[Question] New mmap64 syscall?

Dr. Philipp Tomsich
2016-12-07T11:07:24Z

[Resend, as my mail-client had insisted on using the wrong MIME type?]

> On 07 Dec 2016, at 11:34, Yury Norov <ynorov@caviumnetworks.com> wrote:
>
>> If there is a use case for larger than 16TB offsets, we should add
>> the call on all architectures, probably using your approach 3. I don't
>> think that we should treat it as anything special for arm64 though.
>
> From this point of view, 16+TB offset is a matter of 16+TB storage,
> and it's more than real. The other consideration to add it is that
> we have 64-bit support for offsets in syscalls like sys_llseek().
> So mmap64() will simply extend this support.

I believe the question is rather if the 16TB offset is a real use-case for ILP32. This
seems to bring the discussion full-circle, as this would indicate that 64bit is the
preferred bit-width for all sizes, offsets, etc. throughout all filesystem-related calls
(i.e. stat, seek, etc.).

But if that is the case, then we should have gone with 64bit arguments in a single
register for our ILP32 definition on AArch64.

In other words: Why not keep ILP32 simple an ask users that need a 16TB+ offset
to use LP64? It seems much more consistent with the other choices takes so far.

?Phil.