Re: [Bug-gsl] gsl with cblas patch

[Sébastien Fabbro]

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On Wednesday January 21 Brian Gough wrote:

> At Mon, 19 Jan 2009 19:24:42 +0000,
> Sébastien Fabbro wrote:
> > A cblas library is needed to link with the shared gsl library
> > even if no cblas function is used, or when LDFLAGS="-Wl,--as-needed"
> > is used to build gsl. 
> > 
> > One possibility is to link directly either from an external
> > external cblas library or from the builtin gslcblas at compile time
> > instead of the GSL_CBLAS_LIB as suggested in gsl-config.
> > 
> > This could be done as a cblas configure option as proposed in the
> > attached patch (also in the Gentoo public cvs repository).
> 
> Hi,
> 
> Thanks for your email.  Can you explain what problem this solves?  Is
> it that you want to compile everything with -Wl,--as-needed?
> 

Hi,

The patch allows to link gsl with -Wl,--as-needed, but also
* adds more consistency between the pkg-config file and gsl-config
  script
* links the tests, the gsl-histogram and gsl-randist binaries with
  selected cblas instead of forced gslcblas

I originally did the patch because a lot of Gentoo users have
LDFLAGS="-Wl,as-needed". Really the gain when linking gsl with as-needed
is not as much as for other packages, apart from reducing the final
shared lib of 3Mb.

There may be a better way to make sure that gsl links with as-needed
than the proposed patch. Also switching dynamically the cblas
library at run time is not allowed because of the cblas library soname
added at link time (added by @CBLAS_LINK_LIBS@ in libgsl_la_LIBADD).

- --
Sébastien Fabbro
Gentoo / Scientific Applications

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