Re: [RFC v3 05/23] sysdeps/timespec_get: Use clock_gettime64 if avaliable

[Florian Weimer <fweimer at redhat dot com>]

* Arnd Bergmann:

> I understand that it would be much slower on that particular combination,
> I just can't think of anyone who would run into this in practice outside of
> validation testing that makes sure glibc does run this way.

I think it will happen if you run a glibc which has been built against
current kernel headers (and with this patch or something like it) on a
host which has an older kernel.  Due to the way the patch has been
written, it will also impact legacy applications which call the 32-bit
functions, not just 32-bit applications which use the 64-bit interfaces.
(I have not checked the impact on 64-bit kernels yet, hopefully they
will never define __NR_clock_gettime64.)

I could be totally wrong about this, or our disagreement could be about
the relevance of this scenario.  Not sure which.

(I think supporting old host kernels is important to our users.)

Thanks,
Florian