linux/scripts/make_fit.py
Simon Glass 7a23b027ec arm64: boot: Support Flat Image Tree
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 uses the 'dtbs-list' file but processes only .dtb files, ignoring
the overlay .dtbo files.

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. Use
FIT_COMPRESSION to select an algorithm other than gzip.

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>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20240329032836.141899-3-sjg@chromium.org
Signed-off-by: Will Deacon <will@kernel.org>
2024-04-12 15:48:32 +01:00

291 lines
9.0 KiB
Python
Executable File

#!/usr/bin/env python3
# SPDX-License-Identifier: GPL-2.0+
#
# Copyright 2024 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
-o arch/arm64/boot/image.fit -k /tmp/kern/arch/arm64/boot/image.itk
@arch/arm64/boot/dts/dtbs-list -E -c gzip
Creates a FIT containing the supplied kernel and a set of devicetree files,
either specified individually or listed in a file (with an '@' prefix).
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, fromfile_prefix_chars='@')
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', '--output', type=str, required=True,
help='Specifies the output file (.fit)')
parser.add_argument('-O', '--os', type=str, required=True,
help='Specifies the operating system')
parser.add_argument('-k', '--kernel', type=str, required=True,
help='Specifies the (uncompressed) kernel input file (.itk)')
parser.add_argument('-v', '--verbose', action='store_true',
help='Enable verbose output')
parser.add_argument('dtbs', type=str, nargs='*',
help='Specifies the devicetree files to process')
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
"""
seq = 0
size = 0
fsw = libfdt.FdtSw()
setup_fit(fsw, args.name)
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 fname in args.dtbs:
# Ignore overlay (.dtbo) files
if os.path.splitext(fname)[1] == '.dtb':
seq += 1
size += os.path.getsize(fname)
model, compat = output_dtb(fsw, seq, fname, 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.output, '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.output],
stdout=subprocess.DEVNULL)
with open(args.output, 'rb') as inf:
data = inf.read()
ext_fit = libfdt.FdtRo(data)
ext_fit_size = ext_fit.totalsize()
if args.verbose:
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())