Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200720204925.3654302-1-ndesaulniers@google.com>
 <20200720204925.3654302-12-ndesaulniers@google.com> <87365izj7i.fsf@nanos.tec.linutronix.de>
 <87zh7qy4i4.fsf@nanos.tec.linutronix.de> <CA+icZUVz0opOb0LihLvPvKM-t0Y=pcUWDyb+u-L_UVnnbPh1rQ@mail.gmail.com>
 <CAK8P3a3Ms1uvLcbhmbsU+-u11BCrXPaU5Dro=P9LjAG7CYm8ww@mail.gmail.com>
 <CA+icZUXzjcQ7ekTg8LvwcaBZFn_HeDjif+rKaFAKy=0gUrx=Xg@mail.gmail.com> <CAK8P3a0gFG8z_qdY2gPm5p7kjpj8xq-APyazk390FpHUJiZ7Hw@mail.gmail.com>
In-Reply-To: <CAK8P3a0gFG8z_qdY2gPm5p7kjpj8xq-APyazk390FpHUJiZ7Hw@mail.gmail.com>
Reply-To: sedat.dilek@gmail.com
From:   Sedat Dilek <sedat.dilek@gmail.com>
Date:   Fri, 24 Jul 2020 15:22:03 +0200
Message-ID: <CA+icZUVGnfO1w6CpHh5cbZ9-ozMo6LhoyKxCq9mBpVF1jCZi-Q@mail.gmail.com>
Subject: Re: [PATCH v3 11/11] x86: support i386 with Clang
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
        Christoph Lameter <cl@linux.com>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Clang-Built-Linux ML <clang-built-linux@googlegroups.com>,
        David Woodhouse <dwmw2@infradead.org>,
        Dmitry Golovin <dima@golovin.in>,
        Linus Torvalds <torvalds@linux-foundation.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Jul 23, 2020 at 3:56 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Thu, Jul 23, 2020 at 3:14 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> > What happens when there is no CONFIG_64BIT line?
> > There exist explicit checks for (and "inverse") of CONFIG_64BIT like
> > "ifdef" and "ifndef" or any "defined(...)" and its opposite?
> > I remember I have seen checks for it in x86 tree.
>
> As long as you consistently pass ARCH=i386 when running 'make',
> nothing bad happens, as ARCH=i386 just hides that option.
>
> If you run "make ARCH=i386 defconfig" followed by "make olddefconfig"
> (without ARCH=i386) on a non-i386 machine, the absence of that
> CONFIG_64BIT line will lead to the kernel going back to a 64-bit
> configuration.
>

Again thank you for your feedback.

Unsure if people are aware of the different behaviours and results.

That's why I keep the same make line with and without "defconfig".

Unfortunately, I had no opportunity to test the patchset :-(.

For testing I had done:
$ MAKE_OPTS="..."
$ ARCH=x86 make V=1 -j3 $MAKE_OPTS i386_defconfig (whereas V=1 and -j3
can be dropped of course)
$ ARCH=x86 make V=1 -j3 $MAKE_OPTS

Side-note:
How wonderful my patch "x86/defconfigs: Remove CONFIG_CRYPTO_AES_586
from i386_defconfig" landed in <tip.git#x86/build>.

- Sedat -

[1] https://git.kernel.org/tip/tip/c/6526b12de07588253a52577f42ec99fc7ca26a1f