The real reason RISC-V is succeeding, relative to ARM:

If you make your own CPU

- With ARM, You have to pay ARM for ISA license (after a several months long negotiation), and you cannot license your CPU design to anyone, as ARM has the exclusive right to do that with their designs.

- With RISC-V, you get a free ISA license, and you can license your CPU design to others.

If you do not make your own CPU

- With ARM, you can (after a several months long negotiation) license one of the few designs ARM has available. There's no other vendors that can offer you ARM CPU designs.

- With RISC-V, right now, you can license any among hundreds of options available, from tens of vendors. The licensing process is usually very short and straightforward. Alternatively, there are some open hardware designs. You can get commercial support for some of them.

Frankly, unless ARM does radically change their business model, I do not expect them to survive.

Their business model was to be sold to NVIDIA, but that didn't work out.

Anyway, that's all well good, but - does anyone end up making decent RISC-V processors that could replace a desktop CPU, or a RPi CPU, or something weaker but not in a small niche? Or is this still a vision for the future?

My take is that RISC-V is not that great of an architecture and might never compete at the high end. (e.g displace ARM, Intel, POWER, etc.)

On the other hand there is a vast market for low-end CPUs that have specializations to be disk controllers and things like that. If the ISA and all the IP required to make specialized devices is free and particularly if there is a culture in which it is easy to learn how to do that then RISC-V will have a special place.

My next spatial computing project is going to be RP 2040 based mostly because I have the parts in stock (other projects are blocked because of supply chain issues) but I am really an AVR8 fanatic and the only path forward I see to higher performance AVR8 systems is a soft core running on an FPGA where very hard tasks (vision? comms?) get offloaded to the FPGA and that can be a very appealing architecture where somebody might prefer RISC-V particularly if the tooling and accelerator integration are there.)

> might never compete at the high end. (e.g displace ARM, Intel, POWER, etc.)

It might also be successful, even in that segment. The RISC-V ISA was specifically designed to scale up (e.g. to OOO and vector processors) while still being very simple, especially at the low-end - a basic RV32E is really comparable in complexity with many real-world 8- and 16-bit chips.

But, the similarly minimal Arm Cortex M0 is, drumroll, 12k gates.

Not saying this means Arm is better than RISC-V, such a small difference can probably be explained by some microarchitectural feature or lack of it. Just that you can scale down Arm as well.

But yes, I can see tiny chips like these putting a squeeze on 8 and 16 bit microcontrollers.