Per iniziare con un kernel speciale, controlla questo da Apple: Avvio con il kernel a 32-bit o 64-bit in 10.6 e versioni successive :
Startup key combination (for current startup only)
If your Mac uses the 32-bit kernel by default, but supports the 64-bit
kernel, you can start up using the 64-bit kernel by holding the
6 and 4 keys during startup.
If your Mac uses the 64-bit kernel by default, you can start up with
the 32-bit kernel by holding the 3 and 2 keys
during startup.
Your Mac will revert to the default kernel the next time you reboot
it.
On-disk setting (persistent)
To select the 64-bit kernel for the current startup disk, use the
following command in Terminal:
sudo systemsetup -setkernelbootarchitecture x86_64
To select the 32-bit kernel for the current startup disk, use the
following command in Terminal:
sudo systemsetup -setkernelbootarchitecture i386
Note: This setting is stored in the
/Library/Preferences/SystemConfiguration/com.apple.Boot.plist
file
and will take effect every time you start up from this disk. If you
start up from a different disk, the setting on that disk, or the
hardware default, will take effect.
Per determinare il tuo kernel attualmente in esecuzione apri Terminal.app
e inserisci:
uname -a
Funzionando con il kernel a 64 bit, l'output terminerà con RELEASE_X86_64 x86_64
. Funzionando con il kernel a 32 bit, l'output terminerà con RELEASE_I386 i386
.
Nel tuo caso devi solo aggiornare a Mavericks (Mac OS X 10.9). Mavericks non contiene più un kernel a 32 bit e dal momento che il tuo processore i7 è a 64 bit, tutto funziona senza l'uso di tratti chiave o modifica di com.apple.Boot.plist
.