Message-ID: <2d737cec-8cfa-4a72-9028-4601c3e51185@pengutronix.de>
Date: Thu, 25 Sep 2025 09:43:29 +0200
From: Ahmad Fatoum <a.fatoum@...gutronix.de>
To: Simon Glass <sjg@...omium.org>, linux-arm-kernel@...ts.infradead.org
Cc: Nicolas Schier <nicolas@...sle.eu>, Tom Rini <trini@...sulko.com>,
 J . Neuschäfer <j.ne@...teo.net>,
 Masahiro Yamada <masahiroy@...nel.org>, Chen-Yu Tsai <wenst@...omium.org>,
 linux-kernel@...r.kernel.org, "kernel@...gutronix.de" <kernel@...gutronix.de>
Subject: Re: [PATCH v3 4/5] scripts/make_fit: Provide a way to add built
 modules

Hello Simon,

Thanks for looking into this!

On 9/23/25 12:48 AM, Simon Glass wrote:
> +def build_ramdisk(args, tmpdir):
> +    """Build a cpio ramdisk containing kernel modules
> +
> +    Similar to mkinitramfs, this creates a compressed cpio-archive containing
> +    the kernel modules for the current kernel version.
> +
> +    Args:
> +        args (Namespace): Program arguments
> +        tmpdir (str): Temporary directory to use for modules installation
> +
> +    Returns:
> +        tuple:
> +            bytes: Compressed cpio data containing modules
> +            int: total uncompressed size
> +    """
> +    suppress = None if args.verbose else subprocess.DEVNULL
> +    # Use provided tmpdir or custom install path
> +    if args.path:
> +        mod_path = args.path
> +    else:
> +        mod_path = os.path.join(tmpdir, 'modules_install')
> +        os.makedirs(mod_path, exist_ok=True)
> +
> +    if args.verbose:
> +        print(f'Installing modules to {mod_path}')
> +
> +    cmd = ['make', '-s', '-j']

Executing `make image.fit FIT_MODULES=1` in a fresh build will result in
a python stack trace, because image.fit only has dependencies for the
kernel image and the device trees, but none for the modules.

Even with that added, I don't think it's a good idea to have make call a
script only for it to call make again.

Instead, there should probably be a modules.cpio.gz make target or
similar in its own right and image.fit should depend on it if
FIT_MODULES is set.

Thanks,
Ahmad

> +
> +    # It seems that the only way to prevent a 'jobserver unavailable' warning
> +    # is to remove it from the makeflags
> +    env = os.environ.copy()
> +    makeflags = env.get('MAKEFLAGS', '')
> +    env['MAKEFLAGS'] = ' '.join(f for f in makeflags.split()
> +                                if not f.startswith('--jobserver-auth'))
> +
> +    if args.build_dir:
> +        cmd.append(f'O={args.build_dir}')
> +    cmd.extend(['INSTALL_MOD_PATH=' + mod_path, 'modules_install'])
> +    subprocess.check_call(cmd, cwd=os.getcwd(), stdout=suppress, env=env)
> +
> +    # Find the modules directory that was created (e.g. due to dirty tree)
> +    base_dir = os.path.join(mod_path, 'lib', 'modules')
> +    if not os.path.exists(base_dir):
> +        raise ValueError(f'Modules base directory {base_dir} not found')
> +    dirs = [d for d in os.listdir(base_dir)
> +            if os.path.isdir(os.path.join(base_dir, d))]
> +    if not dirs:
> +        raise ValueError(f'No module directories found in {base_dir}')
> +    if len(dirs) > 1:
> +        raise ValueError(f'Must have only one module directory in {base_dir}')
> +
> +    # Create initramfs-style directory structure (usr/lib/modules instead of
> +    # lib/modules) and move modules into it
> +    outdir = os.path.join(tmpdir, 'initramfs')
> +    new_dir = os.path.join(outdir, 'usr', 'lib', 'modules')
> +    os.makedirs(new_dir, exist_ok=True)
> +    shutil.move(os.path.join(base_dir, dirs[0]), os.path.join(new_dir, dirs[0]))
> +
> +    if args.verbose:
> +        print(f'Creating cpio archive from {outdir}')
> +
> +    with tempfile.NamedTemporaryFile() as cpio_file:
> +        # Change to initramfs directory and create cpio archive
> +        with subprocess.Popen(['find', '.', '-print0'], cwd=outdir,
> +                              stdout=subprocess.PIPE) as find:
> +            with subprocess.Popen(['cpio', '-o', '-0', '-H', 'newc'],
> +                                  stdin=find.stdout, stdout=cpio_file,
> +                                  stderr=suppress, cwd=outdir) as cpio:
> +                find.stdout.close()
> +                cpio.wait()
> +                find.wait()
> +
> +                if cpio.returncode != 0:
> +                    raise RuntimeError('Failed to create cpio archive')
> +
> +        cpio_file.seek(0)  # Reset to beginning for reading
> +        return compress_data(cpio_file, args.compress), cpio_file.tell()
> +
> +
>  def process_dtb(fname, args):
>      """Process an input DTB, decomposing it if requested and is possible
>  
> @@ -318,11 +414,12 @@ def _process_dtbs(args, fsw, entries, fdts):
>      return seq, size
>  
>  
> -def build_fit(args):
> +def build_fit(args, tmpdir):
>      """Build the FIT from the provided files and arguments
>  
>      Args:
>          args (Namespace): Program arguments
> +        tmpdir (str): Temporary directory for any temporary files
>  
>      Returns:
>          tuple:
> @@ -344,20 +441,29 @@ def build_fit(args):
>  
>      # Handle the ramdisk if provided. Compression is not supported as it is
>      # already compressed.
> +    ramdisk_data = None
>      if args.ramdisk:
>          with open(args.ramdisk, 'rb') as inf:
> -            data = inf.read()
> -        size += len(data)
> -        write_ramdisk(fsw, data, args)
> +            ramdisk_data = inf.read()
> +        size += len(ramdisk_data)
> +    elif args.modules_ramdisk:
> +        if args.verbose:
> +            print('Building modules ramdisk...')
> +        ramdisk_data, uncomp_size = build_ramdisk(args, tmpdir)
> +        size += uncomp_size
> +
> +    if ramdisk_data:
> +        write_ramdisk(fsw, ramdisk_data, args)
>  
>      count, fdt_size = _process_dtbs(args, fsw, entries, fdts)
>      size += fdt_size
>  
> -    finish_fit(fsw, entries, bool(args.ramdisk))
> +    finish_fit(fsw, entries, has_ramdisk=bool(ramdisk_data))
>  
> -    # Include the kernel itself in the returned file count
>      fdt = fsw.as_fdt()
>      fdt.pack()
> +
> +    # Count FDT files, kernel, plus ramdisk if present
>      return fdt.as_bytearray(), count + 1 + bool(args.ramdisk), size
>  
>  
> @@ -365,7 +471,12 @@ def run_make_fit():
>      """Run the tool's main logic"""
>      args = parse_args()
>  
> -    out_data, count, size = build_fit(args)
> +    tmpdir = tempfile.mkdtemp(prefix='make_fit_')
> +    try:
> +        out_data, count, size = build_fit(args, tmpdir)
> +    finally:
> +        shutil.rmtree(tmpdir)
> +
>      with open(args.output, 'wb') as outf:
>          outf.write(out_data)
>  

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