RE: cache problem

[Duft Markus]

> 
> Hello Markus,
> 
> thanks for the reports.
> 
[snip]
> 
> FWIW, I'm not yet sure whether this is a valid problem.  Even if it
is,
> you should be able to work around it by adding AC_CANONICAL_HOST to
the
> toplevel configure.ac.  But anyway, before discussing validity let's
> try
> to reproduce it:
> 
> I haven't been able to do so yet.  Here's what I tried.  Please modify
> the example so that it shows the failure (maybe it only needs
different
> flags passed to configure?)

Hehe, the problem occured when using the same cache file for building
autoconf or automake (which both check for build only) and after that
libtool :) so I guess, you have everything you need to reproduce... I
must admit, that I didn't have any look at the configure.{in,ac} files
yet, but you should know them very well anyway.

If that doesn't give a problem for you, I'll be happy trying to
reproduce in a smaller test case...

In the meantime, I work around the issue, by passing --build and --host
all the time, since our build scripts know those anyway, and it doesn't
even cause any more work for me. I just feel, that this is still a
problem, thus I pointed it out...

> 
[snip]
> 
> I recently posted a patch to do just this.  It wasn't applied, one
> reason being that we didn't see a way how two configure scripts could
> be
> running simultaneously; with AC_CONFIG_SUBDIRS at least (the GCC tree
> uses a different way but uses per-configure cache files).  How do you
> get two concurrent configure scripts updating the same config.cache
> file?

We have a self-written build system which is much like portage, running
on rather powerfull machines with for example 32 CPUs... Our build
system knows how to build as many packages as possible in parallel, so
it is most of the time the case that more than one configure script
runs. It is - more or less - just luck which saved us from failures so
far :) I came across this problem by just thinking about what could
happen when I enable caches for our build system, and reading a little
in a configure script. I havent' (yet) really hit the problem, and don't
even know I could be able to produce it (but I saw another posting about
this already...).

Cheers, Markus

> 
> Thanks,
> Ralf
> 
> 
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