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From: Masahiro Yamada <masahiroy@kernel.org>
Date: Fri, 29 Mar 2024 19:00:44 +0900
Message-ID: <CAK7LNAQWYvysMd8WjTj4+hh7ajL_1tV5rh1=BTgjc5OrMH6FiA@mail.gmail.com>
Subject: Re: [PATCH v12 2/2] arm64: boot: Support Flat Image Tree
To: Simon Glass <sjg@chromium.org>
Cc: linux-arm-kernel@lists.infradead.org, 
	Ahmad Fatoum <a.fatoum@pengutronix.de>, Nicolas Schier <nicolas@fjasle.eu>, 
	Catalin Marinas <catalin.marinas@arm.com>, Jonathan Corbet <corbet@lwn.net>, 
	Nathan Chancellor <nathan@kernel.org>, Nick Terrell <terrelln@fb.com>, Will Deacon <will@kernel.org>, 
	linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org, 
	linux-kernel@vger.kernel.org, workflows@vger.kernel.org
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On Fri, Mar 29, 2024 at 12:29=E2=80=AFPM Simon Glass <sjg@chromium.org> wro=
te:
>
> Add a script which produces a Flat Image Tree (FIT), a single file
> containing the built kernel and associated devicetree files.
> Compression defaults to gzip which gives a good balance of size and
> performance.
>
> The files compress from about 86MB to 24MB using this approach.
>
> The FIT can be used by bootloaders which support it, such as U-Boot
> and Linuxboot. It permits automatic selection of the correct
> devicetree, matching the compatible string of the running board with
> the closest compatible string in the FIT. There is no need for
> filenames or other workarounds.
>
> Add a 'make image.fit' build target for arm64, as well.
>
> The FIT can be examined using 'dumpimage -l'.
>
> This uses the 'dtbs-list' file but processes only .dtb files, ignoring
> the overlay .dtbo files.
>
> This features requires pylibfdt (use 'pip install libfdt'). It also
> requires compression utilities for the algorithm being used. Supported
> compression options are the same as the Image.xxx files. Use
> FIT_COMPRESSION to select an algorithm other than gzip.
>
> While FIT supports a ramdisk / initrd, no attempt is made to support
> this here, since it must be built separately from the Linux build.
>
> Signed-off-by: Simon Glass <sjg@chromium.org>
> ---
>
> Changes in v12:
> - Avoid showing FIT message if V=3D0


Acked-by: Masahiro Yamada <masahiroy@kernel.org>


--=20
Best Regards
Masahiro Yamada