IDE 1.6.12 - WARNING on Burn Bootloader

[logicaprogrammabile]

hi
i burned bootloader to an atmega328p with ArduinoISP and the result is:

***failed;
avrdude: WARNING: invalid value for unused bits in fuse "efuse", should be set to 1 according to datasheet
This behaviour is deprecated and will result in an error in future version
You probably want to use 0xfd instead of 0x05 (double check with your datasheet first).

but the ide returns:
done burning bootloader

i have modified the board.txt at line
uno.bootloader.extended_fuses=0x05

to
uno.bootloader.extended_fuses=0xFD

This change eliminates the warning message
it's correct?

tnks

[facchinm]

It's indeed the correct behaviour. The first run didn't fail indeed (I don't know where that ***failed; comes from). We still didn't merge #5182 for compatibility, we'll do it in one of the future releases.
Closing as expected (please reopen it if the first run really failed => the bootloader was not burned)

[JeroenIoT]

Thanks. I had the same message / warning when burning bootloader. However the funny thing is that when I change the boards.txt (to 0xfd) I still get the same warning (restarted of course and using Arduino IDE 1.6.12)

SOLVED -> avrdude.conf which was used was in another directory (AppData/local/Arduino .....). So conf file was at 2 different dir

[RichieDevereux]

Where do I find the boards.txt file?