On Mon, Jan 06, 2025 at 02:52:59PM +0100, Christophe Leroy wrote:

Le 02/01/2025 à 19:31, J. Neuschäfer via B4 Relay a écrit :

quoted

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From: "J. Neuschäfer" <redacted>

The Flat Image Tree (FIT) format combines a kernel, a set of
devicetrees, and optionally additional resources into a single file that
can be loaded by a bootloader such as U-Boot. Generating a FIT image as
part of the kernel build reduces the need for additional build scripts,
and produces a single boot image without falling back to one of the
many legacy methods implemented in arch/powerpc/boot/Makefile, which
would require additional changes for arch/powerpc/boot for each board.

Will that allow compressed vmlinux ?

Yes, the make_fit.py script can compress included data (kernel, dtb),
and the logic in scripts/Makefile.lib makes use of this feature.
By default, gzip is used:

# Use this to override the compression algorithm
FIT_COMPRESSION ?= gzip

quiet_cmd_fit = FIT     $@
      cmd_fit = $(MAKE_FIT) -o $@ --arch $(UIMAGE_ARCH) --os linux \
		--name '$(UIMAGE_NAME)' \
		$(if $(findstring 1,$(KBUILD_VERBOSE)),-v) \
		$(if $(FIT_DECOMPOSE_DTBS),--decompose-dtbs) \
		--compress $(FIT_COMPRESSION) -k $< @$(word 2,$^)


Best regards,
J. Neuschäfer