Hi David, > On May 31, 2016, at 08:06 , David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> wrote: > > On Fri, May 27, 2016 at 05:33:06PM +1000, David Gibson wrote: >> On Tue, May 24, 2016 at 08:50:38PM +0300, Pantelis Antoniou wrote: >>> This patch enable the generation of symbols & local fixup information >>> for trees compiled with the -@ (--symbols) option. >>> >>> Using this patch labels in the tree and their users emit information >>> in __symbols__ and __local_fixups__ nodes. >>> >>> The __fixups__ node make possible the dynamic resolution of phandle >>> references which are present in the plugin tree but lie in the >>> tree that are applying the overlay against. >>> >>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx> >>> Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> >>> Signed-off-by: Jan Luebbe <jlu@xxxxxxxxxxxxxx> >> >> So, I think I've identified the underlying thing which was bothering >> me about these patches. >> >> With the new dynamic patching stuff, "overlays" (for want of a better >> term) now have a real existence both in the dts source format, and in >> the dtb object format. However, these patches don't give them a >> concrete, explicit representation within dtc itself - instead we just >> kind of mangle one representation to the other as we're parsing. I >> think this is a mistaken approach. >> >> I'm toying with some patches to give overlays a full representation in >> dtc which I think will handle these cases better - and allow for >> easier experimentation with different possible ways of encoding the >> overlays. >> >> One side point - writing plugins in dts format leads to an irritating >> little ambiguity in the grammar. Well, not an ambiguity technically, >> but a place where we need more lookahead than normal, meaning we get >> shift/reduce conflicts. It arises because both memreserves and >> overlays can have a label in front of them. So, if we see a label as >> our next token after the version tag, we don't know if a memreserve or >> overlay is coming next, so the parser doesn't know which path to go >> down (with a single token lookahead). We could handle it with >> %glr-parser, of course, but I have been trying to avoid that. I think >> this will apply both with your patches and with the approach I'm >> working on - not sure what to do about it yet. > > I now have a first cut at said experiments, see: > https://github.com/dgibson/dtc/tree/overlay > Rebased my work and will submit again a couple of minutes. Everything works besides a small niggle with the overlay syntax. You cannot get rid of the basetree token. So… &foo { }; Does not work for an overlay, you need a dummy basetree / { }; &foo { }; Regards — Pantelis > -- > 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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
