Re: [PATCH v9 2/2] arm64: boot: Support Flat Image Tree

Nicolas Schier
2023-12-08T13:21:18Z

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On Fri, Dec 01, 2023 at 08:54:42PM -0700, Simon Glass 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. Use
> FIT_COMPRESSION to select a different algorithm.
>
> 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>
> ---

for the kbuild parts:

Reviewed-by: Nicolas Schier <n.schier@avm.de>

> Changes in v9:
> - Move the compression control into Makefile.lib
>
> 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 | 6 +-
> scripts/Makefile.lib | 16 ++
> 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 9d46229fe21b..d2d17f0d6e64 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..b835c0880d1c 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 +40,9 @@ $(obj)/Image.lzo: $(obj)/Image FORCE
> $(obj)/Image.zst: $(obj)/Image FORCE
> $(call if_changed,zstd)
>
> +$(obj)/image.fit: $(obj)/Image FORCE
> + $(call cmd,fit)
> +
> EFI_ZBOOT_PAYLOAD := Image
> EFI_ZBOOT_BFD_TARGET := elf64-littleaarch64
> EFI_ZBOOT_MACH_TYPE := ARM64
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 1a965fe68e01..1c60d594932c 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -496,6 +496,22 @@ quiet_cmd_uimage = UIMAGE $@
> -a $(UIMAGE_LOADADDR) -e $(UIMAGE_ENTRYADDR) \
> -n '$(UIMAGE_NAME)' -d $< $@
>
> +# Flat Image Tree (FIT)
> +# This allows for packaging of a kernel and all devicetrees files, using
> +# compression.
> +# ---------------------------------------------------------------------------
> +
> +MAKE_FIT := $(srctree)/scripts/make_fit.py
> +
> +# Use this to override the compression algorithm
> +FIT_COMPRESSION ?= gzip
> +
> +quiet_cmd_fit = FIT $@
> + cmd_fit = $(MAKE_FIT) -f $@ --arch $(UIMAGE_ARCH) --os linux \
> + --name '$(UIMAGE_NAME)' \
> + --compress $(FIT_COMPRESSION) -k $< \
> + $(<D)/dts
> +
> # XZ
> # ---------------------------------------------------------------------------
> # Use xzkern to compress the kernel image and xzmisc to compress other things.
> diff --git a/scripts/make_fit.py b/scripts/make_fit.py
> new file mode 100755
> index 000000000000..e616b0d7a84a
> --- /dev/null
> +++ b/scripts/make_fit.py
> @@ -0,0 +1,291 @@
> +#!/usr/bin/env python3
> +# SPDX-License-Identifier: GPL-2.0+
> +#
> +# Copyright 2023 Google LLC
> +# Written by Simon Glass <sjg@chromium.org>
> +#
> +
> +"""Build a FIT containing a lot of devicetree files
> +
> +Usage:
> + make_fit.py -A arm64 -n 'Linux-6.6' -O linux
> + -f arch/arm64/boot/image.fit -k /tmp/kern/arch/arm64/boot/image.itk
> + /tmp/kern/arch/arm64/boot/dts/ -E -c gzip
> +
> +Creates a FIT containing the supplied kernel and a directory containing the
> +devicetree files.
> +
> +Use -E to generate an external FIT (where the data is placed after the
> +FIT data structure). This allows parsing of the data without loading
> +the entire FIT.
> +
> +Use -c to compress the data, using bzip2, gzip, lz4, lzma, lzo and
> +zstd algorithms.
> +
> +The resulting FIT can be booted by bootloaders which support FIT, such
> +as U-Boot, Linuxboot, Tianocore, etc.
> +
> +Note that this tool does not yet support adding a ramdisk / initrd.
> +"""
> +
> +import argparse
> +import collections
> +import os
> +import subprocess
> +import sys
> +import tempfile
> +import time
> +
> +import libfdt
> +
> +
> +# Tool extension and the name of the command-line tools
> +CompTool = collections.namedtuple('CompTool', 'ext,tools')
> +
> +COMP_TOOLS = {
> + 'bzip2': CompTool('.bz2', 'bzip2'),
> + 'gzip': CompTool('.gz', 'pigz,gzip'),
> + 'lz4': CompTool('.lz4', 'lz4'),
> + 'lzma': CompTool('.lzma', 'lzma'),
> + 'lzo': CompTool('.lzo', 'lzop'),
