Message-ID: <20250919211000.1045267-1-sjg@chromium.org>
Date: Fri, 19 Sep 2025 15:09:57 -0600
From: Simon Glass <sjg@...omium.org>
To: linux-arm-kernel@...ts.infradead.org
Cc: Chen-Yu Tsai <wenst@...omium.org>,
	J . Neuschäfer <j.ne@...teo.net>,
	Masahiro Yamada <masahiroy@...nel.org>,
	Tom Rini <trini@...sulko.com>,
	Nicolas Schier <nicolas@...sle.eu>,
	Ahmad Fatoum <a.fatoum@...gutronix.de>,
	Simon Glass <sjg@...omium.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] scripts/make_fit: Support an initial ramdisk

FIT (Flat Image Tree) allows an ramdisk to be included in each
configuration. Add support for this to the script.

This feature is not available via 'make image.fit' since the ramdisk
likely needs to be built separately anyway, e.g. using modules from
the kernel build.

Signed-off-by: Simon Glass <sjg@...omium.org>
---

 scripts/make_fit.py | 47 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 41 insertions(+), 6 deletions(-)

diff --git a/scripts/make_fit.py b/scripts/make_fit.py
index 1683e5ec6e67..c43fd9d60809 100755
--- a/scripts/make_fit.py
+++ b/scripts/make_fit.py
@@ -10,10 +10,12 @@
 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
+        -r /boot/initrd.img-6.14.0-27-generic @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).
+Creates a FIT containing the supplied kernel, an optional ramdisk, 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
@@ -29,8 +31,6 @@ looks at the .cmd files produced by the kernel build.
 
 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
@@ -81,6 +81,8 @@ def parse_args():
           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('-r', '--ramdisk', type=str,
+          help='Specifies the ramdisk/initrd input file')
     parser.add_argument('-v', '--verbose', action='store_true',
                         help='Enable verbose output')
     parser.add_argument('dtbs', type=str, nargs='*',
@@ -133,7 +135,30 @@ def write_kernel(fsw, data, args):
         fsw.property_u32('entry', 0)
 
 
-def finish_fit(fsw, entries):
+def write_ramdisk(fsw, data, args):
+    """Write out the ramdisk image
+
+    Writes a ramdisk 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'
+            compress: Compression algorithm to use, e.g. 'gzip'
+    """
+    with fsw.add_node('ramdisk'):
+        fsw.property_string('description', 'Ramdisk')
+        fsw.property_string('type', 'ramdisk')
+        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)
+
+
+def finish_fit(fsw, entries, has_ramdisk=False):
     """Finish the FIT ready for use
 
     Writes the /configurations node and subnodes
@@ -143,6 +168,7 @@ def finish_fit(fsw, entries):
         entries (list of tuple): List of configurations:
             str: Description of model
             str: Compatible stringlist
+        has_ramdisk (bool): True if a ramdisk is included in the FIT
     """
     fsw.end_node()
     seq = 0
@@ -154,6 +180,8 @@ def finish_fit(fsw, entries):
                 fsw.property_string('description', model)
                 fsw.property('fdt', bytes(''.join(f'fdt-{x}\x00' for x in files), "ascii"))
                 fsw.property_string('kernel', 'kernel')
+                if has_ramdisk:
+                    fsw.property_string('ramdisk', 'ramdisk')
     fsw.end_node()
 
 
@@ -274,6 +302,13 @@ def build_fit(args):
     size += os.path.getsize(args.kernel)
     write_kernel(fsw, comp_data, args)
 
+    # Handle the ramdisk if provided
+    if args.ramdisk:
+        with open(args.ramdisk, 'rb') as inf:
+            comp_data = compress_data(inf, args.compress)
+        size += os.path.getsize(args.ramdisk)
+        write_ramdisk(fsw, comp_data, args)
+
     for fname in args.dtbs:
         # Ignore non-DTB (*.dtb) files
         if os.path.splitext(fname)[1] != '.dtb':
-- 
2.43.0

base-commit: 846bd2225ec3cfa8be046655e02b9457ed41973e
branch: fit

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