[darwinbuild] Selecting arch to build for

Shantonu Sen ssen at opendarwin.org
Thu Aug 4 06:57:26 PDT 2005

On Aug 4, 2005, at 4:35 AM, Alastair Rankine wrote:

> (Darwinports newbie, obviously)

I hope you mean darwinbuild ;-)

> So it seems that when you build xnu, it builds a ppc/i386 universal  
> binary. What is the darwinbuild magic to disable this and allow me  
> to build a kernel that will run on my Powerbook G4?

The universal binary will work fine on your PowerBook. Did you try it?

> I tried modifying the .build/8C46.plist file to add the following  
> to the xnu definition:
>            environment = {
>                RC_ARCHS = "ppc";
>            };
> But no dice. What am I missing?

Which plist did you edit? (the on in $DARWIN_BUILDROOT/.build/ 
8C46.plist, the one in your darwinbuild distribution, or one  
downloaded independently?) Did you do this before or after you did  
"darwinbuild -init 8C46.plist"?

If you did it after, note that plists are only used as a transport  
mechanism to seed your local SQLite database. Once you've done either  
"darwinbuild -init" (or the corresponding set of "darwinxref  
loadIndex" commands), the plist is no longer consulted.

If you edited the plist after configuring your environment, you want  
to reload the index for that build with:
/usr/local/bin/darwinxref loadIndex /path/to/plist/8C46.plist

This worked for me. Your RC_ARCHS change is the right one. The only  
thing this will save you is time, at the expense of falling outside  
the norm of the standard Darwin build configuration. Some projects  
don't built at all unless they are built for all supported  
architectures, but "xnu" should build fine for ppc only if you really  
want this.

> Alternatively, how can I turn the universal binary back into a  
> bootable PPC binary? (possibly not a darwinbuild question)

You can use lipo(1). See the man page for more information. But this  
shouldn't be necessary to get a working kernel.

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