Re: [PATCHv3 00/24] ILP32 support in ARM64

[Rich Felker <dalias@libc.org>]

On Wed, Feb 11, 2015 at 11:16:58AM -0800, H.J. Lu wrote:
> >> > I don't know if this has been discussed on libc-alpha yet or not, but
> >> > I think we need to open a discussion of how it relates to open glibc
> >> > bug #16437, which presently applies only to x32 (ILP32 ABI on x86_64):
> >> >
> >> > https://sourceware.org/bugzilla/show_bug.cgi?id=16437
> >>
> >> Please leave x32 out of this discussion.  I have resolved this bug
> >> as WONTFIX.
> >
> > From the glibc side, I thought things went by a consensus process
> > these days, not the old WONTFIX regime of he who shall not be named.
> > If this is not fixed for x32, then x32 cannot provide a conforming C
> > environment and thus it's rather a toy target. But I think we should
> > discuss this on libc-alpha. In the mean time please leave it REOPENED.
> 
> As I said in PR,  the issue has been raised in Mar, 2012 when the
> x32 port was submitted.  It has been decided that x32 won't conform
> to tv_nsec, blksize_t, and suseconds_t as long.  I don't believe we
> will change them to conform to POSIX.

I briefly reviewed that discussion and I think the decision made was
about an obscure POSIX requirement about supporting at least one
compilation environment where certain types have rank <= long. This is
trivially satisfied if you consider x32 and x86_64 separate
compilation environments, but it's not related to the core issue: that
the definition of timespec violates core (not obscure) requirements of
both POSIX and C11. At the time you were probably unaware of the C11
requirement. Note that it's a LOT harder to effect change in the C
standard, so even if the Austin Group would be amenable to changing
the requirement for timespec to allow something like nseconds_t,
getting WG14 to make this change to work around a Linux/glibc mistake
does not sound practical.

Rich