Surely it is because of the open source ecosystem, especially open-source tooling, reaching a critical mass?
From article: “The open-source community developed key tools that are crucial to make RISC-V-based processors ubiquitous, such as chip technology process design kits, design verification suites, implementation tools, and more”
Closed source tooling was available and “smart”, but licensing, cost, and inflexibility were significant roadblocks. Disclaimer: I don’t work in the industry.
I think to really have the conversation we would have to define the terms. Much of the original CAD tooling was open source because it was written at Universities.
Things like: is it enough for one to make any core or does one have to make the "best" core? If it just has to exist that was pretty much always possible. Definitely not the lowest friction way to go. But possible.
It's just over 400 lines of verilog and super easy to follow. The tooling changes that happened in the 90s made that possible.
I experimented making cores that were taped-out in my University, as an undergraduate, in the late 90s. It didn't cost my University even close to 9 figures. It was definitely a lot harder than now but the designs were also a lot more modest. Things, essentially untrained, students can do now would've been unthinkable then.
From article: “The open-source community developed key tools that are crucial to make RISC-V-based processors ubiquitous, such as chip technology process design kits, design verification suites, implementation tools, and more”
Closed source tooling was available and “smart”, but licensing, cost, and inflexibility were significant roadblocks. Disclaimer: I don’t work in the industry.