3
\$\begingroup\$

This is a long shot, and may come under fire as not being EE-enough of a question for this site, but what conditions will result in a PowerPC processor (e.g. Freescale 7448) taking a jump to address 0xfff00800? My reading of the family reference manual suggests this is a Floating-Point Unavailable Exception, but in talking to people it's been suggested this is a common place where programs go to die on a bad instruction decode. Assuming that's accurate is there any way to recover what the errant instruction was via poking and prodding with a JTAG debugger?

\$\endgroup\$
1
\$\begingroup\$

I don't know the architecture in question, but from general processor knowledge, could you not examine the stack to find the PC (or equivalent) from when the interrupt was triggered and look at the memory pointed to by that? You woudn't even really need JTAG - you could do it in the interrupt routine.

\$\endgroup\$
1
\$\begingroup\$

Turns out Flash was not mapped correctly through an FPGA in the design and the "instruction" 0xFFFFFFFF was literally being fetched and executed out of flash, resulting in the vector in question. Took a lot of debugging to come to that conclusion.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.