Re: [Question] New mmap64 syscall?

[Florian Weimer]

On 12/07/2016 04:48 PM, Yury Norov wrote:
> On Wed, Dec 07, 2016 at 02:23:55PM +0100, Florian Weimer wrote:
> > On 12/06/2016 07:54 PM, Yury Norov wrote:
> > > 3. Introduce new mmap64() syscall like this:
> > > sys_mmap64(void *addr, size_t len, int prot, int flags, int fd, struct off_pair *off);
> > > (The pointer here because otherwise we have 7 args, if simply pass off_hi and
> > > off_lo in registers.)
> >
> > I would prefer a batched mmap/munmap/mremap/mprotect/madvise interface, so
> > that VM changes can be coalesced and the output reduced.  This interface
> > could then be used to implement mmap on 32-bit architectures as well because
> > the offset restrictions would not apply there.
>
> Hi Florian,
>
> I frankly don't understand what you mean, All syscalls you mentioned
> doesn't take off_t or other 64-bit arguments. 'VM changes' - virtual
> memory? If so, I don't see any changes in VM with this approach, just
> correct handling of big offsets.

What I was trying to suggest is a completely different interface which 
is not subject to register size constraints and which has been requested 
before (a mechanism for batching mm updates).

Thanks,
Florian