On 1/5/21 9:21 AM, Rob Herring wrote: > On Tue, Jan 5, 2021 at 4:24 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote: >> >> Hello, >> >> Here is an attempt to make some changes in the kernel to allow building >> of device tree overlays. >> >> While at it, I would also like to discuss about how we should mention >> the base DT blobs in the Makefiles for the overlays, so they can be >> build tested to make sure the overlays apply properly. >> >> A simple way is to mention that with -base extension, like this: >> >> $(overlay-file)-base := platform-base.dtb >> >> Any other preference ? > > I think we'll want something similar to how '-objs' works for modules: > > foo-board-1-dtbs := foo-board.dtb foo-overlay1.dtbo > foo-board-2-dtbs := foo-board.dtb foo-overlay2.dtbo > foo-board-1-2-dtbs := foo-board.dtb foo-overlay1.dtbo foo-overlay2.dtbo > dtbs-y += foo-board-1.dtb foo-board-2.dtb foo-board-1-2.dtb (Thinking ahead....) I'm not sure how to fit connector nodes and the corresponding plugin overlays into this model. A single plugin .dtbo will need to be relocated onto one or more connector nodes. fdtoverlay and the run time overlay apply code do not know how to do this yet. -Frank > > (One difference here is we will want all the intermediate targets > unlike .o files.) > > You wouldn't necessarily have all the above combinations, but you have > to allow for them. I'm not sure how we'd handle applying any common > overlays where the base and overlay are in different directories. > > Another thing here is adding all the above is not really going to > scale on arm32 where we have a single dts directory. We need to move > things to per vendor/soc family directories. I have the script to do > this. We just need to agree on the vendor names and get Arnd/Olof to > run it. I also want that so we can enable schema checks by default > once a vendor is warning free (the whole tree is going to take > forever). > >> Also fdtoverlay is an external entity right now, and is not part of the >> kernel. Do we need to make it part of the kernel ? Or keep using the >> external entity ? > > Part of the kernel. We just need to add it to the dtc sync script and > makefile I think. > > Rob >
