How do I tell if I'm using the 64-bit kernel?
Use the System Profiler to determine if you're running a 64-bit kernel.
- From the Apple () menu, choose About this Mac, then click More Info.
- In the Contents pane, select Software.
- If 64-bit Kernel and Extensions is set to Yes, you are running a 64-bit kernel.
Note: A 64-bit kernel is not the same thing as a 64-bit processor.
Does running a 64-bit kernel have an impact on applications I usually run?
No, but it can have a significant impact on kernel extensions, usually used to enable third-party product hardware and special features. 32-bit kernel extensions will not work when your computer is running a 64-bit kernel. Products that use 32-bit kernel extensions may not work or may not recognize their associated hardware. Learn more about compatibility with the 64-bit kernel.
Can I switch between the 64-bit kernel and 32-bit kernel?
If you are using OS X Mountain Lion, switching to a 32-bit kernel is not supported. Mountain Lion uses 64-bit mode.
OS X Lion and earlier versions of OS X support a 32-bit kernel. Switching to the 32-bit kernel allows you use products that use 32-bit kernel extensions.
Can I find out if a kernel extension is 32-bit?
Yes.
- From the Apple () menu, choose About this Mac, then click More Info.
- In the Contents pane, select Extensions. It may take a few moments for all your extensions to be listed.
- Look in the 64-Bit column to determine if an kernel extension is 64-bit compatible. If it is, the entry will be Yes.
Which Apple products ship with a 64-bit kernel as the default configuration?
A list of Macs that use the 64-bit kernel is available here.
