linux-kernel - Re: [PATCH] powerpc: remove meaningless KBUILD

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Message-ID: <87v9w393r5.fsf@concordia.ellerman.id.au>
Date:   Mon, 15 Jul 2019 17:05:34 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Segher Boessenkool <segher@...nel.crashing.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH] powerpc: remove meaningless KBUILD_ARFLAGS addition

Segher Boessenkool <segher@...nel.crashing.org> writes:
> On Sun, Jul 14, 2019 at 07:45:15AM +0900, Masahiro Yamada wrote:
>> On Sat, Jul 13, 2019 at 10:17 PM Segher Boessenkool
>> <segher@...nel.crashing.org> wrote:
>> > On Sat, Jul 13, 2019 at 07:47:44AM -0500, Segher Boessenkool wrote:
>> > > On Sat, Jul 13, 2019 at 12:21:06PM +0900, Masahiro Yamada wrote:
>> > > > The KBUILD_ARFLAGS addition in arch/powerpc/Makefile has never worked
>> > > > in a useful way because it is always overridden by the following code
>> > > > in the top Makefile:
>> > > >
>> > > >   # use the deterministic mode of AR if available
>> > > >   KBUILD_ARFLAGS := $(call ar-option,D)
>> > > >
>> > > > The code in the top Makefile was added in 2011, by commit 40df759e2b9e
>> > > > ("kbuild: Fix build with binutils <= 2.19").
>> > > >
>> > > > The KBUILD_ARFLAGS addition for ppc has always been dead code from the
>> > > > beginning.
>> > >
>> > > That was added in 43c9127d94d6 to replace my 8995ac870273 from 2007.
>> > >
>> > > Is it no longer supported to build a 64-bit kernel with a toolchain
>> > > that defaults to 32-bit, or the other way around?  And with non-native
>> > > toolchains (this one didn't run on Linux, even).
>> >
>> > It was an --enable-targets=all toolchain, somewhat common for crosses,
>> > if that matters.
>> 
>> I always use the same toolchain
>> for compile-testing PPC32/64.
>> 
>> I have never been hit by the issue you mention.
>> Somebody would have reported it if it were still a problem.
>
> But did you use --enable-targets=all?

I do. And I don't see any errors with this patch applied.

> The problem was empty archives IIRC.  Not a problem anymore with thin
> archives, maybe?

Maybe? Though I can't get it to break even before we switched to them.

>> Moreover, commit 43c9127d94d6
>> translated the environment variable "GNUTARGET"
>> into the command option "--target="
>> 
>> My powerpc-linux-ar does not know it:
>> 
>> powerpc-linux-ar: -t: No such file or directory
>
> Yes, that is why I used the environment variable, all binutils work
> with that.  There was no --target option in GNU ar before 2.22.

Yeah, we're not very good at testing with really old binutils, so I
guess we broke that.

I'm inclined to merge this, it doesn't seem to break anything, and it
fixes using --target on old binutils that don't have it.

cheers