On Thu, Feb 21, 2019 at 12:10:08PM +0800, Chen-Yu Tsai wrote:
> On Thu, Feb 21, 2019 at 12:03 PM David Gibson
> <david@xxxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > On Thu, Feb 21, 2019 at 11:51:05AM +0800, Chen-Yu Tsai wrote:
> > > Commit 4038fd90056e ("dtc: add ability to make nodes conditional on them
> > > being referenced") added the new /omit-if-no-ref/ directive to mark
> > > nodes as eligible to be discarded if not referenced. The mechanism to
> > > process this happens before the symbol generation phase. This means even
> > > if symbol generation is requested and the node has a label, it will be
> > > discarded if there are no references to it within the same file.
> > >
> > > This is probably not what people expect. When using symbol generation to
> > > compile base device trees for applying overlays, nodes with labels could
> > > be referenced by the overlays, and therefore should be preserved.
> >
> > Hmm.. actually that does seem like the behaviour I'd expect. Using
> > /omit-if-no-ref/ and then expecting the node to appear without
> > referencing it seems like a user error.
>
> I suppose the use-case we're looking at is keeping the size small for
> standard blobs, but having the nodes available when targeting overlay
> uses. We're currently targeting pinctrl nodes for this. There are a
> whole lot of muxing options for every SoC, but a board will only use
> a small set of them. But with overlays, we'd want all the options to
> be available so the overlays don't have to redefine them again.
>
> Not sure if this is practical, but it's the use case I had in mind.
> Maybe we could come up with some new directive or compiler option?
Hm, ok.
Maxime, since you introduced omit-if-no-ref in the first place could
you chime in on how this compares to your use case?
--
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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