> Thinking about it now, it is clear that journaling only makes sense
> for something that is internally self consistent - does not need any
> reference to anything outside itself.
Or when it is necessary to maintain consistency with the real universe, as when remembering the fact that you have already dispensed cash at an ATM machine...
> Just a question about the checkpointing:
> Is there a way to ask for a checkpoint - eg when the machine is going to
be
> shut down/
> suspended. I assume these keys would be closely held.
There is, and they are. In fact, in one of the early EROS designs the periodic checkpoint was accomplished by having a dedicated user-level program invoke the checkpoint capability periodically. The current kernel is more flexible than the KeyKOS kernel in allowing in-kernel processes, and I ended up moving this function into the kernel proper.
shap