On Apr 29, 2008, at 10:24 PM, Paul Mackerras wrote:

Kumar Gala writes:

quoted

quoted

Wouldn't it be better and safer to have the exception prolog for
critical interrupts save SRR0/1 in the stack frame, and have the
prolog for machine checks save SRR0/1 and CSRR0/1 likewise?

If we do this I guess we can use SRR0/1 regardless of which level we
came from.

That's the idea.  I actually thought the booke exception prologs
already did that, but it seems I'm wrong.

What sort of things do you expect critical and machine-check handlers
to be needing to do?

It varies on the parts but remember critical level can be anything  
from watchdog, critical input (equivalent of external input, but at  
the critical level), and debug.  So there is a pretty wide set of  
possibility.

- k