Re: support for BookE hardware debug features

[Thiago Jung Bauermann <bauerman at br dot ibm dot com>]

Em Seg, 2009-05-25 Ãs 16:19 -0300, SÃrgio Durigan JÃnior escreveu:
> On Sun, 2009-05-24 at 16:38 -0300, Thiago Jung Bauermann wrote:
> 
> > I implemented a "watch-range" command, which takes a start address (or
> > expression which evaluates to an address) and an end address (or
> > expression). Not sure if I'll keep it that way or change. Didn't think
> > much about it yet.
> 
> Just to complement (I don't know if it's worth mentioning, but
> anyway...) it seems we may have found a little bug regarding
> watchpoint's expression evaluation.  Basically, the problem was
> occurring when GDB tried to see if a block of memory changed in order to
> determine whether it should trigger the watchpoint.  GDB was basically
> comparing the address of this memory region, and not the content itself,
> which made it impossible to trigger the watchpoint.

Indeed. I was meaning to submit the fix as a separate patch, but I
forgot. Will regression test it and submit the fix ASAP.

> > We are just starting to work on the DVC (conditioned hw watchpoint), but
> > for now I'm inclined to use it automagically for simple expressions with
> > just one == or != operator. We're taking into account Joel's comments
> > and suggestions on this. Thanks Joel for your input!
> 
> That is what I was thinking, too.  I don't know if it's possible to use
> the DVC registers for more complex expressions, do you?

I think not, but I may be wrong. As we get more familiar with the
hardware feature, we'll see.
-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center