MSVC and DIA

["Gabe Black" <gabebblack at gmail dot com>]

In a couple of other posts I alluded to debugging a target in which I
did not have symbol information.  The target is a custom RTOS running
on an i386 architecture built using different versions of the MSVC
compiler.  I've investigated using Visual Studio to debug the target
and even talked with MS but the amount of work to implement a
"Debugging Engine" to provide this facility is really not worth it.
Furthermore, Microsoft will not allow us to use WinDBG to debug on the
target as well since it isn't a "Windows" target (even though WinDBG
did work for us).

GDB seems like a viable alternative, and all that seems to be missing
is symbol interpretation.  Microsoft provides the Debug Interface
Access SDK (DIA) which I did not find referenced in any of the mailing
lists.  It is an SDK that allows you to get at any of the debug/symbol
information in a PDB even if the format of the PDB changes.  I would
like to add PDB symbol support to GDB.  I am fairly new to GDB but I
have been able to implement the remote stub running on the target
without much trouble.  However the challenge lies in adding the symbol
support.  From what I understand, BFD is where I would need to add the
PDB symbol support.  I didn't find much about it in the gdb online
documentation, both in the user manual and internal documentation.

Does anyone have any pointers or references of documentation/files to
look at to help me get started?  We've tasted the sweetness of using a
source-level debugger and we want more! Am I off my rocker in
attempting this?!

Thanks,
Gabe