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Subject: Re: [PATCH V6 2/6] scripts: dtc: Build fdtoverlay tool
To:     Viresh Kumar <viresh.kumar@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
        Masahiro Yamada <masahiroy@kernel.org>
Cc:     Vincent Guittot <vincent.guittot@linaro.org>,
        linux-kernel@vger.kernel.org, anmar.oueja@linaro.org,
        Bill Mills <bill.mills@linaro.org>,
        David Gibson <david@gibson.dropbear.id.au>,
        devicetree@vger.kernel.org, Michal Marek <michal.lkml@markovi.net>
References: <cover.1611312122.git.viresh.kumar@linaro.org>
 <2dfec4acb1bfbab08b431908ace0a77cc3279434.1611312122.git.viresh.kumar@linaro.org>
From:   Frank Rowand <frowand.list@gmail.com>
Message-ID: <1f6408aa-9900-fe4a-d885-028ff8329707@gmail.com>
Date:   Fri, 29 Jan 2021 00:03:23 -0600
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On 1/22/21 4:50 AM, Viresh Kumar wrote:
> We will start building overlays for platforms soon in the kernel and
> would need fdtoverlay going forward. Lets start building it.
> 
> The fdtoverlay program applies (or merges) one or more overlay dtb
> blobs to a base dtb blob. The kernel build system would later use
> fdtoverlay to generate the overlaid blobs based on platform specific
> configurations.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  scripts/dtc/Makefile | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/dtc/Makefile b/scripts/dtc/Makefile
> index 4852bf44e913..5f19386a49eb 100644
> --- a/scripts/dtc/Makefile
> +++ b/scripts/dtc/Makefile
> @@ -1,13 +1,17 @@
>  # SPDX-License-Identifier: GPL-2.0
>  # scripts/dtc makefile
>  
> -hostprogs-always-$(CONFIG_DTC)		+= dtc
> +hostprogs-always-$(CONFIG_DTC)		+= dtc fdtoverlay
>  hostprogs-always-$(CHECK_DT_BINDING)	+= dtc
>  
>  dtc-objs	:= dtc.o flattree.o fstree.o data.o livetree.o treesource.o \
>  		   srcpos.o checks.o util.o
>  dtc-objs	+= dtc-lexer.lex.o dtc-parser.tab.o
> 

Please add this comment:

# The upstream project builds libfdt as a separate library.  We are choosing to
# instead directly link the libfdt object files into fdtoverly

> +libfdt-objs	:= fdt.o fdt_ro.o fdt_wip.o fdt_sw.o fdt_rw.o fdt_strerror.o fdt_empty_tree.o fdt_addresses.o fdt_overlay.o
> +libfdt		= $(addprefix libfdt/,$(libfdt-objs))
> +fdtoverlay-objs	:= $(libfdt) fdtoverlay.o util.o
> +
>  # Source files need to get at the userspace version of libfdt_env.h to compile
>  HOST_EXTRACFLAGS += -I $(srctree)/$(src)/libfdt
>  
>