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

On 02/11/2015 11:57 AM, H.J. Lu wrote:
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.

That is very unfortunate.  I consider it is too late for x32 to change.

Why? It's hardly an incompatible ABI change, as long as the
kernel/libc fills the upper bits (for old programs that read them
based on the old headers) when structs are read from the kernel to the
application, and ignores the upper bits (potentially set or left
uninitialized by the application) when strings are passed from
userspace to the kernel. Newly built apps using the struct definition
with 32-bit tv_nsec would need new libc to ensure that the high bits
aren't interpreted, but this could be handled by symbol versioning.

We have considered this option.  But since kernel wouldn't change
tv_nsec/tv_usec handling just for x32, it wasn't selected.

Did anyone *ask* the kernel people (e.g. hpa)?


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