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

[Sergei Steshenko]

--- "John W. Eaton" <address@hidden> 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 have never called 'gfortran' explicitly, I called 'make' instead.
I give gcc-4.2.1 libraries first in the search path, so whatever can be taken 
from
gcc-4.2.1 libraries is taken.

Probably I'm lucky because I'm using 'math-atlas' (ATLAS), so not much of the
original linear algebra remains.

'octave' built-in tests pass OK - are they insufficient ?

I do not remember exactly, but I think libg2c is needed for the self-test part
of 'lapack'; self-test apparently pass.

Building the whole thing is not that easy, so I need a compelling reason to try
to use "-ff2c" - the reason would be a failing test case.

Regards,
  Sergei.


Applications From Scratch: http://appsfromscratch.berlios.de/


       
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