[PATCH v2 1/2] scripts/make_fit: Support an initial ramdisk

[PATCH v2 1/2] scripts/make_fit: Support an initial ramdisk

[Simon Glass]

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@chromium.org>
---

Changes in v2:
- Don't compress the ramdisk as it is already compressed

 scripts/make_fit.py | 46 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/scripts/make_fit.py b/scripts/make_fit.py
index 1683e5ec6e67..b4caa127d2c3 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 +135,28 @@ 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'
+    """
+    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('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 +166,7 @@ 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 +178,8 @@ 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 +300,14 @@ def build_fit(args):
     size += os.path.getsize(args.kernel)
     write_kernel(fsw, comp_data, args)
 
+    # Handle the ramdisk if provided. Compression is not supported as it is
+    # already compressed.
+    if args.ramdisk:
+        with open(args.ramdisk, 'rb') as inf:
+            data = inf.read()
+        size += len(data)
+        write_ramdisk(fsw, 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

[PATCH v2 2/2] scripts/make_fit: Speed up operation

[Simon Glass]

The kernel is likely at least 16MB so we may as well use that as a step
size when reallocating space for the FIT in memory. Pack the FIT at the
end, so there is no wasted space.

This reduces the time to pack by an order of magnitude, or so.

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

---

(no changes since v1)

 scripts/make_fit.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/scripts/make_fit.py b/scripts/make_fit.py
index b4caa127d2c3..904f45088978 100755
--- a/scripts/make_fit.py
+++ b/scripts/make_fit.py
@@ -100,7 +100,7 @@ def setup_fit(fsw, name):
         fsw (libfdt.FdtSw): Object to use for writing
         name (str): Name of kernel image
     """
-    fsw.INC_SIZE = 65536
+    fsw.INC_SIZE = 16 << 20
     fsw.finish_reservemap()
     fsw.begin_node('')
     fsw.property_string('description', f'{name} with devicetree set')
@@ -330,10 +330,12 @@ def build_fit(args):
 
         entries.append([model, compat, files_seq])
 
-    finish_fit(fsw, entries)
+    finish_fit(fsw, entries, bool(args.ramdisk))
 
     # Include the kernel itself in the returned file count
-    return fsw.as_fdt().as_bytearray(), seq + 1, size
+    fdt = fsw.as_fdt()
+    fdt.pack()
+    return fdt.as_bytearray(), seq + 1, size
 
 
 def run_make_fit():
-- 
2.43.0

base-commit: 846bd2225ec3cfa8be046655e02b9457ed41973e
branch: fit

Re: [PATCH v2 2/2] scripts/make_fit: Speed up operation

[J. Neuschäfer]

On Fri, Sep 19, 2025 at 04:46:25PM -0600, Simon Glass wrote:
> The kernel is likely at least 16MB so we may as well use that as a step
> size when reallocating space for the FIT in memory. Pack the FIT at the
> end, so there is no wasted space.
> 
> This reduces the time to pack by an order of magnitude, or so.
> 
> Signed-off-by: Simon Glass <sjg@chromium.org>
> 
> ---
> 
> (no changes since v1)
> 
>  scripts/make_fit.py | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/scripts/make_fit.py b/scripts/make_fit.py
> index b4caa127d2c3..904f45088978 100755
> --- a/scripts/make_fit.py
> +++ b/scripts/make_fit.py
> @@ -100,7 +100,7 @@ def setup_fit(fsw, name):
>          fsw (libfdt.FdtSw): Object to use for writing
>          name (str): Name of kernel image
>      """
> -    fsw.INC_SIZE = 65536
> +    fsw.INC_SIZE = 16 << 20
>      fsw.finish_reservemap()
>      fsw.begin_node('')
>      fsw.property_string('description', f'{name} with devicetree set')
> @@ -330,10 +330,12 @@ def build_fit(args):
>  
>          entries.append([model, compat, files_seq])
> 

> -    finish_fit(fsw, entries)
> +    finish_fit(fsw, entries, bool(args.ramdisk))

It seems like this line should rather go into the previous patch.

>  
>      # Include the kernel itself in the returned file count
> -    return fsw.as_fdt().as_bytearray(), seq + 1, size
> +    fdt = fsw.as_fdt()
> +    fdt.pack()
> +    return fdt.as_bytearray(), seq + 1, size

The rest looks good to me. Easy optimization, big win :)


Best regards,
J. Neuschäfer

Re: [PATCH v2 2/2] scripts/make_fit: Speed up operation

[Simon Glass]

Hi J,

On Sun, 21 Sept 2025 at 04:31, J. Neuschäfer <j.ne@posteo.net> wrote:
>
> On Fri, Sep 19, 2025 at 04:46:25PM -0600, Simon Glass wrote:
> > The kernel is likely at least 16MB so we may as well use that as a step
> > size when reallocating space for the FIT in memory. Pack the FIT at the
> > end, so there is no wasted space.
> >
> > This reduces the time to pack by an order of magnitude, or so.
> >
> > Signed-off-by: Simon Glass <sjg@chromium.org>
> >
> > ---
> >
> > (no changes since v1)
> >
> >  scripts/make_fit.py | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/scripts/make_fit.py b/scripts/make_fit.py
> > index b4caa127d2c3..904f45088978 100755
> > --- a/scripts/make_fit.py
> > +++ b/scripts/make_fit.py
> > @@ -100,7 +100,7 @@ def setup_fit(fsw, name):
> >          fsw (libfdt.FdtSw): Object to use for writing
> >          name (str): Name of kernel image
> >      """
> > -    fsw.INC_SIZE = 65536
> > +    fsw.INC_SIZE = 16 << 20
> >      fsw.finish_reservemap()
> >      fsw.begin_node('')
> >      fsw.property_string('description', f'{name} with devicetree set')
> > @@ -330,10 +330,12 @@ def build_fit(args):
> >
> >          entries.append([model, compat, files_seq])
> >
>
> > -    finish_fit(fsw, entries)
> > +    finish_fit(fsw, entries, bool(args.ramdisk))
>
> It seems like this line should rather go into the previous patch.

Ah yes, will fix in v3, thanks.

>
> >
> >      # Include the kernel itself in the returned file count
> > -    return fsw.as_fdt().as_bytearray(), seq + 1, size
> > +    fdt = fsw.as_fdt()
> > +    fdt.pack()
> > +    return fdt.as_bytearray(), seq + 1, size
>
> The rest looks good to me. Easy optimization, big win :)
>

Regards,
Simon