If you've gone to the trouble of migrating to RISC-V then you allow that, it's on you. But even then working around custom extensions is a lot easier than a wh

If you've gone to the trouble of migrating to RISC-V then you allow that, it's on you. But even then working around custom extensions is a lot easier than a whole ISA. Short of patents you can always reimplement them. No one can copyright instruction code numbers.