August 19th, 2009

Hold 6 and 4 keys at boot to enable 64-bit Snow Leopard (Updated)

Posted by Jason D. O'Grady @ 9:00 am

Categories: 10.6, 64-bit, kernel

Tags: Kernel, 64-Bit, Network Technology, Processors, Semiconductors, Hardware, Components, Networking, Jason D. O'Grady

As I mentioned in a post last night, the latest developer release of Snow Leopard, a.k.a. Mac OS 10.6 (build 10A432, presumed to be GM) doesn’t automatically boot into the 64-bit kernel except on an Xserve. To boot into 64-bit on any other Mac you must hold down the “6″ and “4″ keys at boot.

Update: There’s a solution to the “64 finger salute” at the end of this post…

Here’s how to tell if you’ve successfully loaded the 64-bit kernel in Snow Leopard:

1. Launch System Profiler (Applications > Utilities > System Profiler or About This Mac > More Info…)
2. Click on the “Software” heading in the left pane
3. Check the “64-bit Kernel and Extensions” line for a Yes or a No.

This is what it looks like in 32-bit:

This is what it looks like when the 64-bit kernel and extensions are loaded:

As I posted yesterday, you can check to see if your Mac has the 64-bit EFI (required to load the 64-bit kernel) by entering the following command in Terminal:

It will return either “EFI32″ or “EFI64.”

According to Apple all system applications except DVD Player, Front Row, Grapher, and iTunes have been rewritten in 64-bit. All we need now is for third-party developers like Mozilla, Microsoft and Adobe (hint, hint!) to start releasing 64-bit apps :)

What applications do you want to go 64-bit first?

Update: If you’re not a fan of having to remember to hold down the “6″ and “4″ keys each time you re-boot, there’s a fix courtesy of Netkas.org:

Edit this file:

Change this:

<key>Kernel Flags</key>
<string></string>

To this:

<key>Kernel Flags</key>
<string>arch=x86_64</string>

Boots into the 64-bit kernel like a charm every time on my MBP.