Re: AIX shared libraries - Mailing list pgsql-hackers

Tom Lane wrote:
>>> I think there's a reasonable argument that by installing
>>> a .a file that isn't a shared library, we are violating
>>> the platform's conventions.
>
> Hm.  This seems possible with some moderate hacking on Makefile.shlib
> (certainly it'd be no more invasive than the existing Windows-specific
> platform variants). [...]
>
> Another issue with installing only .a is that there's no provision
> for versioning in .a library names ... what happens to someone who
> needs two generations of libpq on his machine?

Ok, I have spent some time researching and thinking, and I
have three proposals how to deal with linking on AIX.

1) Leave everything as it is and add the LDAP libraries to the  AIX hack in Makefile.shlib.
Pros:
- Little work.
Cons:
- PostgreSQL will continue to be statically linked on AIX (unless somebody feeds configure the right LDFLAGS).

2) Remove the AIX hack from Makefile.shlib, add -brtl and   -blibpath:"$(rpathdir)":*-L directories in
LDPATH*:/usr/lib:/lib(this sets the AIX equivalent for RPATH) to LDFLAGS for AIX. 
Pros:
- Dynamic linking on AIX.
- The organization of the libraries (libpq.a static, libpq.so dynamic) is similar to other operating systems.
Cons:
- The library organization is counter-intuitive to AIX people, and most people will inadvertedly link statically when
linkingagainst libpq. 
- According to Rocco Altier it will not work on historic versions of AIX (no -brtl flag).

3) Major hacking in Makefile.shlib to achieve the following:  - libXX.so.n is built from libXX.a in the traditional
way.   Then libXX.a is deleted, and recreated as archive    containing libXX.so.n.  - Linking takes place withOUT
-brtl,but with -blibpath:...    as in 2).  - When the shared libs are installed, I see two options:    a) copy (and
overwrite)libXX.a to libdir, do not       install libXX.so.n    b) Look for existing libXX.a in libdir, extract all
 libXX.so.k from it, mark them LOADONLY with       'strip -e libXX.so.k', create a new libXX.a with       these objects
andthe new libXX.so.n 

Pros:
- Dynamic linking on AIX.
- AIX-conforming organization of libraries.
- In the case of 3)b), multiple versions of the library can be retained in the same archive. Linking is only possible
withthe latest versions, but old programs continue to work. 
- 3)a) will probably work on older versions of AIX (I hope there's a -blibpath flag).
Cons:
- Much work, particularly with 3)b).
- Library organization on AIX will be different from other platforms.
- 3)b) will probably not work on old versions of AIX (I read a posting that makes me believe that 'strip -e' was not
aroundbefore 4.3.3. 

I am willing to implement whatever solution we decide upon.
I personally would prefer 3)a), but am happy with anything
except 1).

Yours,
Laurenz Albe

I personally would prefer 3)a)