Do you have any examples? Apple Silicon cores took pieces of the pwerficient cores, and everything else I know of either tweaked an official ARM design or started more or less from scratch.
I don't know the details of how much rework they had to do.
As I understand it cavium still sells processors but only directly to hyperscalers.
Ironically Cavium may have gone through the same process with their previous design, but given that they then acquired this one from broadcom, perhaps it didn't go very well! I have no concrete information though.
That is a frustrating pattern in the RISC-V world. Many companies that boast having x wide cores with y SPECint numbers but nothing that has been independently verified.
