AMD Ex-Chip Architect, Jim Keller Says He Worked on Zen 1, Zen 2, Zen 3 But K12 ARM CPU Was Cancelled By His Former Employer
The 'Future of Compute' conference was held by the Department of Computer Science and Automation, Indian Institute of Science where Jim Keller gave a brief overview of the various projects he has worked on and the fundamentals of chip design.
Jim states that while he was at AMD, he worked on Zen 1 and laid down the plans to do Zen 2 and Zen 3 which means that Zen 3 could probably be the last Jim Keller design we got from him as the latest Zen 4 and Zen 5 projects could be designed internally by a new team at AMD. During his time at AMD, Jim and his team noticed that the cache design for ARM and x86 CPU was mostly the same among other things such as the execution unit and the only difference between the two processor architectures was the decode unit so they decided to work on a new chip, known to us as K12 that was later canceled by AMD.
It is revealed by Jim Keller that the K12 ARM CPU project was actually canceled after he left the company by certain managers. As he puts it, most managers are scared of changing stuff but because he himself was an architect, he isn't scared of changes like this and the work he did during his time at AMD was 'Fun'.
As for what AMD's K12 was going to be, the ARMv8-A-based CPU was designed to launch alongside the Zen project and was expected to focus on high-frequency and power efficiency environments, aiming at the dense server, embedded, and semi-custom market segments. AMD has since brought various semi-custom server chips based on the Zen core architecture and they are moving into the dense compute segment with their new Zen 4C architecture next year which will debut on the EPYC Bergamo platform. AMD's embedded chips also make use of Zen silicon so it looks like AMD had a really different plan to utilize Zen for its entire computing needs rather than relying on a separate ARM-focused architecture.
"But I'll tell you from my standpoint, when you look at compute solutions, whether it's x86 or ARM or even other areas, that is an area for our focus on investment for us," AMD CFO Devinder Kumar responded to a question about the company's view of competing Arm chips. "We know compute really well. Even ARM, as you referenced, we have a very good relationship with ARM. And we understand that our customers want to work with us with that particular product to deliver the solutions. We stand ready to go ahead and do that even though it's not x86, although we believe x86 is a dominant strength in that area."
With that said, AMD's CFO, Devinder Kumar, has already stated that they are ready to make ARM chips if there's a need and demand for them. AMD is also entering the semi-custom arena where it plans to utilize 3rd party chiplets in the near future so that's also something that might utilize ARM chips but those won't be an entirely in-house design that AMD was making with K12 when Jim was around. Jim also joined Intel back in 2018 and left in 2020 after working on various chip projects & is currently the acting CTO at Tenstorrent.