Re: [PATCH v8] y2038: Introduce __ASSUME_TIME64_SYSCALLS define

[Lukasz Majewski <lukma at denx dot de>]

Hi Alistair,

> On Wed, Aug 14, 2019 at 11:47 AM Alistair Francis
> <alistair23@gmail.com> wrote:
> >
> > On Mon, Jul 8, 2019 at 4:23 AM Joseph Myers
> > <joseph@codesourcery.com> wrote:  
> > >
> > > On Thu, 27 Jun 2019, Lukasz Majewski wrote:
> > >  
> > > > Dear Joseph,
> > > >
> > > > Do you have any more comments regarding the
> > > > __ASSUME_TIME64_SYSCALL flag patch [1] ?  
> > >
> > > I think it still needs major editing for clarity as well as
> > > idiomatic English usage.  Rather than sending a long list of
> > > detailed issues with particular words and phrases it probably
> > > makes more sense for me (or another native speaker with good
> > > familiarity with all the issues involved) to do that editing; I
> > > hope to look at that around August / September / October if
> > > no-one else does it first.  
> >
> > I'm a native English speaker and I think I now have a good sense of
> > what is going on, would it help if I read through it and send an
> > updated version?  
> 
> I had a go at it anyway, this is the updated comment I came up with:
> 
> /* Support for the 64-bit time Linux kernel syscalls.
> 
>    This flag indicates support for Linux kernel syscalls, which are
> able to handle the 64 bit time ABI. It is defined for all 64-bit
> architectures as they have always supported 64 bit time support. It
> is also defined for all 32-bit architectures when using Linux kernel
> version 5.1 or newer.
> 
>    When __ASSUME_TIME64_SYSCALLS is defined glibc should call the
> *64/time64 suffixed syscalls. These should be #defined to the the
> unsuffixed versions when required (such as when running on 64-bit
> systems).
> 
>    __ASSUME_TIME64_SYSCALLS being defined does not mean that
> __TIMESIZE is 64-bit. In cases where the __TIMESIZE is 64-bit the
> 64-bit syscalls can be used directly. In cases where __TIMESIZE is
> 32-bit conversions between the original 32-bit values and the
> kernel's 64-bit values will need to occur.
> 
>    As an example - the syscall to set clock (clock_settime) - if the
>    __ASSUME_TIME64_SYSCALLS is defined, it indicates that 64 bit time
> can be set in the system.
> 
>    On systems with __WORDSIZE == 64 the __NR_clock_settime syscall is
> used to achieve this goal. Contrary, systems with __WORDSIZE == 32 do
> use new __NR_clock_settime64 syscall available from Linux version 5.1.
> 
>    The __ASSUME_TIME64_SYSCALLS is defined for:
> 
>    1. Systems with intrinsic 64 bit time support (__WORDSIZE == 64).
> 
>    2. For x32 architecture, which is a special case in respect to 64
> bit time support (it has __WORDSIZE==32 but __TIMESIZE==64)
> 
>    3. Systems with __WORDSIZE==32, which gain 64 bit time support
>       with new set of syscalls added to Linux kernel 5.1.
> 
>    4. All new 32-bit architectures that only support 64-bit time,
> such as RV32. */
> 

Thanks for providing the new description. Let's wait for comments from
glibc community members.

> Alistair
> 
> 
> >
> > Alistair
> >  
> > >
> > > --
> > > Joseph S. Myers
> > > joseph@codesourcery.com  



Best regards,

Lukasz Majewski

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