[PATCH v2 1/1] kbuild: dtc: Allow adding device tree fragments via config
antonynpavlov at gmail.com
Wed Jan 26 04:29:45 PST 2022
On Wed, 22 Sep 2021 11:13:36 -0700
Trent Piepho <trent.piepho at igorinstitute.com> wrote:
This patch was applied to barebox source tree as
2ae7ac7ab2 kbuild: dtc: Allow adding device tree fragments via config
With this patch I see build error if device tree file name starts with digit (0-9),
barebox$ git checkout v2022.01.0
barebox$ make mrproper
barebox$ export ARCH=arm
barebox$ export CROSS_COMPILE=arm-none-eabi-
barebox$ sed -i "s/virt2real.dtb/2virt2real.dtb/" arch/arm/dts/Makefile
barebox$ mv arch/arm/dts/virt2real.dts arch/arm/dts/2virt2real.dts
barebox$ make virt2real_defconfig
barebox$ make -s
<stdin>:1:9: error: macro names must be identifiers make: [scripts/Makefile.lib:352: arch/arm/dts/2virt2real.dtb] Error 1
make: [Makefile:952: arch/arm/dts] Error 2
> This introduces a config variable that allows adding additional fragments
> to the Barebox device tree(s).
> Example uses are adjusting the flash partition layout, adding barebox
> state variables, or adding an I2C device. These can be now be done with
> build configuration only, without needing to patch the existing dts
> files in the Barebox source.
> The advantage is greater when an external build system, such as Yocto or
> Buildroot, is being used to build Barebox. The build system can drop in
> a dts fragment to partition flash and build from unaltered Barebox
> source. This avoids the need for cumbersome maintenance of patch files
> to modify Barebox's source for each flash partition layout.
> Preprocessing the dts file gains another layer, where a generated dts
> source consisting of an include directive for the original dts source is
> followed by more includes for each fragment. This is piped to the
> existing preprocessor call on stdin to avoid another temporary file.
> cpp/dtc will correctly identify errors in the source files they occur
> in. The -MT option is used so the cpp auto-dependencies reference the
> original dts source and not the generated code passed on stdin.
> A preprocessor macro named after the base dts file, e.g. foo-bar.dts
> will define foo_bar_dts, will be defined so that the fragments can
> possibly operate differently based on which image's dts is being built.
> Signed-off-by: Trent Piepho <trent.piepho at igorinstitute.com>
> Changes from v1:
> - Remove 2nd config variable for in-tree fragments.
> - Add macro to preproccessed dts
> common/Kconfig | 18 ++++++++++++++++++
> scripts/Makefile.lib | 8 +++++++-
> 2 files changed, 25 insertions(+), 1 deletion(-)
> diff --git a/common/Kconfig b/common/Kconfig
> index a9feae2ae..6fdc14148 100644
> --- a/common/Kconfig
> +++ b/common/Kconfig
> @@ -1091,6 +1091,24 @@ config SYSTEMD_OF_WATCHDOG
> in the kernel device tree. If the kernel is booted without a device
> tree or with one that lacks aliases, nothing is added.
> +config EXTERNAL_DTS_FRAGMENTS
> + string "external dts file fragments"
> + depends on OFTREE
> + help
> + List of dts fragment files that will be appended to Barebox's device
> + tree(s) source when building the dtb file(s). If multiple files are
> + listed, they will be appended in order. Relative filenames will use
> + the dtc include search path.
> + A preprocessor macro based on the name of the main dts will be
> + defined, which allows the dts fragments to based on which image of a
> + multi image build they are being used in.
> + It not intended that this be put into into Barebox defconfig files.
> + Instead, it's an external build system, like Yocto or buildroot, to
> + add dts fragments from outside the Barebox source tree into the
> + Barebox build.
> menu "OP-TEE loading"
> config OPTEE_SIZE
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 80d76b177..4496f1a70 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -201,6 +201,7 @@ cpp_flags = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(__cpp_flags)
> ld_flags = $(KBUILD_LDFLAGS) $(ldflags-y)
> dtc_cpp_flags = -Wp,-MD,$(depfile).pre -nostdinc \
> + -Wp,-MT,$(basename $(notdir $@)).o \
> -I$(srctree)/arch/$(SRCARCH)/dts/include \
> -I$(srctree)/dts/include \
> -I$(srctree)/include \
> @@ -335,8 +336,13 @@ cmd_dt_S_dtb = $(srctree)/scripts/gen-dtb-s $(subst -,_,$(*F)) $< $(CONFIG_IMD)
> $(obj)/%.dtb.S: $(obj)/%.dtb $(srctree)/scripts/gen-dtb-s FORCE
> $(call if_changed,dt_S_dtb)
> +dts-frags = $(subst $(quote),,$(CONFIG_EXTERNAL_DTS_FRAGMENTS))
> quiet_cmd_dtc = DTC $@
> -cmd_dtc = $(CPP) $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
> +# For compatibility between make 4.2 and 4.3
> +H := \#
> +cmd_dtc = /bin/echo -e '$(H)define $(subst -,_,$(*F))_dts 1\n'$(foreach f,$< $(dts-frags),'$(H)include "$(f)"\n') | \
> + $(CPP) $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) - ; \
> $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 \
> -i $(srctree)/arch/$(SRCARCH)/dts $(DTC_FLAGS) \
> -i $(srctree)/dts/src/$(SRCARCH) \
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