Password prompt before OS is boot My Macbook previous OS is Mavericks,one day, i use find my iphone to lock my macbook and the Computer started to prompt me enter password(not the lock my mac Firmware password, i removed it right after the first Firmware password prompt) before the OS start to boot(It's like asking for password on BIOS if it were a PC).Then i upgraded to Yosemite and it's no longer ask me for password before system start booting up. The question is how i can get back the old password prompt, or is it just me confusing that the password is prompt before system start.
To re-enable an EFI password:


Boot into Recovery holding Command+R at the startup chime
From the menu bar, select Utilities > Firmware Password Utility
Enter a Firmware password and quit the Utility pane. 


Note that you’ll only be prompted for this EFI password if you attempt to boot the machine differently than you would normally. Otherwise, you’ll boot directly into OS X at startup without being prompted for the EFI password. 

To re-enable a login password:

Open System Preferences. 


Select Users &amp; Groups > Login Options > Automatic Login: OFF