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Guido van Rossumbed266a1996-10-22 22:08:02 +00001Subject: AIX-NOTES FOR 1.4
Guido van Rossum9dc78331996-08-09 14:38:40 +00002From: Manus Hand <Manus.Hand@evolving.com>
3To: Guido van Rossum <guido@CNRI.Reston.VA.US>
Guido van Rossumbed266a1996-10-22 22:08:02 +00004Date: Tue, 22 Oct 1996 16:02:07 -0600 (MDT)
Guido van Rossum9dc78331996-08-09 14:38:40 +00005
6==============================================================================
7 COMPILER INFORMATION
8------------------------------------------------------------------------------
9
10(1) A problem has been reported with "make test" failing because of "weird
11 indentation." Searching the comp.lang.python newsgroup reveals several
12 threads on this subject, and it seems to be a compiler bug in an old
13 version of the AIX CC compiler. However, the compiler/OS combination
14 which has this problem is not identified. In preparation for the 1.4
15 release, Vladimir Marangozov (Vladimir.Marangozov@imag.fr) and Manus Hand
16 (mhand@csn.net) reported no such troubles for the following compilers and
17 operating system versions:
18 AIX C compiler version 3.1.2 on AIX 4.1.3 and AIX 4.1.4
19 AIX C compiler version 1.3.0 on AIX 3.2.5
20 If you have this problem, please report the compiler/OS version.
21
22(2) Stefan Esser (se@MI.Uni-Koeln.DE), in work done to compile Python
23 1.0.0 on AIX 3.2.4, reports that AIX compilers don't like the LANG
24 environment varaiable set to European locales. This makes the compiler
25 generate floating point constants using "," as the decimal seperator,
26 which the assembler doesn't understand (or perhaps it is the other way
27 around, with the assembler expecting, but not getting "," in float
28 numbers). "LANG=C; export LANG" solves the problem, as does
29 "LANG=C $(MAKE) ..." in the master Makefile.
30
31(3) The cc (or xlc) compiler considers "Python/ceval.c" too complex to
32 optimize, except when invoked with "-qmaxmem=4000"
33
34(4) Some problems (due to _AIX not being #defined) when python 1.0.0 was
35 compiled using 'gcc -ansi' were reported by Stefan Esser, but were not
36 investigated.
37
38(5) The cc compiler has internal variables named "__abs" and "__div". These
39 names are reserved and may not be used as program variables in compiled
40 source. (As an anecdote in support of this, the implementation of
41 Python/operator.c had this problem in the 1.4 beta releases, and the
42 solution was to re#define some core-source variables having these names,
43 to give these python variables different names if the build is being done
44 on AIX.)
45
46(6) As mentioned in the README, builds done immediately after previous builds
47 (without "make clean" or "make clobber") sometimes fail for mysterious
48 reasons. There are some unpredictable results when the configuration
49 is changed (that is, if you "configure" with different parameters) or if
50 intermediate changes are made to some files. Performing "make clean" or
51 "make clobber" resolves the problems.
52
53==============================================================================
54 THREAD SUPPORT
55------------------------------------------------------------------------------
56
57AIX uses pthreads. However, as of AIX version 4, there are two (incompatible)
58types of pthreads on AIX:
59 a) AIX DCE pthreads (on AIX 3.2.5)
60 b) AIX 4 pthreads (on AIX 4.1 and up)
61Support has been added to Python to handle the distinction.
62
63The cc and gcc compilers do not initialize pthreads properly. The only
64compilers that can initialize pthreads properly are IBM *_r* compilers,
65which use the crt0_r.o module, and which invoke ld with the reentrant
66version of libc (libc_r).
67
68In order to enable thread support, follow these steps:
69 1. Uncomment the thread module in Modules/Setup
70 2. configure --without-gcc --with-thread ...
71 3. make CC="cc_r" OPT="-O -qmaxmem=4000"
72
73For example, to make with both threads and readline, use:
74 ./configure --without-gcc --with-thread --with-readline=/usr/local/lib
75 make CC=cc_r OPT="-O2 -qmaxmem=4000"
76
77If the "make" which is used ignores the "CC=cc_r" directive, one could alias
78the cc command to cc_r (for example, in C-shell, perform an "alias cc cc_r").
