Re: Claim on IEEE1275

[Hollis Blanchard]

On Dec 29, 2004, at 5:20 AM, Marco Gerards wrote:
> > > Hollis, is the map call really required?  We can better go back to
> > > using grub_ieee1275_claim if it is not.  If it is required, do you
> > > have an idea of how to detect this?
> >
> > It is certainly required: how would you like it if you claimed some
> > memory to write to but it was never mapped?
>
> I assume it is mapped by claim.

If claim also called map, we would not have needed to add an explicit 
map call. See also the IEEE1275 description of "claim":
	Claim does not automatically create an address translation for the 
allocated resource.
        See 3.6.5.

> Anyway, yaboot does not use map and neither does linux, as it seems.

Linux does not because it terminates OF and takes over the MMU itself.

As for yaboot, it does not run on Old World Macintosh, and described in 
the thread starting at 
http://lists.gnu.org/archive/html/grub-devel/2004-09/msg00014.html, I 
needed to use map on Old World. If it is *only* needed on Old World, 
then we could add another flag to grub_ieee1275_flags.

> > There is a "real-mode?" configuration variable, but I think that just
> > specifies OF's translation mode, independent of the client's mode (see
> > the IEEE1275 PowerPC and CHRP bindings). Knowing the value of that
> > variable might be interesting but I wouldn't recommend changing it, as
> > Apple firmware in particular is known to die a horrible death by
> > mucking with one of those settings (I'm pretty sure it's 
> > "real-mode?").
>
> On my powerbook it is set to false, while it is set to true on the
> pegasos.  So what do you suggest?  Using map when it is set to false?

You said that both the PowerBook and the Pegasos work without the map 
call, so if the briQ works too then I think we should use the approach 
described above.

-Hollis