Extended Addressing Mode

[Kumar Gala]

On Oct 22, 2008, at 9:22 AM, Matt Sealey wrote:

>
>
> Kumar Gala wrote:
>> Your bigger issue is if you can setup the DDR controller for the  
>> hole you want.
>
> I just remembered;;
>
> ~~
> The CCSR window always takes precedence over all local access  
> windows. However, the CCSR window must not overlap an LAW that maps  
> to the DDR controller. Otherwise, undefined behavior occurs.
> ~~
>
> So, it's not really possible to map 4GB of RAM in the lower 32-bit  
> area, without interacting badly with the CCSR. This means you're  
> forced to select a 2GB LAW for DDR, then leave 2GB free, then map  
> the rest above.. using more than 2Gb therefore absolutely requires  
> non-contiguous memory..?

As I said, its all about your physical DDR layout.  If you have two  
DDR dimms each 2Gb you can do:

0..2G  - DDR DIMM A
2G..4G - IO
4G..6G - DDR DIMM B

- k