[avr-gcc-list] Fixed Registers -ffixed

[Ram Kumar Rengaswamy]

Hi,
     I need to prevent the C code from using a pair of registers  
that I wish to use in an assembly routine.

When I try to compile my application with the option -ffixed-r2 and - 
ffixed-r3, I get the following error:

error: can't find a register in class `BASE_POINTER_REGS' while  
reloading `asm'

Is there a work around to this problem or is it a limitation of the  
compiler ?
Is there any particular set of registers that are better suited to be  
fixed than others ?

Thanks,
-Ram