rEFIt defaulting to 32bit kernel rEFIt is defaulting to the 32bit kernel of OS X which will not boot and will show this error message:



at boot I have to press F2 then manually select the 64bit kernel.  How do I change the default kernel to load?
At the OS X command line, try: sudo nvram boot-args="arch=x86_64".



EDIT:

Try resetting your NVRAM to get you back into OS X.  Since we added a value to the boot-args variable in NVRAM, resetting it will clear it out.

If/Once you get back into OS X, try the following per Apple:

sudo systemsetup -setkernelbootarchitecture x86_64


Rather than write into the NVRAM (which was likely modified by rEFIt), this writes a value to com.apple.Boot.plist and persists on the volume.