Re: [Xen-devel] [PATCH 0/1] Dom0less guest device tree format

[Will Abele <will.abele@xxxxxxxxxx>]

The 07/08/2019 16:18, Julien Grall wrote:
> Hi Will,
> 
> Anything written after -- is usually seen as a signature. This confused my
> e-mail client as it will strip the signature on reply.
> 
> On 7/6/19 10:10 PM, Will Abele wrote:
> > I said in my message that Linux was interpreting the device tree as version 
> > 16.
> > Looking through the code again, I realize it was being interpreted as 
> > earlier
> > than 16. As mentioned in Linux commit 
> > a7e4cfb0a7ca4773e7d0dd1d9c018ab27a15360e,
> > Linux had already broken support for FDT versions earlier than 16.
> > populate_node() in drivers/of/fdt.c would stop parsing the fdt at the root 
> > node
> > if it thought the fdt version was earlier than 16.
> > 
> > Xen sets the FDT version to 17 in fdt_create().
> 
> Thank you for your explanation. However, I still can't match what you say
> with a specification. Please provide a link to the specification and the
> exact paragraph.
> 
> Cheers,
> 
> -- 
> Julien Grall
Hi Julien,

Sorry about my email issues. I'm still getting used to using Mutt.

The Device Tree specification is here:
https://github.com/devicetree-org/devicetree-specification/releases/download/v0.2/devicetree-specification-v0.2.pdf.

Section 2.2.1 paragraph 5 specifies that the root node does not have a node name
or a unit address. Furthermore, a "/" does not appear in the list of valid node
name characters in table 2.1.

There's an example of creating an empty device tree using "" as the root node
name in xen/common/libfdt/fdt_empty_tree.c.

Thanks,
Will

-- 
Will Abele
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