gdb: Overlay Sample Program
14.4 Overlay Sample Program
===========================
When linking a program which uses overlays, you must place the overlays
at their load addresses, while relocating them to run at their mapped
addresses. To do this, you must write a linker script (
(ld.info)Overlay Description). Unfortunately, since linker scripts
are specific to a particular host system, target architecture, and
target memory layout, this manual cannot provide portable sample code
demonstrating GDB's overlay support.
However, the GDB source distribution does contain an overlaid
program, with linker scripts for a few systems, as part of its test
suite. The program consists of the following files from
'gdb/testsuite/gdb.base':
'overlays.c'
The main program file.
'ovlymgr.c'
A simple overlay manager, used by 'overlays.c'.
'foo.c'
'bar.c'
'baz.c'
'grbx.c'
Overlay modules, loaded and used by 'overlays.c'.
'd10v.ld'
'm32r.ld'
Linker scripts for linking the test program on the 'd10v-elf' and
'm32r-elf' targets.
You can build the test program using the 'd10v-elf' GCC
cross-compiler like this:
$ d10v-elf-gcc -g -c overlays.c
$ d10v-elf-gcc -g -c ovlymgr.c
$ d10v-elf-gcc -g -c foo.c
$ d10v-elf-gcc -g -c bar.c
$ d10v-elf-gcc -g -c baz.c
$ d10v-elf-gcc -g -c grbx.c
$ d10v-elf-gcc -g overlays.o ovlymgr.o foo.o bar.o \
baz.o grbx.o -Wl,-Td10v.ld -o overlays
The build process is identical for any other architecture, except
that you must substitute the appropriate compiler and linker script for
the target system for 'd10v-elf-gcc' and 'd10v.ld'.
Info Catalog
gdb: Automatic Overlay Debugging
gdb: Overlays