RE: [vhdl-200x] Requirements to do verification

Ken,

UVM cannot be implemented in VHDL today. At best, an interface from UVM TB to a VHDL design could be defined. However, changes to VHDL are not required in order for VHDL users to benefit from SV and UVM. All vendors support SV and VHDL mixed simulations. Languages are tools. VHDL designers have the same verification tools available to them as Verilog or SystemVerilog designers.

I disagree that VHDL must be enhanced in order to support UVM. There are no technical barriers preventing VHDL users from using UVM today; they only need be willing to use SV as a language for verification. Providing UVM capabilities in VHDL does not advance technology for verification. It is solving the same problems for the 9th time (e, Vera, Superlog, SystemVerilog, AVM, RVM, OVM, UVM). If the effort to do so was equivalent to painting the handle of a screwdriver a different color, there would be no discussion. However, the reality is that the effort required will be many man-years of effort in the standards committee followed by at least 10x that level of effort for EACH vendor to implement & support it. And, at the end of the day, VHDL users will be able to do the same thing that they could do today, just in a different syntax.

There are real new and emerging verification challenges that need to be addressed. Throwing such a massive amount of resources at forging (not inventing as there is no new technology) the 9th version of the same wheel is an irresponsible waste of resources.

The future of VHDL is determined by the market (the aggregate of decisions made by individuals and individual corporations/entities). Harry Foster has been reporting on the Mentor's blog the results of our blind survey of the verification market. In that survey, it is very clear that all languages are on the decline except SystemVerilog which is being adopted at an unprecedented rate and SystemC (as well as C/C++) which are relatively stable in usage. I reported the preliminary (North America only) data to this email list previously. Here's the world-wide data (languages used in verification):

VHDL: 27% in 2007, 21% in 2010, 16% projected this year
Verilog: 68%, 53%, 47%
Vera: 11%, 8%, 3%
SystemC: 17%, 16%, 19%
SystemVerilog: 24%, 60%, 74%
e: 16%, 15%, 11%
C/C++: 30%, 35% and 32%
Other: 5%, 3%, 2%

I have already pointed out the question of market timing/window. SV incubated for years in Accellera (5-7 years) before emerging as a viable standard. And, that was with the benefit of a precursor to use as the foundation (Superlog). My company must have 100+ man-years in building and maintaining SV tooling and the AVM/OVM/UVM methodologies.

To answer your question: The purpose of specifying new language features is to provide value that addresses market (user) needs. The purpose of a business undertaking any effort to support language standardization efforts and the consequential R&D and marketing effort to create products based on that standard is the ability to earn a return on their investment. If it were your millions of $'s to spend, could you justify spending it on VHDL language changes that address a declining niche in the market WITHOUT providing any compelling value over existing solutions available to that market? NOTE: e and SV already have significant footholds in the VHDL market so that 16% will continue to decline.

Or would you look to invest that money solving problems that have yet to be solved that could give you competitive advantage and target a larger market (if the problems have yet to be solved, you have 100% of the target market available)?

It is not an unknown effort to add these capabilities to a new language. We know the cost will be very high. Several man-years over several years is not an exaggeration.

This group is self-selecting and they have a lot of passion for VHDL. I entered the EDA industry via VHDL (I worked at Intermetrics which defined the language). I chaired the 1076 group for ~4 years. However, if I attempt to evade reality and try to live in a fantasy world, I will get fired because I will not be defining solutions that the market needs AND my employer can make money delivering (aka, I will be a failure). Therefore, I cannot allow my sentimental attachment to VHDL distort the objective reality.

If I were an unemployed verification engineer who saw the above survey data, I would be doing everything possible to learn SV and UVM. After all, you are your own businessman. There is a market that you are targeting. Are you offering value that employers want? 3 out of 4 employers want SV/UVM verification skills. About 1 in 3 to 5 want SystemC and/or C/C++. Less than 1 in 5 (and declining) are looking for VHDL verification skills. You would be hard pressed to find a more compelling set of data related to career decisions.

-Steve Bailey

-----Original Message-----
From: owner-vhdl-200x@eda.org [mailto:owner-vhdl-200x@eda.org] On Behalf Of Ken Campbell
Sent: Friday, April 22, 2011 5:10 PM
To: vhdl-200x@eda.org
Subject: RE: [vhdl-200x] Requirements to do verification

Steve,

Correct me if I am wrong, but the UVM method is based on a library written
in SystemVerolog. UVM is a product of 5 or more years of practical use.
It is a collaboration of several methodologies implemented with an OOP,
SystemVerolog. I would expect someone to create a C++ or SystemC version
of UVM eventually.

