Re: [PATCH] of: build dbts with symbols when CONFIG_OF_OVERLAY is set

Frank Rowand
2017-12-15T21:06:58Z

On 12/14/17 07:12, Andre Heider wrote:
> The overlay feature requires the base dtb to be built with symbols, so
> lets build the dtbs with symbols when overlay support was explicitly
> enabled.
>
> With CONFIG_OF_ALL_DTBS on ARCH=arm the 989 dtb files grow about ~38% on
> average.
>
> Totals in bytes with the 3 biggest ones:
>
> Before:
> 90471 arch/arm/boot/dts/am57xx-beagle-x15-revc.dtb
> 90521 arch/arm/boot/dts/am57xx-beagle-x15-revb1.dtb
> 92639 arch/arm/boot/dts/dra7-evm.dtb
> 25731296 total
>
> After:
> 133203 arch/arm/boot/dts/am57xx-beagle-x15-revc.dtb
> 133237 arch/arm/boot/dts/am57xx-beagle-x15-revb1.dtb
> 134545 arch/arm/boot/dts/dra7-evm.dtb
> 35464440 total
>
> Signed-off-by: Andre Heider <a.heider@gmail.com>
> ---
>
> Hi,
>
> while playing around with overlays I noticed that I needed to rebuilt
> my distro's device trees because they didn't come with symbols.
>
> Is that for a reason, maybe the not so minor increase in size?

Yes, size is the issue.

>
> Thanks,
> Andre
>
> drivers/of/unittest-data/Makefile | 7 -------
> scripts/Makefile.lib | 5 +++++
> 2 files changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/of/unittest-data/Makefile b/drivers/of/unittest-data/Makefile
> index 32389acfa616..b65061013512 100644
> --- a/drivers/of/unittest-data/Makefile
> +++ b/drivers/of/unittest-data/Makefile
> @@ -15,13 +15,6 @@ targets += overlay.dtb overlay.dtb.S
> targets += overlay_bad_phandle.dtb overlay_bad_phandle.dtb.S
> targets += overlay_bad_symbol.dtb overlay_bad_symbol.dtb.S
> targets += overlay_base.dtb overlay_base.dtb.S
> -
> -# enable creation of __symbols__ node
> -DTC_FLAGS_overlay := -@
> -DTC_FLAGS_overlay_bad_phandle := -@
> -DTC_FLAGS_overlay_bad_symbol := -@
> -DTC_FLAGS_overlay_base := -@
> -
> endif
>
> .PRECIOUS: \

No. The unittests require these to be set unconditionally.

> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 1ca4dcd2d500..c7ba4aa8a07a 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -278,6 +278,11 @@ DTC_FLAGS += -Wnode_name_chars_strict \
> -Wproperty_name_chars_strict
> endif
>
> +ifeq ($(CONFIG_OF_OVERLAY),y)
> +# enable creation of __symbols__ node
> +DTC_FLAGS += -@
> +endif
> +
> DTC_FLAGS += $(DTC_FLAGS_$(basetarget))
>
> # Generate an assembly file to wrap the output of the device tree compiler
>

Not needed. Instead set DTC_FLAGS in the make command. For example:

DTC_FLAGS=-@ make qcom-apq8074-dragonboard.dtb

There are a few architecture Makefiles that need to be fixed to not unconditionally
set DTC_FLAGS.

-Frank