From: Matthew Wilcox <willy@xxxxxxxxxxxxx> > Sent: 22 October 2020 17:41 > > On Thu, Oct 22, 2020 at 04:35:17PM +0000, David Laight wrote: > > Wait... > > readv(2) defines: > > ssize_t readv(int fd, const struct iovec *iov, int iovcnt); > > It doesn't really matter what the manpage says. What does the AOSP > libc header say? The only copy I can find is: /usr/include/x86_64-linux-gnu/sys/uio.h:extern ssize_t readv (int __fd, const struct iovec *__iovec, int __count) /usr/include/x86_64-linux-gnu/sys/uio.h- __wur; and not surprisingly agrees. POSIX and/or TOG will (more or less) mandate the prototype. > > But the syscall is defined as: > > > > SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec, > > unsigned long, vlen) > > { > > return do_readv(fd, vec, vlen, 0); > > } I wonder when the high bits of 'fd' get zapped? David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)