I've been following this closely and put a fair bit of time into porting a CAD tool to this new process.
I won't be submitting a design at this time.
The Google sponsorship comes with a lot of strings attached. That's okay, "he who pays the piper calls the tune". Unfortunately unlike MOSIS and IMEC there is no option to pay your own way in order to drop the strings. Based on MPW charges for other foundries through MOSIS+IMEC the Google subsidy is worth around $5k-$10k per submission [1]. But there isn't any option to pay that amount yourself.
One of the most problematic "strings" is the fact that you do NOT get a reserved booking. This is a big issue because for anything more serious than an undergrad-level "hey I threw a pile of verilog at the place+route tool" the designer time invested will be worth a lot more than $5k-$10k. But they expect you to invest this with zero guarantee of getting it fabbed, which means that investment can easily get dumped in the trash bin. Project selection is "random" which is sort of just another way of saying "unaccountable".
The other problematic "string" is the Management Engine Padframe [2] they wrap around your design. You can't touch it or change any part of it, and it sits beteween your design and every single pad that faces the outside world. This sort of Management Engine garbage is exactly what we need open silicon in order to avoid. Yet here Google and Skywater and eFabless are sticking it back into the mix. Oh, by the way, this makes "OpenMPW" totally unusable for any RF work, or any design that needs an analog input.
Kinda miffed about all this, especially that they sprung the "Management Padframe" on us two weeks before the tapeout deadline. That screams to me "this is not for serious designs, please undergrads only thanks".
[1] https://europractice-ic.com/schedules-prices/
[2] https://github.com/efabless/caravel
PS, It's also intensely irritating that you're forced to create a LinkedIn account and must use your LinkedIn account to log in to the MPW upload site. That is some amateur-grade personal data harvesting there. Serious MPW providers, like MOSIS who have been doing this for 25 years, give you their PGP key for you to encrypt the GDS with and don't put you at the mercy of deplatforming by LinkedIn for whatever lame reason LinkedIn cooked up this week.
I agree the submission process has been somewhat chaotic, but I don't think it has been exceedingly so. The fact that this was gonna be an alpha test of new technology was clear from the start. Taping out with a modern PDK and open source tools just hasn't been done before. Also, the caravel requirement has been known for at least three months. True the design wasn't done yet and the details were sparse, but saying it was added two weeks before the tapeout deadline is disingenuous when it was announced at the start of the program. As for not taking your money to get your own tapeout, I'm sure they'll be most happy to do so once they've worked out the kinks, which is exactly what they're using the shuttle runs for.
(Not affiliated with the project in any way, just watching closely out of professional interest).
That is simply false. Maybe known to insiders at eFabless.
Seriously where do you see any public mention of "caravel" three months ago? There's absolutely nothing about it on the mailing lists [1] [2].
> it was announced at the start of the program
Where?
I heard about this in late July and have been following this very closely since they posted the design rules in early September. I've probably read through the DRC rule document more closely than anybody outside of Google/Skywater/eFabless. Two weeks ago there was nothing anywhere in any of that about having to use their "Caravel" management padframe.
As of 15-Sep (git commit 107103f922db43408f59a1540cd4bd3737b30172) the text "caravel" does not appear anywhere in the PDK [3]. I checked with:
$ find . -not -type d -exec grep -Hi caravel {} \;
[1] https://groups.google.com/d/forum/skywater-pdk-announce