position independent code

Hi -

for my application I need the ability to load code from a filesystem.

My problem is, that this works only with position independent code.

And as far as I know the nios2-gnutools don't support the generation of pic code.

To get around this, my approach so far is to 'patch' the elf-binary after linking.

I straightened out my issues with data access but I can't think of a way to get around the 'call' opcode for function calls.

In effect 'call' transfers execution to the constant address encoded in the opcode.

But for position independent code I need something of a pc-relative jump.

I know there is 'callr', but the compiler generated code doesn't provide the address in a register as needed by 'callr'.

And I can't modify the opcode, because I only have 1 instruction 'slot' available.

I can't insert new opcodes because this would break the (compiler calculated) intra-function branches.

My question is, has anybody previously tried to load code to an (at link time) unknown address, and what are your experiences?

Thanks,

Wolfgang