[U-Boot] [PATCH 00/26] spl: Support loading a FIT image containing U-Boot

From: Belisko Marek <marek.belisko@gmail.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH 00/26] spl: Support loading a FIT image containing U-Boot
Date: Wed, 17 Feb 2016 12:00:04 +0100	[thread overview]
Message-ID: <CAAfyv34var5T==6z35BQnzWa7O1J=0OHHAp3QMaMkfUei7PAYA@mail.gmail.com> (raw)
In-Reply-To: <1453999186-18747-1-git-send-email-sjg@chromium.org>

Hi Simon,

On Thu, Jan 28, 2016 at 5:39 PM, Simon Glass <sjg@chromium.org> wrote:
> We need a way to support more than one board per binary in U-Boot with
> device tree. Various methods have been discussed. The one that seems to make
> the most sense is to adjust SPL so that it can load a FIT which contains
> U-Boot and several device tree binaries. This is how things with with Linux:
> load a FIT and select the correct device tree to pass to Linux.
Some time ago I rise question [0] to load FIT kernel directly in SPL
using falcon mode.
I did look at your patches and I have a feeling that with small
adaptions it should be possible?
Am I right or it's impossible? (Trying to use it on am33xx boards). Many thanks.
>
> This series:
>
> - Adjusts the build system to optionally build a u-boot.img in FIT format
> that includes the U-Boot binary and >1 device tree files
> - Adjusts SPL to support loading this
> - Adds a way for SPL to determine which device tree to select (by calling a
> board-specific function)
> - Adjusts SPL to pass this selected device tree to U-Boot when it starts
>
> It would be painful to require an .its file for each board just to support
> this feature. In any case various people have commented that it would be
> nice not to have to write this file in general. Therefore, this series
> enhances mkimage to automatically generate a FIT without a .its file. So far
> it understands how to add a main image and a number of device tree files. It
> does not support hashing or verified boot as yet.
>
> One problem with the FIT format as it stands is that all the data is inline.
> This means that the entire file must be read in order to figure out what
> device-tree files are available. It is then possible to copy the images into
> place.
>
> This is not really suitable for SPL since copying can be slow, and reading
> unnecessary data would make the FIT format less efficient than the legacy
> format.
>
> Therefore this series adds a new feature to FIT which allows the images to
> be stored immediately after the FIT itself ends. This makes the FIT very
> small. It can be read quickly and in its entirety. Then the images can be
> loaded one by one as needed. This allows SPL to support FITs containing lots
> of images very efficiently.
>
> To achieve this, mkimage is enhanced to convert between the 'normal' and
> 'external' version of a FIT file. The latter is only used for the SPL loader.
> The main difference is that viewing an 'external' FIT will not show the
> contents of each image.
>
> This series also includes a few other tidy-ups, such as moving mkimage's
> tricky argument-processing code to use getopt().
>
> NOTE: There are a few problems remaining with the Kconfig conversion. I'm
> still fiddling with this but thought it best to send this series out for
> comment in the meantime.
>
> This series is available at u-boot-fdt/spl-working.
>

[0] - http://lists.denx.de/pipermail/u-boot/2015-February/203938.html
>
>
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> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot

BR,

marek

-- 
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Marek Belisko - OPEN-NANDRA
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