ONGOING DEVELOPMENT
RISC-V patches include an updated (version 9) series adding support for future AIA (Advanced Interrupt Architecture) interrupt controllers, and SCS (Shadow Call Stack, similar to the x86 and Arm features). A number of posted patches implement support for custom vendor-defined ISA extensions, such as conditional arithmetic and conditional select/move. These are fairly fundamental in any architecture, so there is an implication of gratuitous (binary incompatible) differentiation. Indeed, the discussion covered this scenario, saying that vendors A and B might collaborate to add non-standard architecture extensions together. Which would be interesting.