Re: devicetree repository separation/migration

[Sascha Hauer <s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

On Fri, Feb 21, 2014 at 11:27:29AM -0700, Warner Losh wrote:
> 
> On Feb 20, 2014, at 4:38 AM, Grant Likely wrote:
> 
> > On Wed, 19 Feb 2014 13:20:15 -0800, Olof Johansson <olof-nZhT3qVonbNeoWH0uzbU5w@public.gmane.org> wrote:
> >> On Wed, Feb 19, 2014 at 1:12 PM, Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >>> One way to minimize the inconvenience is keep versioning and dev
> >>> cycles in sync with the kernel. We could also start doing things to
> >>> align the kernel workflow with how things will work when we do have a
> >>> separate repository.
> >> 
> >> I don't think aligning development cycles is what we want most here it
> >> might be useful for us in Linux but it'll make things difficult for
> >> other projects since they're not aware of our release cycles. The
> >> device tree bindings and DT contents in that repo should be "always
> >> stable", i.e. no merge window / rc concept. As soon as something goes
> >> in it's live, and from then out only fixes to the DTS files (or
> >> appending the binding).
> >> 
> >> For example, I don't want to have to track two trees to test against
> >> -- I'll want to keep one repo of the very latest DT files and always
> >> use those to boot any and all boards.
> > 
> > This approach does have the subtle side effect that differs from what we
> > discussed in Edinburgh.  We've talked about always being able to boot a
> > new kernel on an old devicetree, but not a new devicetree on an old
> > kernel. With a separate board database repo we are going to hit both
> > cases. At least to a limited extent we're going to need older kernels
> > booting with the latest devicetree, and we'll need some rules about how
> > that gets applied.
> 
> I wasn't in Edinburgh...  Was this at the binary level or at the
> source level? I'm thinking specifically about the move to cpp in the
> back of my mind...

Only the binary compatibility matters. The source can change
without breaking compatibility between kernels and devicetrees.

Sascha

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