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Re: [RFC v4 07/24] time: Deprecate struct timezone members
On Mon, 12 Aug 2019, Zack Weinberg wrote:
> On Mon, Aug 12, 2019 at 4:20 PM Joseph Myers <joseph@codesourcery.com> wrote:
> >
> > On Mon, 12 Aug 2019, Zack Weinberg wrote:
> >
> > > - Our implementation of gettimeofday should always pass NULL for
> > > struct timezone to the kernel, and write zeroes to any struct timezone
> > > argument that is supplied. (This will transitively apply to ftime.)
> >
> > Given that the kernel timezone is in fact meaningful (for the kernel's
> > interpretation of data shared with other OSes, such as the RTC clock and
> > some filesystem timestamps, that is kept in local time - just not for the
> > purpose for which the timezone settings in gettimeofday / settimeofday
> > were originally intended), I think gettimeofday should continue to read
> > that information from the kernel when the kernel provides it
>
> Insisting on this would mean that we'd have to go back to the kernel
> people to request a new API _before_ we could proceed with the time64
No, but it might mean that these two functions are exceptions to the
general rule of functions for 32-bit time being thin wrappers round their
64-bit counterparts. (For the existing ABIs I think keeping interfacing
with the kernel timezone is also a matter of ABI compatibility for these
functions, even if the new _TIME_BITS=64 version of gettimeofday just
writes zeroes to the timezone.)
--
Joseph S. Myers
joseph@codesourcery.com