Re: Kbuilds and Makefiles in building the kernel

On Thu, 2025-11-27 at 19:26 +0800, Nick Huang wrote:
> Abraham Zsombor Nagy <[email protected]> =E6=96=BC 2025=E5=B9=B411=E6=
=9C=8827=E6=97=A5=E9=80=B1=E5=9B=9B =E4=B8=8B=E5=8D=886:43=E5=AF=AB=E9=81=
=93=EF=BC=9A
> >=20
> > Hello,
> >=20
> > https://docs.kernel.org/kbuild/makefiles.html#the-kbuild-files=C2=A0sta=
t
> > es
> > that when a directory contains a Kbuild file, the Makefile is
> > skipped in
> > that directory.
> >=20
> > It feels to me that both files are in use e.g. under arch/x86/
> > directory.
> >=20
> > I'm trying to see what files are the core of the kernel and what
> > files
> > can be configured for x86 by partially parsing the Makefiles and
> > the
> > Kbuild files. Would it be sufficient to parse them as:
> >=20
> > if file =3D=3D "Makefile" or file =3D=3D "Kbuild":
> >=20
> > =C2=A0> parse(file)
> >=20
> > or it should prefer the Kbuild file when present, or it is using
> > some
> > other logic?
> >=20
> > Sincerely,
> >=20
> > Abraham Nagy
> >=20
> >=20
>=20
> Hi=C2=A0 Abraham Zsombor Nagy
> What functionality are you trying to add that would require modifying
> the Makefile or Kbuild?
>=20
> Sincerely,
> Nick Huang

Hi Nick,

I'm not modifying the build files, only writing a script that walks
through the source tree and parses Makefiles and Kbuild files to list
what source files are linked to the kernel by default and by CONFIG_*
options. This is to see what to read through to get a basic
understanding of the kernel at a given config.

As I understand the documentation linked above, I should skip Makefiles
when Kbuild files are present in a directory, but Makefiles feels to
have important lines too.

The approach is something like to extract object files and
subdirectories from lines that start with python regex "^\S+-y" or
"^\S+-\$\(CONFIG.*\)".

Sincerely,
Abraham