On Thu, Jun 24, 2010 at 9:34 AM, nathan binkert <n...@binkert.org> wrote:
>> if checkpoint arg provided:
>> for each SimObject:
>> if checkpoint has section for this SimObject:
>> call unserialize()
>> else:
>> call unserializeNoData()
>> else:
>> for each SimObject:
>> call initWithoutCheckpoint()
>
> I don't have a major objection to the code, but what if we instead
> added a flags argument to startup?
>
> checkpoint_data = set()
> if checkpoint arg provided:
> for obj in SimObject:
> if checkpoint has section for obj:
> checkpoint_data.add(obj)
> obj.unserialize()
>
> for obj in SimObject:
> obj.startup(checkpoint arg provided, checkpoint_data[obj])
>
> I'm just slightly concerned about adding yet more functions to the
> startup process that could be confusing. It also seems pretty likely
> that a lot of the code in startup() won't care about the status of the
> flags.
In fact the vast majority of the code that's currently in various
startup() functions is code that only gets executed when there was no
checkpoint restored. According to doxygen, the only objects that
override startup are:
- Process, LiveProcess, and ISA-specific subclasses (12 total, almost
entirely non-checkpoint initialization)
- System, X86System, and LinuxX86System (the ones giving me problems,
again almost entirely non-checkpoint initialization)
- AlphaBackdoor and MIPSBackdoor (checkpoint-independent
initialization, could go in init() I think)
- BaseCPU
- Bus
Only the last two really do anything I'd characterize as "startup",
and only BaseCPU seems to use startup() to actually schedule any
events (though Bus::startup() does depend on curTick, so it needs to
come after unserialization).
My inclination right now is to do this:
if checkpoint:
internal.core.unserializeGlobals(checkpoint)
for obj in SimObject: obj.setState(checkpoint)
else:
for obj in SimObject: obj.setState()
for obj in SimObject: obj.startup()
where setState() (w/no arg) is the same as initWithoutCheckpoint()
above (only a nicer name). The default implementation of
SimObject::setState(checkpoint) in C++ is:
void
SimObject::setState(Checkpoint *cp)
{
if (cp && cp->sectionExists(name()))
unserialize(cp, name());
}
So now if someone really wants the "unserializeNoData()" hook (e.g.,
to print the warning we now issue by default) they can override
setState(Checkpoint*) to get it, but by default the current
unserialize() interface still works.
Steve
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