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Georg Brandl6c9ba242011-02-19 08:44:47 +00001
2This documentation tries to help people who intend to use Python on
3AIX.
4
5There used to be many issues with Python on AIX, but the major ones
6have been corrected for version 3.2, so that Python should now work
7rather well on this platform. The remaining known issues are listed in
8this document.
9
10
11======================================================================
12 Compiling Python
13----------------------------------------------------------------------
14
15You can compile Python with gcc or the native AIX compiler. The native
16compiler used to give better performances on this system with older
17versions of Python. With Python 3.2 it may not be the case anymore,
18as this compiler does not allow compiling Python with computed gotos.
19Some benchmarks need to be done.
20
21Compiling with gcc:
22
23cd Python-3.2
24CC=gcc OPT="-O2" ./configure --enable-shared
25make
26
27There are various aliases for the native compiler. The recommended
28alias for compiling Python is 'xlc_r', which provides a better level of
29compatibility and handles thread initialization properly.
30
31It is a good idea to add the '-qmaxmem=70000' option, otherwise the
32compiler considers various files too complex to optimize.
33
34Compiling with xlc:
35
36cd Python-3.2
37CC=xlc_r OPT="-O2 -qmaxmem=70000" ./configure --without-computed-gotos --enable-shared
38make
39
40Note:
41On AIX 5.3 and earlier, you will also need to specify the
42"--disable-ipv6" flag to configure. This has been corrected in AIX
436.1.
44
45
46======================================================================
47 Memory Limitations
48----------------------------------------------------------------------
49
50Note: this section may not apply when compiling Python as a 64 bit
51application.
52
53By default on AIX each program gets one segment register for its data
Victor Stinner8c663fd2017-11-08 14:44:44 -080054segment. As each segment register covers 256 MiB, a Python program that
55would use more than 256 MiB will raise a MemoryError. The standard
Georg Brandl6c9ba242011-02-19 08:44:47 +000056Python test suite is one such application.
57
58To allocate more segment registers to Python, you must use the linker
59option -bmaxdata or the ldedit tool to specify the number of bytes you
60need in the data segment.
61
Victor Stinner8c663fd2017-11-08 14:44:44 -080062For example, if you want to allow 512 MiB of memory for Python (this is
Georg Brandl6c9ba242011-02-19 08:44:47 +000063enough for the test suite to run without MemoryErrors), you should run
64the following command at the end of compilation:
65
66ldedit -b maxdata:0x20000000 ./python
67
Victor Stinner8c663fd2017-11-08 14:44:44 -080068You can allow up to 2 GiB of memory for Python by using the value
Georg Brandl6c9ba242011-02-19 08:44:47 +0000690x80000000 for maxdata.
70
Victor Stinner8c663fd2017-11-08 14:44:44 -080071It is also possible to go beyond 2 GiB of memory by activating Large
Georg Brandl6c9ba242011-02-19 08:44:47 +000072Page Use. You should consult the IBM documentation if you need to use
73this option. You can also follow the discussion of this problem
74in issue 11212 at bugs.python.org.
75
76http://publib.boulder.ibm.com/infocenter/aix/v6r1/index.jsp?topic=/com.ibm.aix.cmds/doc/aixcmds3/ldedit.htm
77
78
79======================================================================
80 Known issues
81----------------------------------------------------------------------
82
83Those issues are currently affecting Python on AIX:
84
85* Python has not been fully tested on AIX when compiled as a 64 bit
86 application.
87
88* issue 3526: the memory used by a Python process will never be
89 released to the system. If you have a Python application on AIX that
90 uses a lot of memory, you should read this issue and you may
91 consider using the provided patch that implements a custom malloc
92 implementation
93
Georg Brandl6c9ba242011-02-19 08:44:47 +000094* issue 11192: test_socket fails
95
96* issue 11190: test_locale fails
97
98* issue 11193: test_subprocess fails
99
100* issue 9920: minor arithmetic issues in cmath
101
102* issue 11215: test_fileio fails
103
Georg Brandl6c9ba242011-02-19 08:44:47 +0000104
105
106======================================================================
107 Implementation details for developers
108----------------------------------------------------------------------
109
110Python and python modules can now be built as shared libraries on AIX
111as usual.
112
113AIX shared libraries require that an "export" and "import" file be
114provided at compile time to list all extern symbols which may be
115shared between modules. The "export" file (named python.exp) for the
116modules and the libraries that belong to the Python core is created by
117the "makexp_aix" script before performing the link of the python
118binary. It lists all global symbols (exported during the link) of the
119modules and the libraries that make up the python executable.
120
121When shared library modules (.so files) are made, a second shell
122script is invoked. This script is named "ld_so_aix" and is also
123provided with the distribution in the Modules subdirectory. This
124script acts as an "ld" wrapper which hides the explicit management of
125"export" and "import" files; it adds the appropriate arguments (in the
126appropriate order) to the link command that creates the shared module.
127Among other things, it specifies that the "python.exp" file is an
128"import" file for the shared module.
129
130This mechanism should be transparent.