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Comment by kevmo314 | Hacker News Reader

The difficult part is the place and route algorithm, not the bitstream. The proprietary ones already take quite a long time to solve: I regularly have 12-24h runs. Perhaps an open source one could do better? But it's not quite as straightforward as reverse engineering a proprietary bitstream.

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That's why nextpnr exists :)

https://github.com/YosysHQ/nextpnr

As someone actively working on nextpnr support for a fairly new FPGA architecture, it really is amazing that we have something like that in the open source world.

YosysHQ are one of my favorite companies to exist.

Nextpnr and Project X-Ray are amazing projects. Reverse engineering the physical map of, say, a 7-series FPGA is no small feat. However, I wonder if they'll ever be able to really compete with Vivado without getting access to the characterization models for timing. I would love to switch over, but the Fmax of my project routed with nextpnr is less than half of what I get with Vivado.

When I first started doing chip design my boss paid more for tools per year than he paid me ... now days open source tool chains are leaping ahead ... I don't need a boss (or VCs) in order to design chips

I have to admit that I haven't looked too closely into this but my understanding is that place & route is essentially an NP hard optimization problem. Would it be possible to translate this into a SAT problem and solve it with a state of the art SAT solver?

It's surely possible but if it's, for example, 10% slower, that easily eats into execution time and that directly translates into a sense of "maybe it's just worth it to pay the license fee for this year" after just a few 20h place and route runs.

Of course, if it were faster, that would be a huge win for the open source implementation.

Possible but the problem statement is generally way too large to throw into a SAT solver. You can do local problems with SAT though.

Somewhere in reverse-engineering-land is the desire to figure out undocumented hardware blocks. I’m not disagreeing about PNR here.

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