OpenBoot callback function

[Vincent Pelletier <subdino2004@yahoo.fr>]

Hi.
I'm working on grub2 port on ultrasparc, and I'm searching for docs 
describing how args are passed to the callback function, and how to read 
the result.
I saw silo and kernel uses lots of asm to do that, and I would like to 
avoid it as much as possible.

Thanks,
Vincent Pelletier