Subject: [PATCH v6 9/9] ARM: vexpress: Add Device Tree for V2P-CA15 core tile (TC1 variant)

From: [email-masked] (David Vrabel)
Date: Thu, 19 Jan 2012 17:00:56 +0000

On 19/01/12 14:51, Pawel Moll wrote:
> On Thu, 2012-01-19 at 14:01 +0000, Rob Herring wrote:
>> On 01/19/2012 07:43 AM, Pawel Moll wrote:
>>> On Thu, 2012-01-19 at 13:34 +0000, Rob Herring wrote:
>>>>> You're right - the skeleton.dtsi contains "memory" mode... Funnily
>>>>> enough originally I was using that name, but then Rob Herring suggested
>>>>> changing it to @80000000, which seemed reasonable.
>>>>>
>>>>> Now I wonder - is the "memory" node special and should not contain
>>>>> "@address", or the skelton shouldn't contain the empty "memory" node...
>>>>>
>>>>
>>>> Hummm... I guess you should just use "memory" if you are using
>>>> skeleton.dtsi.
>>>
>>> Well, I don't mind _not_ using skeleton, but I had an impression the
>>> general policy was to use it?
>>
>> Either way is fine. I don't really think it buys you much.
> 
> Ok, /include/ "skeleton.dtsi" is gone then :-)

The problem wasn't with including skeleton.dtsi.  With
CONFIG_ARM_ATAG_DTB_COMPAT the zImage decompressor modifies the appended
DTB using information from the ATAGs (see atags_to_fdt()).

If there's an ATAG giving the amount of RAM the DTB's "memory" node is
replaced with a new one.  Since the vexpress DTBs don't have a "memory"
node it's added and the DTB ends up with two nodes describing memory.

I don't expect any real production vexpress system to use this config
options -- we're using it now when running as a guest under Xen because
Xen doesn't (yet) support device tree and we're using ATAGs to tell the
guest how much RAM it's been allocated.

David