postgresql/src/port/README
Tom Lane 4a1b05caa5 Restore AIX support.
The concerns that led us to remove AIX support in commit 0b16bb877
have now been alleviated:

1. IBM has stepped forward to provide support, including buildfarm
animal(s).
2. AIX 7.2 and later seem to be fine with large pg_attribute_aligned
requirements.  Since 7.1 is now EOL anyway, we can just cease to
support it.
3. Tossing xlc support overboard seems okay as well.  It's a bit
sad to drop one of the few remaining non-gcc-alike compilers, but
working around xlc's bugs and idiosyncrasies doesn't seem justified
by the theoretical portability benefits.
4. Likewise, we can stop supporting 32-bit AIX builds.  This is
not so much about whether we could build such executables as that
they're too much of a pain to manage in the field, due to limited
address space available for dynamic library loading.
5. We hit on a way to manage catalog column alignment that doesn't
require continuing developer effort (see commit ecae09725).

Hence, this commit reverts 0b16bb877 and some follow-on commits
such as e6bb491bf, except for not putting back XLC support nor
the changes related to catalog column alignment.

Some other notable changes from the way things were in v16:

Prefer unnamed POSIX semaphores on AIX, rather than the default
choice of SysV semaphores.

Include /opt/freeware/lib in -Wl,-blibpath, even when it is not
mentioned anywhere in LDFLAGS.

Remove platform-specific adjustment of MEMSET_LOOP_LIMIT; maybe
that's still the right thing, but it really ought to be re-tested.

Silence compiler warnings related to getpeereid(), wcstombs_l(),
and PAM conversation procs.

Accept "libpythonXXX.a" as an okay name for the Python shared
library (but only on AIX!).

Author: Aditya Kamath <Aditya.Kamath1@ibm.com>
Author: Srirama Kucherlapati <sriram.rk@in.ibm.com>
Co-authored-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CY5PR11MB63928CC05906F27FB10D74D0FD322@CY5PR11MB6392.namprd11.prod.outlook.com
2026-02-23 13:34:22 -05:00

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src/port/README
libpgport
=========
libpgport must have special behavior. It supplies functions to both
libraries and applications. However, there are two complexities:
1) Libraries need to use object files that are compiled with exactly
the same flags as the library. libpgport might not use the same flags,
so it is necessary to recompile the object files for individual
libraries. This is done by removing -lpgport from the link line:
# Need to recompile any libpgport object files
LIBS := $(filter-out -lpgport, $(LIBS))
and adding infrastructure to recompile the object files:
OBJS= execute.o typename.o descriptor.o data.o error.o prepare.o memory.o \
connect.o misc.o path.o exec.o \
$(filter strlcat.o, $(LIBOBJS))
The problem is that there is no testing of which object files need to be
added, but missing functions usually show up when linking user
applications.
2) For applications, we use -lpgport before -lpq, so the static files
from libpgport are linked first. This avoids having applications
dependent on symbols that are _used_ by libpq, but not intended to be
exported by libpq. libpq's libpgport usage changes over time, so such a
dependency is a problem. Windows, Linux, AIX, and macOS use an export
list to control the symbols exported by libpq.