[PATCH v2] Makefile: Fix include directory for OF_UPSTREAM

[Michael Nazzareno Trimarchi]

Hi Tom

On Mon, Jun 3, 2024 at 5:08 PM Patrick Barsanti
<patrick.barsanti at amarulasolutions.com> wrote:
>
> 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.

Do you have some comments here? We would like to move upstream dts for
imx6 boards
too

Michael

>
> 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@amarulasolutions.com/
> Signed-off-by: Patrick Barsanti <patrick.barsanti at amarulasolutions.com>
> Tested-by: Michael Trimarchi <michael at 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)
>
> --
> 2.45.1
>


-- 
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael at amarulasolutions.com
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