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cc-licenses - What happens to the GPL in FPGA & VLSI implementations?

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Subject: Development of Creative Commons licenses

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  • From: Jeff Carr <jcarr AT linuxmachines.com>
  • To: licensing AT fsf.org, cc-licenses AT lists.ibiblio.org
  • Cc:
  • Subject: What happens to the GPL in FPGA & VLSI implementations?
  • Date: Fri, 18 Mar 2005 08:09:44 -0800

I wasn't able to find a public thread on this issue. I'd happily read whatever conclusions have already been written. I would also request that a statement be made on http://www.fsf.org/licensing/licenses/

Due to the growing number of cores released under the GPL (opencores.org for example), it's not entirely clear if those cores can be used in VLSI or FPGA designs along with non-free software.

It is not entirely clear if changes to GPL code need to be released when VLSI hardware is manufactured because the actual GPL changes are never passed on to third parties. This is due to the strange way in which the GPL HDL (Hardware Description Language) "code" describes the way in which the hardware works; not the way in which the code is compiled in the normal sense of GPL code. This problem seems similar to what caused the GNU Documentation License to be written.

FPGA manufacturers provide development enviornments that "compile" HDL into a bit stream that can be feed into the chip to control it's circuitry. This HDL code can also be used to manufacture chips (VLSI) that contain this description of the code. Perhaps a way of thinking about this GPL HDL this would be analogous to some gpl code that describes a map between cities. This code can be used to generate a map with lines between the cities. Then then manufacturer can make copies of the maps by etching lines in silicon.

The problems here are compounded because there are not many (or any?) free or open source compiliers for these FPGA parts. So, it's not always clear if some GPL code would be mixed in with not-gpl code.

Some of the people writing these free cores (the PCI design comes to mind) are using the GPL and want it to be used as much as possible. They feel, with similar principles to the free software movement, that the PCI core will be superior if more and more people use it. Eventually better than commercially available cores. I suspect that they would want a license that would allow it to be used with commercial cores on the same chip, but want the changes that are made to the PCI core released under the GPL.

It is important to figure out the legal issues here and, if necessary, draft a license that will solve these issues as soon as possible. There are many people writing and releasing these cores, and if the GPL is found to not adequately protect, or too much restrict the use of the cores, then it gets increasingly difficult for projects with many developers to change the license as more time passes.

I see a need for two licenses with the principles:
1) allows use with non-free code on the same chip
2) doesn't allow use with non-free code on the same chip

Thanks,
Jeff Carr




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