[OpenBIOS] [PATCH] Use exception vectors from ROM instead of copying them to page zero

[Segher Boessenkool]

> >Many OSes use 0000..00ff for their own purposes.  OpenBIOS should
> >not use that area for anything, for its own good.
> 
> Really?

Yes, really.  I'm sorry.

The elephant in the room is Linux of course (although it kills OF
really early so things might just work).

> That's really useful to know - is this documented anywhere so we 
> can find more information about it?

0000..00ff is documented as "reserved".  Many people read that as
"reserved for me to abuse" :-/

> While the patch works, like Alex I'm 
> slightly nervous as to why it was written this way in the first place. 
> Are there any other assumptions that we're not aware of?

Don't use anything below 3000 for anything else than exception vectors.
Don't forget that sometimes new exception vectors are added, sometimes
not at multiples of 100 or even 80.

I expect this code was written this way to save some code space; the
big empty holes in the exception table just beg to be filled up.


Segher