Re: Open Firmware: claiming and mapping memory

[Hollis Blanchard]

On Sep 5, 2004, at 4:30 AM, Marco Gerards wrote:
> > FYI, the linux loader didn't need any modifications other than adding
> > a "map" call-method in addition to the current "claim".
>
> Perhaps it would be better to change claim so it checks for a buggy
> claim.  What do you think about that?

What do you mean by "buggy claim"? There are two operations
you must perform before using memory: claim, which notifies other 
potential users (e.g OF or the Linux kernel) that those physical 
addresses are in use; and map, which allows us to actually touch those 
addresses we claimed.

IEEE1275 Appendix A's description of "claim" states this explicitly: 
"Claim does not automatically create an address translation for the 
allocated resource. See 3.6.5". The reason that confuses me is that 
3.6.5's description of claim says the first argument is a "virtual" 
address...

Ah. The trouble may be that there are two "claim" words. One is 
generic, and one is a method of of the MMU package. I suspect the MMU's 
claim will both reserve and map the region requested. I'll try this out 
later, or maybe tomorrow...

-Hollis