> + 'zstd': CompTool('.zstd', 'zstd'),
> +}
> +
> +
> +def parse_args():
> + """Parse the program ArgumentParser
> +
> + Returns:
> + Namespace object containing the arguments
> + """
> + epilog = 'Build a FIT from a directory tree containing .dtb files'
> + parser = argparse.ArgumentParser(epilog=epilog)
> + parser.add_argument('-A', '--arch', type=str, required=True,
> + help='Specifies the architecture')
> + parser.add_argument('-c', '--compress', type=str, default='none',
> + help='Specifies the compression')
> + parser.add_argument('-E', '--external', action='store_true',
> + help='Convert the FIT to use external data')
> + parser.add_argument('-n', '--name', type=str, required=True,
> + help='Specifies the name')
> + parser.add_argument('-O', '--os', type=str, required=True,
> + help='Specifies the operating system')
> + parser.add_argument('-f', '--fit', type=str, required=True,
> + help='Specifies the output file (.fit)')
> + parser.add_argument('-k', '--kernel', type=str, required=True,
> + help='Specifies the (uncompressed) kernel input file (.itk)')
> + parser.add_argument('srcdir', type=str, nargs='*',
> + help='Specifies the directory tree that contains .dtb files')
> +
> + return parser.parse_args()
> +
> +
> +def setup_fit(fsw, name):
> + """Make a start on writing the FIT
> +
> + Outputs the root properties and the 'images' node
> +
> + Args:
> + fsw (libfdt.FdtSw): Object to use for writing
> + name (str): Name of kernel image
> + """
> + fsw.INC_SIZE = 65536
> + fsw.finish_reservemap()
> + fsw.begin_node('')
> + fsw.property_string('description', f'{name} with devicetree set')
> + fsw.property_u32('#address-cells', 1)
> +
> + fsw.property_u32('timestamp', int(time.time()))
> + fsw.begin_node('images')
> +
> +
> +def write_kernel(fsw, data, args):
> + """Write out the kernel image
> +
> + Writes a kernel node along with the required properties
> +
> + Args:
> + fsw (libfdt.FdtSw): Object to use for writing
> + data (bytes): Data to write (possibly compressed)
> + args (Namespace): Contains necessary strings:
> + arch: FIT architecture, e.g. 'arm64'
> + fit_os: Operating Systems, e.g. 'linux'
> + name: Name of OS, e.g. 'Linux-6.6.0-rc7'
> + compress: Compression algorithm to use, e.g. 'gzip'
> + """
> + with fsw.add_node('kernel'):
> + fsw.property_string('description', args.name)
> + fsw.property_string('type', 'kernel_noload')
> + fsw.property_string('arch', args.arch)
> + fsw.property_string('os', args.os)
> + fsw.property_string('compression', args.compress)
> + fsw.property('data', data)
> + fsw.property_u32('load', 0)
> + fsw.property_u32('entry', 0)
> +
> +
> +def finish_fit(fsw, entries):
> + """Finish the FIT ready for use
> +
> + Writes the /configurations node and subnodes
> +
> + Args:
> + fsw (libfdt.FdtSw): Object to use for writing
> + entries (list of tuple): List of configurations:
> + str: Description of model
> + str: Compatible stringlist
> + """
> + fsw.end_node()
> + seq = 0
> + with fsw.add_node('configurations'):
> + for model, compat in entries:
> + seq += 1
> + with fsw.add_node(f'conf-{seq}'):
> + fsw.property('compatible', bytes(compat))
> + fsw.property_string('description', model)
> + fsw.property_string('fdt', f'fdt-{seq}')
> + fsw.property_string('kernel', 'kernel')
> + fsw.end_node()
> +
> +
> +def compress_data(inf, compress):
> + """Compress data using a selected algorithm
> +
> + Args:
> + inf (IOBase): Filename containing the data to compress
> + compress (str): Compression algorithm, e.g. 'gzip'
> +
> + Return:
> + bytes: Compressed data
> + """
> + if compress == 'none':
> + return inf.read()
> +
> + comp = COMP_TOOLS.get(compress)
> + if not comp:
> + raise ValueError(f"Unknown compression algorithm '{compress}'")
