Comment by sweden | Hacker News Reader

Comment by sweden | Hacker News Reader

People like to compare RISC-V to Linux, which I think it is just wrong.

Linux is something that you can download from kernel.org, compile it and bring it up over night. It's a package with a bunch of scripts that compiles a working kernel for your machine. All the work is already done for you.

RISC-V, on the other hand, it is just a document describing an ISA. It is far different from a working implementation.

RISC-V might shine on micro-controllers and on power management control units, since those applications are more simple and more affordable to implement from scratch.

But on high-end applications, it will be no different from ARM's path. Implementing an high performant CPU costs money, someone will have to cater those costs, either by hiring a full team of highly specialized engineers (which will cost a bunch of money) or by licensing to third parties (which will also cost money through licenses or royalties).

You can download a RISC-V core today, "compile" it and run it on an FPGA. You can tweak it or add stuff to it, test on the FPGA and go to custom silicon when ready. Not all designs can be downloaded for free, but some can and there are several you can license already. It's not as simple as software like Linux but it is the hardware equivalent.

As the article (and you) point out, the datacenter and mobile space is already lost to Intel and ARM respectively. The only path forward is through the IoT space. It's the only area where you might need something even smaller than ARM.

ARM Cortex-M is quite likely much smaller and more power efficient than RISC-V will be for the foreseeable future.

If RISC-V is going to go anywhere, it's going to have to start with hobbyists and RaspPi-like devices.

Krste Asanovic in https://www.youtube.com/watch?v=KxuQW8HWBXI shows numbers that the Berkeley Rocket implementation of RISC-V is both faster and has smaller die size than the ARM Cortex-A5 and that the Berkeley BOOM is faster and smaller than the ARM Cortex-A9.

The Cortex-A series are big processors. They're generally used when compute power is more important than power consumption. While it's a promising benchmark, the RISC-V will need to compete with the M-series (and other 8/16 bit cores) to break into the IoT market.

As impressive as that is, I doubt there's much room for RISC-V in Cortex-A's target market (phones, smart TVs, etc etc). I explicitly mentioned Cortex-M.

Reply on news.ycombinator.com