Initialize DBCR0 for PPC440 targets

[srikanth krishnakar]

Hello Grant,

Is there any conclusion of the below discussion:

http://www.nabble.com/Question-about-DBCR0-initialization-for-440-td23049044.html

Xilinx target (virtex5) hangs (while running GDBServer & KGDB) without
the DBCR0 initialization.

Can you please comment on this ?


Thanks,
-Srikanth

On Wed, May 20, 2009 at 11:20 AM, srikanth krishnakar
<skrishnakar at gmail.com> 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 !
>
> Thanks,
> Srikanth
>
> On Wed, May 20, 2009 at 5:23 AM, David Gibson
> <david at gibson.dropbear.id.au> wrote:
>> On Tue, May 19, 2009 at 06:38:53PM +0530, srikanth krishnakar wrote:
>>> 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
>> david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
>>                                | _way_ _around_!
>> http://www.ozlabs.org/~dgibson
>>
>
>
>
> --
> "The Good You Do, The Best You GET"
>
> Regards
> Srikanth Krishnakar
> **********************
>



-- 
"The Good You Do, The Best You GET"

Regards
Srikanth Krishnakar
**********************