Some developers wanted to use the IBM provided PHP packages on our AIX pSeries servers to use with the IHS web server. So, we installed the corresponding RPMs from the AIX Toolbox for Linux Applications CD.

But quickly, the following error messages show up when loading the PHP module:

Cannot load /opt/freeware/apache/libexec/libphp4.so into server:
rtld: 0712-001 Symbol ap_child_terminate was referenced from module
/opt/freeware/apache/libexec/libphp4.so(), but a runtime definition of the symbol
was not found.
rtld: 0712-001 Symbol ap_signal was referenced from module
/opt/freeware/apache/libexec/libphp4.so
(), but a runtime definition of the symbol was not found.
rtld: 0712-001 Symbol ap_hard_timeout was referenced from module
/opt/freeware/apache/libexec/libphp4.so(), but a runtime definition of the symbol
was not found.
rtld: 0712-001 Symbol ap_reset_timeout was referenced from module
/opt/freeware/apache/libexec/libphp4.so(), but a runtime definition of the symbol
was not found.
rtld: 0712-001 Symbol ap_table_get was referenced from module
/opt/freeware/apache/libexec/libphp4.so(), but a runtime definition of the symbol
was not found.
rtld: 0712-001 Symbol ap_pstrdup was referenced from module
/opt/freeware/apache/libexec/libphp4.so
(), but a runtime definition of the symbol was not found.
rtld: 0712-001 Symbol ap_table_add was referenced from module
/opt/freeware/apache/libexec/libphp4.so(), but a runtime definition of the symbol
was not found.
Additional errors occurred but are not reported.

However, we can see that:

  1. The dependencies (dynamic linked libraries) are all resolved: 
    # ldd /opt/freeware/apache/libexec/libphp4.so
/opt/freeware/apache/libexec/libphp4.so needs:
         /usr/lib/libc.a(shr.o)
         /usr/lib/libdl.a(shr.o)
         /usr/lib/libbind.a(shr.o)
         /usr/lib/libcrypt.a(shr.o)
         /usr/lib/libz.a(libz.so.1)
         /unix
  2. The needed symbols are not found anyway: 
    # nm /opt/freeware/apache/libexec/libphp4.so | grep ap_hard_timeout
.ap_hard_timeout     T      843164
.ap_hard_timeout     t      843164          40
ap_hard_timeout      U           -
ap_hard_timeout      d      247100           4
    The U means Undefined symbol in this case.

In fact, the system calls which begin with ap_ are generally Apache specific. In fact, here is what we can found on a FreeBSD system with the 2.2 release of the Apache web server installed:

# find /usr/local -print | xargs grep ap_allow_options
/usr/local/include/apache22/http_core.h:AP_DECLARE(int)
ap_allow_options(request_rec *r);
Binary file /usr/local/libexec/apache22/mod_include.so matches
Binary file /usr/local/libexec/apache22/mod_autoindex.so matches
Binary file /usr/local/libexec/apache22/mod_cgi.so matches
Binary file /usr/local/libexec/apache22/mod_negotiation.so matches Binary file
/usr/local/libexec/apache22/mod_rewrite.so matches
/usr/local/libexec/apache22/httpd.exp:ap_allow_options
Binary file /usr/local/sbin/httpd matches
#
# nm /usr/local/sbin/httpd | grep -i ap_allow_options
0000000000429c50 T ap_allow_options

So, it seems that the RPMs provided for the PHP support is compiled for Apache exclusively (since the function prototypes are declared in a header file provided by the core Apache distribution), which seems very reasonable at a second though.

Ended to compile it by hand; which isn't finally too bad for the last PHP5 version.