RE: Cadence Goals Comments - 2

From: Bojsen, Per <bojsen_at_.....>
Date: Fri Apr 01 2005 - 11:13:29 PST
> When coming out of reset ( a likely case ), the simulation-only run of
> a model may propagate Xs and U's such that the simulation will fail
> whereas on an emulator, these may default to 0's and 1's and allow the
> simulation to pass. That is one common scenario.

Right, that was one case I was thinking of.

> Do we need to address this? It could get a little complicated.

Yes, it could.  That's why I wanted to qualify your original statement
to say that the goal should be to make it possible to write transactors
that can run without change in both simulation and emulation rather than
what I thought was a stronger statement.

> I've always felt it's important to address the simulation-only mode
> in SCEMI. The question is; how deep do we go? 

Big question.  But when you say `simulation-only mode' you're not just
talking about simulating SCE-MI transactors as they are written today.
The problem is solved if you're willing to write your transactors using
synthesizable RTL code and qualify your code on all the platforms you
want to use.  But I'm sensing you actually define `simulation-only
mode' as something more than that.

> No, that is not what I meant at all. What I said was, in order to be
> able to run in simulation-only mode, the "whole" transactor model (sw
> side and hw side) ought to consist of LRM compliant HDL (on the hw side)
> and C/C++ (on the SW side).

Ok, that's what I thought, but I had to make sure.  It was not obvious
to me.  So all you're really stating is that SCE-MI shall not require
language extensions on neither side, right?  Or am I still missing
something?

> Hmm, we've always used the term "transactor" for the whole tool
> -- sw side and hw side.

At Zaiq we used to use `transactor' in the same sense as SCE-MI, but
over the years there has been a trend to include portions of the
software side, i.e., the `proxy model' in what is considered the
transactor.  We have been getting away with not doing this because
we have standardized the interface to the transactors at a higher
level and use a common library to implement this interface.  Hence,
the portion of the proxy model that is unique to each transactor
is extremely thin, and in fact non-existent in many cases.

> When someone calls me and asks "do you have a transactor for the
> XYZ bus?" if I were to say, "yes, and I also have a proxy model"
> that would cause a lot of unnecessary confusion.

Actually, that is not so crazy as it might sound because the software
side is dependent on the language environment being used.

> But you're right, the spec defines it to be the hw side only. I
> guess I just don't like the term "BFM", but I'll drop this point
> until/unless we take up writing a new glossary for the new spec.

I doubt it is worth our time to change the definitions in the glossary
at least at this point.  But it is a common point of confusion so
we should consider it.

Per

-- 
Per Bojsen                                Email: <bojsen@zaiqtech.com>
Zaiq Technologies, Inc.                   WWW:   http://www.zaiqtech.com
78 Dragon Ct.                             Tel:   781 721 8229
Woburn, MA 01801                          Fax:   781 932 7488
Received on Fri Apr 1 11:13:10 2005

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