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Subject: Re: [hwloc-devel] Embedding: is it worth it?
From: Samuel Thibault (samuel.thibault_at_[hidden])
Date: 2010-04-06 17:36:47


Jeff Squyres, le Tue 06 Apr 2010 09:05:24 -0400, a écrit :
> On Apr 4, 2010, at 12:15 PM, Samuel Thibault wrote:
> > Why
> > is it so? Can't the main ./configure call the hwloc m4 stuff or not
> > depending on whether the internal or the external version is used?
>
> No -- we wouldn't want to call the m4 stuff in the external case,

That is what I said above (if not, please tell me, that's probably just
an English language issue): if the user requests the external version to
be used, do not call the m4 stuff; if he doesn't, call the m4 stuff.

> because what if it came to different answers vs. how the external one is configured?

That should appear in the hwloc/config.h file, be it internally
generated, or the installed external one.

> (e.g., if OMPI is built using icc and the external copy was built with gcc)

ABIs are supposed to be system-wide (plus multilib cases), not
compiler-wide. If it's not the case we have a bug that really needs
to be fixed, since we don't want to impose the use of a particular
compiler.

> In the external case, OMPI should just use the external's hwloc.h and whatever decisions were already made there (sizes, types, etc.).

In the internal case too, the only difference is the -I parameter to
reach the hwloc.h.

So I still don't see why going back to ./configure instead of using m4.
That being said, we do not have embedding needs, so we do not really
have an opinion one way or the other :)

Samuel