Reboot Command Makes kernel to hang (MPC8560)

Ansari ma.harounansari at
Thu Aug 2 16:48:16 EST 2007

Hi Koller & Kumar

Thanks for ur reply.

Is there a way to reset the full chip (MPC8560)  whenever core reset occurs 
(using hardware or software) ??

Haroun Ansari M A

----- Original Message ----- 
From: "Kumar Gala" <galak at>
To: "Clemens Koller" <clemens.koller at>
Cc: "Ansari" <ma.harounansari at>; <linuxppc-embedded at>
Sent: Tuesday, July 31, 2007 7:41 PM
Subject: Re: Reboot Command Makes kernel to hang (MPC8560)

On Jul 31, 2007, at 6:44 AM, Clemens Koller wrote:

> Hi, Ansari!
> Ansari schrieb:
>> Hi Kumar,
>> First of all thanks for ur reply .
>> Even i went through the linux source . And i have observe that the 
>> reboot command used to hard reset the core . I have few doubts can  u 
>> please clarify me.
>> 1. Is there any way to reset the full chip with out using any  external 
>> signal (MPC8560) ? (like any register that can be used  for reseting the 
>> processor)
> It should be the bits RST[1:0] in the Debug Control Register 0  (DBCR0).

This only resets the core on the 8560.

> I didn't find details how the external signals are affected:  HRESET_REQ# 
> and friends.
> The HRESET_REQ# is usually fed back to the CPU's HRESET#.
> So if the HRESET_REQ# gets asserted by writing to above registers  it 
> should really bring
> down the CPU, it's internal as well as it's external components,  which 
> are usually
> connected to a replication of that signal.

This is roughly correct.  The only way on 8560 to generate
HRESET_REQ# is to cause a core watchdog timeout.

> However the existence of cpm2_reset() and a qe_reset() (QuiccEngine?)
> in the code tells me that the above expectations could be wrong.
> Would be nice to have that verified by some hardware guys from 
> freescale...

cpm2_reset/qe_reset are more related to SW than any HW reset.

>> 2. Even same reboot command works fine for MPC8540 Processor ?.
> ...because it doesn't have a cpm ?

That's more luck than anything else.

>> 3. what are the factors that makes ramdisk hangs . When its 
>> uncompressing ?
> Well, side effects ?
> Regards,
> -- 
> Clemens Koller
> __________________________________
> R&D Imaging Devices
> Anagramm GmbH
> Rupert-Mayer-Straße 45/1
> Linhof Werksgelände
> D-81379 München
> Tel.089-741518-50
> Fax 089-741518-19

More information about the Linuxppc-embedded mailing list