Is Snow Leopard on a late 2009 Macbook 64bit or 32?

[Damn Dirty Ape]

Is Snow leopard on a late 2009 macbook 64bit or 32 bit? Can't seem to locate it yet on my stumblings around the OS..

 

[Ka0t1x]

From Wiki:
Mac OS X v10.6 is Apple's first Operating system (OS) that is capable to run on a 64-bit kernel. However, with its first release (v10.6.0), not all 64-bit computers are currently supported. Older 32-bit Cocoa and Carbon applications are still supported.[17] Those Macs with 64-bit capable processors but that can not run the 64-bit kernel can still run 64-bit applications due to Apple's implementation.

This means that you can run a 32bit kernel (OS) and still run 64bit applications. Launching Activity Monitor will show which apps that are currently running in 64bit mode. For 10.6 a lot of the core applications were re-written and optimized for 64bit while stripping out PPC code.

Running uname will give you a current kernel.

hackPro:~ twist$ uname -a
Darwin hackPro.local 10.2.0 
Darwin Kernel Version 10.2.0: Tue Nov  3 10:35:19 PST 2009;
[b]root:xnu-1486.2.11~1/RELEASE_X86_64 x86_64[/b]
hackPro:~ twist$

i386 is 32bit
x86_64 is 64bit

 

[TheStu]

You can force it into 64 bit mode by holding 6 and 4 at boot. And even if the kernel is not in 64bit mode, you can still run 64bit apps.

 

[TheWart]

You can force it into 64 bit mode by holding 6 and 4 at boot. And even if the kernel is not in 64bit mode, you can still run 64bit apps.

As someone who got a June 09 MBP and got SL as part of the $10 upgrade deal, is this forcing the 64 bit mode during install the best way to go?

 

[Damn Dirty Ape]

looks like everything in my activity monitor except the iantivirus by pctools is showing 64-bit so I guess I'm good. Just trying to learn what I can.
thanks

 

[sjwaste]

I think from what I've read elsewhere that it's not really necessary to run the 64 bit kernel unless you plan to run applications that will themselves need to access more than 4GB of RAM.

I'm not sure if I'm recalling correctly, but if you force the 64 bit kernel, you can't run 32 bit binaries at all. Or is that wrong?

 

[Nothinman]

I think from what I've read elsewhere that it's not really necessary to run the 64 bit kernel unless you plan to run applications that will themselves need to access more than 4GB of RAM.

That's true for any OS. Windows muddies the waters by having artificial memory limitations on their 32-bit client OSes though.

I'm not sure if I'm recalling correctly, but if you force the 64 bit kernel, you can't run 32 bit binaries at all. Or is that wrong?

You should be able to. AMD64 CPUs in 64-bit mode can run 32-bit code natively, the OS really just has to make sure the right shared libraries are mapped and such. The fact that OS X runs 64-bit binaries in 32-bit mode is incredibly surprising since it's a huge hack and had to have been so much more work for them to make that work than to just get the 64-bit kernel going.