Re: remote debugging with m68k-stub

["William A. Gatliff" <bgat at billgatliff dot com>]

Pascal:


Here's a short list of things I usually screw up:

* Is someone setting up the bus state controller and other critical
peripherals properly before you download your program?

* Does the stub put the stack pointer in a useful place for the
application?  Does the application need to move its stack pointer to a
larger memory space durining initialization?

* Is application code accidentally getting placed on the stub or
application stack space?

* Are you downloading the program properly?  If you disassemble memory
after typing 'load' at the gdb prompt, you should see your code.

Immediate halts, in my case, usually signal a problem in the handoff
between the stub and the application during the 'step' and 'continue'
commands.  Focus on those parts of your implementation.

You don't need an "application" to test your stub.  Just use a memory
write command to write the opcode for TRAP #1 (or whatever your stub
will use for the breakpoint opcode) to a known memory location, read
it back to verify that it's there, set the PC to that address, and do
a continue.  You should get an immediate breakpoint exception.

Throw in a few NOP opcodes, and you can test 'stepi' as well.  Once
'continue' and 'stepi' are working, you're usually in pretty good
shape.

If you'd like a second stub implementation to use as a guide, see the
gdbstubs project at http://sourceforge.net/projects/gdbstubs .  It
supports CPU32.


HTH,


b.g.

On Wed, Aug 07, 2002 at 02:54:45PM +0200, Squal wrote:
> Hello!
> 
> I have done all the remote target gdb instructions:
>   - define all the low level routines
>   - insert set_debug_traps(); and breakpoints(); at
>     the beginning of the program
>   - compiling stub and program together
> 
> After that, I downloaded my program and the m68k-stub in the target. 
> My problem is when I start the program in the remote target, the program
> stop and never restart (the halt indicator is set).
> Normally, the program will stop at the breakpoint (TRAP #1) and will
> continue after gdb be connected to the stub but the program seems to 
> be stopped.
> 
> Somebody can help me ?
> 
> Thanks
> 
> Pascal

-- 
Bill Gatliff
bgat@billgatliff.com