By: Leo D'Adderio
Date Submitted: 2010-03-24
Users who want to run the new 64-bit kernel on late-model Macs (pretty much anything released after early 2008) can do so by booting with the 6 and 4 keys held down. If you're wondering whether your Mac has a 64-bit EFI firmware, you can type this command in Terminal: ioreg -l -p IODeviceTree | grep firmware-abi The response will identify the machine as either having 32-bit or 64-bit EFI.
You can also view additional information on booting 64 bit Mac OS X at this link: