Re: [PATCH v2 3/7] y2038: Provide conversion helpers for struct __timespec64

[Lukasz Majewski <lukma at denx dot de>]

Hi Joseph,

> On Thu, 2 May 2019, Lukasz Majewski wrote:
> 
> > As we discussed in the other thread - kernel relies on
> > "implementation depended" behaviour from GCC (which is now to
> > discard higher 32 bits from tv_nsec [1]).  
> 
> The kernel and glibc use a common-usage profile of C, which defines 
> conversion of integer types to narrower integer types as modulo.  We
> do not need to be concerned about strange implementations making
> other choices for such conversions; they are not relevant for
> building the kernel.  (This is a separate matter from undefined
> behavior for signed arithmetic overflow.)
> 
> In the current draft of the next C++ standard revision, this is
> required for C++, and it's entirely plausible that C will follow at
> some point.
> 

Thank you for a detailed explanation.

As Arnd in the other mail [1] confirmed that the intention of the
kernel is to ignore padding - zero'ing padding can be safely removed
from this glibc patch series.


Note:

[1] - https://lkml.org/lkml/2019/4/22/824

Best regards,

Lukasz Majewski

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