8e35bb07eb mkimage: Support automatic creating of a FIT without a .its

Simon Glass sjg at chromium.org
Wed May 27 15:24:25 CEST 2020

Hi Wolfgang,

On Mon, 25 May 2020 at 05:38, Wolfgang Denk <wd at denx.de> wrote:
> Hi Simon,
> your commit 8e35bb07eb (2016-03-14) "mkimage: Support automatic
> creating of a FIT without a .its" added the "-f auto" option to
> mkimage.  While convenient in many situation, I had to notice that
> with "-f auto" there is no checksum information included with any of
> the blobs stored in the FIT image.
> I guess the rationale was that the primary use case for this was to
> generate combinations of a U-Boot image with several device tree
> blobs to be used / selected by the SPL, as one can see for example
> in scripts/Makefile.spl :
> MKIMAGEFLAGS_$(SPL_BIN).multidtb.fit = -f auto -A $(ARCH) -T firmware -C none -O u-boot \
>         -n "Multi DTB fit image for $(SPL_BIN)" -E \
>         $(patsubst %,-b %,$(SHRUNK_ARCH_DTB))
> And - at least at that time - most implementations of the SPL did
> not need/want checksum verification.
> However I'm asking myself if this is not an unfortunate choice.
> It is trivial for a not-checksum-enabled SPL to ignore any checksum
> in the image, but not the other way round: if there is no checksum
> in the images, the SPL will never be able to verify one.
> Would it not be a more reasonable default for operation unter the
> "-f auto" flag to enable at least simple checksumming, say by
> auto-adding something like
>         hash-1 {
>                 algo = "crc32";
>         };
> to the generated descriptions?

Yes it should be easy to add that. I'll take a look.


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