On Thu, 20 Dec 2001, Brian W. Barrett wrote:
> A couple important notes. First, you will need to include more than
> just libmpi.so in order to use LAM. If you run 'mpicc -showme', you
> can see all the libraries LAM/MPI is going to link in.
An important note on this: I ***highly*** discourage users from specifying
a list of LAM libraries to manually link their own applications (e.g.,
hard coding the results of "mpicc -showme" in a Makefile and using it with
a different compiler). We wrote mpicc to be a lightweight wrapper
compiler where you can change the underlying compiler if you need to (via
environment variable), and where we hide all the LAM-specific stuff for
compiling and linking MPI programs.
More specifically, the results of "mpicc -showme" may change between
versions of LAM. If you hard-code a list of -I, -L, and -l switches into
your Makefile, you could be hosed the next time LAM is released.
There is no advantage to hard-coding a list of LAM-specific flags in your
Makefile vs. using LAM's mpicc (or whatever MPI implementation you are
using).
-----
Sorry, this is a personal pet peeve of mine; I've seen 3rd party packages
do this and then complain because we changed LAM's internal list of
libraries between LAM 6.3.x and 6.5.x. If they had used mpicc, they never
would have noticed the difference.
{+} Jeff Squyres
{+} jsquyres_at_[hidden]
{+} http://www.lam-mpi.org/
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