Re: failure of cross-compilation detection on BlueGene/L

[Steven G. Johnson]

Christian Rössel wrote:
> Therefore I usually specify --host *and* --build if I want to cross 
> compile. If $host != $build, configure sets cross_compiling to yes 

Ah yes, that is an easier workaround than hacking the configure script.

However, this doesn't change the fact that there is a bug: autoconf's 
detection of cross-compiling when cross_compiling=maybe should be fixed 
on BlueGene.  Specifying --build is only a workaround, not a fix.

> Note that we are working on some heuristics to detect supercomputer 
> platforms like Blue Gene, Cray, NEC etc. that require cross compilation. 
> This detection will be available as a macro soon and render it 
> unnecessary that the user specifies --host and --build on the supported 
> platforms.

I'm not sure that's the right approach.  The default when running 
configure should be to compile for the build host (i.e., the front-end 
nodes on BlueGene etc.).  Also, the autoconf philosophy is to do feature 
tests rather than platform-specific heuristics whenever possible.

How do the autoconf developers feel about my proposed solution, which 
should allow --host to work normally on BlueGene?

Steven