It’s the time of the year when I try to correlate
Mythology with Verification. Yes, festive season is back in India and this is the
time when we celebrate the fact that good prevails over evil. Given the
diversity of Indian culture, there are a variety of mythological stories about
demigods taking over evil. Well for us in the verification domain, it is the
BUG that plays the evil preventing us from achieving first silicon success. While
consumerism of electronic devices worked wonders in increasing the size of business, it
actually forced the ASIC teams to gear up for developing better products in
shrinking schedules. Given that verification is the long pole in achieving this
goal, verification teams need a solution that ensures the functionality on chip
is intact in a time bound fashion. The rising nature of design complexity has
further transformed verification into a diverse problem where a single tool or methodology
is unable to solve it. Clearly a multi pronged approach.... a TRISHOOL is
required!
TRISHOOL is a Sanskrit word meaning 'three spears'. The symbol is polyvalent and is wielded by
the Hindu God Shiva and Goddess Durga. Even the Greek God
of sea – Poseidon
and Neptune – the Roman God of the sea, are known to
carry it. The three points have various meanings and significance. One of the common explanations being
that Lord Shiva uses the Trishool to destroy the three worlds: the physical
world, the world of culture drawn from the past and the world of the mind representing
the processes of sensing and acting. In physical sense, the three spears would
actually be fatal as compared to a single one.
So basically
we need a verification strategy equivalent to a Trishool to confirm that the efforts
converge in rendering a fatal blow to the hidden bugs. The verification tools available
today correlate well with the spears of Trishool and if put together would weed
out bugs in a staged manner moving from IP to SoC verification. So which are
the 3 main tools that should be part of this strategy to nail down the complex
problem we are dealing with today?
Constrained RandomVerification (CRV) is the workhorse for IP verification & reuse of the
efforts at SoC level makes it as the main spear or the central spear of the
verification Trishool strategy. CRV is further complimented by the other two
spears on either side i.e. Formal Verification and Graph based
Verification. The focus of CRV is more at the IP level wherein the design is stressed
under constraints to attack the thought through features (verification plan & coverage) and also hit corner cases or areas not comprehended. As we move
from IP to SoC level, we face two major challenges. One is repetitive code typically
combinational in nature where Formal techniques can prove the functionality
comprehensively and in limited simulation cycles. Second is developing SoC
level scenarios that cover all aspects of SoC and not just integration of IPs. The
third spear or graph based verification comes to rescue at this level where multi
processor integration, use cases, low power scenarios and performance
simulations are enabled with much ease.
Hope this
festive season while we enjoy the food & sweets, the stories and enacts
that we experience around will also given enough food for thought towards a
Trishool strategy for verification.
Happy
Dussehra!!!
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