Hi,
This is a patch against r1272 which implements fully bootcode booting via Apple boot partition descriptors. The current implementation in libopenbios/bootcode_load.c hardcoded values for QUIK (the old OldWorld bootloader), which is useless if you try to boot anything else.
In particular, I implemented this to simplify my development and test cycle on iQUIK (https://github.com/andreiw/quik), but I also tested this with the NetBSD floppy. The later now boots to stage 2 as well, although it tries using some functionality unavailable in the OpenBIOS implementation when compared to Apple's.
I did this in the simplest way possible.
Btw, I see that the optimization bugs are still present. I had to compile with -O0, otherwise the resulting image doesn't boot (GCC 4.8 here).