[Etherboot-developers] Relocation problems

[Michael B. <mb...@fe...>]

I'm having big problems getting the UNDI driver to work with relocation.  
An UNDI API call that works fine when the Etherboot code is in base memory 
fails when called with the *exact* same parameters (i.e. all the real-mode 
segment:offset addresses are the same) if the Etherboot code has been 
relocated out of base memory.  This is the very first UNDI API call: the 
one that installs the UNDI driver into base memory (the base memory having 
been allocated using allot_base_memory()).

The problem is not intrinsic to -DRELOCATE; I have tried compiling with 
-DRELOCATE and an edited version of core/relocate.c that forces the 
relocation target address to be the original address (i.e. no move).  This 
works, proving that there is no problematic code included by -DRELOCATE.  
The Etherboot UNDI driver itself is -DRELOCATE-agnostic; the only call 
that cares about relocation (undi_transmit()) sorts itself out at run-time 
rather than compile-time and, in any case, it's not even getting that far.

I am certain that the correct parameters are being passed to the UNDI API 
routine.

Within the "10: .code16" section of a real-mode call, are there any 
registers (other than %ss and %sp) that need to be preserved in order for 
the return from real mode to function correctly?

Any other ideas very welcome; I've run out.

Michael