_IOC_NRBITS        38 include/asm-generic/ioctl.h #define _IOC_NRMASK	((1 << _IOC_NRBITS)-1)
_IOC_NRBITS        44 include/asm-generic/ioctl.h #define _IOC_TYPESHIFT	(_IOC_NRSHIFT+_IOC_NRBITS)