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

Becky Bruce
2008-11-06T22:07:43Z

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