Re: [PATCH] powerpc: remove meaningless KBUILD_ARFLAGS addition

From: Segher Boessenkool <segher@kernel.crashing.org>
To: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Paul Mackerras <paulus@samba.org>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH] powerpc: remove meaningless KBUILD_ARFLAGS addition
Date: Thu, 18 Jul 2019 15:46:31 -0500	[thread overview]
Message-ID: <20190718204631.GV20882@gate.crashing.org> (raw)
In-Reply-To: <CAK7LNAR7jkq1fAi_=xgsANCkgP2AAej9Yv7RZB3B_cpD7C_71Q@mail.gmail.com>

Hi!

On Thu, Jul 18, 2019 at 11:19:58AM +0900, Masahiro Yamada wrote:
> On Thu, Jul 18, 2019 at 1:46 AM Segher Boessenkool
> <segher@kernel.crashing.org> wrote:
> Kbuild always uses thin archives as far as vmlinux is concerned.
> 
> But, there are some other call-sites.
> 
> masahiro@pug:~/ref/linux$ git grep  '$(AR)' -- :^Documentation :^tools
> arch/powerpc/boot/Makefile:    BOOTAR := $(AR)
> arch/unicore32/lib/Makefile:    $(Q)$(AR) p $(GNU_LIBC_A) $(notdir $@) > $@
> arch/unicore32/lib/Makefile:    $(Q)$(AR) p $(GNU_LIBGCC_A) $(notdir $@) > $@
> lib/raid6/test/Makefile:         $(AR) cq $@ $^
> scripts/Kbuild.include:ar-option = $(call try-run, $(AR) rc$(1)
> "$$TMP",$(1),$(2))
> scripts/Makefile.build:      cmd_ar_builtin = rm -f $@; $(AR)
> rcSTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
> scripts/Makefile.lib:      cmd_ar = rm -f $@; $(AR)
> rcsTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
> 
> Probably, you are interested in arch/powerpc/boot/Makefile.

That one seems fine actually.  The raid6 one I don't know.

My original commit message was

    Without this, some versions of GNU ar fail to create
    an archive index if the object files it is packing
    together are of a different object format than ar's
    default format (for example, binutils compiled to
    default to 64-bit, with 32-bit objects).

but I cannot reproduce the problem anymore.  Shortly after my patch the
thin archive code happened to binutils, and that overhauled some other
things, which might have fixed it already?

> > Yes, I know.  This isn't about built-in.[oa], it is about *other*
> > archives we at least *used to* create.  If we *know* we do not anymore,
> > then this workaround can of course be removed (and good riddance).
> 
> If it is not about built-in.[oa],
> which archive are you talking about?
> 
> Can you pin-point the one?

No, not anymore.  Lost in the mists of time, I guess?  I think we'll
just have to file it as "it seems to work fine now".

Thank you (and everyone else) for the time looking at this!

Segher