( ESNUG 342 Item 5 ) --------------------------------------------- [2/03/00]
From: Vallath Nandakumar <vallath.nandakumar@amd.com>
Subject: Help! Synopsys Is Killing Our Vera Ethernet Transactor Library!
John,
At AMD, we designed the SwitchIT family of ethernet switch chips. Most of
our verification (simulation) we did using Vera. An important part of it
was the Vera Ethernet Transactor Library, or ETL. Even though it was the
first time we used Vera, it was a BIG time-saver for our project, compared
to our prior experience with Verilog testbenches.
When we first looked at Vera ETL, it had no RMII (Reduced Media Independent
Interface) support, and no half-duplex support. Systems Science added these
features for our support. We added to Vera ETL lots of code to support our
proprietary interfaces, with help from Systems Science and Synopsys.
We did waste some time in debugging ETL, particularly the half-duplex code.
Certain other parts of the code, like the tricky Gigabit 10-bit interface,
was completely bug-free. Having the source code helped us a great deal,
since we could fix minor (and major) bugs ourselves. Synopsys usually
wanted test cases, and their response time wasn't always fast enough for
us, so it was useful for us to have the code handy.
Large parts of the testbench remained unchanged for block level and chip
level verification, for RTL and gate, and for simulation with and without
backannotated timing. Having the exact same testbench for all these saved
us a bundle of time, too. Vera 3.13 is not perfect for timing simulation,
since asynchronous drives etc. are a little tricky, but we did bypass
the hurdles. Partly by having Verilog wrappers to do some of the timing
functions.
Synopsys unfortunately no longer supports Vera ETL; instead they are
diverting everyone to SmartModels and other models from their LMC group.
Vera ETL has powerful features for packet checking at output ports, but
the new simulation models don't have these features. They are not offering
source code for the new models. These negatives are not good news for us
right now, having invested quite a bit of time in learning, debugging,
and maintaining Vera ETL.
We plan to continue using Vera, since it is well-suited to our networking
needs. Vera has improved tremendously between 3.13 and 4.x in features.
I would be interested in hearing from other users here on ESNUG who use
Vera in networking applications.
- Vallath Nandakumar
AMD Network Products Division
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