[avr-gcc-list] avoiding custom linker scripts by passing CLI arguments

[kitts]

This is probably nothing to do with AVR, but a recent discussion here and my 
own requirement makes me ask this question...

If i want to use some variables in code that are linker defined, can i pass 
them as information to command line?

Can i define memory sections such that i can use its start and end address 
variables in code?

In the context of AVR, can i write bootloader and application code 
separately and build binary images? In other words, can i inform the linker 
the address range in which the image shall reside?

Although i know this list is for the AVR, my interest in this information is 
generic of the GCC toolchain. My immediate requirement of this kind is for 
the coldfire port.

Any help will be appreciated.
-- 
Cheers!
kitts