[En-Nut-Discussion] newbie question - NutThreadSwitch in avr

[ares.discuss at gmail.com]

hello

in function NutThreadSwitch() of avr_thread.c
why don't we pop and push r18 ~ r27 ??

another question
when we firstly enter a thread, we pass it a argument by r24 and r25.
But what happend then after reti from nutThreadEntry? Do the argument
will be saved in stack or not? Do we still need r24 and r25 to represent 
argument?

i use avr-gcc compiler.

Thanks a lot
ares.qi