[PATCH v3 2/5] y2038: Introduce internal for glibc struct __timespec64

[Andreas Schwab]

On Mai 07 2019, Lukasz Majewski <lukma@denx.de> wrote:

> Hi Andreas,
>
>> On Mai 07 2019, Lukasz Majewski <lukma@denx.de> wrote:
>> 
>> > +struct __timespec64
>> > +{
>> > +  __time64_t tv_sec;         /* Seconds */
>> > +# if BYTE_ORDER == BIG_ENDIAN
>> > +  int tv_pad: 32;            /* Padding named for checking/setting
>> > */
>> > +  __int32_t tv_nsec;         /* Nanoseconds */
>> > +# else
>> > +  __int32_t tv_nsec;         /* Nanoseconds */
>> > +  int tv_pad: 32;            /* Padding named for checking/setting
>> > */ +# endif  
>> 
>> No need to use a bitfield, since the padding is not fractional.
>
> That bitfield is for following reasons:
>
> 1. Have a backup plan in the case if we need to copy and clear the
> padding anyway before passing this structure to the kernel in the future
> (as recently we discovered that for example x32 has a kernel bug with
> clearing it).
>
> 2. Kernel syscalls (e.g. clock_settime64) expects on those systems two
> values - each 8 bytes. To avoid any nasty surprises the explicit
> padding was added.

None of that requires a bitfield.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
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