Message-Id: <199804041626.SAA04065@en1.engelschall.com>
Subject: Re: building with mod_so
To: new-httpd@apache.org
Date: Sat, 4 Apr 1998 18:26:17 +0200 (MET DST)
From: rse@engelschall.com (Ralf S. Engelschall)
Organization: Engelschall, Germany.
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In article <9804041605.AA13117@gensym1.gensym.com> you wrote:

> I have been building with mod_so configured out.
> If I enable it, then it fails on: hp9000s700, hp9000s800, and mips. 
> On the mips, and hp9000s800 it then complains about how perl is missing.
> Is perl part of what we require of all users?   - ben hyde
>[...]
> ** FAILURE: Sorry, no shared object support available.
> ** Either compile all modules statically (use AddModule instead
> ** of SharedModule in the Configuration file) or at least provide
> ** us with the apropriate compiler and linker flags via the
> ** CFLAGS_SHLIB, LDFLAGS_SHLIB and LDFLAGS_SHLIB_EXPORT entries
> ** in the Configuration file.

A few facts:

1. mod_so cannot be used under HP/UX because this system
   has no dlopen() function. So, the definitive list of supported platforms is
   in Configuration.tmpl.  Any other platform which has dlopen() could be
   used, but only because...

2. when a platform is used for which we have no explicit knowledge
   about shared object support but Configure sees that shared object support
   is wanted (because you use SharedModule or at least compile with mod_so),
   he usually had to fail. But instead of failing immediately, we give the
   platform a second chance.  We look for an existing Perl interpreter and if
   one exists and _already uses dlopen_ we guess the shared object compilation
   flags from it and instead of failing with an error we proceed with just a
   warning.  If no Perl exists, we fail immediately, of course.

So, Perl is not needed. Configure just tries to use its knowledge for shared
object support before failing instead of failing immediately.  In other words:
You can only use mod_so on platforms which have the dlopen-style interface.
And when the platforms is already configured by us for shared object support,
all is fine. If not, we try the second Perl-based chance. And if this no
success we finally fail.

Just one thing is confusion: The error from the Perl test which confuses
people like it confused you. But I don't know how I can get rid of it. It is
the line:
  
  if [ ".`perl -V:dlsrc 2>/dev/null | grep dlopen`" != . ]; then

it works correctly, of course, but on failure case with this confusion "perl:
not found". Even with the 2>/dev/null above.  What else have to be arranged to
avoid this confusion error message? Any hints?

                                       Ralf S. Engelschall
                                       rse@engelschall.com
                                       www.engelschall.com