.TH "todo" 3 "24 Jun 2019" "Version 2.0.0" "avr-libc" \" -*- nroff -*- .ad l .nh .SH NAME todo \- Todo List .IP "\fBGroup \fBavr_boot\fP \fP" 1c From email with Marek: On smaller devices (all except ATmega64/128), __SPM_REG is in the I/O space, accessible with the shorter 'in' and 'out' instructions - since the boot loader has a limited size, this could be an important optimization. .PP .PP