The code density beats ARMv8 (the best they could do with a fresh start do-over) and beats x86 too. They gave serious consideration to creating a compact instru

The code density beats ARMv8 (the best they could do with a fresh start do-over) and beats x86 too. They gave serious consideration to creating a compact instruction set that also doesn't cause the performance impacts seen in Thumb. There's various reasons for a new ISA. The most appealing right now is the patent pool. Most other open ISAs are explicitly patent encumbered (recent MIPS versions) or provide zero protection (openrisc). The chances of getting sued over RISCV seem very small until you start moving to non-ISA parts of the chip. For an ISA to succeed, the ISA itself is a distant second to the ecosystem as x86 shows so well. The amount of money an R&D being poured into RISCV would single-handedly be enough reason to adopt.