On Thu, Feb 16, 2006 at 01:57:39PM +0100, Fran?ois-Xavier Coudert wrote: > > I guess libgfortran has configury to figure out if kind=16 is available? > > Yes. > > > If so then libgfortran should be built with -mlong-double-128, as this > > should only add extra symbols that do not conflict with kind=4 and kind=8 > > ones. > > Hum, that has to be done early in the configury (before all > autodetection). Do you think it's better suited at the beginning of > libgfortran/configure.ac (a special test, to see if -mlong-double-128 > is available, and if it is add it to CFLAGS), or should it be done in > an upper level (and here is the limit of my understanding of the build > mechanism)?
That will not work. It is not enough if GCC supports -mlong-double-128 switch, you also need runtime library support for that. So the check needs to be something like http://gcc.gnu.org/ml/gcc-patches/2006-02/msg01075.html (still not reviewed :( ). If you configure gcc with --with-long-double-128 (what I'm using e.g. on redhat/gcc-4_1-branch now for {ppc*,s390*,sparc,alpha}-*-linux*), then libgfortran is automatically built with -mlong-double-128 and can cope with both -mlong-double-128 and -mlong-double-64 code. libstdc++.so will only support both -mlong-double-{64,128} if it is built with -mlong-double-128, so it is in the same boat as libgfortran. Not sure if it makes any sense to detect the presence of glibc 2.4+ and build libstdc++-v3/libgfortran with -mlong-double-128 even if configured with --without-long-double-128. Jakub
