Re: can libtool do universal binary

[Peter O'Gorman]

On May 11, 2007, at 4:45 AM, Perrog wrote:

> Hi!
>
> Has anyone been using libtool for universal binary builds on Mach-O/ 
> Mac OS X? Are there any other platform that have similar  
> requirements? In summary, an "universal build" is a Mach-O object  
> or binary file format containing both PowerPC and Intel  
> architectures, in an architecture independend file format.  
> Basically, you run gcc two times and build it for ppc, then for  
> i386. Lastly you use a magic tool, in this case "lipo", that   
> combines the two architectures into a single binary file.
>
> Are there other platforms having parallells to universal builds?  
> What would this really require from libtool? Or should universal  
> builds be handled by other methods?

If you look at the libtool script you'll see that it uses lipo if it  
sees a universal static library that it needs to extract. You'll also  
see that it takes the -arch and -isysroot flags (libtool-1.5.22 and  
later). And if you actually try it, you'll see that it passes its  
testsuite with multiple -arch flags in CFLAGS and CXXFLAGS.

That being said, multi-arch builds with autoconf based projects  
require more than just adding a few -arch flags. You must inspect the  
configure and m4 files and the code to see if there is anywhere that  
needs to test endianness, sizes of pointers etc etc, because  
configure will only run the tests with the native arch. You might  
have to #ifdef a few places in the project.

Peter
--
Peter O'Gorman
http://pogma.com