AVR Assembler options:
-mmcu=[avr-name] select microcontroller variant
[avr-name] can be:
avr1 - classic AVR core without data RAM
avr2 - classic AVR core with up to 8K program memory
avr25 - classic AVR core with up to 8K program memory
plus the MOVW instruction
avr3 - classic AVR core with up to 64K program memory
avr31 - classic AVR core with up to 128K program memory
avr35 - classic AVR core with up to 64K program memory
plus the MOVW instruction
avr4 - enhanced AVR core with up to 8K program memory
avr5 - enhanced AVR core with up to 64K program memory
avr51 - enhanced AVR core with up to 128K program memory
avr6 - enhanced AVR core with up to 256K program memory
avrxmega2 - XMEGA, > 8K, < 64K FLASH, < 64K RAM
avrxmega3 - XMEGA, > 8K, <= 64K FLASH, > 64K RAM
avrxmega4 - XMEGA, > 64K, <= 128K FLASH, <= 64K RAM
avrxmega5 - XMEGA, > 64K, <= 128K FLASH, > 64K RAM
avrxmega6 - XMEGA, > 128K, <= 256K FLASH, <= 64K RAM
avrxmega7 - XMEGA, > 128K, <= 256K FLASH, > 64K RAM
or immediate microcontroller name.