Re: Installing GCC-4.x in userspace / Compiling Octave from CVS

[Muthiah Annamalai]

--- "John W. Eaton" <jwe at bevo.che.wisc.edu> wrote:

> On  2-Oct-2007, Sergei Steshenko wrote:
>
> | And that was my point, and this is how I built it, but you will still need 
> "-l g2c"
> | and for that something like
> |
> | LOADOPTS = -L /maxtor5/sergei/AppsFromScratchWD/install/gcc-4.2.1/lib -L
> | 
> /maxtor5/sergei/AppsFromScratchWD/install/gcc-4.2.1/libexec/gcc/i686-pc-linux-gnu/4.2.1
>  -L
> | /maxtor5/sergei/AppsFromScratchWD/install/gcc-3.4.6/lib -lgfortran -l g2c#
> |
> | - like I posted.
> |
> | I.e. build everything using gcc-4.2.1, but where needed, give linker libg2c 
> from gcc-3.4.6
>
> I don't see how this can be the right solution.  You should not need
> -lg2c if you are compiling with gfortran, and in fact, if some code
> you are linking with requires -lg2c, then it means you are mixing g77
> and gfortran compiled code, which the gfortran manual now warns
> against because of differences in calling conventions.  So if you are
> doing this, then you should probably be using -ff2c to force gfortran
> to use the g77/f2c calling conventions.
>
> FWIW, I just tried building the latest blas and lapack sources from
> netlib and all I had to do was
>
>   tar zxf blas.tgz
>   tar zxf lapack-3.1.1.tgz
>   cd BLAS
>   gfortran -c -O2 *.f
>   ar rcv ../lapack-3.1.1/blas_LINUX.a *.o
>   cd ../lapack-3.1.1
>   cp INSTALL/make.inc.gfortran make.inc
>   make
>
> There doesn't seem to be any need to have -lg2c here.
>
> Note also that if you compile the Fortran bits of Octave with gfortran
> and you use an optimized BLAS/LAPACK library, you need to be sure that
> the Fortran interface to your optimized BLAS/LAPACK library is
> compatible with the new gfortran calling conventions, or you need to
> use the -ff2c option for gfortran when you compile the Fortran bits of
> Octave.
>
> jwe
>


I just write to report that following JWE's instructions, after
getting gfortran to
work, I had compiled BLAS, LAPACK and everything else falls into place like a
dovetail. No massaging scripts, no editing.

The exact configure lines I used (note, I installed to a local directory) are,


./configure --prefix=$HOME/GCC42/ --with-f77=gfortran --enable-shared
--disable-static --with-blas=$HOME/GCC42/lib/libblas.a
--with-lapack=$HOME/GCC42/lib/liblapack.a

Again, thanks for all the support & help.
Cheers,
-Muthu