Re: Call for Testing: Switching back to our BSD licensed dtc(1)

On Fri, Jul 22, 2016 at 1:03 AM, David Chisnall <theraven_at_freebsd.org> wrote:
> On 22 Jul 2016, at 03:40, Warner Losh <imp_at_bsdimp.com> wrote:
>>
>> On Wed, Jul 20, 2016 at 9:51 AM, David Chisnall <theraven_at_freebsd.org> wrote:
>>> On 20 Jul 2016, at 16:46, Warner Losh <imp_at_bsdimp.com> wrote:
>>>>
>>>> I've been trying to get the final spec for it. Right now it's a
>>>> disorganized series
>>>> of patches, some of which have been merge some that haven't. I'll send you a
>>>> copy when I can find something better than "here's the code."
>>>
>>> Thanks.  From the information I can find, it looks as if most of the machinery required to implement it is already in dtc, so it should (hopefully) just be a matter of adding a new keyword to detect plugins, a scan to find the cross-references (or possibly reusing the existing one) and then a little bit of extra logic.
>>
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/overlay-notes.txt
>> has the specs.
>
> Hmm, that’s even less complete than the docs that I’d found.

Can you share that then?

>From that, it seems as if the only thing that dtc needs to do is support the /plugin/ syntax and emit a section describing unresolved references?

I believe so, yes.

>Or is dtc also expected to be able to do the merging?

I think that's TBD. We'll need, at the very least, an update libfdt
from upstream that knows how to do the merging, as well as changes to
/boot/loader to be able to pick and choose which plugins to add to the
base. If we can do all that with the BSDL DTC and it passes all the
other GPL test cases, then we may have a winner and we can get started
integrating plugin support to /boot/loader. I know my RPi would be
happier if it had a 'standard' DTB with a plugin for whatever 1-wire
stuff I'm playing with today.

Warner