Turn your MacBook in 64 bit

Yes, yes, I know what you’re thinking… sure , boot with 6 and 4 pressed and your Mac will boot in 64 bit mode.

But I’m talking aout the other way around: haveing your modern MacBook booting in 64 bit mode, and possibly turn it into 32 bit only when you need it (sure, by keeping 3 and 2 pressed while booting).

Here’s howto:

1. Check your Mac is capable of doing it by issuing in terminal the command:
   ioreg -l -p IODeviceTree | grep firmware-abi
2. If output is something like “| |   “firmware-abi” = <“EFI64”>” this means Yes, you can!
3. Open a Terminal and cd to /Library/Preferences/SystemConfiguration/
4. edit com.apple.Boot.plist
5. under Kernel Flags insert
   arch=x86_64
   between the <string> and </string> tags
6. reboot
7. Enjoy

Of course, a good pre-check if you could be fine is to boot keeping pressed 6 and 4… if it boots 64bit then you’re ok.