linux-kernel - Re: [PATCH v2 2/2] efi/libstub: refactor Makefile to not use lib-y syntax

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Message-ID: <CAMj1kXFhULbche0kbGr+mHofOYBU2WT8i7Bgx-qgz6Cp6AE8ow@mail.gmail.com>
Date:   Mon, 15 Jun 2020 12:41:18 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-efi <linux-efi@...r.kernel.org>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Atish Patra <atish.patra@....com>,
        Ingo Molnar <mingo@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] efi/libstub: refactor Makefile to not use lib-y syntax

On Mon, 15 Jun 2020 at 12:26, Ard Biesheuvel <ardb@...nel.org> wrote:
>
> On Thu, 4 Jun 2020 at 04:20, Masahiro Yamada <masahiroy@...nel.org> wrote:
> >
> > Documentation/kbuild/makefiles.rst says:
> >
> >   Use of lib-y is normally restricted to `lib/` and `arch/*/lib`.
> >
> > This is because lib-y is inteded to be hooked to KBUILD_VMLINUX_LIBS,
> > which is passed down to scripts/link-vmlinux.sh.
> >
> > Besides, lib-y is not so interesting because objects from lib-y are
> > mostly linked in normal usecases. For example, lib-y only saves 364
> > bytes for x86_64_defconfig. You can see the details in commit
> > 7273ad2b08f8 ("kbuild: link lib-y objects to vmlinux forcibly when
> > CONFIG_MODULES=y").
> >
> > I think we should consider to deprecate lib-y syntax at some point
> > because we should aim for better solution like dead code elimination
> > or LTO.
> >
> > Other than lib/ and arch/*/lib, this Makefile is the only user of
> > lib-y. Replace lib-y with a custom rule.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
>
> Series queued in efi/urgent.
>

Actually, I am seeing this now

/home/ard/linux/scripts/Makefile.build:421: warning: overriding recipe
for target 'drivers/firmware/efi/libstub/lib.a'
/home/ard/linux/drivers/firmware/efi/libstub/Makefile:131: warning:
ignoring old recipe for target 'drivers/firmware/efi/libstub/lib.a'