Subject: Re: [PATCH 08/19] powerpc: boot: Enable FIT image generation

From: J. Neuschäfer <[email-masked]>
Date: Tue, 7 Jan 2025 23:00:58 +0000

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 :
> > [Vous ne recevez pas souvent de courriers de [email-masked]. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> > 
> > From: "J. Neuschäfer" <[email-masked]>
> > 
> > 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