Re: [PATCH v8 2/2] arm64: boot: Support Flat Image Tree

[Masahiro Yamada <masahiroy@kernel.org>]

On Fri, Dec 1, 2023 at 5:34 AM Simon Glass <sjg@chromium.org> wrote:
>
> 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 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. For now there
> is no way to change the compression other than by editing the rule for
> $(obj)/image.fit
>
> While FIT supports a ramdisk / initrd, no attempt is made to support
> this here, since it must be built separately from the Linux build.
>
> Signed-off-by: Simon Glass <sjg@chromium.org>
> ---
>
> Changes in v8:
> - Drop compatible string in FDT node
> - Correct sorting of MAINTAINERS to before ARM64 PORT
> - Turn compress part of the make_fit.py comment in to a sentence
> - Add two blank lines before parse_args() and setup_fit()
> - Use 'image.fit: dtbs' instead of BUILD_DTBS var
> - Use '$(<D)/dts' instead of '$(dir $<)dts'
> - Add 'mkimage' details Documentation/process/changes.rst
> - Allow changing the compression used
> - Tweak cover letter since there is only one clean-up patch
>
> Changes in v7:
> - Add Image as a dependency of image.fit
> - Drop kbuild tag
> - Add dependency on dtbs
> - Drop unnecessary path separator for dtbs
> - Rebase to -next
>
> Changes in v5:
> - Drop patch previously applied
> - Correct compression rule which was broken in v4
>
> Changes in v4:
> - Use single quotes for UIMAGE_NAME
>
> Changes in v3:
> - Drop temporary file image.itk
> - Drop patch 'Use double quotes for image name'
> - Drop double quotes in use of UIMAGE_NAME
> - Drop unnecessary CONFIG_EFI_ZBOOT condition for help
> - Avoid hard-coding "arm64" for the DT architecture
>
> Changes in v2:
> - Drop patch previously applied
> - Add .gitignore file
> - Move fit rule to Makefile.lib using an intermediate file
> - Drop dependency on CONFIG_EFI_ZBOOT
> - Pick up .dtb files separately from the kernel
> - Correct pylint too-many-args warning for write_kernel()
> - Include the kernel image in the file count
> - Add a pointer to the FIT spec and mention of its wide industry usage
> - Mention the kernel version in the FIT description
>
>  Documentation/process/changes.rst |   9 +
>  MAINTAINERS                       |   7 +
>  arch/arm64/Makefile               |   7 +-
>  arch/arm64/boot/.gitignore        |   1 +
>  arch/arm64/boot/Makefile          |   9 +-
>  scripts/Makefile.lib              |  13 ++
>  scripts/make_fit.py               | 291 ++++++++++++++++++++++++++++++
>  7 files changed, 334 insertions(+), 3 deletions(-)
>  create mode 100755 scripts/make_fit.py
>
> diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
> index bb96ca0f774b..cad51bd5bd62 100644
> --- a/Documentation/process/changes.rst
> +++ b/Documentation/process/changes.rst
> @@ -62,6 +62,7 @@ Sphinx\ [#f1]_         1.7              sphinx-build --version
>  cpio                   any              cpio --version
>  GNU tar                1.28             tar --version
>  gtags (optional)       6.6.5            gtags --version
> +mkimage (optional)     2017.01          mkimage --version
>  ====================== ===============  ========================================
>
>  .. [#f1] Sphinx is needed only to build the Kernel documentation
> @@ -189,6 +190,14 @@ The kernel build requires GNU GLOBAL version 6.6.5 or later to generate
>  tag files through ``make gtags``.  This is due to its use of the gtags
>  ``-C (--directory)`` flag.
>
> +mkimage
> +-------
> +
> +This tool is used when building a Flat Image Tree (FIT), commonly used on ARM
