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Subject: Re: [hwloc-devel] hwloc embedding vs libltdl
From: Jeff Squyres (jsquyres) (jsquyres_at_[hidden])
Date: 2013-05-09 06:43:49

On May 8, 2013, at 4:16 PM, Brice Goglin <Brice.Goglin_at_[hidden]> wrote:

> But this issue is only in the embedders (OMPI), not in the embeddee
> (hwloc), right?


> I can get plugins to work in tests/embedded by adding 2 lines to its
> (see the attached patch, which also removes your error
> message and creates a shared lib containing libhwloc_embedded).
> In short, I don't really see what risk we would be taking on the hwloc
> side if we keep embedding+plugins possible (and still don't enable
> plugins by default).

Ok. It's probably worth documenting, though. In the OMPI case, for example, OMPI cannot be opened in a private namespace (e.g., as a python plugin) and then have hwloc also opened in a private namespace; hwloc must be opened in a public namespace. This has caused unhappiness in certain cases where upper-layer application authors were trying to open all plugins in private namespaces but couldn't. The same will be true with hwloc: those who embed hwloc should be *strongly advised* to not use libltdl (even though it's not the default) because of the private/public namespace issue.

Jeff Squyres
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