[oc] Volunteer for GPL'd CAD tool

[MoT <Sebastien.Villemot@ens.fr>]

Hi folks !

First I'd like to congratulate you for yor job. Making open hardware is
obviously a great idea and I hope it will have the same success than open
software.

I'm a graduate level student in theoretical computer science ; I also
have good programming experience (asms/C/C++/Java), and some hardware
design experience (though it was not with VHDL, I can learn it).

I've some ideas of things for which I could help, but first I'd like to
let you know about a problem that concerns me.

I feel really frustrated of the fact that it is impossible to do the whole
design of a core under my favourite development plateform, namely
GNU/Linux :) There are some GPL'd VHDL simulation tools (Savant, which
seems almost usable, and FreeHDL which is under heavy development).
However it is impossible to actually produce a netlist, do the placement
and routing phase, and generate the configuration bitstream of my target
FPGA. The only solution to do so is to buy proprietary CAD software and to
run it on Microsoft's proprietary OS.

The main raison for this situation is the fact that FPGA manufacturers do
not provide full technical information about their chips (let me know if
I'm wrong, maybe I'm missing something). For example, Xilinx provide a
"Virtex Series Configuration Architecture User Guide" for their Virtex
chips, which explains parts of the configuration bitstream for logical
units, but there is no information about how to actually configure routing
between CLBs and IOBs.

Of course, not providing these informations is a deliberate choice;
designers wanting to use FPGAs have no other solution than buying the
proprietary CAD software of the chip manufacturer. And in the same state
of mind, manufacturers do not provide any Linux support because it doesn't
seem worth; it is a well known fact that Linux is a closed environment
only used by hackers and mad students :)

Apart from the fact that designers must set up a Windows box, there are
some other negative consequences of this situation. For example, I worked
with computer science researchers who developped a new HDL (it is called
Jazz, available on http://www.cma.ensmp.fr/jazz/). It can describe
synchronous digital circuits, and has some very interesting features not
found in other HDLs. But to actually run a design in a FPGA with this HDL,
we had to do ugly hacks, create our own tools to convert the netlist
produced by jazz to the input format of the xilinx tools. The tool chain
becomes far bigger and more complex than it should be; moreover, the
different tools run on different hardware platforms, which is very
annoying.

Proprietary CAD tools have the usual inconvenients of proprietary
software. They are impossible to debug for the end user, the
interfaces and file formats are not unified, each manufacturer
redesigns its own place and route algorithms... It is obviously a stupid
waste of time and intellectual effort.

So why not try to change this situation ? I suggest that the opencores
project (and maybe other open hardware projects) officially publishes an
open letter intended for FPGAs manufacturer (or individually mails
them), asking them for donating complete specifications of their chip's
configuration bitstream. In return, opencores.org would start a
project of developping a GPL'd CAD tool which would target the chips of
the manufacturer(s) answering this call.

As it would have a modular design, such a tool could have different
frontends, the most important probably being for the AIRE IIR or FIR
format (for integration with Savant and FreeHDL). One could add a frontend
for the Jazz language netlist. Several backends for the different
supported FPGA architectures would be implemented. Of course, if we
obtained sponsoring from a FPGA manufacturer, I would volunteer for this
project.

But one could wonder why FPGA manufacturers would accept this deal. Maybe
am I only dreaming... However the recent decisions of hardware
manufacturers (such as Creative Labs donating GPL'd driver for their
SB Live) can give us some hope, though it is not exactly the same context.
The Open Hardware movement is just at its beginning, but one could imagine
(and it is probably the hope of everyone on this list) that it may become
as important as the Open Software movement from an economical vuepoint. It
could then look very attractive for a FPGA manufacturer to be the
"official" sponsor of this movement, by giving complete specifications of
their chips, and being the main target for cores designed by this
community.

I'm waiting for your thoughts or reactions :)

Keep up the good work !

	MoT