gdb: Debug Session
20.5.3 Putting it All Together
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In summary, when your program is ready to debug, you must follow these
steps.
1. Make sure you have defined the supporting low-level routines (
What You Must Do for the Stub Bootstrapping.):
'getDebugChar', 'putDebugChar',
'flush_i_cache', 'memset', 'exceptionHandler'.
2. Insert these lines in your program's startup code, before the main
procedure is called:
set_debug_traps();
breakpoint();
On some machines, when a breakpoint trap is raised, the hardware
automatically makes the PC point to the instruction after the
breakpoint. If your machine doesn't do that, you may need to
adjust 'handle_exception' to arrange for it to return to the
instruction after the breakpoint on this first invocation, so that
your program doesn't keep hitting the initial breakpoint instead of
making progress.
3. For the 680x0 stub only, you need to provide a variable called
'exceptionHook'. Normally you just use:
void (*exceptionHook)() = 0;
but if before calling 'set_debug_traps', you set it to point to a
function in your program, that function is called when 'GDB'
continues after stopping on a trap (for example, bus error). The
function indicated by 'exceptionHook' is called with one parameter:
an 'int' which is the exception number.
4. Compile and link together: your program, the GDB debugging stub for
your target architecture, and the supporting subroutines.
5. Make sure you have a serial connection between your target machine
and the GDB host, and identify the serial port on the host.
6. Download your program to your target machine (or get it there by
whatever means the manufacturer provides), and start it.
7. Start GDB on the host, and connect to the target (Connecting
to a Remote Target Connecting.).
Info Catalog
gdb: Bootstrapping
gdb: Remote Stub