Re: Simics & reverse execution

Greg Law
2009-09-08T12:08:28Z

Jakob Engblom wrote:
> [...]
>
> The problem is that different backends have different natural semantics here.
>
> A simulator has a natural semantic of synchronous stop across all processors,
> devices, and everything else going on. A hardware across JTAG is far more
> likely to stop just a few cores and keep the rest running. Hardware with
> recording: ????
>
> That's why an abstract bookmark concept is so appealing: it can hide anything in
> the backend, and let it worry about setting up times on multiple processors,
> multiple machines, or hardware recorders.

Ok, yes, I see what you're getting at here: bookmarks might be more
easily implemented in some targets than some global linear notion of
time.

>
>> Again, you could go a lot further than I'm proposing right now. But
>> that's not to say you need to for this stuff be useful.
>
> Yes, for us, a 64-bit integer count of time would be quite useful as a general
> tool.

Cool - so is the general agreement that a scalar notion of time is a
useful thing to add, even if it's not supported in all reversible
targets? (And bookmarks is an (at least) equally useful notion.)

Greg
--
Greg Law, Undo Software http://undo-software.com/