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Re: PowerPC malloc alignment
- From: Steve Munroe <sjmunroe at us dot ibm dot com>
- To: Roland McGrath <roland at redhat dot com>
- Cc: Jakub Jelinek <jakub at redhat dot com>, libc-alpha at sourceware dot org, Ryan Arnold <ryanarn at us dot ibm dot com>
- Date: Wed, 31 Oct 2007 17:02:35 -0500
- Subject: Re: PowerPC malloc alignment
Roland McGrath <roland@redhat.com> wrote on 10/31/2007 04:36:48 PM:
> > 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.
>
This thing has been a problem for many moons. Anything we can do to help?
>
Steven J. Munroe
Linux on Power Toolchain Architect
IBM Corporation, Linux Technology Center