/Misc/AIX-NOTES
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- Subject: AIX - Misc/AIX-NOTES
- From: Vladimir Marangozov <Vladimir.Marangozov@imag.fr>
- To: guido@CNRI.Reston.Va.US (Guido van Rossum)
- Date: Wed, 6 Aug 1997 11:41:00 +0200 (EET)
- ==============================================================================
- COMPILER INFORMATION
- ------------------------------------------------------------------------------
- (1) A problem has been reported with "make test" failing because of "weird
- indentation." Searching the comp.lang.python newsgroup reveals several
- threads on this subject, and it seems to be a compiler bug in an old
- version of the AIX CC compiler. However, the compiler/OS combination
- which has this problem is not identified. In preparation for the 1.4
- release, Vladimir Marangozov (Vladimir.Marangozov@imag.fr) and Manus Hand
- (mhand@csn.net) reported no such troubles for the following compilers and
- operating system versions:
- AIX C compiler version 3.1.2 on AIX 4.1.3 and AIX 4.1.4
- AIX C compiler version 1.3.0 on AIX 3.2.5
- If you have this problem, please report the compiler/OS version.
- (2) Stefan Esser (se@MI.Uni-Koeln.DE), in work done to compile Python
- 1.0.0 on AIX 3.2.4, reports that AIX compilers don't like the LANG
- environment varaiable set to European locales. This makes the compiler
- generate floating point constants using "," as the decimal separator,
- which the assembler doesn't understand (or perhaps it is the other way
- around, with the assembler expecting, but not getting "," in float
- numbers). "LANG=C; export LANG" solves the problem, as does
- "LANG=C $(MAKE) ..." in the master Makefile.
- (3) The cc (or xlc) compiler considers "Python/eval.cc" too complex to
- optimize, except when invoked with "-qmaxmem=4000"
- (4) Some problems (due to _AIX not being #defined) when python 1.0.0 was
- compiled using 'gcc -ansi' were reported by Stefan Esser, but were not
- investigated.
- (5) The cc compiler has internal variables named "__abs" and "__div". These
- names are reserved and may not be used as program variables in compiled
- source. (As an anecdote in support of this, the implementation of
- Python/operator.c had this problem in the 1.4 beta releases, and the
- solution was to re#define some core-source variables having these names,
- to give these python variables different names if the build is being done
- on AIX.)
- (6) As mentioned in the README, builds done immediately after previous builds
- (without "make clean" or "make clobber") sometimes fail for mysterious
- reasons. There are some unpredictable results when the configuration
- is changed (that is, if you "configure" with different parameters) or if
- intermediate changes are made to some files. Performing "make clean" or
- "make clobber" resolves the problems.
- ==============================================================================
- THREAD SUPPORT
- ------------------------------------------------------------------------------
- As of AIX version 4, there are two (incompatible) types of pthreads on AIX:
- a) AIX DCE pthreads (on AIX 3.2.5)
- b) AIX 4 pthreads (on AIX 4.1 and up)
- Support has been added to Python to handle the distinction.
- The cc and gcc compilers do not initialize pthreads properly. The only
- compilers that can initialize pthreads properly are IBM *_r* compilers,
- which use the crt0_r.o module, and which invoke ld with the reentrant
- version of libc (libc_r).
- In order to enable thread support, follow these steps:
- 1. Uncomment the thread module in Modules/Setup
- 2. configure --without-gcc --with-thread ...
- 3. make CC="cc_r" OPT="-O -qmaxmem=4000"
- For example, to make with both threads and readline, use:
- ./configure --without-gcc --with-thread --with-readline=/usr/local/lib
- make CC=cc_r OPT="-O2 -qmaxmem=4000"
- If the "make" which is used ignores the "CC=cc_r" directive, one could alias
- the cc command to cc_r (for example, in C-shell, perform an "alias cc cc_r").
- Vladimir Marangozov (Vladimir.Marangozov@imag.fr) provided this information,
- and he reports that a cc_r build initializes threads properly and that all
- demos on threads run okay with cc_r.
- ==============================================================================
- SHARED LIBRARY SUPPORT
- ------------------------------------------------------------------------------
- AIX shared library support was added to Python in the 1.4 release by Manus
- Hand (mhand@csn.net) and Vladimir Marangozov (Vladimir.Marangozov@imag.fr).
- Python modules may now be built as shared libraries on AIX using the normal
- process of uncommenting the "*shared*" line in Modules/Setup before the
- build.
- AIX shared libraries require that an "export" and "import" file be provided
- at compile time to list all extern symbols which may be shared between
- modules. The "export" file (named python.exp) for the modules and the
- libraries that belong to the Python core is created by the "makexp_aix"
- script before performing the link of the python binary. It lists all global
- symbols (exported during the link) of the modules and the libraries that
- make up the python executable.
- When shared library modules (.so files) are made, a second shell script
- is invoked. This script is named "ld_so_aix" and is also provided with
- the distribution in the Modules subdirectory. This script acts as an "ld"
- wrapper which hides the explicit management of "export" and "import" files;
- it adds the appropriate arguments (in the appropriate order) to the link
- command that creates the shared module. Among other things, it specifies
- that the "python.exp" file is an "import" file for the shared module.
- At the time of this writing, neither the python.exp file nor the makexp_aix
- or ld_so_aix scripts are installed by the make procedure, so you should
- remember to keep these and/or copy them to a different location for
- safekeeping if you wish to use them to add shared extension modules to
- python. However, if the make process has been updated since this writing,
- these files MAY have been installed for you during the make by the
- LIBAINSTALL rule, in which case the need to make safe copies is obviated.
- If you wish to add a shared extension module to the language, you would follow
- the steps given in the example below (the example adds the shared extension
- module "spam" to python):
- 1. Make sure that "ld_so_aix" and "makexp_aix" are in your path.
- 2. The "python.exp" file should be in the current directory.
- 3. Issue the following commands or include them in your Makefile:
- cc -c spammodule.c
- ld_so_aix cc spammodule.o -o spammodule.so
- For more detailed information on the shared library support, examine the
- contents of the "ld_so_aix" and "makexp_aix" scripts or refer to the AIX
- documentation.
- NOTE: If the extension module is written in C++ and contains templates,
- an alternative to "ld_so_aix" is the /usr/lpp/xlC/bin/makeC++SharedLib
- script. Chris Myers (myers@TC.Cornell.EDU) reports that ld_so_aix
- works well for some C++ (including the C++ that is generated
- automatically by the Python SWIG package [SWIG can be found at
- http://www.cs.utah.edu/~beazley/SWIG/swig.html]). However, it is not
- known whether makeC++SharedLib can be used as a complete substitute
- for ld_so_aix.
- According to Gary Hook from IBM, the format of the export file changed
- in AIX 4.2. For AIX 4.2 and later, a period "." is required on the
- first line after "#!". If python crashes while importing a shared
- library, you can try modifying the LINKCC variable in the Makefile.
- It probably looks like this:
- LINKCC= $(srcdir)/Modules/makexp_aix Modules/python.exp \"\" $(LIBRARY); $(PURIFY) $(CXX)
- You should modify the \"\" to be a period:
- LINKCC= $(srcdir)/Modules/makexp_aix Modules/python.exp . $(LIBRARY); $(PURIFY) $(CXX)
- Using a period fixed the problem in the snake farm. YMMV.
- This fix has been incorporated into Python 2.3.
- ==============================================================================