But the way VHDL is today, there is not much chance of making a
verification environment that looks and feels like a UVM SystemVerolog
environment. Not in an employers eyes anyway, I personally can derive
similarities, but it is not OOP.

The extensions being considered to VHDL, like those defined in White paper
by Peter Ashenden, I would hope would enable a library to be created that
could be based on UVM. Though this may be some time in the future, and
UVM may change, the language extensions should be made so that VHDL can
continue provide the facilities users need or think they need. Is it the
purpose of specifying new language enhancements to sway usage? What is
considered the future of VHDL as a language? Is that determined by user
base, the tool vendors or the standards community?

I think there is an advantage to building on market success, and SV has
been successful. VHDL seems to be lagging other languages when it comes
to OOP. I can understand this as, thankfully, as VHDL is a strongly typed
language. Waiting to put OOP capabilities into VHDL will not benefit
anyone. The implementation of OOP in languages is not new, so after a
standard is created, it should not be a huge unknown effort to implement
in tools. VHDL has a huge user base, I am sure OOP additions would be
adopted and used as soon as they became available. I would think that
users would create the UVM library for VHDL, there are many that like
VHDL.

I have looked over the UVM Class Reference Manual 1.0 and really do not
see why things have to be so complicated. There must be some reason for
it all or it would not be so successful.

So I guess what I am suggesting is that VHDL be specified to enable what
ever the methodology of the day is, whether that be common or special, to
be implemented using modern techniques.

I hope that answered your questions.

Ken
> Ken,
>
> Sounds like you have identified what the (job) market needs.
>
> What's the smart thing to do? Create a product that the market needs?
>
> Or convince the market that it doesn't need what it thinks it needs,
> instead it needs something else? If so, what does that something else
> offer that gives it significantly more value than what the market knows it
> requires?
>
> And, consider market windows. Will your superior offering gain market
> acceptance if it is delivered 5 years from now? Will the inertial
> barriers to entry be too great by then or will the creator of that
> speculative product go bankrupt first?
>
> -Steve Bailey
>
> -----Original Message-----
> From: owner-vhdl-200x@eda.org [mailto:owner-vhdl-200x@eda.org] On Behalf
> Of Ken Campbell
> Sent: Friday, April 22, 2011 12:37 PM
> To: vhdl-200x@eda.org
> Subject: Re: [vhdl-200x] Requirements to do verification
>
> Hello everyone,
> As an answer to the question.
> I think the additions to VHDL should enable the implementation of a "look
> and feel" of UVM. Initially the target should be the objects that provide
> the most value to a verification environment. Like some kind of subset of
> UVM that would enable the most important verification tasks to be
> automated, basic building blocks and interfacing...
>
> The reason I say this is because there is a wave of SV usage. I currently
> can not get employed because I do not have experience with any SV methods,
> but have been doing verification for 15 years now. I got left behind
> using a VHDL test bench system I published on OpenCores. Now after 3
> months, at least 10 ASIC/FPGA verification jobs have gone by because of my
> lack of specific verification tool methods / language.
>
> So, to improve the chances of cross employment and standardization for the
> future of verification people, I recommend a UVM methods implementation as
> a target for VHDL language enhancements.
>
> As Jim said, VHDL is very capable and very much alive. I have recently
> started a blog describing how to best use the VHDL test bench package I
> published. This has increased the downloads from 1-3 per day to 4-7. The
> blog is getting more attention than I thought it would and for me that is
> evidence that VHDL is very much alive.
>
> Is this the kind of input you were looking for?
>
> Regards,
> Ken Campbell
>
>
>> All,
>> If we are to make VHDL a viable verification language,
>> what features do we require?
>>
>> I am thinking the main ones are functional coverage,
>> randomization, data structures (ie: scoreboards,
>> memories, fifos, ...) and interfaces.
>>
>> While I realize some have expressed concern about a language's
>> ability to be suited for both design (RTL and above) and
>> verification, I am not sure I agree. I think a frugal
>> implementation of all of the above is possible.
>>
>> The more I work with VHDL the more I am impressed by the
>> capability.
>>
>> Best,
>> Jim
>> --
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> Jim Lewis
>> Director of Training mailto:Jim@SynthWorks.com
>> SynthWorks Design Inc. http://www.SynthWorks.com
>> 1-503-590-4787
>>
>> Expert VHDL Training for Hardware Design and Verification
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> --
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