How to tell when app will run in 64-bit mode?

[Jon Gotow]

At 12:12 PM -0500 2/6/08, Ben Allison wrote:
>You can use the cpusubtype member of the fat_arch struct in the 
>Mach-O header to determine the CPU type for a particular section. 
>man arch enumerates the CPU types; in particular, you would look for 
>CPU_SUBTYPE_POWERPC64_ALL and CPU_SUBTYPE_X86_64_ALL.

Heh - I was busy answering your last post.  NXGetLocalArchInfo() 
gives me a cputype of CPU_TYPE_X86 and a cputsubtype of 
CPU_SUBTYPE_486 on both my Core Duo and Core 2 Duo machines, so that 
doesn't appear to be any help.

How does the loader determine which binary to run?  It doesn't appear 
to be using NXFindBestFatArch() with the results of 
NXGetLocalArchInfo(), because when I do that, it always gives me the 
32-bit section.

  - Jon

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         Jon Gotow                     gotow at stclairsoft.com
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