Review request -- splitting OF enumeration from nexus

[Justin Hibbits]

On Sun, Oct 31, 2010 at 4:44 PM, Nathan Whitehorn <nwhitehorn at freebsd.org>wrote:

> Nexus on OF platforms doesn't behave like nexus on x86, which generates
> some periodic difficulty with cryptosoft or syscons attaching to all devices
> and taking over the system when someone makes a wrong assumption. I have
> done some work to split out OF enumeration into a new, acpi(4)-like bus
> called ofwbus that does all of the OF enumeration previously done by
> nexus(4). The patch can be found at
> http://people.freebsd.org/~nwhitehorn/ofwbus.diff.
>
> Doing this also provides a number of other benefits: it shares code between
> PowerPC and sparc64, unifies the AIM and Book-E nexus implementations on
> PPC, and makes it easier to have non-Open Firmware platforms on PPC (the
> original motivation for the work). I have tested this code with no obvious
> problems on a variety of Apple PPC machines and a Sun Ultra 5. More testing
> and comments would be much appreciated. If no has any objections, I will
> commit these changes in 2 weeks.
> -Nathan
>

Building world now, and will test when I get home this evening.

A note to others:  powerpc/powerpc/nexus.c is a resurrected file, so I
needed to copy it from powerpc/aim/nexus.c before the patch would apply.

- Justin