Experts At The Table: ESL Standards
Friday, November 6th, 2009By Ed Sperling
System-Level Design sat down with Frank Schirrmeister, director of product development in Synopsys’ solutions group; Ghislain Kaiser CEO of DOCEA Power: John Sanguinetti, CTO at Forte Design Systems; Vincent Perrier, Cofluent Design co-founder and director of products and marketing.
SLD: Where do models fit into the standards world?
Perrier: Models are becoming the central things that engineers work with. But it goes much further than just translating the code into gates on the chip. There are power models, performance models and virtual platform models. It can be a custom-based approach by aggregating multiple IP blocks or a top-down approach starting from a functional or architectural description or a power model. These are very different approaches for designs.
Sanguinetti: There’s a lot more impetus to settle on a standard when you have models that people want to use from different sources.
Perrier: The whole point of models in ESL is to make sure those models work together.
Sanguinetti: Right, but those models are coming from different places.
Perrier: There also are a lot of them. Today you cannot find one model to represent all the different facets of a design. If you want a full picture of a system, you need to get all those models together, combine them, and simulate them so you can make your architectural tradeoff decisions on the basis of power. Power is becoming as important as everything.
Kaiser: The first goal for a system now is to improve interoperability because of all the complexity. You need to adapt that for every domain. That’s the case with power and timing.
SLD: Whenever a company turns over technology to a standards group, they have a jump on everyone else because they know the technology better. Is that window shrinking or growing?
Sanguinetti: It depends on the technology. If you need a standard to make models interoperate, no one has a big advantage.
Schirrmeister: It’s not a complexity issue. That’s solved according to how a design process is structured. The standards support that structure. If you look at the next big systems on chip, you have blocks in there and you need to be able to deal with those blocks. That includes development of the blocks, which is where high-level synthesis comes in. You need standards for a language that you can use to synthesize. You need to be able to deal with re-use of those blocks. That’s where SPIRIT comes in. You characterize those blocks and give them power formats. And then you need to integrate those blocks into the full chip. So you need the higher-level model for verification and for performance analysis, which is where TLM simulation comes in. It’s not that complexity influences the window. It’s that the complexity changes the design process, and for the different components you have individual windows on how to deal with this.
SLD: How far along are we with this?
Schirrmeister: With TLM 2.0, it’s like we’ve standardized on the VCR with VHS, but all the remotes don’t interoperate because everyone has different controls. That’s the next thing we’re trying to standardize on—the configuration and control of those TLM models. Those standards grow and build on each other.
Perrier: The EDA industry has a lot to learn from the software industry in this domain. They are way ahead of us in this area because they have been dealing with interoperability for a long time.
Schirrmeister: They have been dealing with this problem since 1968, and the last time I checked they still haven’t figured it out. But there is at least some interoperability in the software world. I assume you’re talking about UML (Unified Modeling Language).
Perrier: UML is one. There are also meta-model techniques. IP-XACT is an XML-based standard. In the software world you have Ecore, which an Eclipse implementation of the [Object Management Group] standard.
SLD: The software world has its own issues that have been going on for decades, most notably in operating systems, interfaces and parallelization.
Schirrmeister: And I’m not sure what we’ll actually learn from the software side. In the software world you have a company like Microsoft saying, ‘Here it is,’ and everyone has to deal with it. The same was true with UML for awhile, where Rational and Telelogic were dominating the market.
SLD: But isn’t this still a top-down definition?
Schirrmeister: Everything does need to fit into a top-down model, but the work is being done in two directions. The problem is that it’s like digging a tunnel from both sides where you don’t meet in the middle. You’re pushing down with high-levels of abstraction and UML is tunneling up, but they don’t quite meet. Now we are trying to figure out ways to see how UML will fit.
Kaiser: This is the challenge of the ESL domain. But if a new standard appears, there is a question of whether it will survive because it has to join these two worlds, from UML to hardware constraints.
Schirrmeister: When you talk about standardization, it’s always about restriction. You have this big item about what UML covers, and conceivably you can develop a profile of UML that may fit into something that will be able to synthesize down to RTL. That’s like a UML for hardware profiler. If this is SystemC, there is a subset that is synthesizable. The same happened with Verilog in the past.
Perrier: The software industry calls this domain-specific languages.
SLD: So is UML the answer?
Kaiser: I’m not sure that today UML can respond to the hardware constraints. We may have to modify UML because it was not created for hardware.
Schirrmeister: A standard never does something for itself. You always have to have a user need. Hardware developers are not that concerned if something is UML compliant. They have a very specific need to get to a virtualized model of the embedded hardware they’re developing as fast as possible so they can start software development. If my solution happens to be that I have a technology that takes UML, restrains it to a domain-specific subset and then allows a fast implementation, they will happily adopt it because it serves their need. But they won’t do it because it’s UML.
Sanguinetti: That’s a very relevant point to this discussion. Back when Synapse was working on a precursor to SystemC, I looked at UML. It was too far removed from the kinds of problems we were looking at.
Schirrmeister: I think we are getting closer. It’s just a question of how fast is the train going.




