PPC exception 0x320

[Becky Bruce]

Jeanwelly,

I'd really like to help you here, but you still haven't explained  
what you mean by "PPC alarmed exception 0x320".  Since there is no  
such exception that I'm aware of on the 750, I'm trying very hard to  
figure out what you mean, and it's impossible for me to do that  
without more information from you.   I need to know exactly what it  
is that you're seeing in order to help you.  If the kernel is  
printing out a message, please include the *entire message* in your  
email.

Are you getting a message that says "Bad trap at PC: ....."?

A quick mini-tutorial on PPC exceptions:  Whenever hardware detects  
an exception condition, the hardware starts executing at a vector  
location for that particular exception.  On the PPC 750, these  
exception vectors are, for the most part, aligned at multiples of  
0x100.  There is a list of exception vectors and their associated  
causes in Table 4.2 of the User's manual (see below for a URL).  Some  
exceptions are caused by software, and others, like the Decrementer  
Interrupt, are generated by the hardware itself. There is often more  
than one way to cause a particular exception.

For example, a DSI exception can be caused by a miss in the hardware  
page table, or by a load to a direct-store segment, among other  
things.  *All* of these events will result in running the exception  
vector starting at 0x300 because all of these conditions cause a  
DSI.  Although there are multiple causes for DSI, they all go to the  
same vector address.  The system software at that address must use  
methods described in the user's manual to determine what kind of DSI  
exception has occurred so it can handle the fault.

While the hardware detects the exception, it is the job of the system  
software to handle it.  The User's manual for a processor will list  
the events that hardware will detect and cause an exception.  You  
have to look at your system software source code to figure out if  
your operating system supports a given exception.  In Linux, this  
code is mostly in arch/ppc/head.S and arch/ppc/traps.c.

You can get a copy of the 750 User's Manual at:

http://www.freescale.com/files/32bit/doc/ref_manual/MPC750UM.pdf

The exception information is in Chapter 4.

Cheers,
Becky

On May 29, 2006, at 9:22 AM, jeanwelly wrote:

> Hi Becky Bruce,
> Sorry for late response. I got mail traffic...
>
> I encountered the exception 0x320 which caused the PPC card crash.  
> Based on my understanding, I think exception is a HW behaviour, so  
> I guess there maybe exist some reference on all the supported  
> exceptions of some version of PPC. Do you know this?
>
> My system take that exception as an "unknown exception" and crash  
> the card. So, I think the exception is from the PPC CPU, but don't  
> the concrete meanings.
>
> Appreciate your suggestions.
> ---
> Jeanwelly
>
> ----------------------------------------
>
>> Is there some error message you can show me?
>>
>> -B
>>
>> On Apr 25, 2006, at 10:03 AM, jeanwelly wrote:
>>
>>> Hi Becky Bruce,
>>> I'm using PPC 750... Just as you said, 0x300 is for DSI, and I
>>> guess they are a set of exceptions, not just one. And 0x320 is one
>>> of them.
>>> I got a board crash, and PPC alarmed exception 0x320. Could you
>>> show me the mechanism of handling of a special exception not one  
>>> set.
>>> 	
>>>
>>> ======= 2006-04-25 02:53:35 您在来信中写道：=======
>>>
>>>> Could you try to be more specific?  What processor do you have,  
>>>> what
>>>> linux version are you running, and what do you mean exactly when  
>>>> you
>>>> say you "encountered PPC exception 0x320"?  As far as I know, the
>>>> powerpc architecture does not define an exception 0x320.  0x300 is
>>>> usually DSI on classic powerpc parts.  BookE parts handle things
>>>> differently.
>>>>
>>>> Thanks,
>>>> -Becky
>>>>
>>>> On Apr 24, 2006, at 8:51 AM, jeanwelly wrote:
>>>>
>>>>> Hi,
>>>>> I encountered PPC exception 0x320, but don't know what it for. Any
>>>>> one could help me on this?
>>>>> Thanks!
>>>>>  				
>>>>>
>>>>> 　　　　　　　　jeanwelly
>>>>> 　　　　　　　　jeanwelly at 126.com
>>>>> 　　　　　　　　　　2006-04-24
>>>>> _______________________________________________
>>>>> Linuxppc-embedded mailing list
>>>>> Linuxppc-embedded at ozlabs.org
>>>>> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
>>>>
>>>>
>>>> .
>>>
>>> = = = = = = = = = = = = = = = = = = = =
>>> 			
>>>
>>> 　　　　　　　　致
>>> 礼！
>>>
>>> 				
>>> 　　　　　　　　jeanwelly
>>> 　　　　　　　　jeanwelly at 126.com
>>> 　　　　　　　　　　2006-04-25
>>>
>>
>>
>> .
>
> = = = = = = = = = = = = = = = = = = = =
> 			
>
> 　　　　　　　　致
> 礼！
>
> 				
> 　　　　　　　　jeanwelly
> 　　　　　　　　jeanwelly at 126.com
> 　　　　　　　　　　2006-05-29
>