MVME2304 Exception 3

[Joel Sherrill]

Paul D Jines wrote:

> 
> 
> 
> Hello -
> 
>    We are trying to run RTEMS on a MVME2304-0143
> and are experiencing Exception 3 errors.  Any help or
> advice anyone could give would be greatly appreciated.

Isn't exception 3 a protection violation?  If so, then
I would be betting on an access to an invalid address.
My quick perusal of the documentation for a different
PowerPC model hints that it is more likely to be a write
since it could also be to a read only region of memory.

>   Our setup and problem description are:
> 
> - The card is a MVME2304-0143, which, if I am correct, is
>   the same as a MVME2308, a 2307 with twice the memory
>   (128MB). It is the only card in the crate.
> - We are using the MVME2307 BSP, and have configured the
>   card as per the README.MVME2300 and BOOTING files.
> - The exceptions occur while in the routine memset, called
>   from RTEMS_Malloc_Initialize.  The strange thing is that
>   it occurs in both our build of small EPICS applications
>   and in Dr. Straumann's GeSys prebuilt binary (version
>   20030731).

One side-effect of RTEMS_Malloc_Initialize is that is zeroes
all of the heap memory.  I don't recall the exact memory layout
on these BSPs, but this all would leave me to believe that
the probes in the BSP that determine how much RAM you have
are spuriously returning the wrong amount.

Just checked and I think the heap is assigned to the end
of RAM (high addresses) on this BSP.  So an autoprobe of
RAM size failing to give a correct value would definitely
do this.

Till.. any ideas on why this might be happening?  Since they
are using your binaries, you might have to help them turn on
some debugging in the BSP startup.

> - We have tried several snapshots of RTEMS (our current
>   version is 4.6.0pre4 with the prebuilt 3.2.2 gcc, newlib
>   1.11.0-2, and 2.13.2.1-1 binutils).  We have tried 3.2.3
>   and 3.2.1 gcc, but with the same result.
> - The exception 3's occur most of the time, but maybe 10% of
>   the time do NOT occur and run the GeSys application.  It
>   has never succeeded in running the epics applications.
> - Our host platform is RedHat 8.0 Linux on an Intel Pentium.
> 
> Does anyone have any ideas as to what we are doing wrong?


> Thank you for any assistance you can provide....
> 
> - Paul
> 
> 
> 
> 
> Paul Jines
> 
> Center for Advanced Microstructures and Devices
> Louisiana State University
> 


-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
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