David Laight wrote:
> On Tue, Nov 06, 2007 at 06:39:38PM -0500, Greg Troxel wrote:
>> "Steven M. Bellovin" <smb@cs.columbia.edu> writes:
>>
>>> Some time back, a change was made (by Greg Troxel, I thought) so that
>>> rbus was calculated automatically.  It doesn't seem to happen on
>>> amd64.  I have 3GB machine; here's what happened:
>> That's what I'd expect - I put the heuristic in the i386 machdep code.
>> If you want to add it for amd64, or a different one that matches those
>> platforms, that sounds sensible.  We could also have a common ruotine
>> somewhere, since i386 and amd64 seem to share a lot.
>>
>> But, with amd64 having more address space, the whole notion of using 1G
>> or 2G as the rbus place seems odd.
> 
> It may have more address space, but there is still a physical address
> boundary at 4GB.

David, can you provide some insight into that?

FWIW I several TYAN (and Supermicro, I think) Allow the phyiscal memory 
to be set to continuous or discrete.

I'm otherwise unaware of any boundaries besides the physical address 
size, but there's generally a lot that I'm unaware of :-).

skd

> 
> 	David
>