_RUMP_IOC
#define _RUMP_IO(g,n) _RUMP_IOC(RUMP_IOC_VOID, (g), (n), 0)
#define _RUMP_IOR(g,n,t) _RUMP_IOC(RUMP_IOC_OUT, (g), (n), sizeof(t))
#define _RUMP_IOW(g,n,t) _RUMP_IOC(RUMP_IOC_IN, (g), (n), sizeof(t))
#define _RUMP_IOWR(g,n,t) _RUMP_IOC(RUMP_IOC_INOUT, (g), (n), sizeof(t))