Which Bootloader hex file for Arduino uno r3

Other Hardware 3rd Party Boards
1

HI all,
I'm not sure that this is a correct section of forum but I thin to have a sinple question

I need ti know which bootloader Hex file I can upload to the micro (atmega328) for uni R3 board

In the folder C:\Programmi\Arduino\hardware\arduino\bootloaders there are many file, I'm comfused

Somebody can you suggest me the correct bootloader file?
Thanks
Andrea

2

The bootloader is: hardware/<build.core>/bootloaders/<bootloader.path>/<bootloader.file>

The boards.txt file says:

uno.name=Arduino Uno
uno.bootloader.path=optiboot
uno.bootloader.file=optiboot_atmega328.hex
uno.build.core=arduino

So that means the UNO bootloader (all revisions) is:
hardware/arduino/bootloaders/optiboot/optiboot_atmega328.hex