Re: AIX 5.2 module without AR container?

[Ralf Wildenhues]

Hello Kent,

* Kent Boortz wrote on Tue, Sep 12, 2006 at 12:19:15PM CEST:
> 
> All is well, except on AIX 5.2. What happens is that libtool part of
> the build produces a binary with soname ".so", but this file is also,
> according to AIX tradition, put into a AR archive. And this is what is
> installed with "make install".

Libtool supports two different "modes" on AIX: runtimelinking and no
runtimelinking.  (The exact AIX linker semantics are more complex,
Libtool uses somewhat of a simplification by distinguishing these cases.)

>  - How do I prevent the AR version to be installed with "make install",
>    but instead get the ".so" version, i.e. a module I can load?

Use runtimelinking when compiling libltdl:
  ./configure LDFLAGS=-Wl,-brtl

If in doubt, use that always, as runtimelinking is closer to what people
used to ELF semantics expect.

>  - I saw there are some versions, or hacked versions, of "ltdl.c"
>    floating round that sets RTLD_MEMBER on AIX, enabling opening
>    a "module" inside a AR container. As far as I can see, this never
>    made it to the official source, why not?

Please post a reference.

>  - Browsing the source of libtool (in no way claiming I understand
>    anything I see), I come across a symbol "aix_use_runtimelinking"
>    that seems to prefer ".so" over the AR container, but it is set if
>    "-brtl" is in LDFLAGS. I thought libtool was to protect me from
>    depending on flags, that I in my Makefile.am need to write
>    something like
> 
>      # Set with AM_CONDITIONAL in configure.in
>      if WANT_AIX_RUNTIMELINKING
>      mymodule_la_LDFLAGS = -brtl

That would have to be "-Wl,-brtl", I believe.  (At least if you also
want to use GCC on AIX.)  And you should pass this flag to configure,
else that will make some wrong settings.

I don't know why Libtool supports both modes on AIX (and thus exposes
the user to take care of this difference).  That was way before my
exposure to Libtool.  Flexibility, I guess, and the hassles of getting
the non-runtimelinking mode to work well enough.

> Sorry if part of this is automake questions, it is so hard to tell
> sometimes from the user perspective.

No, you're quite right here.

Cheers,
Ralf