Re: [ANNOUNCEMENT] Uploads for 12 August

[Ryan Johnson <ryan dot johnson at cs dot utoronto dot ca>]

On 14/08/2013 7:59 AM, Corinna Vinschen wrote:
> On Aug 14 13:33, Corinna Vinschen wrote:
> > On Aug 14 12:53, Corinna Vinschen wrote:
> > > On Aug 14 06:28, Ken Brown wrote:
> > > > On 8/14/2013 5:16 AM, Corinna Vinschen wrote:
> > > > > On Aug 14 10:10, Corinna Vinschen wrote:
> > > > > > On Aug 13 18:00, Ken Brown wrote:
> > > > > > > On 8/13/2013 2:26 PM, Corinna Vinschen wrote:
> > > > > > > > What function is not implemented?  Is that something we can fix,
> > > > > > > > perhaps in the Cygwin DLL?
> > > > > > > It's memalign, or at least that's what it was in 2007.  See
> > > > > > >
> > > > > > >    http://cygwin.com/ml/cygwin/2007-02/msg00678.html
> > > > > > So it's using its own malloc but we don't support overriding other
> > > > > > functions besides malloc/realloc/calloc/free.
> > > > > >
> > > > > > In theory we could do that in future.  We still have room for 10 (x86)
> > > > > > resp. 12 (x86_64) pointers in the per_process structure, which could be
> > > > > > used for this purpose.  This would only require applications which need
> > > > > > this feature to be rebuilt with the next Cygwin version providing these
> > > > > > pointers.
> > > > > More precisely, they have to be rebuild using crt0.o from the next
> > > > > Cygwin release, and they would have to run under the next Cygwin
> > > > > release.  If you omit one step, you're back to the current behaviour.
> > > > >
> > > > > > But we shouldn't waste those unused slots either, so the number of
> > > > > > overridable functions should be kept small.  In theory we have mallopt,
> > > > > > mallinfo, posix_memalign, memalign, and valloc.
> > > > > >
> > > > > > I guess we can skip mallopt and mallinfo since they are pretty
> > > > > > seldomly used in user-provided malloc implementations.
> > > > > >
> > > > > > Memalign is an old, deprecated function, so I wonder why it's used at
> > > > > > all.  GSlice should use posix_memalign instead.  Yaakov, is there an
> > > > > > option to use posix_memalign rather than memalign?
> > > > I just checked the glib source, and it does use posix_memalign if
> > > > it's available.  I was quoting a 2007 discussion when I said it was
> > > > memalign that GSlice wanted to use.
> > > Given that, we should perhaps skip the memalign override.
> > On second (third? fourth?) thought, I think we should do this with
> > posix_memalign only.  valloc is just as obsolete as posix_memalign.
> I applied the patch to allow overriding posix_memalloc only, and I'm
> building snapshots right now.  For testing, this requires to rebuild
> either emacs, or glib, or both, I'm not sure.  Make sure to link against
> the new crt0.o/libcygwin.a and use the new Cygwin DLL for testing.
Wait, it's "memalign" that's obsolete and "posix_memalign" that you 
added a patch for, right? The last couple of paragraphs were a little 
confusing...

Ryan


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