These days, the majority of new chip designs feature embedded processors and the software content of products is ramping up dramatically. If your verification environment simulates at anything less than around 10 MIPS, then it's of no use for software developers in the context of an edit-compile-run-debug cycle.
This means that traditional software-based solutions involving an instruction set simulator (ISS) are typically way too slow for any level of realistic software development. For a solution to be really useful to the software folks, it needs to allow them to develop and verify everything from the system initialization routines and hardware abstraction layer through the real-time operating system (RTOS) and its associated device drivers, all the way up to the embedded application code itself.
As I reported in my 15 May 2003 column, “A 'vast' move in co-design,” Vast Systems has developed a pure software simulation solution that can be used to realize “virtual platforms” that allow embedded designers to develop software long before the silicon is ready. Vast's claim to fame is that that they have developed a revolutionary modeling technology with a “secret squirrel sauce.”
This allows them to simulate entire SoC systems at an equivalent rate of 25-160 MIPS on a modern, high-end, off-the-shelf PC, which is 100-1000x the performance of a traditional instruction set simulator. Furthermore, Vast's models are not just fast but accurate, because they provide cycle-accurate processor and bus modeling. This means that these models can be used to fully boot an RTOS (Windows CE in under a minute, for example), develop device drivers, and even develop real-time embedded application code.
Vast's two core products are Comet and Meteor. The former, Comet, is used by system architects in the early stages of the design process to create and analyze the virtual platform. This is where one performs architectural evaluation and analyzes performance considerations, such as cache sizing, looking at processor and bus capacity issues, and detecting resource sharing contention and synchronization issues.
Once the virtual platform has been locked down, a Meteor representation of the system is generated. This Meteor representation is subsequently used by the embedded software developers to design and test their code.
A 'vast' improvement
The original release of these tools was pretty impressive, but the lads and lasses at Vast haven't been sitting around twiddling their thumbs, because they've just announced a new version featuring the Comet 5 System Engineering Environment (SEE).
Comet 5 includes a new Virtual Prototype Constructor tool. Once a platform evaluation has been completed, the Virtual Prototype Constructor cuts the task of constructing the platform representation for use by the embedded software developers down from a day to just an hour or so.
Another new utility is the Peripheral Builder, which enables semiconductor and systems engineers to create and modify virtual prototypes of peripheral systems without compromising the performance and accuracy of any models created by the folks at Vast.
And yet another cunning application is the Virtual Prototype Transformer, which allows users to take existing Vast-supplied processor models and experiment by varying L1, L2, and L3 cache sizes, adding and removing instructions, and so forth.
Matching processor performance to bus performance can have a huge impact on the overall performance of the final system. Thus, Comet 5 now includes a really cool technology called the Communication Infrastructure Fabric (CIF) that extends the virtual prototypes from the processors themselves all the way out to the busses and the peripheral devices.
Last, but not least, Comet 5 now supports System C, thereby allowing existing SystemC-based peripheral models to run unchanged in Vast's System Engineering Environment.
All in all this is a very cool solution to an increasingly painful problem, so I have no qualms at all on bestowing an official “Cool Beans” on the guys and gals at Vast in general and on their recent Comet 5 release in particular. Until next time, have a good one!
Clive (Max) Maxfield is president of Techbites Interactive, a marketing consultancy firm specializing in high-tech. Author of Bebop to the Boolean Boogie (An Unconventional Guide to Electronics) and co-author of EDA: Where Electronics Begins, Max was once referred to as a “semiconductor design expert” by someone famous who wasn't prompted, coerced, or remunerated in any way.