79
80Vladimir Marangozov (Vladimir.Marangozov@imag.fr) provided this information,
81and he reports that a cc_r build initializes threads properly and that all
82demos on threads run okay with cc_r.
83
84==============================================================================
85 SHARED LIBRARY SUPPORT
86------------------------------------------------------------------------------
87
88AIX shared library support was added to Python in the 1.4 release by Manus
89Hand (mhand@csn.net) and Vladimir Marangozov (Vladimir.Marangozov@imag.fr).
90
Guido van Rossumbed266a1996-10-22 22:08:02 +000091Python modules may now be built as shared libraries on AIX using the normal
Guido van Rossum9dc78331996-08-09 14:38:40 +000092process of uncommenting the "*noconfig*" line in Modules/Setup.in before the
93build. There is one additional step required, and that is to also uncomment
94the line in Modules/Setup.in which reads
95 LINKCC= makexp_aix python.exp "" $(MYLIBS) $(ADDOBJS) ; $(CC)
96
97AIX shared libraries require that an "export" and "import" file be provided
98at compile time to list all extern symbols which may be shared between
99modules. The effect of uncommenting the LINKCC line in Modules/Setup.in is
100to create the "export" file for the modules and the libraries that belong to
101the Python core. This is done by the "makexp_aix" script, which creates a
102file named python.exp before performing the link of the python binary.
103
104When shared library modules (.so files) are made, a second shell script
105is invoked. This script is named "ld_so_aix" and is also provided with
106the distribution in the Modules subdirectory. This script acts as an "ld"
107wrapper which hides the explicit management of "export" and "import" files;
108it adds the appropriate arguments (in the appropriate order) to the link
109command that creates the shared module. Among other things, it specifies
110that the "python.exp" file is an "import" file for the shared module.
111
112A default python.exp file is provided with the distribution. It will be
113overwritten (by the action of the makexp_aix script) if you build with shared
114libraries. The python.exp file which comes with the distribution contains
Guido van Rossum5c8e2561996-08-20 20:53:04 +0000115all extern symbols of a completely statically built python executable.
Guido van Rossum9dc78331996-08-09 14:38:40 +0000116Any python.exp file which is created from a build of python with some of the
117modules linked as shared modules will obviously not list symbols from the now
118dynamic modules. The distributed python.exp is provided so that, with
119assistance from the ld_so_aix and makexp_aix scripts, shared extension
120modules may be added to an otherwise completely static python build.
121
122At the time of this writing, neither the python.exp file nor the makexp_aix
123or ld_so_aix scripts are installed by the make procedure, so you should
124remember to keep these and/or copy them to a different location for
125safekeeping if you wish to use them to add shared extension modules to
126python. However, if the make process has been updated since this writing,
127these files MAY have been installed for you during the make by the
128LIBAINSTALL rule, in which case the need to make safe copies is obviated.
129
130If you wish to add a shared extension module to the language, you would follow
131the steps given in the example below (the example adds the shared extension
132module "spam" to python):
133 1. Make sure that "ld_so_aix" and "makexp_aix" are in your path.
134 2. The "python.exp" file should be in the current directory.
135 3. Issue the following commands or include them in your Makefile:
136 cc -c spammodule.c
137 ld_so_aix cc spammodule.o -o spammodule.so
138
139For more detailed information on the shared library support, examine the
140contents of the "ld_so_aix" and "makexp_aix" scripts or refer to the AIX
141documentation.
142
Guido van Rossumbed266a1996-10-22 22:08:02 +0000143NOTE: If the extension module is written in C++ and contains templates,
144 an alternative to "ld_so_aix" is the /usr/lpp/xlC/bin/makeC++SharedLib
145 script. Chris Myers (myers@TC.Cornell.EDU) reports that ld_so_aix
146 works well for some C++ (including the C++ that is generated
147 automatically by the Python SWIG package [SWIG can be found at
148 http://www.cs.utah.edu/~beazley/SWIG/swig.html]). However, it is not
149 known whether makeC++SharedLib can be used as a complete substitute
150 for ld_so_aix.
151
Guido van Rossum9dc78331996-08-09 14:38:40 +0000152==============================================================================