Wrong lock bits for UNO, MEGA and other boards with 328 and 2560

[vidmo91]

Datasheet states (Atmel-42735B-ATmega328/P_Datasheet_Complete-11/2016, chapter 31, page 347), that lock bits 6 and 7 are unused and by default value is 1. Avrdude cant verify them after programming to 0, because they can't be programmed:
avrdude: verification error, first mismatch at byte 0x0000
         0xff != 0x3f

wrong, not working, default values:
uno.bootloader.unlock_bits=0x3F
uno.bootloader.lock_bits=0x0F
correct, working ones:
uno.bootloader.unlock_bits=0xFF
uno.bootloader.lock_bits=0xCF

[facchinm]

Hi @vidmo91 ,
this problem was fixed by updating avrdude just before 1.6.12 (see #5202 for more info). The mainline version (6.3) doesn't contain the patch so it fails when checking the fuses. We didn't change all the values in boards.txt for compatibility reasons and only a warning should be reported if you use the bundled tools.