Re: Initialize DBCR0 for PPC440 targets

[David Gibson <david@gibson.dropbear.id.au>]

On Mon, May 25, 2009 at 05:04:35PM +1000, Benjamin Herrenschmidt wrote:
> On Wed, 2009-05-20 at 16:00 +1000, David Gibson wrote:
> > On Wed, May 20, 2009 at 11:20:46AM +0530, srikanth krishnakar wrote:
> > > Hi David,
> > > 
> > > I am not sure how the IDM behaves on few of PPC440 targets which don't
> > > have boot loaders. I have a reference for your question:
> > > 
> > > http://www.nabble.com/Question-about-DBCR0-initialization-for-440-td23049044.html
> > > 
> > > Without this fix (given patch) I am facing problems with GDB, and
> > > further target hangs while running gdbserver !
> > 
> > That doesn't answer my question.  It's not enough to say "this fixes a
> > problem" you need to explain *how* it fixes the problem.
> > 
> > And I don't see why IDM would have any effect on *software*
> > breakpoints.
> 
> No but gdb can use the DABR emulation and single step would be busted
> too. GDB internally heavily uses single step in places you wouldn't
> expect it to :-) Like I think when breaking on main, it sometimes single
> step the whole init process of the executable until it hits it. At least
> I've seen it do that when I was debugging the debug support for 64-bit
> Book3E.

Right, but I believe the kernel does turn on IDM when it turns on
single step, or the DAC event bit.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
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