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Subject: Re: [OMPI devel] RFC - "system-wide-only" MCA parameters
From: Ralph Castain (rhc_at_[hidden])
Date: 2009-09-04 09:50:21

Let me point out the obvious since this has plagued us at LANL with
regard to this concept. If a user wants to do something different, all
they have to do is download and build their own copy of OMPI.

Amazingly enough, that is exactly what they do. When we build our
production versions, we actually "no-build" modules we don't want them
using (e.g., certain BTL's that use privileged network interfaces) so
even MCA params won't let them do something undesirable.

No good - they just try until they realize it won't work, then
download and build their own version...and merrily hose the system.

My point here: this concept can help, but it should in no way be
viewed as a solution to the problem you are trying to solve. It is at
best a minor obstacle as we made it very simple for a user to
circumvent such measures.

Which is why I never made the effort to actually implement what was in
that ticket. It was decided that it really wouldn't help us here, and
would only result in further encouraging user-owned builds.


On Sep 4, 2009, at 12:42 AM, Jeff Squyres wrote:

> On Sep 4, 2009, at 8:26 AM, Nadia Derbey wrote:
>> > Can the file name ( openmpi-priv-mca-params.conf ) also be
>> configurable ?
>> No, it isn't, presently, but this can be changed if needed.
> If it's configurable, it must be configurable at configure time --
> not run time -- otherwise, a user could just give a different
> filename at runtime and get around all the "privileged" values.
> --
> Jeff Squyres
> jsquyres_at_[hidden]
> _______________________________________________
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