[U-Boot] [PATCH] toplevel Makefile: Add MPC8641HPCN_36BIT target

[Becky Bruce]

On Nov 6, 2008, at 3:59 PM, Scott Wood wrote:

> Becky Bruce wrote:
>> We don't want PHYS_64BIT on unconditionally.  It has the effect of  
>> moving all the devices into high physical memory, which means you  
>> need a different Linux/dts.
>
> Another reason we should really be packaging the device trees with u- 
> boot.
>
>> I expect the normal case to be that it is off.  Just those few  
>> customers that actually want to do this will use the PHYS_64BIT  
>> version.
>
> OK, though ideally it could be chosen dynamically based on how much  
> memory there is (in u-boot) or #address-cells (in linux).
>

Well, in an ideal world, I'd have an IOMMU ;-)  I left this build-time  
configurable because turning on PHYS_64BIT makes u-boot bigger, and  
there are always people who shout about that.  There are also  
scenarios where you want to run with it enabled, and you don't have a  
lot of RAM.  And, last but not least, I want to be consistent with  
linux, where 36-bit is a build-time configurable thing.  Going to 36- 
bit requires that you know what you're doing - you need a 36b enabled  
kernel and .dts in order to boot - I don't want u-boot silently  
turning it on.  At least not for a while.

-Becky