[U-Boot] [PATCH v3] common/image.c: align usage of fdt_high with initrd_high

[Shawn Guo]

Hi Simon,

Thanks for looking at the patch.

On 9 February 2012 09:37, Simon Glass <sjg at chromium.org> wrote:
...
>>   fdt_high     - if set this restricts the maximum address that the
>>                  flattened device tree will be copied into upon boot.
>> +                 For example, if you have a system with 1 GB memory
>> +                 at physical address 0x10000000, while Linux kernel
>> +                 only recognizes the first 704 MB as low memory, you
>> +                 may need to set fdt_high as 0x3C000000 to have the
>> +                 device tree blob be copied to the maximum address
>> +                 of the 704 MB low memory, so that Linux kernel can
>> +                 access it during the boot procedure.
>
> I don't entirely understand that - 0x3c000000 is at a 768MB offset
> into kernel space think - where does the 64MB difference come from?
> Perhaps explain that a bit more.
>
All the numbers above come from the real case of Freescale i.MX6Q
Sabrelite board:

0x2C000000 (704 MB) + 0x10000000 (physical base) = 0x3C000000

Regards,
Shawn