| > Anyone have some insight into why RISC-V seems to be getting traction? Because its a a change in business model. Its simple, in the past you had to pick a chip vendor and then make your software work on that. So you decide to get MIPS or ARM and then put your software on that. RISC-V is different, you decide on RISC-V and you can start working on that. Then you can decide what vendor you want to get, or go with open source or do it yourself. So in the past it was 'vendor -> isa', no its 'isa -> vendor'. So bunch of guys in a big company lab can simply take an open source chip, throw it on an FPGA, develop the software and tell their manager "We can ship this, we just need to select a vendor for the actual chip". And then after 2 years if the vendor sucks, just switch vendor. If you go to ARM. First there are lawyers and it can take months. Then once your software is on ARM, well now they have you by the balls. RISC-V is free and vendors compete on an open playing field. > Has there not been prior attempts to make an open source cpu? As others have said, its not a CPU. Its an ISA specification. The RISC-V Foundation does not design chips. As the other commenter has explained, there were other open ISA but they all had various technical and historical issues. If you want actual open implementation of those specification, look at Chips Alliance, LowRisc or CORE-V for example. > Is there a lot of skill in making the ISA? Yes. Not for the base ISA, but if you want to have Crypto, Vectors, Atomics and so on and so on, its a huge effort. Yes some students designed the core, but RISC-V is far more then that by now. But the real cost is actually that you have to port an insane amount of software, huge amount of man-hours to port everything and keep up with new extensions. > I assume that there are a reference implementations in VHDL/Verilog and Cadence and good support in compilers. Is this what pushed through, where others failed? There was just demand for something like it. Other efforts had historical issues or technical issues. Once Berkley pushed it, even before the standard, various people started adopting it and it took of like a rocket after that. |