My Xperia P is one of that specials one that canīt be bootloader unlock. I already make the process:
First, you should confirm that it is possible to unlock the boot loader of your phone by checking the service menu. In your phone, open the dialler and enter *#*#7378423#*#* to access the service menu.
In your phone, tap Service info > Configuration > Rooting Status. If Bootloader unlock allowed says Yes, then you can continue with the next step. If it says No, or if the status is missing, your device cannot be unlocked.
and of course is NO.
After all this time , out there is any solution for unlock bootloader?