Re: [PATCH v4 0/4] Introduce fdtgrep for subsetting and hashing FDTs

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Wed, Feb 09, 2022 at 06:19:01PM -0600, Rob Herring wrote:
> On Wed, Feb 9, 2022 at 10:04 AM Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> wrote:
> >
> > +Rob Herring
> >
> > Hi David and Rob,
> >
> > On Tue, 8 Feb 2022 at 23:31, David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org> wrote:
> > >
> > > On Tue, Feb 08, 2022 at 02:43:44PM -0700, Simon Glass wrote:
> > > > Hi David,
> > > >
> > > > On Sun, 6 Feb 2022 at 21:10, David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6ryscVyMRj84@public.gmane.org.au> wrote:
> > > > >
> > > > > On Sun, Nov 07, 2021 at 03:43:42PM -0700, Simon Glass wrote:
> > > > > > Note: This was last sent 6 years ago. It really belongs upstream and I
> > > > > > believe it is useful functionality for libfdt, so I am trying again.
> > > > > > Please take a fresh look at this. It is cut back from the previous series.
> > > > > > If accepted we can expand the feature set piece by piece from here.
> > > > >
> > > > > Sorry it's taken me so long to look at this.  Again.  I can't dispute
> > > > > that it's useful for certain use cases.  But as for belonging
> > > > > upstream...
> > > > >
> > > > > This series adds quite a lot of conceptual complexity.  It introduces
> > > > > a new data structure, new state structures, a entirely new mode of
> > > > > working with a tree and a bunch of configuration parameter types on
> > > > > top of the new entry points and new tool.  I still find the semantics
> > > > > of the different criteria for inclusion/exclusion from a region pretty
> > > > > bewildering.
> > > >
> > > > It is sufficient to achieve its purpose, but I don't think it is any
> > > > more complex than that.
> > >
> > > I don't disagree, but that still ends up being quite complex.
> > >
> > > > > That makes me pretty disinclined to add this to the scope of
> > > > > maintenance for libfdt.  As you've probably noticed, I'm already
> > > > > struggling to keep on top of maintenance for the existing libfdt
> > > > > interfaces.  AFAICT everything here can be implemented fairly
> > > > > naturally in terms of libfdt's existing public interface. so I'm not
> > > > > really seeing a compelling reason for this to be merged into libfdt,
> > > > > rather than being its own separate library that depends on libfdt.
> > > >
> > > > Are you suggesting:
> > > >
> > > > 1. that libfdt should move to a new maintainer
> > > > 2. that you would accept these patches if someone else maintained them
> > > > within the libfdt tree
> > > > 3. that we set up a separate tree to fork libfdt, with these changes in
> > > > 4. that we put these changes in a separate tree?
> > >
> > > Right now (4) is what I'm suggesting.  Or to be more precise, creating
> > > a new repo with "libfdtrange" or whatever, that depends on libfdt.
> > >
> > > (1) and/or (2) are potentially worthy of further discussion.  (3) is
> > > just a bad idea, IMO.
> >
> > Where are things going with device tree validation in terms of
> > source-code location?
> 
> Right now it doesn't use libfdt at all, but that's what I'm working on
> if we can get pieces in place to package pylibfdt sorted out. If not,
> I may be doing 3 just for packaging.

It doesn't seem to me that the validation should be using libfdt,
except in a limited capacity for an initial read.  Schema checking is
likely to do lots of random access to various nodes and properties, so
pre-reading the dtb into a "live" tree format seems like it would be a
good idea.

> > Is it likely there might be a separate tree for
> > that, which could perhaps hold other libfdt dependent things?
> 
> It is a separate tree[1], but it's a pure python project and I don't
> think it's the right place for a C library. But we can setup a new
> project in the GH devicetree.org group[2] if you want.
> 
> Rob
> 
> [1] https://github.com/devicetree-org/dt-schema/
> [2] https://github.com/devicetree-org/
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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