Always prioritizing u-boot includes causes problems when trying to migrate boards to OF_UPSTREAM that have different local devicetree files with respect to the upstream ones, if local DT headers are not dropped. At the same time if local and upstream files are the same, migrations can be, and have been, introduced without dropping local DT headers. This also causes problems whenever upstream DTS and DT headers are patched.
For example, now migrating a board based on `imx6ul.dtsi` to OF_UPSTREAM breaks it, as there are some missing defines in a local DT header file (`imx6ul-clock.h`); the solution would be to drop it, which has not always been done in previous OF_UPSTREAM migration patches for other boards because most of the time the two are the same. This solution is also vulnerable to ABI breakage, although this has not yet happened since the introduction of OF_UPSTREAM support and is unlikely.
Maintainers assure backwards compatibility for DT headers when syncing the upstream folder with the kernel. The problem is that, at the current state, all boards that have not dropped their local headers when migrating to OF_UPSTREAM will break once the upstream devicetrees are patched, for example, to use any newly added define which is not present in the local DT header file, even if those changes are backwards compatible.
This patch fixes these problems by prioritizing upstream includes when `CONFIG_OF_UPSTREAM=y`, while keeping current prioritization when it is not.
Also in case of ABI breakage in the kernel, keeping redundant header files (only until strictly necessary, e.g. until all boards including them have been migrated to OF_UPSTREAM) together with this selective prioritization of the include folder is a solution for keeping not-yet-migrated boards from breaking.
Link: https://lore.kernel.org/u-boot/20240528084224.113385-1-patrick.barsanti@amar... Signed-off-by: Patrick Barsanti patrick.barsanti@amarulasolutions.com Tested-by: Michael Trimarchi michael@amarulasolutions.com ---
Changes in v2: - Reword and correct the commit message following the discussion with Sumit, per Michael's suggestion.
Makefile | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/Makefile b/Makefile index 79b28c2d81..899ae664ca 100644 --- a/Makefile +++ b/Makefile @@ -826,6 +826,19 @@ KBUILD_HOSTCFLAGS += $(if $(CONFIG_TOOLS_DEBUG),-g)
# Use UBOOTINCLUDE when you must reference the include/ directory. # Needed to be compatible with the O= option +ifeq ($(CONFIG_OF_UPSTREAM),y) +UBOOTINCLUDE := \ + -I$(srctree)/dts/upstream/include \ + -Iinclude \ + $(if $(KBUILD_SRC), -I$(srctree)/include) \ + $(if $(CONFIG_$(SPL_)SYS_THUMB_BUILD), \ + $(if $(CONFIG_HAS_THUMB2), \ + $(if $(CONFIG_CPU_V7M), \ + -I$(srctree)/arch/arm/thumb1/include), \ + -I$(srctree)/arch/arm/thumb1/include)) \ + -I$(srctree)/arch/$(ARCH)/include \ + -include $(srctree)/include/linux/kconfig.h +else UBOOTINCLUDE := \ -Iinclude \ $(if $(KBUILD_SRC), -I$(srctree)/include) \ @@ -837,6 +850,7 @@ UBOOTINCLUDE := \ -I$(srctree)/arch/$(ARCH)/include \ -include $(srctree)/include/linux/kconfig.h \ -I$(srctree)/dts/upstream/include +endif
NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)