glibc 2.21 - Machine maintainers, please test your machines.

[Torvald Riegel]

On Mon, 2015-01-26 at 16:03 +0100, Andreas Schwab wrote:
> The compiler can simplify operations based on the known alignment of
> objects.  This is like any other undefined behaviour.

Is your concern regarding glibc code (ie, sem_*()) or code outside
glibc?

For glibc, the accesses which might not be aligned as promised are to
either the private field, or in the form of atomic operations.  Do you
seem examples of badness happening in both cases, or is this more a case
of not being able to prove absence of badness (which would be a valid
concern too).

For code outside of glibc, I'm not sure something can actually happen.
If an application picks up the new semaphore.h, sem_t will be
8B-aligned.  If not, then not.  I don't think this can be partially
8B/4B-aligned, or can it?