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Subject: Re: [PATCH V3 2/2] scripts: dtc: Build fdtoverlay and fdtdump tools
To:     Viresh Kumar <viresh.kumar@linaro.org>,
        Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
        Rob Herring <robh+dt@kernel.org>
Cc:     devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-kbuild@vger.kernel.org,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Bill Mills <bill.mills@linaro.org>, anmar.oueja@linaro.org,
        Masahiro Yamada <masahiroy@kernel.org>
References: <CAK7LNAQT5nVHGAZDhj4dct0v8UMzQ+-mdfBXJsfedR-7mZTnyA@mail.gmail.com>
 <72c3a4f63dde3c172c11153e9a5b19fb6cdb4498.1610000585.git.viresh.kumar@linaro.org>
From:   Frank Rowand <frowand.list@gmail.com>
Message-ID: <1d9369aa-b7aa-6d06-0d44-6ef21bc639e3@gmail.com>
Date:   Mon, 11 Jan 2021 18:44:55 -0600
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On 1/7/21 12:25 AM, Viresh Kumar wrote:
> We will start building overlays for platforms soon in the kernel and
> would need these tools going forward. Lets start building them.
> 
> The fdtoverlay program applies (or merges) one ore 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.
> 
> The fdtdump program prints a readable version of a flat device-tree
> file. This is a very useful tool to analyze the details of the overlay's
> dtb and the final dtb produced by fdtoverlay after applying the
> overlay's dtb to a base dtb.

You can calso dump an FDT with:

   dtc -O dts XXX.dtb

Is this sufficient for the desired functionality, or is there something
additional in fdtdump that is needed?

If nothing additional needed, and there is no other justification for adding
another program, I would prefer to leave fdtdump out.

-Frank

> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> V3:
> - Updated log
> - Remove libfdt_dir
> 
>  scripts/dtc/Makefile | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/dtc/Makefile b/scripts/dtc/Makefile
> index 4852bf44e913..472ab8cd590c 100644
> --- a/scripts/dtc/Makefile
> +++ b/scripts/dtc/Makefile
> @@ -1,12 +1,17 @@
>  # SPDX-License-Identifier: GPL-2.0
>  # scripts/dtc makefile
>  
> -hostprogs-always-$(CONFIG_DTC)		+= dtc
> +hostprogs-always-$(CONFIG_DTC)		+= dtc fdtdump 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
> +fdtdump-objs	:= fdtdump.o util.o
> +
> +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
>