Arm is a dominant force in mobile and embedded processors, but recently we’ve heard more and more about RISC-V open source and royalty-free alternatives, and for example SiFive has launched both application processors / IP with solutions like Linux capable Freedom U540 SoC found in HiFive Unleashed board, as well as RISC-V MCU Cores competing with Arm Cortex-M4 and Cortex-M0+ cores.
There’s certainly a lot of activity around RISC-V, but I have not seen many commercial solutions yet, and the platform needs to mature. However, Arm apparently takes the competition seriously with the company setting up a website – riscv-basics.com – comparing Arm and RISC-V, notably through the infographics below.
Arm recognizes RISC-V has no recurring license fees, but claims those fees are only a small fraction of the total investment required for a commercial processor. The company also questions RISC-V maturity, and at this stage is may be true, but it will eventually improve. The next argument is the risk of fragmentation with RISC-V processor since each implementation can be customized. It’s hard to not laugh at that one, since Arm is the king of fragmentation, which also brings benefits such as flexibility, lower costs, and higher efficiency.
Security in Arm is indeed likely to be better at this stage due to the whole ecosystem around the architecture, although that’s always a complex matter. For example, AFAIK RISC-V processors do not suffer from Sprectre / Meltdown bugs, but some Arm processors do.
Finally, Arm explains re-validation costs can be very high, and since RISC-V instructions set architecture can easily be modified, re-validating the processor and customizing software will be costly. I suppose this argument is valid if you extend/amend the default RISC-V architecture set.