[RFC 00/10] y2038: nptl: futex: Provide support for futex_time64

[Arnd Bergmann]

On Fri, Jul 17, 2020 at 9:27 AM Lukasz Majewski <lukma@denx.de> wrote:
> >
> > Yes, it is on my list. I am trying to handle the mess of stat
> > functions
>
> Regarding stat - it is indeed a mess - many versions of the same
> functions for generic, LFS, and architectures (like ARM). Conversion to
> 64 bit time support is challenging there as well.
>
> But as fair as I can tell - more than "code base" cleanup - the raise
> of glibc minimal kernel supported version would help much more in this
> situation as code for many "use cases" would be just removed.
>
> A side remark - now the oldest LTS kernel supported is 4.4 and oldest
> supported kernel for glibc is 3.2.
> Maybe it is a good time to bump the minimal supported kernel for glibc?
>
> > before starting on the lowlevellock-futex.h.
>
> If you don't have time to do the conversion in next two weeks then
> - I can in the meantime do a conversion for the above code snippet -
> futex_reltimed_wait_time64() (and up to pthread_mutex_{timed,clock}).
> This work shall be orthogonal to lowlevellock-futex.h cleanup.
>
> What do you think?

I don't think it makes any difference for stat: linux-3.2 and linux-5.0
appear to have the exact same kernel interface for newstat/stat64
and newfstatat/fstatat64 on all architectures, though there are two
special cases that need to be handled:

- mips-n32 and ix86-x32 are lacking the stat64 version, so they only
  have the non-LFS newstat/newfstatat version but not stat64/fstatat64.
  The x32 version is wide enough to support 64-bit offsets but uses
  the non-LFS name for it.

- alpha, parisc and sparc are 64-bit architecture with stat64/fstatat64,
  but they lack newstat/newfstatat.

While statx() was added in in linux-4.11, it was not enabled in ia64
until linux-5.1 when we sanitized the syscall tables across architectures,
so you can't rely on that until v5.1 is the minimum kernel for glibc,
and that will still be a long time.

There may be other reasons to increase the minimum runtimer kernel
level or the minimum kernel header version for glibc in the meantime.

     Arnd