Hi, AFAIU, you build the AVR RTL with dwarf 3 ( doesn't support dwarf 2 ) if you want RTL debugging information. But, the avr-gdb ( at least the latest 3.5.4.1709 from Microchip ( Atmel ) ) supports only dwarf 2. How can I debug the RTL ? regards, -- Dimitrios Chr. Ioannidis