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From: Tom Hawkins<tom@l...>
Date: Thu May 13 06:37:13 CEST 2004
Subject: [oc] One issue about free hardware
On Wednesday 12 May 2004 02:42 pm, Richard Stallman wrote:
> So
> in my previous post, when I say "open-source", I really mean
> "free software". Your comments would be appreciated.
>
> Ok.
>
> The bigger problem is the complete lack of an free-software
> flow from=20 RTL to implementation. There is simply no GCC
> equivalent for=20 compiling digital logic -- every ASIC and FPGA
> designer is at the=20 mercy of [non-free] tools on the font-end.
> (My biggest pet-peeve is=20 FPGA synthesis. FPGAs have had
> dual-port RAMs for ~7 years now, yet=20 we still can't infer
> dual-port block RAM from HDL. Arggh!)
>
> One hurdle to free-software synthesis and place&route is
> proprietary=20 architectures. The major FPGA vendors refuse to
> disclose the=20 underlying details needed to for a quality PAR tool
> or physical=20 synthesis.
>
> Can people figure that out by studying some FPGAs' design
> structure, or does it change so often that it would be useless?

The architectures are well known. It's the configuration bit stream
and the timing characteristics that are hidden from view. The
proprietary bit stream locks you into to the vendors tools; which are
typically no-cost, but are certainly not free.

>
> But oddly enough the biggest roadblock to free-software EDA
> is=20 ourselves. For some reason or another, there is an apparent
> lack of=20 interest and motivation. Just a few examples:
>
> 1. Every couple of months the topic of free-software tools
> arise. =20 Generates quite a bit of discussion, then dies as
> quickly as it=20 started.
>
> It always takes more than just superficial interest to get
> something to work.
>
> 2. With Confluence under GPL, I have yet to receive a single
> bug=20 report or source code contribution.
>
> What is Confluence, and what does it do?

A functional programming language for digital logic and hard-real-time
software design. The Confluence compiler emits C, HDL, and NuSMV: a
language for formal verification (also GPL).

>
> (I can't see access a web page except by sending mail, and I would
> not get the page contents it until the next batch of mail.)
>
> 3. Icarus Verilog, the foremost free-software Verilog
> implementation,=20 still only has one active developer.
>
> The FSF could put that on our list of projects to recommend people
> contribute to. Would the developer of it like to contact me?
> (If you know how to contact him, could you ask him to?)

I second Bill's assesment of Icarus. Semantically speaking, Verilog
is a pretty ugly language to implement. I applaud Stephen's efforts.

>
> 4. The only semi-successful FPGA packing, placement, and
> routing=20 project haulted activity in March, 2000.
>
> What stopped it?

The authors were acquired by a major FPGA vendor. (Bill, I'm refering
to VPR.)

>
> 5. The one person who came the closest to reverse engineering
> the=20 Virtex bit stream -- the critical step for physical
> synthesis --=20 became frustrated with the lack of support and
> interest from the FPGA=20 community, and finally closed shop on
> 12/24/2003.
>
> What kind of support did he need? Also, who does "FPGA community"
> refer to in this context? (I see multiple possibilities.)

He sited opposition from the vendors, but that is to be expected. He
probably needed moral support more than anything. That, and a free
FPGA architecture.

I was primarily refering to the small firms and consultants-for-hire
that make up the bulk of FPGA designers. Quite a few have a weird
attitude towards free EDA -- it's hard to explain. In short, he
wasn't receiving any recognition from the group that could have
directly benefited in the end.

Promoting Confluence for the last 2 years, I clearly understand his
frustrations. The audience is small, yet the commercial presents of
EDA/FPGA is enormous. The marketing machines that drive
$200K/software sales and $3K/chip sales are unlike any other
industry.

>
> Depending on what he needs, maybe the FSF could provide it,
> if you can put me in touch with him. Neil Franklin (neil at franklin period ch) http://neil.franklin.ch/Projects/VirtexTools/ -- Tom Hawkins Launchbird Design Systems, Inc. Home of the Confluence Logic Design Language http://www.launchbird.com/