1 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 54segment. As each segment register covers 256 MiB, a Python program that 55would use more than 256 MiB will raise a MemoryError. The standard 56Python 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 62For example, if you want to allow 512 MiB of memory for Python (this is 63enough 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 68You can allow up to 2 GiB of memory for Python by using the value 690x80000000 for maxdata. 70 71It is also possible to go beyond 2 GiB of memory by activating Large 72Page 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 94* 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 103 104 105 106====================================================================== 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. 131