[U-Boot] 4K padding of ARM DT blob

[Simon Glass]

Hi,

On 10 March 2015 at 23:48, Masahiro Yamada
<yamada.masahiro at socionext.com> wrote:
> Hi Yehuda, Tom, Simon,
>
>
>
> 2015-03-07 0:12 GMT+09:00 Tom Rini <trini at konsulko.com>:
>> On Thu, Mar 05, 2015 at 06:20:35PM +0000, Yehuda Yitschak wrote:
>>> Hey Tom
>>>
>>> In arch/arm/dts/Makfile: line 56
>>> "DTC_FLAGS += -R 4 -p 0x1000"
>>>
>>> this tell the dtc tool to add a 4K padding to the device tree blob.
>>>
>>> i can't figure out why this is needed.
>>> Its creating a 4KB penalty on the dtb file so i guess it has some justification.
>>
>> That's interesting and I don't see a corresponding thing in the kernel.
>> Masahiro?  This dates back to the introduction of the Makefile and
>> that's you in the git log, thanks!
>
> Not me!
> I just converted the Makefile into Kbuild style.
>
>
> The option "-R 4 -p 0x1000" was introduced by:
>
> commit bbb0b128c3956ac549471addc314702fbe0ace63
> Author: Simon Glass <sjg at chromium.org>
> Date:   Sat Oct 15 05:48:21 2011 +0000
>
>     fdt: Add support for embedded device tree (CONFIG_OF_EMBED)
>
>
> Simon,
> Looks like the 4K padding was introduced by you.
> Can you explain why?

I think at the time perhaps we were thinking of modifying the FDT in
early U-Boot init, but that did not happen. I think it can be dropped.
Using my time machine I just sent a patch to do this a few weeks ago:

http://patchwork.ozlabs.org/patch/444847/

Regards,
Simon