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Good evening
I'm in Snow Leopard, a Macbook with Intel Core 2 Duo 2 GHz.
Except that in "About this Mac, I see this mark: "64-bit Kernel and Extensions: No"
Could someone tell me what it means when I'm in Snow Leopard? Thank you and happy new year in advance.
It means that the snow leopard operating system starts in 32-bit by default, which is normal mode. Snow Leopard OS loads with a 32-bit kernel by default , despite running 64-bit applications. The Apple's X-Serve products, using Snow Leopard Server only boots into a 64-bit kernel by default.
The terms 32-bit and 64-bit refer to the way processor process data. In most all cases, the 64-bit version of and O/S will handle data faster, due to the the way it's processed in the hardware. Your Intel processor contain 64 bit cores but the O/S has the limitation due to the lack of 64 bit support.
In addition, the Mac OS X kernel has been rebuilt to run in 64-bit mode on some machines. On those machines, Snow Leopard supports up to 16 terabytes of RAM. Newer Xserve and Mac Pro machines will run a 64-bit kernel by default; newer iMac machines can run a 64-bit kernel, but will not do so by default. Users wishing to use the 64-bit kernel on those machines must hold down the numbers 6 & 4 while booting to get the 64-bit kernel to load. A change to the com.apple.Boot.plist will also enable users with compatible computers to permanently boot into 64-bit for those wishing to do so.
Source: wikipedia.org
Apple has limit 64bit support to Xserve machines for now because 3rd party drivers are not yet updated like for printers, scanner etc for 64bit support. To ensure simplicity and flexibility, Mac OS X still comes in one version that runs both 64-bit and 32-bit applications. So you don’t need to update everything on your system just to run a single 64-bit program. And new 64-bit applications work just fine with your existing storage devices, PCI cards, and Snow Leopard-compatible printers.