Mark,

I have tried this before and this doesn't work.
Execution flow never arrives to "2:".

All the other values are extra info I have collected.
But problem was isolated using breakpoints to avoid
stepping influence.

Best regards,

Alex

Citando Mark Chambers [off-list ref]:

RFI = Return From Interrupt.  In normal usage the current
address is copied into SRR0 when an exception occurs so
the processor will return to that point with an RFI.  So this
code is 'faking out' the RFI instruction to return to 2:

Are you maybe trying to trace through this code?  If so,
and depending on your debugger, you may not be able to.
If your debugger uses trace or some other exception to do
single step, once you get past mtspr SRR0,r4 the single
step exception will overwrite the correct SRR0.  You
can see if this is the case by only tracing to mtspr SRR0,r4
and then putting a breakpoint at 2:

Good luck,
Mark Chambers