Experimental Physics and
Industrial Control System

"J. Lewis Muir" <[email protected]> · Tue, 28 Jun 2011 12:48:29 -0500

On 6/28/11 12:01 PM, Andrew Johnson wrote:
> Oh, and one more reason: The regular darwin i386 class is LP64 anyway, meaning 
> longs and pointers are 64-bits wide even when ARCH_CLASS is i386.

Hi, Andrew.

I'm confused by this.  Are you sure?

On a MacBook Pro running a 32-bit kernel, your test program
prints 32.

On my Mac running a 64-bit kernel, it prints 64.  If I build it
as a fat binary by passing "-arch i386" and "-arch x86_64" as
options to gcc it prints 32 if I run the i386 machine code and
64 if I run the x86_64 machine code.  I did this with the arch
command:

$ lipo -info main
Architectures in the fat file: main are: i386 x86_64
$ arch -arch i386 ./main
32
$ arch -arch x86_64 ./main
64

Lewis

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System