Re: Problems with AIX4 Compiler

[Erik Lindahl]

On Wed, 18 Jul 2001, Tim Mooney wrote:


>>Otherwise, it'd be great if these flags 
>>could go away. 
>
>The -Wl,-blibpath:$libdir/usr/lib:/lib 
>
>is a really really good idea, though. You definitely don't want that to 
>go away, or many of the binaries you generate with libtool will have 
>horrible security problems, because the linker is going to stick *some*
>libpath in the loader section.  If you don't tell it to use a good one
>(like the one above), it's going to use one based on the `-L' flags it
>saw.  That opens you up for all kinds of problems.
>

Tim, while I do agree the security feature is nice this currently breaks
libtool in a bad way when you try to use the MPI compiler mpcc to
build parallel programs on aix; although libtool thinks shared libraries
are supported, they are not. The compile is ok, but you can't run the
program.

Well, actually mpcc isn't a compiler but a wrapper script, but the
user doesn't know that and all the manuals refers to it as a compiler. 
The IBM-provided scripts just adds the MPI library directory with a -L
flag, and trust this parth to be added to the runpath. 

If this was some desktop system it might be irrelevant, but aix/rs6000 is
the most common supercomputer setup, so all parallel programs that haven't
explicitly disabled the shared libtool libraries will fail without
explaining what the problem is!

The best solution would of course have been if the mpcc script was
smarter, but even if it's fixed libtool needs to support old
installations, so I don't see many alternatives besides using the LIBPATH
environment variable at link time instead. 

I'm working on it, and can provide you with a patch, but if you think it's
an extremely bad idea we could try to come up with a better alternative
:-)


Regards,

Erik