On Mon, Jan 19, 2026 at 10:51:29AM +0100, Greg KH wrote:
> On Mon, Jan 19, 2026 at 07:47:17AM +0100, Luis Augenstein wrote:
> > This patch series introduces a Python-based tool for generating SBOM
> > documents in the SPDX 3.0.1 format for kernel builds.
> >
> > A Software Bill of Materials (SBOM) describes the individual components
> > of a software product. For the kernel, the goal is to describe the
> > distributable build outputs (typically the kernel image and modules),
> > the source files involved in producing these outputs, and the build
> > process that connects the source and output files.
> >
> > To achieve this, the SBOM tool generates three SPDX documents:
> >
> > - sbom-output.spdx.json
> > Describes the final build outputs together with high-level
> > build metadata.
> >
> > - sbom-source.spdx.json
> > Describes all source files involved in the build, including
> > licensing information and additional file metadata.
> >
> > - sbom-build.spdx.json
> > Describes the entire build process, linking source files
> > from the source SBOM to output files in the output SBOM.
> >
> > The sbom tool is optional and runs only when CONFIG_SBOM is enabled. It
> > is invoked after the build, once all output artifacts have been
> > generated. Starting from the kernel image and modules as root nodes,
> > the tool reconstructs the dependency graph up to the original source
> > files. Build dependencies are primarily derived from the .cmd files
> > generated by Kbuild, which record the full command used to build
> > each output file.
> >
> > Currently, the tool only supports x86 and arm64 architectures.
> >
> > Co-developed-by: Maximilian Huber <maximilian.huber@tngtech.com>
> > Signed-off-by: Maximilian Huber <maximilian.huber@tngtech.com>
> > Signed-off-by: Luis Augenstein <luis.augenstein@tngtech.com>
>
> This is great work, thank you so much for doing this!
>
> Note, I just tested the series, on 6.19-rc6, and with CONFIG_SBOM
> enabled, I get this following "message" at the end of the build when it
> generates the sbom:
>
> make[3]: Nothing to be done for 'sbom'.
>
> Is that intentional?
Ah, it's on the second run that I see this:
End of the first run that builds the sbom files:
...
OBJCOPY arch/x86/boot/vmlinux.bin
AS arch/x86/boot/header.o
LD arch/x86/boot/setup.elf
OBJCOPY arch/x86/boot/setup.bin
BUILD arch/x86/boot/bzImage
Kernel: arch/x86/boot/bzImage is ready (#526)
DESCEND sbom
GEN sbom-build.spdx.json sbom-output.spdx.json
[INFO] Skipped creating a dedicated source SBOM because source files cannot be reliably classified when the source and object trees are identical. Added source files to the build SBOM instead.
Then I build again and get the following:
DESCEND objtool
CALL scripts/checksyscalls.sh
INSTALL libsubcmd_headers
Kernel: arch/x86/boot/bzImage is ready (#526)
DESCEND sbom
make[3]: Nothing to be done for 'sbom'.
That make message shouldn't probably show up, right?
Also, I don't know if this is even possible, or you care about it, but if you
have ANY sbom file present, it is not regenerated:
$ rm sbom-build.spdx.json sbom-output.spdx.json
$ touch sbom-build.spdx.json sbom-output.spdx.json
$ make
DESCEND objtool
CALL scripts/checksyscalls.sh
INSTALL libsubcmd_headers
Kernel: arch/x86/boot/bzImage is ready (#526)
DESCEND sbom
make[3]: Nothing to be done for 'sbom'.
So, if I change the build config, which will change the sbom output, will the
sbom be regenerated? Should it depend on the config .h files to know this?
thanks,
greg k-h