Re: PowerPC malloc alignment

[Roland McGrath <roland at redhat dot com>]

> The main problem is emacs (aka the only user of
> malloc_set_state/malloc_get_state).  Changing the alignment is really an ABI
> change for these interfaces, unless it does some very ugly hacks in it.

That can at least be made easy to detect gracefully via magic/version.  
Is it pathologically difficult to cope with an old dumped state?
(I'm sure we went into this at the time, but I'm hazy on the details now.)
Ideally, it would be doable enough just to handle the existing misaligned
allocations but always align the new ones.  That copes even if libc itself
or some other new-but-compatible library (X, whatever) has newly-compiled
code that manages to care about the alignment of its own allocations.  It
is probably sufficient in practice just to have the alignment parameterized
by the malloc_save_state so malloc_set_state from an old dumped emacs
reverts the behavior to the smaller alignment.


Thanks,
Roland