On Fri, Dec 12, 2008 at 08:29:29AM -0700, Matthew Wilcox wrote: > On Fri, Dec 12, 2008 at 03:00:40PM +0100, Gerd Hoffmann wrote: > > The patch sports the actual system call implementation and the windup in > > the x86 system call tables. Other archs are TBD. > > > +asmlinkage ssize_t sys_preadv(unsigned long fd, const struct iovec __user *vec, > > + unsigned long vlen, loff_t pos) > > +asmlinkage ssize_t sys_pwritev(unsigned long fd, const struct iovec __user *vec, > > + unsigned long vlen, loff_t pos) > > Are these prototypes required? MIPS and PARISC will need wrappers to > fix them if they are. These two architectures have an ABI which > requires 64-bit arguments to be passed in aligned pairs of registers, > but glibc doesn't know that (and given the existence of syscall(3), > can't do much about it even if it knew), so some of the arguments end up > in the wrong registers. > > Things will go much better if we can prototype these as: > > asmlinkage ssize_t sys_preadv(unsigned int fd, const struct iovec __user *vec, > loff_t pos, unsigned long vlen); > asmlinkage ssize_t sys_pwritev(unsigned int fd, const struct iovec __user *vec, > loff_t pos, unsigned long vlen); > > That way 'pos' ends up split between arg2 and arg3 and vlen ends up in > arg4 instead of having vlen in arg2 and pos in arg3 and arg4 which then > have to be munged to be in arg4 and arg5 by a compat wrapper. > > I seem to recall the s390 folks having some concerns with this kind of > thing too, but I forget what they are, so I'll let them weigh in on > this. I think a lot of stuff that needs to be known for new system calls was written up with these two postings: http://marc.info/?l=linux-arch&m=118277150812137&w=2 http://lkml.org/lkml/2007/8/1/354 -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
