An open PDK was the last road block for making open silicon chips.
It’s as important as say when Linus introduced an open source kernel with Linux after GNU had bumbling around getting nowhere for years.
A PDK is roughly analogous to what an assembler does for code in the code => compiler => assembler => machine code tool chain. Previously there were open silicon compilers but not open silicon assemblers.
A malicious party could inject all sorts of nastiness into your code if they control the assembler. The same is true for PDK’s. A malicious gate placement in just the wrong spot and your entropy source is massively compromised. Every piece of software runs on silicon - this would allow for the entire stack to be auditable for the first time. It lets you verify your open titan chip in your 2FA token is actually an open titan chip and not some made in China clone with a Bluetooth backdoor and titan badging.
I feared Sky Water gave up on releasing this PDK when an earlier initiative with another entity fell through. Glad to see Google step in and push this over the finish line.
> An open source set of EDA tools is actually the last roadblock.
This is not true. As of last year it is possible to design a complete chip with open source EDA tools and has been demonstrated on RISC-V with the Raven platform [1]. Though this was previously true.
There is debate amongst the community if open foundry tools are essential - with rms surprisingly coming down on the side of “no” with many caveats - but to date there has not been a single chip made with an open source design flow and an open source process technology because while previously there were open source EDA tools there previously were not open source PDK’s. Now there are. Hence the watershed moment.
That design used X-FAB proprietary digital standard cells, I/O cells, analog IP, and SRAM.
Basically, they used XFAB to do the detailed design and extraction of the blocks. And then they assembled the blocks via place and route.
They also didn't push the technology very hard so they could get away with simple static timing analysis. 100MHz in 180nm for a really simple RISC is ridiculously slow--PowerPC chips were 100MHz+ in 500nm.
You will note that for EMIR drop--nothing. For signal integrity--nothing. Extraction and DRC is Magic--that's ... laughable is being nice.
Don't get me wrong, this is a great achievement. Pulling all these pieces together is really difficult.
However, we have been able to do this much for almost a decade+ now. I remember a different European initiative that did similar projects. The difference was that it tried to go after the analog blocks, as well. It failed for lack of accurate extraction.
The whole movement flounders on DRC and extraction. Without those, you cannot do the detailed design and analysis to build the fundamental blocks that you need to make interesting chips.
We've had OpenPDK for some time. Check out the ISCA2020 presentation on OpenROAD[0], they mention that they use OpenPDK but the last piece of the puzzle is an open source standard cell library.
Isn't this more analogous to the GNU toolchain being made available? Maybe then RISC V is the "UNIX standard" of which a "Linux" silicon equivalent will yet come to be? ... maybe PULP or otherwise ...?
An open PDK was the last road block for making open silicon chips.
It’s as important as say when Linus introduced an open source kernel with Linux after GNU had bumbling around getting nowhere for years.
A PDK is roughly analogous to what an assembler does for code in the code => compiler => assembler => machine code tool chain. Previously there were open silicon compilers but not open silicon assemblers.
A malicious party could inject all sorts of nastiness into your code if they control the assembler. The same is true for PDK’s. A malicious gate placement in just the wrong spot and your entropy source is massively compromised. Every piece of software runs on silicon - this would allow for the entire stack to be auditable for the first time. It lets you verify your open titan chip in your 2FA token is actually an open titan chip and not some made in China clone with a Bluetooth backdoor and titan badging.
I feared Sky Water gave up on releasing this PDK when an earlier initiative with another entity fell through. Glad to see Google step in and push this over the finish line.