[CMake] Better BlueGene/P and cross-compile support for CMake

[Marcel Loose]

Hi Alex,

On Thu, 2010-06-24 at 22:52 +0200, Alexander Neundorf wrote:
> On Thursday 24 June 2010, Marcel Loose wrote:
> > Oops! Forgot to CC to the list.
> >
> >
> > Hi Tod,
> >
> > I'll try to answer some of your questions below inline (I've snipped
off
> > parts of your mail). We're also using a BlueGeneP, but not for so
many
> > packages/executables as you probably do.
> >
> > On Wed, 2010-06-23 at 01:02 -0700, Todd Gamblin wrote:
> > > Hi,
> >
> > -- 8< ----- 8< ----- 8< ----- 8< ----- 8< ----- 8< ----- 8< ----- 8<
--
> >
> > > I was able to build with either if I just manually specified the
> > >
> > > compilers and linker like this:
> > > > env CC=gcc C++=g++ LD=ld ./bootstrap --prefix=${CMAKE_HOME}
> > > >
> > > >
> > > > env CC=xlc C++=xlC LD=xlC ./bootstrap --prefix=${CMAKE_HOME}
> >
> > That is probably the safest way to do it, anyways. You then have
full
> > control over which compiler is used to build your stuff.
> >
> > > But It would've been nice if I didn't have to do all that.  Is PPC
> > > Linux not used many other places anymore?  I guess this is a
> > > sles10/ppc64 environment, so maybe that is throwing the script
off.
> > >
> > >
> > >
> > >
> > > 2. The FindMPI module's library search breaks because the the
> > > cross-compiler name on BlueGene/P contains -l. Specifically, the
GNU
> > >
> > > compute node compilers on BlueGene/P are named like this:
> > > > powerpc-bgp-linux-g++
> > >
> > > And the FindMPI module claims that it can't find the '-inux-g++'
> > > library, or something similar.  I was able to fix this by
modifying
> > > FindMPI's search to look for -l only when it's followed by a
space.
> > >  This is a little worrisome because I think that is a standard gnu
> > > naming convention, so other platforms with compilers named
blah-linux
> > > are going to have the same bug.
> >
> > That is a known bug. I've filed it in the bug tracker
> > http://www.vtk.org/Bug/view.php?id=9093. I've also uploaded a patch
> > (take the second one), that fixes that problem.
> 
> In the bug report you say "This patch is NOT heavily tested!"
> 
> Is this still true ?
> 
> Alex

By heavily tested, I meant tested by several people on multiple
platforms. It works for me. I think the patch is pretty straightforward
and harmless, but I've been bitten before in the past by supposedly
harmless trivial patches that did have side-effects on some (obscure?)
system. Maybe, my wording was too cautious.

Best regards,
Marcel Loose.