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Re: Debugging question



Peter Dufault wrote:

Can I ask you directly what debugging setup I should setup for the mvme5500, i.e., GDB serial?

AFAIK, there is no support for GDB on this BSP out of the box. In cases Iike yours,
i.e., when hitting an exception you can trace back manually:


a) disassemble the ELF object (powerpc-rtems-objdump -dr <objfile>)
b) work your way through the stack / register dump

With a cross-gdb [powerpc-eabi target] you can do this symbolically, of course,
i.e., gdb will find the source code lines corresponding to the PC addresses on the
stack [list *<pc_address>].


Regarding 'live debugging':

I wrote a GDB stub that can be used on powerpc/shared + derived BSPs. Unfortunately, I had
no time to write documentation yet but the software as such is somewhat working.


Here's what you need:

a) a recent [i.e., yet unreleased] version of 'libbspExt'. This library provides a simple API
to hook/register exception handlers. The GDB stub needs this to register its handler
which intercepts exceptions.


b) rtems-gdb-stub software package. This provides a GDB helper thread implementing
the stub [interpreter of the GDB remote protocol]. Should work on sockets and serial
ports but serial port support is not implemented yet [not hard to do]. This means that
you need a working TCP/IP stack.


The package consists of generic material and architecture specific pieces which are
currently implemented only for PPC/shared and pc386.


c) patch for GDB (small bugfix [i.e. fix is small, implications of the bug are big]
+ support for loadable modules on the target [not an issue if you don't use the cexp shell])


If you want to experiment with this stuff let me know and send you the necessary bits...

HTH
-- Till



I will research these things myself, but if you're willing to answer then I'm willing to ask. I'll be sure to document what I figure out on the mailing list and rtems "wiki".

Thanks,

Peter

Peter Dufault
HD Associates, Inc.