I have almost completed a bootloader which when you burn it includes TinyTuner. At the end of tinyTuner running, it saves the tuned value into the program memory as part of the bootloader, along with another byte which tells the bootloader to not run the tuning process again. Once tuned, the bootloader is unlocked and the tuning code is erased. From then on in, the OSCCAL value is set from the value stored in program memory.
I have got everything working apart from after the first program is downloaded using the bootloader it nothing works anymore and I haven't yet figured out why.
EDIT:
I know why it doesn't work, I am just trying to figure out how to make the compiler put a function in a specific place.
EDIT2:
Got it working! I now have a self rewriting bootloader which has tiny tuner build in, but takes up no more space than it did before.
(ATTinyCore/tiny/bootloaders/optiboot at master · TCWORLD/ATTinyCore · GitHub)