test
  29 suite.  The program consists of the following files from
  30 <code>gdb/testsuite/gdb.base</code>:
  31
  32      <dl>
  33 <dt><code>overlays.c</code>
  34      <dd>The main program file.
  35 <br><dt><code>ovlymgr.c</code>
  36      <dd>A simple overlay manager, used by <code>overlays.c</code>.
  37 <br><dt><code>foo.c</code>
  38      <dd><dt><code>bar.c</code>
  39      <dd><dt><code>baz.c</code>
  40      <dd><dt><code>grbx.c</code>
  41      <dd>Overlay modules, loaded and used by <code>overlays.c</code>.
  42 <br><dt><code>d10v.ld</code>
  43      <dd><dt><code>m32r.ld</code>
  44      <dd>Linker scripts for linking the test program on the <code>d10v-elf</code>
  45 and <code>m32r-elf</code> targets.
  46 </dl>
  47
  48    <p>You can build the test program using the <code>d10v-elf</code> GCC
  49 cross-compiler like this:
  50
  51 <pre class="example">     $ d10v-elf-gcc -g -c overlays.c
  52      $ d10v-elf-gcc -g -c ovlymgr.c
  53      $ d10v-elf-gcc -g -c foo.c
  54      $ d10v-elf-gcc -g -c bar.c
  55      $ d10v-elf-gcc -g -c baz.c
  56      $ d10v-elf-gcc -g -c grbx.c
  57      $ d10v-elf-gcc -g overlays.o ovlymgr.o foo.o bar.o \
  58                        baz.o grbx.o -Wl,-Td10v.ld -o overlays
  59      </pre>
  60
  61    <p>The build process is identical for any other architecture, except that
  62 you must substitute the appropriate compiler and linker script for the
  63 target system for <code>d10v-elf-gcc</code> and <code>d10v.ld</code>.
  64
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