Re: [Pythonmac-SIG] building universal binaries

[Ronald Oussoren]

On 3-feb-2006, at 18:28, Bob Ippolito wrote:

On Jan 27, 2006, at 12:19 AM, Ronald Oussoren wrote:

On 27-jan-2006, at 8:46, Kevin Ollivier wrote:

On Jan 26, 2006, at 10:55 PM, Bob Ippolito wrote:

Some extensions aren't going to build cleanly universal, and most users probably aren't going to have all the SDKs installed so if it shipped with universal flags then it wouldn't be able to build extensions.

Unless we had distutils check for the existence of the Universal SDK before setting the flags, or probably more accurately, remove them if the SDK isn't available. Then perhaps add a distutils 'flag' to manually turn off Universal building for extensions that can't be fixed. This might be a bit of a hack, but I don't imagine it would be too painful. The question is how many extensions would have troubles... But I guess the only way we'll know is to test the waters. In any case, even if it wouldn't be reasonable to make a Universal build the "official" build, it would be very useful to people packaging apps, even if it were Tiger+ only.

I know of one popular extension (cElementTree) that won't build with '-arch i386 -arch ppc' because it calcutes a #define based on the current byte-order. There might be others, I haven't done a thorough search yet.

http://svn.red-bean.com/bob/python24-fat/pyconfig.h.in


   first (like Motorola and SPARC, unlike Intel and VAX). */
#ifdef __BIG_ENDIAN__
#define WORDS_BIGENDIAN 1
#else
#ifndef __LITTLE_ENDIAN__
#undef WORDS_BIGENDIAN
#endif
#endif



#ifdef __BIG_ENDIAN__
#define WORD_BIGENDIAN 1
#else
#ifndef __LITTLE_ENDIAN__
/* #undef WORDS_BIGENDIAN */
#endif
#endif

When configured on PPC, it turns into:

#ifdef __BIG_ENDIAN__
#define WORD_BIGENDIAN 1
#else
#ifndef __LITTLE_ENDIAN__
#define WORDS_BIGENDIAN 1
#endif
#endif

In my python24-fat branch, I made the following change to pyconfig.h.in which I believe will resolve that issue in any extension that doesn't do something dumb like trying to grep the endianness out of pyconfig.h: /* Define to 1 if your processor stores words with the most significant byte GCC defines __BIG_ENDIAN__ to 1 when it's compiling a big endian arch... and __LITTLE_ENDIAN__ to 1 when it's compiling on a little endian arch. Configured on i386, this turns into: Since this is GCC, the #ifndef __LITTLE_ENDIAN__ branch is always false... so I'm making this a compile-time not configure-time value, but I left in the configure-time stuff for other platforms.

Ronald

Did you test this? I'd be surprised if distutils honours the ifdef statement. Luckily the easiest way to find the byteorder is sys.byteorder. I have a patched version of pyconfig.h that #includes "macosx- config.h" at the end. This file redefines a number of values based on the cpu-type. Anyone that grabs CPU information from pyconfig.h will get the values from the platform that was used to generate pyconfig.h (an intel system in my case). I like your trick better, mine is a bit too elaborate and not needed until someone wants to do a ppc64 build.

-bob

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