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README.aix - Perl version 5 on IBM Unix (AIX) systems


This document describes various features of IBM's Unix operating system (AIX) that will affect how Perl version 5 (hereafter just Perl) is compiled and/or runs.

Compiling Perl 5 on AIX

When compiling Perl, you must use an ANSI C compiler. AIX does not ship an ANSI compliant C-compiler with AIX by default, but binary builds of gcc for AIX are widely available.

At the moment of writing, AIX supports two different native C compilers, for which you have to pay: xlC and vac. If you decide to use either of these two (which is quite a lot easier than using gcc), be sure to upgrade to the latest available patch level. Currently:

    xlC.C or or
    vac.C  or  

Perl can be compiled with either IBM's ANSI C compiler or with gcc. The former is recommended, as not only can it compile Perl with no difficulty, but also can take advantage of features listed later that require the use of IBM compiler-specific command-line flags.

The IBM's compiler patch levels and have compiler optimization bugs that affect compiling perl.c and regcomp.c, respectively. If Perl's configuration detects those compiler patch levels, optimization is turned off for the said source code files. Upgrading to at least is recommended.

If you decide to use gcc, make sure your installation is recent and complete, and be sure to read the Perl README file for more gcc-specific details. Please report any hoops you had to jump through to the development team.

OS level

Before installing the patches to the IBM C-compiler you need to know the level of patching for the Operating System. IBM's command 'oslevel' will show the base, but is not always complete (in this example oslevel shows 4.3.NULL, whereas the system might run most of 4.3.THREE):

    # oslevel
    # lslpp -l | grep 'bos.rte '
    bos.rte   COMMITTED  Base Operating System Runtime
    bos.rte    COMMITTED  Base Operating System Runtime

The same might happen to AIX 5.1 or other OS levels. As a side note, perl cannot be built without bos.adt.syscalls and bos.adt.libm installed

    # lslpp -l | egrep "syscalls|libm"
    bos.adt.libm  COMMITTED  Base Application Development
    bos.adt.syscalls  COMMITTED  System Calls Application

Building Dynamic Extensions on AIX

AIX supports dynamically loadable objects as well as shared libraries. Shared libraries by convention end with the suffix .a, which is a bit misleading, as an archive can contain static as well as dynamic members. For perl dynamically loaded objects we use the .so suffix also used on many other platforms.

Note that starting from Perl 5.7.2 (and consequently 5.8.0) and AIX 4.3 or newer Perl uses the AIX native dynamic loading interface in the so called runtime linking mode instead of the emulated interface that was used in Perl releases 5.6.1 and earlier or, for AIX releases 4.2 and earlier. This change does break backward compatibility with compiled modules from earlier perl releases. The change was made to make Perl more compliant with other applications like Apache/mod_perl which are using the AIX native interface. This change also enables the use of C++ code with static constructors and destructors in perl extensions, which was not possible using the emulated interface.

The IBM ANSI C Compiler

All defaults for Configure can be used.

If you've chosen to use vac 4, be sure to run Older versions will turn up nasty later on. For vac 5 be sure to run at least, but vac or up is highly recommended. Note that since IBM has removed vac and from the software depot, these versions should be considered obsolete.

Here's a brief lead of how to upgrade the compiler to the latest level. Of course this is subject to changes. You can only upgrade versions from ftp-available updates if the first three digit groups are the same (in where you can skip intermediate unlike the patches in the developer snapshots of perl), or to one version up where the `base' is available. In other words, the AIX compiler patches are cumulative.

 vac.C. => vac.C.  is OK     (vac.C. not needed)
 xlC.C. => xlC.C. is NOT OK (xlC.C. is not available)

 # ftp
 Connected to
 : welcome message ...
 Name ( anonymous
 331 Guest login ok, send your complete e-mail address as password.
 ... accepted login stuff
 ftp> cd /aix/fixes/v4/
 ftp> dir other other.ll
 output to local-file: other.ll? y
 200 PORT command successful.
 150 Opening ASCII mode data connection for /bin/ls.
 226 Transfer complete.
 ftp> dir xlc xlc.ll
 output to local-file: xlc.ll? y
 200 PORT command successful.
 150 Opening ASCII mode data connection for /bin/ls.
 226 Transfer complete.
 ftp> bye
 ... goodbye messages
 # ls -l *.ll
 -rw-rw-rw-   1 merijn   system    1169432 Nov  2 17:29 other.ll
 -rw-rw-rw-   1 merijn   system      29170 Nov  2 17:29 xlc.ll  

On AIX 4.2 using xlC, we continue:

 # lslpp -l | fgrep 'xlC.C '
   xlC.C             COMMITTED  C for AIX Compiler
   xlC.C             COMMITTED  C for AIX Compiler
 # grep 'xlC.C.3.1.4.*.bff' xlc.ll
 -rw-r--r--   1 45776101 1        6286336 Jul 22 1996  xlC.C.
 -rw-rw-r--   1 45776101 1        6173696 Aug 24 1998  xlC.C.
 -rw-r--r--   1 45776101 1        6319104 Aug 14 1996  xlC.C.
 -rw-r--r--   1 45776101 1        6316032 Oct 21 1996  xlC.C.
 -rw-r--r--   1 45776101 1        6315008 Dec 20 1996  xlC.C.
 -rw-rw-r--   1 45776101 1        6178816 Mar 28 1997  xlC.C.
 -rw-rw-r--   1 45776101 1        6188032 May 22 1997  xlC.C.
 -rw-rw-r--   1 45776101 1        6191104 Sep  5 1997  xlC.C.
 -rw-rw-r--   1 45776101 1        6185984 Jan 13 1998  xlC.C.
 -rw-rw-r--   1 45776101 1        6169600 May 27 1998  xlC.C.
 # wget

On AIX 4.3 using vac, we continue:

 # lslpp -l | grep 'vac.C '
  vac.C              COMMITTED  C for AIX Compiler
  vac.C              COMMITTED  C for AIX Compiler
 # grep 'vac.C.5.0.2.*.bff' other.ll
 -rw-rw-r--   1 45776101 1        13592576 Apr 16 2001  vac.C.
 -rw-rw-r--   1 45776101 1        14133248 Apr  9 2002  vac.C.
 -rw-rw-r--   1 45776101 1        14173184 May 20 2002  vac.C.
 # wget

Likewise on all other OS levels. Then execute the following command, and fill in its choices

 # smit install_update
  -> Install and Update from LATEST Available Software
  * INPUT device / directory for software [ vac.C.    ]
  [ OK ]
  [ OK ]  

Follow the messages ... and you're done.

Using GNU's gcc for building perl

Using gcc-3.0 (tested with 3.0.4) now works out of the box, as do recent gcc-2.9 builds available directly from IBM as part of their Linux compatibility packages, available here:  

Using Large Files with Perl

Should yield no problems.

Threaded Perl

Threads seem to work OK, though at the moment not all tests pass when threads are used in combination with 64bit configurations.

64-bit Perl

If your AIX is installed with 64-bit support, you can expect 64bit configurations to work. In combination with threads some tests might still fail.

AIX 4.2 and extensions using C++ with statics

In AIX 4.2 Perl extensions that use C++ functions that use statics may have problems in that the statics are not getting initialized. In newer AIX releases this has been solved by linking Perl with the libC_r library, but unfortunately in AIX 4.2 the said library has an obscure bug where the various functions related to time (such as time() and gettimeofday()) return broken values, and therefore in AIX 4.2 Perl is not linked against the libC_r.


H.Merijn Brand <>


Version 0.0.5: 22 May 2002




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