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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2013-09-10 at 11:39 +0100, Julien Grall wrote:
> 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.

Bit of a shame to have to jump through such hoop, but OK.

Do we keep the unit-address in the datastructure?



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