RTEMS Available -- PowerPC/virtex feedback

Robert S. Grimes rsg at alum.mit.edu
Thu Aug 9 21:38:16 UTC 2007

Chris Caudle wrote:
> On Thu, August 9, 2007 3:14 pm, Joel Sherrill wrote:
>> Exception 7 is a NOFP exception
> More accurately it is "program exception," which is also triggered by
> illegal opcode.  
Hi Chris,

I'm not sure how to relate the "exception N" messages from RTEMS to the 
exceptions listed in the Xilinx PowerPC Reference Guide.  This is just a 
wild guess, but I'm guessing this is the mapping - is this correct?  Do 
you or someone else know what is, if this is wrong?

Exception          Vector Offset   RTEMS ID
Critical Input        0x0100           1
Machine Check         0x0200           2
Data Storage          0x0300           3
Instruction Storage   0x0400           4
External              0x0500           5
Alignment             0x0600           6
Program               0x0700           7
FPU Unavailable       0x0800           8
System Call           0x0c00           ?
APU Unavailable       0x0f20           ?
Prog. Interval Timer  0x1000           ?
Fix Interval Timer    0x1010           ?
Watchdog Timer        0x1020           ?
Data TLB Miss         0x1100           ?
Instruction TLB Miss  0x1200           ?
Debug                 0x2000           ?

If I _did_ guess right, then I don't know what exception 0 is!

> Did the tool chain change between the two RTEMS versions
> in question?
No, exact same tools.
> If the newer version got compiled with an opcode which
> doesn't exist in the 405 core by some mistake it could trigger the same
> exception.
> FP exception seems more likely, but just wanted to throw that out there.
> Might be worth taking a look at the disassembly.
Suppose so, I'll try, but I don't really know PowerPC assembly - yet!  
Suppose it's time to learn...

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