Tim said:
I think I have a good understanding of this issue now. There is an inherent
problem with this top 1GB of address space. It is possible for boards to
overcome it by remapping. This board doesn't though. Personally, I think it
should;
It can't because a remap would place it outside of 4 gig and it can only
address 4 gig.
Remember, we're talking *physical* address space and to physically remap
memory above 4 gig the board would need at least one more address line,
which would mean it could address 8 gig. But it isn't an 8 gig motherboard.
(I'm not sure what's actually 'missing' on the board because the chipset
specs suggest the chipset itself could address 8 gig but 'something' is
apparently missing. The point being adding that 'feature' may not be as
trivial as it seems.)
and I think Intel should make the problem clearer;
I agree with that. The only explanations I can think of off the top of my
head are 1. they didn't really expect folks putting 4 gig in it would be
all that common and/or 2. their primary market is system
builders/manufacturers who are expected to read the detailed documentation.
but it's no big
deal. I raised it here because I wanted to understand it better.
It either supports it or it doesn't,
That depends on what "it" is.
If "it" is being able to run an EM64T processor in 64 bit mode then the
board supports "it."
If "it" is having an address space larger than 4 gig then the board does
not support "it."
Now, the second 'it', being what? a terabyte?, is not going to be 'fully'
implemented no matter what so you *know* there has to be a limit
*somewhere* with *any* board which 'supports' EM64T. It happens to be 4 gig
on this one.
no matter what the marketers say or
don't say.
Seems to me you might want to consider this example a warning that you need
to pay more attention to what they say
I'd have thought a design engineer would understand that
A design engineer understands what he's told to design and, when designing
a motherboard in the 2003-2004 time period, putting in 'support' for things
that don't yet exist isn't necessarily a part of it. And if the spec says
"design a P4 motherboard with 4 gig address space" then that's what he'll
design, if he's smart.
And, btw, I'm not being frivolous about that. One of the biggest problems
design engineers have is folks coming in after it's all said and done
complaining "how come you didn't include X?"
Because it WASn't IN the SPEC!
The second biggest problem is the poor engineer who thought he'd be clever
and include some neat things having to explain why he's wasting resources
on something that WASn't IN the SPEC.
And I tell ya, it's usually a heck of a lot easier to answer number 1 than
it is to explain number 2.
