Re: Fortran libraries on the Blue Gene with mpi

[John R. Cary]

Hi Ralf,

Ralf Wildenhues wrote:
> Hello John,
>
>
>   
>
> OK.  That's fairly easy to support in Libtool then: the only thing we
> need to get right is to turn off shared library support completely for
> BG/L.
>   

I gave the wrong impression.  This is a BG/P.  My previous reference to the
compilers was because the BG/L compilers (I thought) are the same.

> Can we assume bg* produces code for the compute nodes only?  Let's turn
> the question around: how can we reliably detect that code is being
> compiled for the compute nodes?
>   

I don't know for sure, but the experiments at the end of this indicate that
bg compiled code works on the login nodes.
> What do
>   path/to/config.guess
>   
login5.intrepid$ ./config.guess
./config.guess: unable to guess system type

This script, last modified 2009-02-03, has failed to recognize
the operating system you are using. It is advised that you
download the most up to date version of the config scripts from

 
http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD
and
 
http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD

If the version you run (./config.guess) is already up to date, please
send the following data and any information you think might be
pertinent to <address@hidden> in order to provide the needed
information to handle your system.

config.guess timestamp = 2009-02-03

uname -m = 4400
uname -r = 4.0
uname -s = iainfo2
uname -v = 3.0

/usr/bin/uname -p =
/bin/uname -X     =

hostinfo               =
/bin/universe          =
/usr/bin/arch -k       =
/bin/arch              = ppc64
/usr/bin/oslevel       =
/usr/convex/getsysinfo =

UNAME_MACHINE = 4400
UNAME_RELEASE = 4.0
UNAME_SYSTEM  = iainfo2
UNAME_VERSION = 3.0

> and
>   CC=/opt/ibmcmp/xlc/bg/9.0/bin/bgcc path/to/config.guess
>   
login5.intrepid$ CC=/opt/ibmcmp/vac/bg/9.0/bin/bgcc config.guess
././config.guess: unable to guess system type

This script, last modified 2009-02-03, has failed to recognize
the operating system you are using. It is advised that you
download the most up to date version of the config scripts from

 
http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD
and
 
http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD

If the version you run (././config.guess) is already up to date, please
send the following data and any information you think might be
pertinent to <address@hidden> in order to provide the needed
information to handle your system.

config.guess timestamp = 2009-02-03

uname -m = 4400
uname -r = 4.0
uname -s = iainfo2
uname -v = 3.0

/usr/bin/uname -p =
/bin/uname -X     =

hostinfo               =
/bin/universe          =
/usr/bin/arch -k       =
/bin/arch              = ppc64
/usr/bin/oslevel       =
/usr/convex/getsysinfo =

UNAME_MACHINE = 4400
UNAME_RELEASE = 4.0
UNAME_SYSTEM  = iainfo2
UNAME_VERSION = 3.0


> output for the system triplets?  Please download the latest config.guess
> and config.sub files from <http://savannah.gnu.org/projects/config> for
> this test, and adjust CC so that it points to a C compiler (or MPI
> wrapper compiler like mpixlc) defaulting to code for the compute nodes.
>
>   


> -dy instead of -dynamic (gcc)
> -G instead of -qmkshrobj (xlc)
> -qnostaticlink is for xlc/xlC, -Wl,-dy is for xlf*
>
> It documents LD_LIBRARY_PATH as suitable for shlibpath_var.
> No mention of hardcoding facilities.
>
> I am unsure whether -dy/-dynamic/-qnostaticlink is the default mode of
> operation.  Can you find this out for me, for both compiler suites?
> (Create a shared library without an accompanying static one, link a
> program with it and find out whether you need to pass the flag).
> Untested:
>   echo 'int foo () { return 0; }' > foo.c
>   xlc -qpic -c foo.c
>   xlc -qmkshrobj -o libfoo.so foo.o
>   echo 'extern int foo (); int main () { return foo (); }' > main.c
>   xlc -c main.c
>   xlc -o main main.o -L. -lfoo  # without/with -qnostaticlink
>   
Both link, neither runs

login5.intrepid$ xlc -o main main.o -L. -lfoo  # without/with -qnostaticlink
login5.intrepid$ ./main
./main: error while loading shared libraries: libfoo.so: cannot open 
shared object file: No such file or directory
login5.intrepid$ xlc -o main main.o -L. -lfoo  -qnostaticlink
login5.intrepid$ ./main
./main: error while loading shared libraries: libfoo.so: cannot open 
shared object file: No such file or directory

But with -R they do

login5.intrepid$ xlc -o main main.o -L. -lfoo  -R.
login5.intrepid$ ./main

> Neither of these documents provide any indication as to hardcoding or
> run paths into libraries or programs.  Can you find out whether the
> runtime linker and the link editor have any kind of run path support?
> You might need to look into the man pages for ld and ld.so (or whatever
> its name is on this system) and search for "run path", "rpath",
> "DT_RPATH", "-R", or similar names.
>   

But I am doing all this for the xlc compilers, as in your example.  For 
the bg
compilers, it seems that the -qnostaticlink flag is necessary even to link,
and -R to run.

login5.intrepid$ bgxlc -qpic -c foo.c
login5.intrepid$ bgxlc -qmkshrobj -o libfoo.so foo.o
login5.intrepid$ bgxlc -c main.c
login5.intrepid$ bgxlc -o main main.o -L. -lfoo
/bgsys/drivers/ppcfloor/gnu-linux/powerpc-bgp-linux/bin/ld: cannot find 
-lfoo
login5.intrepid$ bgxlc -o main main.o -L. -lfoo -qnostaticlink
login5.intrepid$ ./main
./main: error while loading shared libraries: libfoo.so: cannot open 
shared object file: No such file or directory
login5.intrepid$ bgxlc -o main main.o -L. -lfoo -qnostaticlink -R.
login5.intrepid$ ./main

rpath also works:

login5.intrepid$ bgxlc -o main main.o -L. -lfoo -qnostaticlink -Wl,-rpath,.
login5.intrepid$ ./main
login5.intrepid$

John