Thanks for this discussion. It is apropos to our decision of whether to join and contribute to the SiFive eco system. We are implementing a high performance low power RISC-V core and are considering adopting the SiFive U5 Coreplex as the basis for the chip infrastructure, versus using the Rocket Chip distribution directly. The heart of our product's value rests in a pending patent that leads to its 60 to 1 advantage over Intel based servers. As such the following clause within the SiFive license, regarding patent rights, is a major concern:
" If You
institute patent litigation against any entity (including a
cross-claim or counterclaim in a lawsuit) alleging that the Work
or a Contribution incorporated within the Work constitutes direct
or contributory patent infringement, then any patent licenses
granted to You under this License for that Work shall terminate
as of the date such litigation is filed."
Our reading of this is that it appears to introduce a form of copy-left mechanism, under the following scenario. We manufacture a device from a mixture of sources, one part being Chisel that you have released under Apache, and another part being our own Chisel, which we have not released publicly. Our Chisel code embodies our patents and has been developed clean-slate, and kept private. We synthesize a chip and sell a system that includes the chip.
We are concerned that the above clause may come into play regarding reverse engineering. For example, a competitor reverse engineers our chip, takes our portion, which was not released in any other form, and uses the reverse-engineered source code to manufacture their own chip. When we sue that competitor for relief, then it appears that there may be a possibility that we lose any patent rights granted through your portion of the source, due to the above clause. This may open us up to counter suits, claiming that because we are suing for relief due to infringement of our patents, and our chip as a whole used code released with the above clause, that now we are infringing patents owned by contributors to SiFive's distribution.
The issue hinges on whether the sale of a chip derived from both sources satisfies the conditions for the above clause. Existing case law may not cover this area clearly. The issue is similar to reverse engineering of the compiled form of code, especially given that the license's definition of "Object" form includes "mechanical transformation", which may cover reducing the code to transistor form. The case can be made that the transistors on the chip are equivalent, legally, to the compiled form of code. As such, by selling a chip that contains this "Object" form of SiFive source code, we are de-facto distributing a derived work that carries the above clause.
Has SiFive legal council considered such an argument? If so, could you share the conclusions and any case law they have uncovered to address this?
Obviously, if the above argument holds, then no company can release a chip that contains patented portions, without either losing the right to enforce the patents or else opening themselves to being sued.
Thank you. And thank you for the work SiFive is doing. We hope to contribute back to the project.