Re: [RFC PATCH v2 4/4] script: make automatic dtb build info generation

Rob Herring
2020-02-26T20:56:19Z

On Fri, Feb 21, 2020 at 05:14:18PM +0100, Alexandre Torgue wrote:
> Append each "xxx.dtb.dts.tmp" file with "build-info" entry during dtb
> build. It allows to get build information (date, source version, ...)
> for each device tree without modify them manually.
>
> Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
>
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index a5af84ef4ffc..f084e78267b2 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -289,6 +289,7 @@ quiet_cmd_dtc = DTC $@
> cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
> $(DTB_GEN_INFO) $(src) ; \

We regenerate this for every dtb?

> $(HOSTCC) -E $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
> + $(DTB_GEN_INFO) $(src) $(dtc-tmp) ; \
> $(DTC) -O $(2) -o $@ -b 0 \
> $(addprefix -i,$(dir $<) $(DTC_INCLUDE)) $(DTC_FLAGS) \
> -d $(depfile).dtc.tmp $(dtc-tmp) ; \
> diff --git a/scripts/gen_dtb_build_info.sh b/scripts/gen_dtb_build_info.sh
> index 0cd8bd98e410..72f31e386787 100755
> --- a/scripts/gen_dtb_build_info.sh
> +++ b/scripts/gen_dtb_build_info.sh
> @@ -6,5 +6,7 @@ set -o nounset
> DTB_DIR=$1
> DTB_COMPILE_BY=$(whoami | sed 's/\\/\\\\/')

Use LINUX_COMPILE_BY #define

> DTB_INFO="From Linux $KERNELRELEASE by $DTB_COMPILE_BY the $(date).\0"

I'd use UTS_RELEASE and UTS_VERSION defines here.

> +DTS_FILE=$2
>
> -printf "$DTB_INFO" > "$DTB_DIR/dtb-build.txt"
> +printf "$DTB_INFO" > "arch/arm/boot/dts/dtb-build.txt"

Obviously, hardcoding this is not right. You probably need to prepend
with $(obj) so this works for out of tree builds too.

> +echo "&{/} {build-info = /incbin/(\"dtb-build.txt\");};" >> $DTS_FILE

You could commit the .dtsi file using the above defines and then just
add a #include of it here. Then we'd get dependency tracking for free.

Rob