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From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2006-10-13 17:11:58


There were long, religious debates about exactly this issue in the
OMPI developer group. The end result is pretty much a generalization
of what Michael said: our wrappers should do the absolute minimum to
compile and link MPI executables. That is, we provide the -I's, -
L's, and -l's necessary to find all the relevant OMPI headers/
libraries, and sometimes a few additional flags required for a
consistent executable (e.g., -pthread, if OMPI was compiled with -
pthread -- i.e., flags that if OMPI was compiled with them, then MPI
apps need to be compiled with them). But nothing else.

If we start including arbitrary features such as -rpath/etc., then
although we make some users happy, we will undoubtedly break
assumptions of other users.

That being said, OMPI does offer two ways for you to control what the
wrapper compilers do:

1. Use the --with-wrapper-*-flags options to OMPI's configure to
directly add flags to the wrapper compilers.

2. Edit $prefix/share/openmpi/*-wrapper-data.txt. These text files
contain the flags that the wrappers will add (the wrapper compiler
program is actually quite dumb; it reads these text files and
directly adds those flags to the command line).

So if you want to add -rpath/etc. to the wrappers, we provide you
with the facilities to do so, but do not do so by default.

Hope that helps!

On Oct 12, 2006, at 7:27 AM, Michael Kluskens wrote:

>
> On Oct 11, 2006, at 10:38 AM, Lisandro Dalcin wrote:
>
>> On 10/11/06, Jeff Squyres <jsquyres_at_[hidden]> wrote:
>>> Open MPI v1.1.1 requires that you set your LD_LIBRARY_PATH to
>>> include the
>>> directory where its libraries were installed (typically, $prefix/
>>> lib). Or,
>>> you can use mpirun's --prefix functionality to avoid this
>>
>> BTW, Why mpicc/mpicxx does not symply pass a -rpath/-R flag to the
>> linker? Do you want to select libraries at runtime? There are
>> portability problem in some target plataform? This behavior can be
>> really useful to experienced unix users/developers but I am not sure
>> if this holds true for all users.
>
> It appears that you want to hardcode the path to libraries in the
> executable?
>
> That is a very bad thing to do.
>
> Example: you compile your code on your system and run the code on
> someone else's system.
>
> Not everyone distributes source code and not everyone wants to
> compile source code.
>
> Michael
>
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-- 
Jeff Squyres
Server Virtualization Business Unit
Cisco Systems