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

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Message-ID: <CAMj1kXGg-w6N7jyG0pBJmeRctAhG2wWGoU=ryWj+Qi2UH-_m9Q@mail.gmail.com>
Date:   Mon, 15 Jun 2020 16:20:01 +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 16:15, Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> On Mon, Jun 15, 2020 at 7:41 PM Ard Biesheuvel <ardb@...nel.org> wrote:
> >
> > 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'
>
>
>
> Sorry, please drop this patch for now.
>
> (Actually, it was working when I submitted it,
> but is broken after e578edc72276280b8fae57f6bf79cb443ceee7a2)
>

OK.