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.

On Wed, May 20, 2009 at 5:23 AM, David Gibson
[off-list ref] wrote:

quoted

On Tue, May 19, 2009 at 06:38:53PM +0530, srikanth krishnakar wrote:

quoted

Hi,

kernel- 2.6.29
Debug technique: KGDB

The PowerPC kernel does not initialize the PPC440 DBCR0 register. This
prevents the use of software breakpoints in case of internal debug
mode. Looking into head_fsl_booke.S for initialization of DBCR0 is
used by boot-loaders.
It seems head_44x.S lacks this step of DBCR0 register initialization.
So fixing this with initializing the DBCR0 register as shown below :

Subject: [PATCH] powerpc: 44x: Initialize DBCR0 for targets not having
bootloader

The kernel does not initialize the PPC440 DBCR0 register.
This prevents (among other things) the use of software
breakpoints with GDB. The boot loaders probably do initialize
this but few targets run without a boot loader

Um.. how does this prevent the use of software breakpoints with gdb?
The trap instructions still work with IDM==0.

-- 
David Gibson			| I'll have my music baroque, and my code
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