[Pw_forum] Compiling pwscf using ifc 7.1 on a x64-64 system

[Jonathan Breeze]

Dear Pwscf users,

Just thought I would share some of my experiences getting pwscf (version 
1.3 and 2.0) to compile using Intel Fortran Compiler (IFC) on a 64-bit 
linux system (AMD64 on Suse 9.0 x86_64).  I had a few tiny troubles 
getting pwscf to compile so here goes.

I use IFC version 7.1 build 20030307Z.

1) Getting IFC to compiler and link 32-bit code and libraries.

ifc needs to be in the execution path, so in a bash shell run :

    export PATH=$PATH:/opt/intel/compiler70/ia32/bin

To prevent having to do this every time you open a new terminal, add 
this to the .bashrc file.

IFC needs the '-Wl,-melf_i386' option in order to compile and link 
32-bit code and libraries.  To make life easier and not have to add this 
option explicitly everytime IFC is called (i.e. editing makefiles), edit 
the file /opt/intel/compiler70/ia32/bin/ifc.cfg and add '-Wl,-melf_i386' 
at the end of the first line.

ifc.cfg should now look like;
-Xlinker -rpath -Xlinker /opt/intel/compiler70/ia32/lib 
 -I/opt/intel/compiler70/ia32/include -Wl,-melf_i386

Test that ifc work properly my running it from the command-line. You 
should see something like;
/usr/lib/crt1.o(.text+0x18): In function `_start':
../sysdeps/i386/elf/start.S:98: undefined reference to `main'

So far so good.

2) evironment variables for configure script.

Make IFC the default Fortran compiler by executing
   
    export F90=ifc
    export F77=ifc

and make gnu C compiler generate 32-bit code by executing    
   
    export CC="gcc -m32"

3) Optimisations (I found that the -axW or -xW option wouldn't compile, 
but it may for your configuration).

export FFLAGS="-Vaxlib -O3 -tpp7"

4) Configure

The x86_64-unkown-linux-gnu architecture is presently not recognised by 
the configure script.  
So, instead of ./configure type
   
    ./configure --build=i686-pc-linux-gnu

for pw.1.3.0 ./configure should be replaced by ./configure.new

3) Make everything as usual

make all; make links

----------------------

This should work hopfeully, as it did for me using Suse 9.0, but it 
might not for other x86_64 distributions.  Please let me know if 
otherwise or if I have made some grevious mistakes in the above.  Thanks.

Kind regards to all Pwscf users,

Jnathan Breeze