The whole 64 Bit Snow Leopard hoopla got a little murky when it was discovered that Snow Leopard’s kernal is really booting into 32 Bit on some systems.
Is your Snow Leopard booting in 32 Bit or 64 Bit? Should you even care? If your Mac could, would you want it to? How do you load the 64Bit Kernal? Fortunately, all those questions are easily answered.
Why 32Bit or 64Bit?
It’s easy for the uninformed to scream that they’ve been robbed, but the truth is that Apple did this so certain models didn’t have hardware conflicts with 64 Bit drivers. The 64Bit Applications, with their better performance and more addressable memory function just fine running as 64Bit apps within a 32Bit Kernal.
See, in 32Bit mode – 32Bit drivers are loaded. In 64Bit, the 64Bit drivers are loaded. You may have noticed that Windows XP, Vista and 7 all have 64Bit counterparts and to run them, you have to wipe the existing OS and do a full install. Those with 64Bit Windows experience know that some drivers, hardware and software don’t work in 64Bit land. Want to go back? Then repeat the wipe and full install.
Apple decided not to put you through this with Snow Leopard.
What if you want to run in 64Bit mode?
First, you need to know if your system is capable of running in full 64Bit glory. While some models are capable, only the XServes run in full 64Bit by default. Then, you need to know if your system is allowed by Apple to boot in 64Bit mode. Does it have 64Bit EFI? Is it disabled by Apple even if it can technically run in 64Bit mode?
You can safely put the 32Bit or 64Bit boot question to rest with Startup Mode Selector by Markus Winter.
Startup Mode Selector will tell you:
– If you have a 32-bit or 64-bit capable processor.
– If you have a 32-bit or 64-bit EFI
– If your Mac’s Kernal is set to boot in 32-bit or 64-bit mode.
– If your Mac is running in 32-bit or 64-bit mode.
– If 64-bit mode is officially supported on your Mac.
You can then select whether you want to boot in 32-bit or 64-bit mode. All without futzing around in the terminal.
Note: As of this writing, Apple does not officially support booting into 64-bit mode in 64-bit capable MacBooks. Selecting 64-bit in Startup Mode Selector may or may not work with a MacBook, depending on your model.