138 lines
5.0 KiB
Plaintext
138 lines
5.0 KiB
Plaintext
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This documentation tries to help people who intend to use Python on
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AIX.
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There used to be many issues with Python on AIX, but the major ones
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have been corrected for version 3.2, so that Python should now work
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rather well on this platform. The remaining known issues are listed in
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this document.
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======================================================================
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Compiling Python
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----------------------------------------------------------------------
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You can compile Python with gcc or the native AIX compiler. The native
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compiler used to give better performances on this system with older
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versions of Python. With Python 3.2 it may not be the case anymore,
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as this compiler does not allow compiling Python with computed gotos.
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Some benchmarks need to be done.
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Compiling with gcc:
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cd Python-3.2
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CC=gcc OPT="-O2" ./configure --enable-shared
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make
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There are various aliases for the native compiler. The recommended
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alias for compiling Python is 'xlc_r', which provides a better level of
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compatibility and handles thread initialization properly.
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It is a good idea to add the '-qmaxmem=70000' option, otherwise the
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compiler considers various files too complex to optimize.
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Compiling with xlc:
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cd Python-3.2
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CC=xlc_r OPT="-O2 -qmaxmem=70000" ./configure --without-computed-gotos --enable-shared
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make
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Note:
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On AIX 5.3 and earlier, you will also need to specify the
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"--disable-ipv6" flag to configure. This has been corrected in AIX
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6.1.
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======================================================================
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Memory Limitations
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----------------------------------------------------------------------
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Note: this section may not apply when compiling Python as a 64 bit
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application.
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By default on AIX each program gets one segment register for its data
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segment. As each segment register covers 256 MB, a Python program that
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would use more than 256MB will raise a MemoryError. The standard
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Python test suite is one such application.
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To allocate more segment registers to Python, you must use the linker
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option -bmaxdata or the ldedit tool to specify the number of bytes you
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need in the data segment.
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For example, if you want to allow 512MB of memory for Python (this is
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enough for the test suite to run without MemoryErrors), you should run
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the following command at the end of compilation:
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ldedit -b maxdata:0x20000000 ./python
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You can allow up to 2GB of memory for Python by using the value
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0x80000000 for maxdata.
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It is also possible to go beyond 2GB of memory by activating Large
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Page Use. You should consult the IBM documentation if you need to use
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this option. You can also follow the discussion of this problem
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in issue 11212 at bugs.python.org.
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http://publib.boulder.ibm.com/infocenter/aix/v6r1/index.jsp?topic=/com.ibm.aix.cmds/doc/aixcmds3/ldedit.htm
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======================================================================
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Known issues
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----------------------------------------------------------------------
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Those issues are currently affecting Python on AIX:
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* Python has not been fully tested on AIX when compiled as a 64 bit
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application.
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* issue 3526: the memory used by a Python process will never be
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released to the system. If you have a Python application on AIX that
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uses a lot of memory, you should read this issue and you may
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consider using the provided patch that implements a custom malloc
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implementation
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* issue 11184: support for large files is currently broken
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* issue 11185: os.wait4 does not behave correctly with option WNOHANG
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* issue 1745108: there may be some problems with curses.panel
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* issue 11192: test_socket fails
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* issue 11190: test_locale fails
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* issue 11193: test_subprocess fails
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* issue 9920: minor arithmetic issues in cmath
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* issue 11215: test_fileio fails
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* issue 11188: test_time fails
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======================================================================
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Implementation details for developers
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----------------------------------------------------------------------
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Python and python modules can now be built as shared libraries on AIX
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as usual.
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AIX shared libraries require that an "export" and "import" file be
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provided at compile time to list all extern symbols which may be
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shared between modules. The "export" file (named python.exp) for the
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modules and the libraries that belong to the Python core is created by
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the "makexp_aix" script before performing the link of the python
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binary. It lists all global symbols (exported during the link) of the
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modules and the libraries that make up the python executable.
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When shared library modules (.so files) are made, a second shell
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script is invoked. This script is named "ld_so_aix" and is also
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provided with the distribution in the Modules subdirectory. This
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script acts as an "ld" wrapper which hides the explicit management of
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"export" and "import" files; it adds the appropriate arguments (in the
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appropriate order) to the link command that creates the shared module.
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Among other things, it specifies that the "python.exp" file is an
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"import" file for the shared module.
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This mechanism should be transparent.
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