this is unfortunately not true (that the RISC-V ISA was designed not to require currently-valid patents). people may believe that to be the case, but it's not. from 3rd hand i've heard that IBM has absolutely tons of patents that RISC-V infringes. whether IBM decide to take action on that is another matter. they're a bit of a heavyweight, so there would have to be substantial harm to their business for the "800 lb gorilla" effect to kick in.