[avr-libc-dev] Position Independent Code / Data (PIC /PID)

[Moritz Struebe]

Hi there,

I developed module support for Nut/OS running on a ATmega128. At the 
moment I allocate memory and then link against this information. Using 
PIC would save me this trouble.

I did some research on PIC/PID & AVR, but mostly found guesswork and/or 
even false information. (Or people complaining that someone posted in an 
AVR and not in the Microchip-Forum. ;-) )
Dunkels et al. say that PIC is limited to 4K [1]. I'm not sure why this 
is the case. Looking at the documentation I come up with +-2^16 words = 
64K.

I'm also not sure how to interpret the |-mshort-calls option. Does this 
mean I get only rjmps and the linker will complain if the jumps get too 
long, or will the Linker silently fail.|

Further on I curious whether it would be (theoretically) possible to let 
the linker decide whether to use jmp or rjmp or even do double rjmps to 
cover the full range. I know, the latter is a bit strange, but would 
enable code > 64K to be position independent.

I was wondering whether PID is supported because it came up in one or 
two threads. But I assume not.

Thanks for your advice.

Cheers
Morty

[1] http://www.sics.se/~adam/dunkels06runtime.pdf