> +platforms. The tool is available via the ``u-boot-tools`` package or can be
> +built from the U-Boot source code. See the instructions at
> +https://docs.u-boot.org/en/latest/build/tools.html#building-tools-for-linux
> +
>  System utilities
>  ****************
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 14587be87a33..9f3eb476ece4 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3037,6 +3037,13 @@ F:       drivers/mmc/host/sdhci-of-arasan.c
>  N:     zynq
>  N:     xilinx
>
> +ARM64 FIT SUPPORT
> +M:     Simon Glass <sjg@chromium.org>
> +L:     linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
> +S:     Maintained
> +F:     arch/arm64/boot/Makefile
> +F:     scripts/make_fit.py
> +
>  ARM64 PORT (AARCH64 ARCHITECTURE)
>  M:     Catalin Marinas <catalin.marinas@arm.com>
>  M:     Will Deacon <will@kernel.org>
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index 1bd4fae6e806..6b893dc454b7 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -150,7 +150,7 @@ libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
>  # Default target when executing plain make
>  boot           := arch/arm64/boot
>
> -BOOT_TARGETS   := Image vmlinuz.efi
> +BOOT_TARGETS   := Image vmlinuz.efi image.fit
>
>  PHONY += $(BOOT_TARGETS)
>
> @@ -162,7 +162,9 @@ endif
>
>  all:   $(notdir $(KBUILD_IMAGE))
>
> -vmlinuz.efi: Image
> +image.fit: dtbs
> +
> +vmlinuz.efi image.fit: Image
>  $(BOOT_TARGETS): vmlinux
>         $(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
>
> @@ -215,6 +217,7 @@ virtconfig:
>  define archhelp
>    echo  '* Image.gz      - Compressed kernel image (arch/$(ARCH)/boot/Image.gz)'
>    echo  '  Image         - Uncompressed kernel image (arch/$(ARCH)/boot/Image)'
> +  echo  '  image.fit     - Flat Image Tree (arch/$(ARCH)/boot/image.fit)'
>    echo  '  install       - Install uncompressed kernel'
>    echo  '  zinstall      - Install compressed kernel'
>    echo  '                  Install using (your) ~/bin/installkernel or'
> diff --git a/arch/arm64/boot/.gitignore b/arch/arm64/boot/.gitignore
> index af5dc61f8b43..abaae9de1bdd 100644
> --- a/arch/arm64/boot/.gitignore
> +++ b/arch/arm64/boot/.gitignore
> @@ -2,3 +2,4 @@
>  Image
>  Image.gz
>  vmlinuz*
> +image.fit
> diff --git a/arch/arm64/boot/Makefile b/arch/arm64/boot/Makefile
> index 1761f5972443..62efb533a9bc 100644
> --- a/arch/arm64/boot/Makefile
> +++ b/arch/arm64/boot/Makefile
> @@ -16,7 +16,8 @@
>
>  OBJCOPYFLAGS_Image :=-O binary -R .note -R .note.gnu.build-id -R .comment -S
>
> -targets := Image Image.bz2 Image.gz Image.lz4 Image.lzma Image.lzo Image.zst
> +targets := Image Image.bz2 Image.gz Image.lz4 Image.lzma Image.lzo \
> +       Image.zst image.fit
>
>  $(obj)/Image: vmlinux FORCE
>         $(call if_changed,objcopy)
> @@ -39,6 +40,12 @@ $(obj)/Image.lzo: $(obj)/Image FORCE
>  $(obj)/Image.zst: $(obj)/Image FORCE
>         $(call if_changed,zstd)
>
> +# Use this to override the compression algorithm
> +FIT_COMPRESS ?= gzip
> +
> +$(obj)/image.fit: $(obj)/Image FORCE
> +       $(call cmd,fit,$(FIT_COMPRESS))



Again, $(FIT_COMPRESS) is not used anywhere.


Please fix it to

      $(call cmd,fit)




See your code.


   cmd_fit = $(MAKE_FIT) -f $@ --arch $(UIMAGE_ARCH) --os linux \
                     --name '$(UIMAGE_NAME)' \
                     --compress $(UIMAGE_COMPRESSION) -k $< \
                     $(<D)/dts


cmd_fit does not take any argument.


The compression is determined by $(UIMAGE_COMPRESSION).







-- 
Best Regards
Masahiro Yamada