New MacBook Pros Default To 64-bit Kernel

by Christopher Paul on March 20, 2011

Here’s an interesting tip if you’re a Mac user & aren’t running the latest laptops.

Even though Apple’s ‘Snow Leopard’ OS is 64-bit capable on supporting hardware, it still defaults to 32-bit mode by default – unless you’re using the newest MacBook Pros, that is. Now, the laptops come with 64-bit enabled by default. I can’t say I’ve ever needed to boot in 64-bit mode so I’ve generally left the defaults the way they were when the computer was shipped to me. But with Apple forcing the system to a new default, I just might follow.

If you just want to play around with it, Snow Leopard users can hold down the ‘6’ and ‘4’ keys at the same time on boot up. If anything goes haywire, just reboot and the defaults will kick in again.

But if you want to enable 64-bit permanently, type this code in the Terminal:

sudo systemsetup -setkernelbootarchitecture x86_64

And if you want to change it back to be 32-bit by default, type this in the Terminal:

sudo systemsetup -setkernelbootarchitecture i386

Once you make 64-bit the defualt setting, you can go back to 32-bit by pressing and holding the ‘3’ and ‘2’ buttons on boot.

New MacBook Pros default boot in 64-bit mode – 9to5mac.com

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