[Pythonmac-SIG] building universal binaries

[Bob Ippolito]

On Jan 26, 2006, at 7:02 PM, Bob Ippolito wrote:

>
> On Jan 26, 2006, at 6:28 PM, Kevin Ollivier wrote:
>
>> On Jan 26, 2006, at 12:48 AM, Ronald Oussoren wrote:
>>
>> [snip]
>>
>>> I'm (very slowly) playing around with adding '-arch ppc -arch i386'
>>> to the build flags and building on an intel host. That way you won't
>>> have to use SDKs, which makes it less likely that configure picks up
>>> other information than the actual compile (not that there should be
>>> any differences if you use the 10.4u SDK).
>>>
>>> With some effort it should be possible to build a version of python
>>> that will run on 10.3 as well. As far as python is concerned the
>>> differences between 10.3 and 10.4 seem to be fairly small. The  
>>> reason
>>> I'd like to do this instead of merging a build-on-10.3 PPC version
>>> and a build-on-10.4 intel version is that the latter would contain
>>> small incompatibilities between the intel and ppc version (some
>>> scripts would work on intel but not on ppc).
>>
>> IMHO, what would be cool is to allow the user to pass the SDK in as
>> some sort of configure flag or maybe a shell variable, something  
>> like:
>>
>> ./configure <flags> MACOSX_SDK=/my/path/to/SDK
>>
>> This, along with the addition of the -arch i386 -arch ppc flags would
>> be enough to enable someone to write a script to create a Panther-
>> compatible Universal build. Which I'm pretty sure someone will do
>> sooner or later. :-)
>
> No, it wouldn't actually.  The 10.3 SDK is ppc only, and a Panther-
> compatible build (well, something compatible with 10.3.8 and below)
> must use GCC 3.3, but an x86 compatible build must use GCC 4.
>
> In other words, something Panther compatible needs to use different
> compilers with totally different options for x86 and PPC.  It's not
> going to be easy, distutils doesn't come anywhere near close to
> supporting anything like that and neither does autoconf.
>
> I think the only approach that doesn't require hacking a significant
> amount of Python's build process and distutils is to have two Python
> installations, one x86 only and one PPC only.  For distribution, you
> would cook up some way to lipo it all together.

Another approach would be to write a little front-end for GCC that  
knows how to mangle the arguments properly so that it ends up running  
GCC 3.3 against the 10.3 SDK then GCC 4 against the universal SDK and  
lipo the object files or output library or bundle together.

-bob