Maybe you skipped the section "What is the benefit of sticking with Risc-V"? > But for a coprocessor you don’t want or need this large instruction-set. You wan

Maybe you skipped the section "What is the benefit of sticking with Risc-V"? > But for a coprocessor you don’t want or need this large instruction-set. You want an eco-system of tools that have been built around the idea of a minimal fixed base instruction-set with extensions. Essentially: the modular nature of Risc-V and tooling/ecosystem built around it, with first class extension support. ARM is closed, too complex and not friendly to extensions, while custom ISAs mandate a huge amount of extra work. I only dabble in this field, but I see the ecosystem rapidly maturing. The open nature also leads to a general propensity to open source designs and tooling, lowering the barrier to entry and reducing cost.