On 05/23/2012 07:29 AM, Barrett, Brian W wrote:
On 5/22/12 10:36 PM, "Orion Poplawski"<or...@cora.nwra.com> wrote:
On 05/22/2012 10:34 PM, Orion Poplawski wrote:
On 05/21/2012 06:15 PM, Jeff Squyres wrote:
On May 15, 2012, at 10:37 AM, Orion Poplawski wrote:
$ mpicc -showme:link
-pthread -m64 -L/usr/lib64/openmpi/lib -lmpi -ldl -lhwloc
-ldl and -lhwloc should not be listed. The user should only link
against libraries that they are using directly, namely -lmpi, and
they should explicitly add -ldl and -lhwloc if their code directly
uses those libraries. There does not appear to be any references to
libdl or libhwloc symbols in the openmpi headers which is the other
place it could come in.
I just read this a few times, and I admit that I'm a little confused.
libmpi does use symbols from libdl; we use it to load OMPI's plugins.
So I'm not sure why you're saying we shouldn't -ldl in the wrapper
compiler...?
libhwloc might be a little questionable here -- I'll have to check to
see whether 1.6 uses hwloc only in a plugin or whether it's used in
the base library (I don't remember offhand).
But libmpi is already linked against libdl and libhwloc. The wrapper
libraries are added when linking user code. But unless a user's code
directly uses libdl or libhwloc they don't need to link to those
libraries.
I should add the caveat that they are need when linking statically, but
not when using shared libraries.
And therein lies the problem. We have a number of users who build Open
MPI statically and even some who build both static and shared libraries in
the same build. We've never been able to figure out a reasonable way to
guess if we need to add -lhwloc or -ldl, so we add them. It's better to
list them and have some redundant dependencies (since you have to have the
library anyways) than to not list them and have odd link errors.
We're open to better suggestions, but keep in mind that they have to be
portable and not require the user to change their build systems (ie, we
can't just depend on libtool to do everything for us).
Brian
Could you not add them if --enable-static is not passed to configure? That
would at least help with building the Fedora packages.
--
Orion Poplawski
Technical Manager 303-415-9701 x222
NWRA, Boulder Office FAX: 303-415-9702
3380 Mitchell Lane or...@nwra.com
Boulder, CO 80301 http://www.nwra.com
