Re: [PATCH V1 16/29] xen/arm: Build DOM0 FDT by browsing the device tree structure

[Julien Grall <julien.grall@linaro.org>]

On 09/10/2013 09:58 AM, Ian Campbell wrote:
> On Mon, 2013-09-09 at 22:53 +0100, Julien Grall wrote:
> 
>>>>>
>>>>> This comment is saying that the name of the name property used to be
>>>>> something else? What was it? Which version of FDT was that -- do we need
>>>>> to care?
>>>>
>>>> Right, on older FDT version (< 0x10) each node has 2 different name:
>>>>     - the name just after FDT_BEGIN_NODE in the fdt which correspond to
>>>> the "filename".
>>>>     - the name in property "name" which is a convenient name.
>>>>
>>>> So we can't use the name field in device tree to retrieve the name to
>>>> create the node.
>>>>
>>>> For the FDT version, I don't know if we need to care. Linux pays
>>>> attention to it in the device tree code.
>>>
>>> I'm not sure we need to care either, I expect we will never see <0x10 in
>>> our uses (they are probbaly burnt into the ROMs of PPC machines) but of
>>> it is easy enough to so we might as well I guess?
>>
>> I forgot that there is another issue, the ePAR describes the name has 
>> node-name@unit-address. The name field will contains node-name and not 
>> the full node name.
>>
>> Lets say Xen only uses the field name (ie node-name) to create the FDT 
>> node name. We Linux will create the procfs for the device tree 
>> (/proc/devicetree), it's possible to have numerous warning because there 
>> is 2 nodes with the same name.
> 
> Yes, we need to avoid that. Isn't there a full_name field or something?

The full_name field contains the full path to this node, for instance
/cpus/cpu@0. So we can retrieve the node-name@unit-address with a
basename-like function.

> (I've tripped over this in debugging, it's a bit annoying that name is
> just node-name and not unit-address too)

-- 
Julien Grall