> +
> + with tempfile.NamedTemporaryFile() as comp_fname:
> + with open(comp_fname.name, 'wb') as outf:
> + done = False
> + for tool in comp.tools.split(','):
> + try:
> + subprocess.call([tool, '-c'], stdin=inf, stdout=outf)
> + done = True
> + break
> + except FileNotFoundError:
> + pass
> + if not done:
> + raise ValueError(f'Missing tool(s): {comp.tools}\n')
> + with open(comp_fname.name, 'rb') as compf:
> + comp_data = compf.read()
> + return comp_data
> +
> +
> +def output_dtb(fsw, seq, fname, arch, compress):
> + """Write out a single devicetree to the FIT
> +
> + Args:
> + fsw (libfdt.FdtSw): Object to use for writing
> + seq (int): Sequence number (1 for first)
> + fmame (str): Filename containing the DTB
> + arch: FIT architecture, e.g. 'arm64'
> + compress (str): Compressed algorithm, e.g. 'gzip'
> +
> + Returns:
> + tuple:
> + str: Model name
> + bytes: Compatible stringlist
> + """
> + with fsw.add_node(f'fdt-{seq}'):
> + # Get the compatible / model information
> + with open(fname, 'rb') as inf:
> + data = inf.read()
> + fdt = libfdt.FdtRo(data)
> + model = fdt.getprop(0, 'model').as_str()
> + compat = fdt.getprop(0, 'compatible')
> +
> + fsw.property_string('description', model)
> + fsw.property_string('type', 'flat_dt')
> + fsw.property_string('arch', arch)
> + fsw.property_string('compression', compress)
> + fsw.property('compatible', bytes(compat))
> +
> + with open(fname, 'rb') as inf:
> + compressed = compress_data(inf, compress)
> + fsw.property('data', compressed)
> + return model, compat
> +
> +
> +def build_fit(args):
> + """Build the FIT from the provided files and arguments
> +
> + Args:
> + args (Namespace): Program arguments
> +
> + Returns:
> + tuple:
> + bytes: FIT data
> + int: Number of configurations generated
> + size: Total uncompressed size of data
> + """
> + fsw = libfdt.FdtSw()
> + setup_fit(fsw, args.name)
> + seq = 0
> + size = 0
> + entries = []
> +
> + # Handle the kernel
> + with open(args.kernel, 'rb') as inf:
> + comp_data = compress_data(inf, args.compress)
> + size += os.path.getsize(args.kernel)
> + write_kernel(fsw, comp_data, args)
> +
> + for path in args.srcdir:
> + # Handle devicetree files
> + if os.path.isdir(path):
> + for dirpath, _, fnames in os.walk(path):
> + for fname in fnames:
> + if os.path.splitext(fname)[1] != '.dtb':
> + continue
> + pathname = os.path.join(dirpath, fname)
> + seq += 1
> + size += os.path.getsize(pathname)
> + model, compat = output_dtb(fsw, seq, pathname,
> + args.arch, args.compress)
> + entries.append([model, compat])
> +
> + finish_fit(fsw, entries)
> +
> + # Include the kernel itself in the returned file count
> + return fsw.as_fdt().as_bytearray(), seq + 1, size
> +
> +
> +def run_make_fit():
> + """Run the tool's main logic"""
> + args = parse_args()
> +
> + out_data, count, size = build_fit(args)
> + with open(args.fit, 'wb') as outf:
> + outf.write(out_data)
> +
> + ext_fit_size = None
> + if args.external:
> + mkimage = os.environ.get('MKIMAGE', 'mkimage')
> + subprocess.check_call([mkimage, '-E', '-F', args.fit],
> + stdout=subprocess.DEVNULL)
> +
> + with open(args.fit, 'rb') as inf:
> + data = inf.read()
> + ext_fit = libfdt.FdtRo(data)
> + ext_fit_size = ext_fit.totalsize()
> +
> + comp_size = len(out_data)
> + print(f'FIT size {comp_size:#x}/{comp_size / 1024 / 1024:.1f} MB', end='')
> + if ext_fit_size:
> + print(f', header {ext_fit_size:#x}/{ext_fit_size / 1024:.1f} KB', end='')
> + print(f', {count} files, uncompressed {size / 1024 / 1024:.1f} MB')
> +
> +
> +if __name__ == "__main__":
> + sys.exit(run_make_fit())
> --
> 2.43.0.rc2.451.g8631bc7472-goog
>

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