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 MB, a Python program that 55would use more than 256MB 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 512MB 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 2GB of memory for Python by using the value 690x80000000 for maxdata. 70 71It is also possible to go beyond 2GB 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 11184: support for large files is currently broken 95 96* issue 11185: os.wait4 does not behave correctly with option WNOHANG 97 98* issue 1745108: there may be some problems with curses.panel 99 100* issue 11192: test_socket fails 101 102* issue 11190: test_locale fails 103 104* issue 11193: test_subprocess fails 105 106* issue 9920: minor arithmetic issues in cmath 107 108* issue 11215: test_fileio fails 109 110* issue 11188: test_time fails 111 112 113====================================================================== 114 Implementation details for developers 115---------------------------------------------------------------------- 116 117Python and python modules can now be built as shared libraries on AIX 118as usual. 119 120AIX shared libraries require that an "export" and "import" file be 121provided at compile time to list all extern symbols which may be 122shared between modules. The "export" file (named python.exp) for the 123modules and the libraries that belong to the Python core is created by 124the "makexp_aix" script before performing the link of the python 125binary. It lists all global symbols (exported during the link) of the 126modules and the libraries that make up the python executable. 127 128When shared library modules (.so files) are made, a second shell 129script is invoked. This script is named "ld_so_aix" and is also 130provided with the distribution in the Modules subdirectory. This 131script acts as an "ld" wrapper which hides the explicit management of 132"export" and "import" files; it adds the appropriate arguments (in the 133appropriate order) to the link command that creates the shared module. 134Among other things, it specifies that the "python.exp" file is an 135"import" file for the shared module. 136 137This mechanism should be transparent. 138