Re: [PATCH v5 11/17] kbuild: Add generic hook for architectures to use before the final vmlinux link

[Hari Bathini]

On 09/10/24 8:53 pm, Masahiro Yamada wrote:
> On Mon, Sep 16, 2024 at 5:58 AM Hari Bathini <hbathini@xxxxxxxxxxxxx> wrote:
> > From: Naveen N Rao <naveen@xxxxxxxxxx>
> >
> > On powerpc, we would like to be able to make a pass on vmlinux.o and
> > generate a new object file to be linked into vmlinux. Add a generic pass
> > in Makefile.vmlinux that architectures can use for this purpose.
> >
> > Architectures need to select CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX and must
> > provide arch/<arch>/tools/Makefile with .arch.vmlinux.o target, which
> > will be invoked prior to the final vmlinux link step.
> >
> > Signed-off-by: Naveen N Rao <naveen@xxxxxxxxxx>
> > Signed-off-by: Hari Bathini <hbathini@xxxxxxxxxxxxx>
> > ---
> >
> > Changes in v5:
> > * Intermediate files named .vmlinux.arch.* instead of .arch.vmlinux.*
> >
> >
> >   arch/Kconfig             | 6 ++++++
> >   scripts/Makefile.vmlinux | 7 +++++++
> >   scripts/link-vmlinux.sh  | 7 ++++++-
> >   3 files changed, 19 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/Kconfig b/arch/Kconfig
> > index 975dd22a2dbd..ef868ff8156a 100644
> > --- a/arch/Kconfig
> > +++ b/arch/Kconfig
> > @@ -1643,4 +1643,10 @@ config CC_HAS_SANE_FUNCTION_ALIGNMENT
> >   config ARCH_NEED_CMPXCHG_1_EMU
> >          bool
> >
> > +config ARCH_WANTS_PRE_LINK_VMLINUX
> > +       def_bool n
>
>
> Redundant default. This line should be "bool".
>
>
>
>
>
>
> > +       help
> > +         An architecture can select this if it provides arch/<arch>/tools/Makefile
> > +         with .arch.vmlinux.o target to be linked into vmlinux.
> > +
> >   endmenu
> > diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
> > index 49946cb96844..edf6fae8d960 100644
> > --- a/scripts/Makefile.vmlinux
> > +++ b/scripts/Makefile.vmlinux
> > @@ -22,6 +22,13 @@ targets += .vmlinux.export.o
> >   vmlinux: .vmlinux.export.o
> >   endif
> >
> > +ifdef CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX
> > +vmlinux: arch/$(SRCARCH)/tools/.vmlinux.arch.o
>
> If you move this to arch/*/tools/, there is no reason
> to make it a hidden file.

Thanks for reviewing and the detailed comments, Masahiro.

> vmlinux: arch/$(SRCARCH)/tools/vmlinux.arch.o
>
>
>
>
> > +arch/$(SRCARCH)/tools/.vmlinux.arch.o: vmlinux.o
>
> FORCE is missing.


I dropped FORCE as it was rebuilding vmlinux on every invocation
of `make` irrespective of whether vmlinux.o changed or not..
Just curious if the changes you suggested makes FORCE necessary
or FORCE was expected even without the other changes you suggested?

Thanks
Hari