Has it been proven that no patent troll holds a patent covering RISC-V?
Of course not because that's impossible to prove.
Patents only last 20 years.
If you build your architecture on ideas that are documented to be older than twenty years, it greatly reduces the risk that a patent holder comes from nowhere: even if they did have the patent, it would have expired.
You might find this relevant: RISC-V Genealogy (2016) https://riscv.org/wp-content/uploads/2025/02/EECS-2016-6.pdf
Or in poster form: https://riscv.org/wp-content/uploads/2025/02/RISC-V-Instruct...
> Of course not because that's impossible to prove.
Why?
If you iterate trough every concept RISC-V has, you might be able to prove it.
The RISC/MIPS concepts date back over 40 years. The base instruction set is intentionally designed with unencumbered, expired, or public-domain architectural concepts.
RICV-V microarchitectures and implementations are at much high risk of violating patents. Especially anything that is even slightly high performance. SiFive, Andes , and Alibaba’s T-Head are filing thousands of patents on microarchitectural optimizations and extensions. China's RISC-V patent-sharing alliances and other industry groups are building defensive patent cross-license around their RISC-V-related patents.