Re: GDB --> Parallel Port --> Target??

[Andrew Batchelor <A.C.Batchelor-99@student.lboro.ac.uk>]

On Tue, 2003-10-07 at 17:27, Jim Blandy wrote: 
> Andrew Batchelor <A.C.Batchelor-99@student.lboro.ac.uk> writes:
> 
> > Hello, 
> > 
> > I was wondering how straightforward it would be to write an extension
> > for GDB to use the parallel port to connect to a target instead of the
> > serial port?  (Changing only a few files?  Many files?  Which ones?,
> > etc.)
> > 
> > Now I'm not really very familiar with GDB and before I jump in at the
> > deep end, I was wondering if any of you guys could give me any pointers?
> > At the moment I'm just having a read through the User Manual and the
> > Internals Manual and looking at some of the C files that look like they
> > might be of some help - can any of you guys point me in the right
> > direction?
> > 
> > Any help or advice you could offer would be much appreciated.

Hi Jim, 

Thanks for your reply. 

> If it turns out that doesn't work because the parallel device needs
> special handling, that can be done pretty easily.  
> Someone asked about this regarding USB recently:
> 
> http://sources.redhat.com/ml/insight/2003-q4/msg00016.html

Ah, that all looks more like what I'm after. 

> Oddly enough, it seems like someone was thinking about this at some
> point.  In serial.c:
[.....] 
> But this is just parsing what comes after "target remote".  So "target
> remote lpt" would try to find a serial interface named "parallel".
> But there is no code I could find that registered an interface by that
> name, so the open would fail.

Yeah, I couldn't find anything either. 

Looks like I need to have a stab at writing something myself:

Can I check the flow of things?

1) Create new serial_ops structure pointing to initialise functions,
etc.
2) Then call this serial_add_interface to register the new structure.

3) Add a new case to serial_open in serial.c for argument parsing to
'target remote'.

I may need to do some protocol conversion from the Remote Serial
Protocol to something else.

Could you offer any advice on this?


Andy