Yes, Rocket Chip generator. From Berkeley, now managed by The CHIPS Alliance. SiFive still contributes improvements to it, I think. K210 seems to be exactly pr

Yes, Rocket Chip generator. From Berkeley, now managed by The CHIPS Alliance. SiFive still contributes improvements to it, I think. K210 seems to be exactly pre May 2017 (when priv 1.10 was published) Rocket plus their "AI" stuff. SiFive's FE310 in HiFive1, Sparkfun RED-V and others is also basically pure Rocket. It's from 2016, but is basically only User mode instructions plus a couple of CSRs, so priv arch is irrelevant. SiFive's FU540 quad core 1.5 GHz Linux chip (HiFive Unleashed) is almost pure Rocket with ethernet and DRR IP added and some GPIO, SPI, UART etc. It came out in early 2018 and implements priv arch 1.10,so is still compatible with the eventual ratified spec. Even the SiFive U74 in the VisionFive 2, Star64, Milk-V Mars etc is mostly Rocket, with the pipeline expanded to dual-issue. But the ALU, MMU, FPU, instruction decoder etc is essentially Rocket. You could certainly run a pretty nice Linux-like OS in 8 MB on the K210. xv6 is interesting, and runs on it, but I think doesn't use the MMU. Maybe a mid-90s Linux could be ported. From sometime just after ISAs other than x86 started to be supported. Linus originally developed Linux on a 4 MB machine, and it could boot with 2 MB. I have a MaixDuino. And a Maix Amigo. They don't get much love now with all the new stuff coming out :-(