Re: Accelerating Y2038 glibc fixes

[Lukasz Majewski <lukma at denx dot de>]

Hi Joseph, Zack,

> On Mon, 29 Jul 2019, Zack Weinberg wrote:
> 
> > I’m prepared to work with you to come up with better wording but I
> > need to ask you a bunch of questions.  Could you please reply to
> > each of the queries marked Qn below?  
> 
> Note that while these cases are things we should think about in
> working out (for example) what the best semantics for
> __ASSUME_TIME64_SYSCALLS are, they shouldn't be part of how it's
> defined (a definition that says this is what happens in each of five
> cases is not a cleanly defined interface); the definition should
> rather be such that readers can see what the answer would be for each
> of those cases - and for any other cases that may arise in future.
> (I think the current definition is that it means either a specified
> set of suffixed syscalls using 64-bit time are guaranteed to be
> available at runtime, *or* that the corresponding unsuffixed syscalls
> use 64-bit time and are guaranteed to be available, so that #define
> of the suffixed names to the unsuffixed ones is OK in that case.)
> 

The above definition is the concise description of
__ASSUME_TIME64_SYSCALLS.

> There is at least one case you didn't list (or a variant of case 5
> that's different as far as glibc's concerned but not as far as the
> kernel's concerned): new glibc ports for ILP32 ABIs where the oldest
> kernel version supported is older than 5.1, should we wish for any
> such port to support only 64-bit time and not 32-bit time (so
> __TIMESIZE == 64, __WORDSIZE == 64, __SYSCALL_WORDSIZE == 64) - and
                    ^^^^^^^^^^^^^^^^ - shouldn't be WORDSIZE == 32 ?

> once we have the support in glibc to make it possible not to support
> 32-bit time in such a case, it seems a good idea for any such new
> ports to use it.
> 
> __WORDSIZE is the size, in bits, of "long int".  __SYSCALL_WORDSIZE
> (when defined) is the size, in bits, of __syscall_slong_t (the "long
> int" type in the syscall interface, which is the same as userspace
> "long int" except for x32).
> 


Best regards,

Lukasz Majewski

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