Compiling python extension on amd64 for 32 bit

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  • Mathias Waack
    #1

    Compiling python extension on amd64 for 32 bit

    After switching my development environment to 64 bit I've got a problem with
    a python extension for a 32 bit application. Compiling the app under Linux
    results in the following error:

    g++ -m32 -Wall -g -O2 -I. -Idb -DPYTHON=25 -o mappy.o -c mappy.cpp
    In file included from /usr/include/python2.5/Python.h:57,
    from mappy.cpp:29:
    /usr/include/python2.5/pyport.h:732:2: error: #error "LONG_BIT definition
    appears wrong for platform (bad gcc/glibc config?)."

    My gcc is:

    Using built-in specs.
    Target: x86_64-suse-linux
    Configured with: ../configure --enable-threads=posix --prefix=/usr
    --with-local-prefix=/usr/local --infodir=/usr/share/info --mandir=/usr/share/man
    --libdir=/usr/lib64 --libexecdir=/usr/lib64
    --enable-languages=c,c++ ,objc,fortran,o bj-c++,java,ada
    --enable-checking=releas e
    --with-gxx-include-dir=/usr/include/c++/4.1.2
    --enable-ssp --disable-libssp
    --disable-libgcj --with-slibdir=/lib64
    --with-system-zlib --enable-shared --enable-__cxa_atexit
    --enable-libstdcxx-allocator=new --program-suffix=-4.1
    --enable-version-specific-runtime-libs --without-system-libunwind --with-cpu=generic
    --host=x86_64-suse-linux
    Thread model: posix
    gcc version 4.1.2 20061115 (prerelease) (SUSE Linux)

    So I've checked this magic LONG_BIT define:

    #:/tmp cat t.c
    #include <stdio.h>
    #include <bits/xopen_lim.h>

    int main()
    {
    printf("%d\n",s izeof(long));
    printf("%d\n",L ONG_BIT);
    return 0;
    }
    #:/tmp gcc t.c
    #:/tmp ./a.out
    8
    64
    #:/tmp gcc -m32 t.c
    #:/tmp ./a.out
    4
    32

    Ok, thats fine. So why is python complaining? Or even more interesting, what
    do I have to do to compile the code?

    Mathias
    Tags: None
    • Andrew MacIntyre
      #2
      Re: Compiling python extension on amd64 for 32 bit

      Mathias Waack wrote:
      After switching my development environment to 64 bit I've got a problem with
      a python extension for a 32 bit application.
      {...}
      Ok, thats fine. So why is python complaining? Or even more interesting, what
      do I have to do to compile the code?
      Is the Python your toolchain is referencing 32 or 64 bit? Based on what
      I can see in pyport.h, I'd guess that you're finding a 64 bit Python (ie
      SIZEOF_LONG == 8).

      --
      -------------------------------------------------------------------------
      Andrew I MacIntyre "These thoughts are mine alone..."
      E-mail: andymac@bullsey e.apana.org.au (pref) | Snail: PO Box 370
      andymac@pcug.or g.au (alt) | Belconnen ACT 2616
      Web: http://www.andymac.org/ | Australia

        Comment

        • Mathias Waack
          #3
          Re: Compiling python extension on amd64 for 32 bit

          Andrew MacIntyre wrote:
          Mathias Waack wrote:
          >After switching my development environment to 64 bit I've got a
          >problem with a python extension for a 32 bit application.
          >
          {...}
          >
          >Ok, thats fine. So why is python complaining? Or even more
          >interesting, what do I have to do to compile the code?
          >
          Is the Python your toolchain is referencing 32 or 64 bit? Based on
          what I can see in pyport.h, I'd guess that you're finding a 64 bit
          Python (ie SIZEOF_LONG == 8).
          There is no such thing as "the Python". A biarch environment offers
          both the 32 bit and the 64 bit versions of each library. And unique
          headers, because its assumed that the headers are independent of the
          architecture. Because of the -m32 Flag the pyport.h is used within a
          32 bit env.

          Mathias

            Comment

            • Andrew MacIntyre
              #4
              Re: Compiling python extension on amd64 for 32 bit

              Mathias Waack wrote:
              Andrew MacIntyre wrote:
              >
              >Mathias Waack wrote:
              >>After switching my development environment to 64 bit I've got a
              >>problem with a python extension for a 32 bit application.
              >{...}
              >>
              >>Ok, thats fine. So why is python complaining? Or even more
              >>interesting , what do I have to do to compile the code?
              >Is the Python your toolchain is referencing 32 or 64 bit? Based on
              >what I can see in pyport.h, I'd guess that you're finding a 64 bit
              >Python (ie SIZEOF_LONG == 8).
              >
              There is no such thing as "the Python". A biarch environment offers
              both the 32 bit and the 64 bit versions of each library. And unique
              headers, because its assumed that the headers are independent of the
              architecture. Because of the -m32 Flag the pyport.h is used within a
              32 bit env.
              Every Python installation has an architecture dependent header
              (pyconfig.h), unless a vendor specifically creates a replacement which
              neutralises this; that header contains the definition (SIZEOF_LONG) that
              triggers your problem.

              --
              -------------------------------------------------------------------------
              Andrew I MacIntyre "These thoughts are mine alone..."
              E-mail: andymac@bullsey e.apana.org.au (pref) | Snail: PO Box 370
              andymac@pcug.or g.au (alt) | Belconnen ACT 2616
              Web: http://www.andymac.org/ | Australia

                Comment

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