Just a side comment: PCIe is as problematic as the Intel and ARM ISA’s to the hardware industry. Both the patent licensing and the absolute control by an oligopoly driven by Intel makes things a big problem.
If we are going to try to move towards a sea of specialized processing units, we need a far better physical and logical interconnect fabric that is fully “open” in all senses of the world. Licensed free to everybody including startups, not locking you into the ARM or Intel ecosystem for economic control, yet evolvable across technologies.
So please let’s not adopt PCIe because it’s there. It’s a bear trap, brilliantly laid by Intel and controlled by the 1% of the industry.
ChipLink at the physical level could be the RJ45 of specialized processor interconnect. It’s better than PCIe because it has a focus on coherency when you need it (like QPI, which fortunately has not polluted the entire industry with Intel lock-in).
It’s not just the RISCV ISA that matters to folks like me. A fully open interconnect fabric is equally important.