ref: d5f2d2cc3fc7c2d3701e906df5d2d53781c4ee9c dir: /sys/src/9/ppc/msaturn.h/
enum { Vecuart0 = 1, Vecuart1 = Vecuart0 + 1, Vectimer0 = 0, Vecether = 3, Vecunused = 15, };