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I'm having issues with interpretting how OSX devices interface with 32/64 bit kernels and architectures. I don't even know how to work this.

So maybe someone can help me out. I need to run in a 64bit environment as I'm trying to test some software that required 64 bit. I'm still running into weird issues that point to it being an architecture issue, however, according to System Profiler and generic commands on the system, I'm running both - which is rather confusing. Sort me out, PLEASE!

Here's the two commands (and their corresponding output):

drew - ~ $ uname -m 
drew - ~ $ arch

And a screenshot:

enter image description here

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As far as your software is concerned, Snow Leopard builds x86_64 by default. – fideli Jul 29 '11 at 3:47
My overall question is why does there appear to be a difference between the two commands? – drewrockshard Jul 29 '11 at 3:53
up vote 1 down vote accepted

My best guess would be that this is a unintended bug in the arch command. All recent Macs are 64-bit and Lion is clearly booting 64 by default (as you have shown). It's quite possible that apple simply didn't update arch in the .0 release of Lion.

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I'll check that out when I upgrade to Lion, but I'm still on Snow Leopard (plan on upgrading in about a week). – drewrockshard Jul 29 '11 at 4:55
Christopher is right. If uname shows x86_64 then you're running the 64-bit kernel. – bahamat Jul 29 '11 at 5:03
I tested it before posting and I'm on Lion, exactly same results as you've gotten, so it definitely may be an older issue. – Christopher Keller Jul 29 '11 at 5:05
Okay, just making sure I'm not crazy. IF you can reproduce it too, then it must be an issue with the arch command. I come from a Unix background, so I'm used to just using uname and I believe that one over the arch command. Just didn't know if OSX used some sort of "special" feature that I didn't know about. – drewrockshard Jul 29 '11 at 6:42

Here's a presentation given a few years ago that gives a good introduction to the OS-X kernel architecture.

The original link was from the XNU wiki.

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This doesn't answer my question. My question would be why uname gives me 64bit and arch command tells me its 32bit. – drewrockshard Jul 29 '11 at 4:03

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