NOKIA POINTS TO MODELING For Finnish telecommunications giant Nokia, an ESL flow serves three main goals. "There's more software content in our products than ever, and the software developers can't wait for hardware delivery," says Tommi Mäkeläinen of Nokia's Research Center.
Like most ESL users, Nokia also adopted its ESL methodology to reduce overall product development time. Moreover, the company understands the growing need for a reusable platform that enables scaling of functionality.
In Mäkeläinen's view, "modeling is the cornerstone of the whole thing" where successful deployment of ESL is concerned. "It's fair to say that it flies or doesn't fly with the availability, interoperability and openness of models."
Nokia is an active member of the Open Core Protocol International Partnership (OCP-IP), an organization that promotes standards surrounding automatic generation of bus interfaces for IP. Also, Nokia is investigating more active involvement in IP-standards efforts with OSCI and/or the SPIRIT Consortium.
A long-term goal for Nokia's modeling efforts is to move to an XML-based (Extensible Markup Language) approach in which the metadata (literally, "data about the data") is the key to the model. This would serve to make the models inherently more portable between tools and flows, as well as more manageable and scalable.
"So for a SystemC model, you'd actually have an XML-based description about the model interface, its contents, and other information, and then you could enable generation of the model from that metadata," says Mäkeläinen. "Such a scheme would eliminate requiring different kinds of models for different architectures or compilers."
Nokia's interest in moving toward this direction would tend to explain its exploration of membership in SPIRIT, whose activities center on establishing standards for IP metadata.
For Mäkeläinen, the issues around the lack of standards for IP models are paramount. "It's better that we (IP consumers) address the issues around the IP itself and let the EDA vendors resolve the tool issues, as opposed to trying to dictate to the vendors what kind of features the tools should have."
It's also critical for Mäkeläinen that models retain their equivalence through various levels of abstraction. Nokia is working to build an architectural-exploration environment in which mixed abstraction will work efficiently.
SAMSUNG SEEKS SPEED
As a major global player in consumer products, Samsung Electronics is sorely in need of ESL's over-all benefits. Ever-larger SoCs with shrinking market windows, cost issues, and growing software content have conspired to make ESL a must for the Korean manufacturer.
"We need to overcome the rising cost of design and the accelerating falloff in the price of consumer electronics," says Soo-Kwan Eo, senior vice president at Samsung's SoC R&D Center. "To reduce costs, we have changed our design paradigm by moving to higher levels of abstraction."
Samsung adopted SystemC as its primary ESL design language, although it also uses C++ in its flow. Eo likes SystemC, particularly for behavioral synthesis work and for performance evaluation. In the latter case, Samsung uses cycle-accurate models to gain higher correlation between TLMs and RTL. The problem there is the duplication of effort required to arrive at those cycle-accurate models.
And, says Eo, the SystemC simulations still aren't fast enough. "I urge EDA vendors to enhance simulation speed. For over 20 years, faster simulation has meant sacrificing accuracy. The tradeoff between accuracy and speed may be true, but we have to move up the slope."
In addition to new technology to boost simulation speed, which Eo believes must happen in the simulation kernels themselves, Eo calls for common guidelines for modeling. "The vendors should provide general information about how to model in a way that will increase the tools' performance," says Eo. "Then more users will adopt ESL methodologies."
Samsung, like other ESL adopters, has benefited from the concept of virtual platforms, which the company refers to as its ViP methodology. "We are adding an architectural-level power estimator to our ViP technology," says Eo. Power estimation will eventually be extended to power optimization.
The company plans to further extend its ViP framework to the embedded software area. Samsung's roadmap for the technology includes development of a Platform Explorer, Platform Integrator, and Platform Verifier. Together, these elements will form a single ViP environment for rapid exploration of architectural variants (Fig. 2).
Before RTL design, Samsung's engineers will be able to use the ViP environment for architecture exploration, performance analysis, embedded-software development, platform integration, and functional verification. Eventually, they'll arrive at a "golden" reference for use throughout the development cycle. The types of models used by Samsung in its ViP environment depend on a given simulation run's intent. "If we are trying to simulate functionality, it's better to use C++ models," says Eo. "For architectural exploration, where we have to measure actual clocks, it must be done with SystemC models for cycle accuracy."
In addition to simulation improvements, Eo's wish list for upgrades to his ESL flow includes a library of models for use in power estimation and optimization. Tool interoperability is high on Eo's list as well. He's aware of the efforts of the SPIRIT Consortium in the area of tool integration and IP reuse, but he points out that the organization's efforts at this time are in the RTL domain.
"We have to work together to accelerate the practical availability of interoperable tools," says Eo. "If we accept the EDA vendors' proprietary approaches, we're forced to use many different tools, making the cost unacceptably high."
Eo's last wish-list item is a unified hardware/software co-design and co-verification environment. Samsung is taking this track with its ViP technology.
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